Naming and Indexing ofChemical Substances for
Chemical AbstractsTM

2007 Edition

A publication of Chemical Abstracts Service
Published by the American Chemical Society

Naming and Indexing ofChemical Substances for
Chemical AbstractsTM

A publication of Chemical Abstracts Service
Published by the American Chemical Society

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Printed in the USA

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1

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 102

NAMING AND INDEXING OF
CHEMICAL SUBSTANCES

101. Foreword. Although the account which follows describes in considerable detail the selection of substance names for Chemical Abstracts (CA) indexes, it is not a nomenclature manual. It has the more restricted aim ofenabling a user of CA indexes to proceed from the structure of an individual
chemical compound to the place in the current Chemical Substance Index
where the particular index name and any associated index entries will be found.
This is the identical operation performed by a CA indexer when assigning an
index name to a new or previously unnamed substance. What follows, in fact,
is a comprehensive summary of CA substance indexing policies, which cover
not only conventional organic and inorganic compounds but other completely
defined substances entered in the Chemical Substance Index and given CAS
Registry Number® identifiers. These substances include specific chemical elements, alloys, minerals, mixtures, polymers, enzymes, polysaccharides, and elementary particles.
The chemical nomenclature used by Chemical Abstracts Service (CAS) has
developed in parallel and generally in accordance with the rules published by
the International Union of Pure and Applied Chemistry (IUPAC). Althoughthese rules provide unambiguous text equivalents for the great majority of substances, equally acceptable alternative rules within the present IUPAC system
often lead to two or more unambiguous names. This causes no difficulty in normal scientific communication, but is totally unacceptable in a formal, rigidly
controlled, alphabetic listing such as the Chemical Substance Index. Here thenames must be not only unambiguous, unique, and totally reproducible, but selected so as to bring the names of structurally related substances into juxtaposition in the alphabetical listing. They must be equally derivable by index users
searching for information about individual substances and by those who prepare the index. It is also desirable that both should be able to use mechanicalaids in name generation and retrieval.
A major revision of CA index names was carried out in 1972 as the Ninth
Collective Index period began. Most trivial names were dropped; exceptional
treatment for various classes of substances was discontinued. Where, becauseof the stereochemical complexity of a natural product name, a trivial name wasretained as a “stereoparent” (see ¶ 202), diagrams were furnished in the Chemical Substance Index to aid interpretation of index entries. The 1972 nomenclature revision and the reasons for its adoption are set forth in greater detail in theNinth Collective Index Guide and in a journal article (J. Chem. Doc. 1974,
14(1), 3-15).
The preferred CA index names for most chemical substances have been
continued unchanged since that date. Changes in name-selection policies for
the Twelfth (1987-1991) and Thirteenth (1992-1996) Collective Index periods
affect alloys, carbohydrates (lactams), coordination compounds, formazans,index name selection (multiplicative names), inorganic compounds (line formulas of clusters, intermetallic compounds), molecular addition compounds(common components; hydrates), nitrilimines, onium compounds (free radicals), peptides, phosphonium ylides, phosphoryl halides and halogenoids,
polymers (block, graft, and hydrolytic), ring systems (list of common systems),
salts (lists of common anions), stereochemistry (sign of optical rotation), andzwitterions (inner salts, sydnones). The changes for the Fourteenth (19972001) Collective Index period affect coordination nomenclature, stereochemical practices, and stereoparents. The most recent changes (2007) involve locants, tautomers, and stereoparents. These changes, as well as the changes
made in 1972, and in the Tenth (1977-1981) and Eleventh (1982-1986) Collective Index periods, are reviewed in Section G (¶¶ 225-293). The nomenclatureof fullerenes is more fully documented in ¶ 163A of Section B.
The arrangement of sections is as follows:
A.
B.
C.
D.
E.
F.
G.
H.
J.
K.
L.
M.

Nomenclature Systems and General Principles (¶¶ 103-139)
Molecular Skeletons (¶¶ 140-163A)
Principal Chemical Groups (Suffixes) (¶¶ 164-177)
Compound Classes (¶¶ 178-201)
Stereochemistry and Stereoparents (¶¶ 202-212)
Specialized Substances (¶¶ 213-224)
Chemical Substance Names for Retrospective Searches (¶¶ 225293A)
Illustrative List of Substituent Prefixes (¶ 294)
Selective Bibliography of Nomenclature of Chemical Substances(¶¶ 295-308)
Chemical Prefixes (¶¶ 309-311)
Chemical Structural Diagrams from CA Index Names (¶¶ 312-318)
Index

The arrangement within each of these sections is indicated by a key at the beginning of the section.
In the development of CAS policies for index names of chemical substances, no new nomenclature systems have been devised. Adaptation of current IUPAC rules to the specific needs of a highly ordered alphabetical index, notarbitrary coinage of new terms, has been the approach taken. It continues to berecognized by CAS that, while a unique name is needed for an index, and that
this name, and the CAS Registry Number, are invaluable aids for substanceidentification, the use of this invariant index name for citation throughout every
context in the scientific community is neither practicable nor desirable. But international agreement in chemical nomenclature, as embodied in the rules of
IUPAC, IUB, and other organizations, continues to be of the greatest importance in restricting the arbitrary proliferation of substance names. References
to individual rules which have formed the basis of CAS policies recorded in thesections that follow have not been cited, but the selective bibliography of thenomenclature of chemical substances which constitutes Section J contains acomprehensive list of current accepted rules.
102. Acknowledgement. CAS acknowledges the large contribution madeby Cecil C. Langham in helping to develop and record CA name-selection policies for the Eighth Collective period (1967-1971) during the years immediately preceding his retirement in 1969. Dr. Langham’s work constituted aninvaluable starting point for the revised name-selection policies introduced in
1972.

A. NOMENCLATURE SYSTEMS AND GENERAL PRINCIPLESIntroduction
Inversion of names
Name selection principles
Order of precedence of compound classes
Spelling
Punctuation
Enclosing marks
Multiplicative prefixes“Mono”
Functional derivatives

¶ 103
104
105
106
107
108
109
110
111
112

Order of citation of derivative terms
Locants
for substituent suffixes
in substituent prefixes (radicals)
for substituents on parents and parent radicals
in multiplicative nomenclaturefor functional derivatives
for indefinite compounds
Alphabetization

¶ 113
114
115
116
117
118
119
120
121

¶ 103Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
¶ 122
123
124
125
126
127
128
129
130

Tautomeric compounds
Additive nomenclature
Conjunctive nomenclature
Multiplicative nomenclatureRadiocofunctional nomenclature
Replacement (“a”) nomenclature
Replacement prefixes
Replacement nomenclature for functions
Substitutive nomenclature

103. Introduction. Many names may be employed in scientific publications for a single compound. Even so simple a compound as H2NCH2CH2OH
can be named 2-Aminoethanol, 2-Aminoethyl alcohol, 2-Hydroxyethylamine,
β-Hydroxyethylamine, 2-Hydroxyethanamine, 1-Amino-2-hydroxyethane etc.,
all of which describe it unambiguously; often, the less systematic (“trivial”)
name Ethanolamine may be encountered. For more complex compounds, thenumber of possible names increases exponentially.
In these circumstances, selection rules are essential if a single preferredname for citation in an index of chemical names is to be determined for eachidentifiable substance; lacking such a single name, information regarding thesubstance becomes scattered in the index. Beyond this, it is desirable that the
selection rules bring chemically related substances close together in the index,
and that they should be as consistent and as free from exceptions as possible.
104. Inversion of names. Ordering in the Chemical Substance Index isbased on the index heading parent (1), which is often made up of a basic skeleton name, e.g., “Butane,” plus a suffix denoting the principal function, e.g.,“-sulfonic acid.” A locant, e.g., “1-,” fixing its position is also often necessary.
Following a comma (the comma of inversion) the
substituents (2) are expressed in alphabetical order, e.g., “2,4-diamino-3- chloro-,” and the modification (3), now printed in boldface, completes the name by citing any
derivatives of the principal function, e.g., “ethyl ester”, and stereochemical information (see ¶ 203) if appropriate. The uninverted name of the acid is 2,4diamino-3-chloro-1-butanesulfonic acid, and of the ester, ethyl 2,4-diamino-3chloro-1-butanesulfonate. The latter appears in the Chemical Substance Index
as follows:2

1

1-Butanesulfonic acid, 2,4-diamino-3-chloro1-ethyl ester

3
Also appearing in the boldface headings of certain very well-known substances are subdivision terms describing properties, etc., of the compound itself, or classifying certain derivatives of it, e.g., reactions, esters.
105. Name selection principles (see also ¶ 138). In choosing 1-Butanesulfonic acid as the heading parent in the example above, rather than, for example, 1,3-Butanediamine, an order of precedence of chemical functions andcompound classes (¶ 106) was followed. In this hierarchy, sulfonic acids areranked higher than amines. In the example cited, so-called substitutive nomenclature (¶ 130) was the type of nomenclature used. Generally, a preferred index
name is determined by proceeding as follows until a decision is reached:(a) determine the most senior compound class;(b) determine the type of nomenclature that is appropriate;(c) determine the preferred index heading parent;(d) name the remainder of the structure as substituents, and/or as functional derivatives by modification phrases;(e) choose between alternatives where more than one unambiguous nameis still possible.
The remainder of Section IVA is devoted to detailing the application of theserules.
106. Order of precedence of compound classes, in descending order:(a) Free radicals and compounds for which substituent prefixes are unavailable, e.g., Sulfur diimide (¶ 200).
(b) Cationic compounds: coordination cations, onium, aminium, ylium
cations.
(c) Neutral coordination compounds, including metallocenes.
(d) Anionic compounds, e.g., Borate(1-).
(e) Acids: peroxy acids, expressed as principal groups, in the order of theparent acids; acids, expressed as principal groups, in the order carbon,1 sulfur,
selenium, tellurium; acids, expressed as functional parent compounds (¶ 130),in the order carbon (including Carbonic acid and Formic acid; see ¶ 183),
chalcogen, nitrogen, phosphorus, arsenic, antimony, silicon, and boron.
(f) Acid halides and related species, first in the order of the parent acid(see (e), above); then, for each acid, in the order fluoride, chloride, bromide,
iodide, azide, isocyanate, isothiocyanate, isocyanide, cyanide (for non-carbon
acid residues only).
(g) Amides, in the same order as the parent acids (see (e), above).
(h) Nitriles, in the same order as the parent acids (see (e), above).

1 Acetic acid and Benzoic acid are ranked here as though they were named
Ethanoic acid and Benzenecarboxylic acid, respectively.

Substituent suffixes
Substituent prefixes
Compound radical names
Carbonyl radicals
Indicated hydrogen
Added hydrogen
Numbering of molecular skeletons
Index name selection
Subtractive nomenclature

2
¶ 131
132
133
134
135
136
137
138
139

(i) Aldehydes, Thials, Selenals, Tellurals.
(j) Ketones, Thiones, Selones, Tellones.
(k) Alcohols and Phenols (of equal rank), Thiols, Selenols, Tellurols.
(l) Hydroperoxides.
(m) Amines.
(n) Imines. (This is the lowest compound class expressed by a functionalsuffix; all the following classes are considered to be nonfunctional. For the
ranking of nonfunctional cyclic and acyclic skeletons, see ¶ 138.)(o) Nitrogen compounds: heterocyclic; acyclic (other than “a”-named
chains; see ¶ 127), e.g., Triazane, Diazene, Hydrazine, Hydroxylamine,
Thiohydroxylamine.
(p) Phosphorus compounds: heterocyclic, acyclic (other than “a”-named
chains; see ¶ 127), e.g., Diphosphine, Phosphine oxide, Phosphine sulfide,
Phosphine imide, Phosphorane, Phosphine.
(q) Arsenic compounds (in similar order).
(r) Antimony compounds (in similar order).
(s) Bismuth compounds (in similar order).
(t) Boron compounds: carbapolyboranes, hetero polyboranes, polyboranes, heterocyclic, Borane.
(u) Silicon compounds: heterocyclic, acyclic (other than “a”-named
chains; see ¶ 127), e.g., Disiloxane, Disilathiane, Trisilane, Disilane. Notethat the order is determined first by the total number of skeletal atoms, then by
the presence of oxygen, sulfur, etc; see ¶ 128.
(v) Germanium compounds (in similar order).
(w) Tin compounds (in similar order).
(x) Lead compounds (in similar order).
(y) Oxygen compounds other than “a”-named chains (see ¶ 127): heterocyclic; acyclic polyoxides, e.g., Trioxide, Peroxide.
(z) Sulfur compounds: heterocyclic; acyclic polysulfides and their oxides, e.g., Trisulfone, Trisulfide, Disulfone, Disulfoxide, Disulfide.
(aa) Selenium and tellurium compounds (in similar order).
(bb) Carbon compounds: carbocyclic(cc) Silane(dd) Carbon compounds: acyclic
107. Spelling. CAS accepts Merriam-Webster’s Collegiate Dictionary2as the primary authority for spelling; e.g. sulfur (not sulphur); aluminum (notaluminium). Random House Webster’s Unabridged Dictionary3 is used forwords not found in the Collegiate Dictionary. Elision of vowels is often practiced in combining the segments of names: e.g., in Butanone and disiloxanyl
the final “e” of the basic skeleton name has been dropped; in Oxazepine an“a” has been omitted twice, after “oxa” and before “ep”; and “a” is often omitted before a multiplied “amine” or “one” suffix, as in Benzenetetramine andCyclohexanehexone; the terminal “o” of acenaphtho, benzo, naphtho, andperylo, and the terminal “a” of cyclobuta, etc., are elided before vowels, e.g.,
Benz[cd]indole, 5H-Cyclobut[f]indene. Other examples of elision are -imidic(not -imidoic) acids; -imidamides (not imidoamides); -thiones (not thioones);and -hydrazonamides (not -hydrazonoamides). Examples will be found in later
paragraphs. In a few cases, the vowel “o” is added for euphony, e.g., Carbonothioic acid (not Carbonthioic acid).
Elision of entire syllables is now uncommon. Remaining examples include
methoxy, ethoxy, propoxy, butoxy, phenoxy (not (methyloxy), etc.) radicals,
and the thienyl (not thiophene-yl) radical. Carbamic acid is an elided form ofCarbonamidic acid (¶ 183); Sulfamic acid is used in place of Sulfuramidic
acid, and Sulfamide instead of Sulfuramide or Sulfuric diamide. The suffix“-carboxylic acid” undergoes various forms of elision in formation of replacement names, e.g., “-carbothioamide.”108. Punctuation in chemical names is frequently of great importance inremoving ambiguities and in differentiating one substance from another. Lower case italic Roman letters are used in fusion prefixes (¶ 151) in ring systemnames, and in as- and s-Indacene; capital italics such as N-, O-, P-, S-, are locants indicating substitution on these hetero atoms; H- denotes indicated or
added hydrogen (¶¶ 135, 136); italic Arabic numerals are locants for atoms inabnormal valency states (¶ 158) and for “labeled” atoms (¶ 220); italic words
and syllables are used in modifications to express isomeric oxides, e.g., thionooxide at a thio acid heading parent, and in stereochemical descriptors (¶ 203),e.g., erythro-, tetrahedro-. The small capitals D-, L-, and DL-, are configurational descriptors (¶ 203); like italic letters, they are disregarded in placing chemical names in order until Roman letters have been alphabetized.
The “comma of inversion” has been mentioned above (¶ 104). Other commas are used between individual locants in index heading parents, substituents,

2 Merriam-Webster’s Collegiate Dictionary, 11th ed., Merriam-Webster,Springfield, MA, 2003.
3Random House Webster’s Unabridged Dictionary, 2nd ed., Random
House, N.Y., 2001.

3

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

and modifications. Different types of functional derivatives are separated bycommas in the text of the modification.
Examples:(a)hydrazone phenylhydrazone(b)diethyl ester, sodium salt(c)ethyl methyl ester, hydrochloride

Hyphens at the end of the set of substituents in the inverted part of a boldface heading signify that no space is intended when the name is uninverted foruse in textual matter. Conversely, absence of a hyphen after substituents atheadings such as Disulfide, Hydroperoxide, Peroxide, indicates that a space
appears at that point in the uninverted name.
Examples:Acetic acid, 2-chloro2-Chloroacetic acid(index name)(uninverted name)

Disulfide, bis(2-chloroethyl)Bis(2-chloroethyl) disulfide(index name)(uninverted name)

Hyphens separate locants from the words and syllables of a name; when used
between locants, the intention is to indicate that such locants refer to different
parts of the name; e.g., in Acetamide, N-2-naphthalenyl-, the “N-” places the
2-naphthalenyl substituent on the nitrogen of the heading parent, Acetamide.
Periods separate ring size descriptors in Von Baeyer and spiro names, e.g.,
Bicyclo[3.2.0]heptane. Colons separate sets of locants already related to one
another; if a further step is called for, semicolons are employed.
Examples:
1,4:5,6-Dimethanonaphthalene
Benzo[1′′,2′′:3,4;5′′,4′′:3′,4′]dicyclobuta[1,2-a:1′,2′-a′]diindene
109. Enclosing marks are placed around compound substituent radicals
and around and within complex radicals (¶ 162). Their presence or absence frequently removes ambiguity, especially when locants are omitted through lackof precise structural information.
Examples:MeSiH 2 C l

Silane, chloromethyl-

C lC H 2 S iH 3

Silane, (chloromethyl)CO 2H

Benzoic acid, 3-(chlorobenzoyl)-

CO
Cl
CO 2H

Benzoic acid, (3-chlorobenzoyl)-

CO
Cl
CO 2H
CO

Benzoic acid, 3-(3-chlorobenzoyl)-Cl

Parentheses are placed around compound substituents like “(chloromethyl)”, above; in a case like (chloromethylamino), it is to be understood that boththe chlorine atom and the unsubstituted methyl group are substituents of theamino group, i.e., Cl(CH3)N-. The alternative structure, ClCH2NH- is named[(chloromethyl)amino], which is a complex substituent prefix. Parentheses areused around simple radicals when they are preceded by “bis,” “tris,” etc. (¶110), e.g., bis(methylene), tris(decyl). They are used also to separate locants ofthe same kind which would otherwise be separated only by hyphens, to indicate
the second atom involved in double-bond formation when it is not the next inthe numbered pathway, to enclose parts of a heading parent, to set off addedhydrogen, and to enclose multiplied terms in modifications, ion terms thatwould otherwise be ambiguous, Ewens-Bassett numbers (¶ 215), descriptive
terms and ratios, and parts of synonym line formulas.
Examples:Benzoic acid, 4-(2-naphthalenyl)Bicyclo[4.2.0]oct-1(6)-ene
Butane(dithioic) acid (see ¶ 165)
1(2H)-Naphthalenone
bis(inner salt)(disulfate) (from Disulfuric acid)iron(3+) salt
compd. with benzenamine (1:1)
acetate (salt)
Thioperoxydiphosphoric acid ([(HO)2P(O)]2S2)
Brackets enclose complex substituent prefixes and derivative terms, as well
as Von Baeyer and spiro ring size designations (already described above). They

¶ 111

are also employed around a ring-assembly name when it is followed by a principal-group suffix or forms part of a radical name.
Examples:[1,2′-Binaphthalene]-2-carboxylic acid
[1,1′-biphenyl]-4-yl
Brackets enclose structural features of bridges or component rings when theenclosed locants are not applicable to the total system.
Examples:
4a,9a-[2]Butenoanthracene(the “2” locates the double bond in
the buteno bridge)

4H-[1,3]Oxathiolo[5,4-g]benzoxazole(formed by fusion of 1,3-oxathio
with benzoxazole; in the totalring system, the oxygen andsulfur atoms of the oxathiole ringare in the 6- and 8-positions
respectively)

When a multiplicative index name is uninverted, brackets are placed aroundthe heading parent.
Examples:Acetic acid, 2,2′-oxybis2,2′-Oxybis[acetic acid](index name)(uninverted name)Benzoic acid, 4,4′-methylenebis[2-chloro4,4′-Methylenebis[2-chlorobenzoic acid](index name)(uninverted name)

Brackets are sometimes needed for functional terms in modifications, especially following locants or multiplicative prefixes.
Examples:S-[(dodecylthio)methyl] esterbis[(2,4-dinitrophenyl)hydrazone]
110. Multiplicative prefixes. Generally, prefixes derived from the Greek(di, tri-, etc.) are used, rather than the Latin (bi-, ter-, etc.); exceptions are nona(not ennea-) for nine, and undeca- (not hendeca-) for eleven. (For lists of Latin
and Greek prefixes, see ¶ 309.) The Latin prefixes bi-, ter-, etc., are used forring assemblies.
The prefixes bis-, tris-, tetrakis-, etc., are used for compound and complex
radicals and functional derivatives, and to avoid misunderstanding in other cases, especially with names beginning with replacement terms like “aza” or“oxa”, fusion prefixes like “benzo” or “naphtho,” or compound fusion prefixes
like “cyclopentapyrido.” They are used always in multiplying a heading parent.
Examples:bis(methylene)bis(2-aminoethyl)[1,2-ethanediylbis(oxymethylene)]bis(O-methyloxime)
bis(cyclohexaneacetate)tris(dihydrogen phosphate)bis(aziridinyl)bis(2,1-diazenediyl)bis([1,1′-biphenyl]-4-yl)bis(bicyclo[2.2.1]hept-2-yl)tris(decyl)
tetrakis(1-aziridinyl)bis(benz[a]anthracen-1-yl)
Benzo[1,2-c:3,4-c′]bis[1,2,5]oxadiazole
Biscyclopenta[5,6]pyrido[4,3b:3′,4′-c]pyridine
Benzoic acid, 2,2′-silylenebisPhosphonic acid, P,P′-1,4phenylenebis-

111. “Mono” is only rarely employed in index heading parents (an example is Peroxymonosulfuric acid) but is needed to express functional derivatives of polyfunctional heading parents and inner salts when needed. It is not
used if a locant is necessary, or when only one functional group is present.
Mono is used for esters of polybasic mononuclear acids having only one typeof chalcogen atom, e.g. monoesters of carbonic acid, phosphonic acid, etc. The
term “hydrogen” in an uninverted ester name precludes the use of “mono.”
Examples:M e C( =N O H ) M e

2−Propanone,oxime

M e O CO 2 H

Carbonic acid,monomethyl esterOH
OAc

E tO P( O ) ( O M e ) 2+
S−MeΜe 2Ν−Ν
N

Me
O

O-

1,2−Naphthalenediol,2−acetate
Phosphoric acid,
ethyl dimethyl ester
1,2,3-Oxadiazolium,
2-(dimethylamino)-4(dimethylsulfonio)-5hydroxy-, mono(inner salt)¶ 111

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

P hN H N

2,5-Cyclohexadiene-1,4-dione
1-(phenylhydrazone), 4-oxime(previously mono(phenylhydrazone),oxime, but now locants are used.)

NOH

Phosphoric acidmonoethyl ester(index name)E tO P (O )(O H ) 2

Ethyl dihydrogen phosphate(uninverted name)112. Functional derivatives of the principal reactive chemical groups ofsystematically-named index heading parents are cited in the modification;these derivatives, as defined for indexing purposes, are restricted to acyclic anhydrides, esters, hydrazides, hydrazones, and oximes. Other derivatives, suchas semicarbazones, azines, acetals, and cyclic esters, are named in other ways,e.g., substitutively at the highest functional heading parent, as substituted hydrazones, etc., or as heterocycles, as detailed in Section D, below.
Functional derivatives of subsidiary functions (those not expressed by thesuffix of the heading parent) are cited in the main boldface heading as compound or complex substituents.
Examples:
E tC O 2

4

1

NNH2

Butanal, 3-hydrazono- (notButanal, 3-oxo-, 3-hydrazone)

C H 3 — C — C H 2 — CHO
4

3

2

(f)
other additive terms describing portions of the molecular structure
not covalently attached, e.g., compd. with..., hydrate, mixt. with..., polymer
with....
114. Locants. When a choice is necessary, italic Roman letters are placed
before Greek letters, and Arabic numerals are placed last, e.g., As, N, P, S, α,β, γ, 1, 2, 3. (For the Greek alphabet see ¶ 310.)
Unprimed locants are followed by primed locants, then by doubly primed
locants, etc., e.g., N, N′, S, α, 1′, 2, 2′, 2′′, 3. Low numbering of indices (superscript Arabic numbers) and application of primes are not considered until
regular numerical locants have been chosen.
Examples:M e P( =N M e ) ( N H M e ) 2

Phosphonimidic diamide, N,N′,N′′,Ptetramethyl-MeCH M e N H M eBenzenemethanamine, N,α,4-trimethyl-

Cl

NH2

1

O

O

1,3-Benzenediamine, 4-chloro-N3methyl- (not 1,3- Benzenediamine, 6-chloro-N1-methyl-)MeNH1,1′:4′,1′′-Terphenyl, 2′,2′′-dichloro(not 1,1′:4′,1′′-Terphenyl,
2,3′-dichloro-)

Benzoic acid, 4-(1-oxopropoxy)methyl ester (not Benzoic acid,
4-hydroxy-, methyl ester,
propanoate)

CO 2 Me

4

Cl

Cl

Locants for unsaturation in compounds named as index heading parents arealways cited when the compound contains three or more skeletal atoms, except
for monocyclic hydrocarbons with one multiple bond and no suffix.
Examples:H N =N N H 2

1-Triazene

H 2 C=C=CH 2

1,2-Propadiene1

3

CH 2 — C — O — C — CH 3
C H 3O O C —C H 2 — CH 2 — CH — CH 2 — CH 2 — COOCH 3
7

5

6

4

3

2

1

Heptanedioic acid, 4-[2-(acetyloxy)2-oxoethyl]1,7-dimethyl ester (not Heptanedioic acid, 4-(carboxymethyl)-, 4-anhydride with acetic
acid, dimethyl ester)

H 2 C=CH C≡ CH

1-Buten-3-yne

H 2 C = CH 2

Ethene14CyclohexeneO

CH 3

H O — P — O — CH 2 — CH 2 — N + — CH 3
2

1

1

−O

CH 3

Ethanaminium, N,N,N-trimethyl-2(phosphonooxy)inner salt (not Ethanaminium,
2-hydroxy-N,N,N-trimethyl-,
dihydrogen phosphate(ester), inner salt)

1,3-Cyclopentadiene

5

Locants denoting ring junctions of ring assemblies are always cited except
for two-component assemblies of cycloalkenes, cycloalkadienes, etc.
Examples:

NOH
F

4

1

C O 2 CH 2 CMe

Benzoic acid, 4-fluoro2-(hydroxyimino)propyl ester(not Benzoic acid, 4-fluoro-,2-oxopropyl ester, oxime)

1,1′-Biphenyl

1 1′

1

6

1′

6′

N

N

2,2′-Bipyrazine
N

N

4

4′

6
1 1′

A cO SO 2

4

1

CO 2 Me

Benzoic acid, 4-[(acetyloxy)sulfonyl]methyl ester (not Benzoic acid,
4-sulfo-, S-anhydride withacetic acid, methyl ester)113. Order of citation of derivative terms in modifications. The normal
order is:(a)the term “inner salt”;(b)functional derivatives in the order: anhydrides, esters, hydrazides,
hydrazones, oximes; multiplicative terms are cited before simple terms, e.g.,
1,3-propanediyl dimethyl ester (with the appropriate locants), otherwise alphabetic order is followed;(c)additive terms describing fragments covalently attached to the index heading compound, e.g., N-oxide;(d)ionic terms, e.g., ion(1-), radical ion(1-), then ionic terms derived
from separate structural fragments, e.g., chloride, acetate, or an “amminium”
heading;(e)metal salts, followed by other salts alphabetically, e.g., acetate, hydrochloride;Bi-2-cyclohexen-1-yl
6′115. Locants for substituent suffixes of index heading parents are cited
except for the following cases: mononuclear skeleton parents, a single substituent suffix on a homogeneous molecular skeleton with two skeletal atoms, ora single substituent suffix on benzene or a saturated homogeneous monocyclic
ring. Locants are not cited for Geneva suffixes which terminate a chain, e.g.,“-oic acid’, “-dial”.
Examples:
CN CN CN CN||||
N C — C = C — C = C — CN
2

1

O

H
N

6

3

O

1

HN

5

O

3

NH

1,3-Butadiene-1,1,2,3,4,4-hexacarbonitrile

4

1,3,5-Triazine-2,4,6(1H,3H,5H)trione

5Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
N

O

CO2 H

2-Pyrazinecarboxylic acid

H2 Si

Si

O

O

N
H O 2 C N =N C O 2 H

1,2-Diazenedicarboxylic acidH 2 C= C H C O 2 H

2-Propenoic acid

14

13 12

11

Si
H2

cyclotrisiloxan-2-ylideneO

1,4-dioxan-2-yl
O

C H 3 C H 2 O C H 2 C H 2 OCH 2 CH 2 OCH 2 CH 2 OCH 2 CH 2 COOH
15

¶ 118

10 9

8

7 6

5

4 3

2

N

1

2-pyrazinyl
4,7,10,13-Tetraoxapentadecanoic

N

acid
O

O

2-oxiranyl

2-Cyclopropen-1-one
116. Locants in substituent prefixes (radicals). Locants are assigned for
multiple bonds and for free valencies in all unsaturated radicals containing
three or more skeletal atoms. Locants are always cited for free valencies involving more than one position of a skeleton.
Examples:H 3 C− C H= C H−CΗ 2 −2-buten-1-yl

H C≡ C C H=

2-propyn-1-ylidene

31

Locants are not cited for free valencies on charged heteroatoms in cationic heterocyclic rings containing only one heteroatom, e.g. oxiranio-.
117. Locants for substituents on index heading parents and parent
radicals are cited when the parent names possess locants for substituent suffixes, unsaturation, hetero atoms, indicated hydrogen, spiro or ring assembly
junctions, or bridges (in fused systems). Locants are dispensed with for “hydro” prefixes in fully saturated ring systems unless ambiguity could result, e.g.,
because of a remaining etheno or other unsaturated bridge. Locants are not cited for a single substituent on a homogeneous monocyclic ring, e.g., benzene,
methyl-. Similarly, locants are not cited for single substituents on homogeneous parents, or parent radicals containing only two skeletal atoms, or for one
or more substituents on mononuclear radicals.
Examples:O

H N= N N H —312-triazen-1-yl

HO

2,3-Oxiranediol, 2,3-dichloro-

OH
Cl

Cl
O

2-Oxirenol, 3-chloro-

2,4-cyclopentadien-1-ylideneCl

1-triazene-1,3-diyl

M e CO CO CH 2Cl

2,3-Butanedione, 1-chloro-—C≡ C C≡C —1,3-butadiyne-1,4-diyl

H 2 N CO N H M e

Urea, N-methyl-—C H 2 C H 2 —1,2-ethanediyl—N= N N H —
1

OH

3

C= C

1,2-ethenediylidene

Me

O

Me

Me

O

Me

1,4-Dioxin, 2,3,5,6-tetramethyl-(4-phenyl-1,3-butadiyn-1-yl)-

Ph C ≡CC ≡C—
41O

1,4-Naphthalenedione, octahydro-

1,2-cyclopropanediylO

1,4-phenylene
Locants are not cited for free valencies of radicals that have lost hydrogenfrom one skeletal atom of a saturated homogeneous cyclic or acyclic molecularskeleton or an unsaturated molecular skeleton of two atoms. Locants are notcited for a phenyl radical. Locants are cited for free valencies of all other radicals derived from cyclic parents. Locants are not cited for free valencies on
acyclic radicals with only one possible site of attachment, e.g., acetyl, ethoxy,
sulfonimidoyl, etc.
Examples:When one or more locants are needed for substituents on a heading parent
or parent radical, all are cited.
Examples:118. Locants in multiplicative nomenclature are always cited for the positions of attachment on the heading parent, even for single atom parents. Skeletal locants are also cited for parents that are multiplied by esterification,
hydrazides, hydrazones or oximes. When a multiplied acid has more than one
kind of chalcogen atom or has both carboxylic and carboperoxoic groups (ortheir chalcogen analogues), superscript skeletal locants are used in combination with the heteroatom locants.
Examples:MeC H 2 —ethyl

H N= N —diazenyl

HP − P —| |HP − PHtetraphosphetanyl

P hC O−

benzoylF2-cyclopenten-1-yl

H O2 CCH 2 N H N H CH 2 CO 2 H

51Methanone, 1,1′-(1,4-phenylene)bis[1phenyl-

CO− PhPh COBenzene, 1,1′-oxybis-

Ph O PhOF

Benzene, 1,1′-oxybis[4-fluoro-

Acetic acid, 2,2′-(1,2-hydrazinediyl)bis-¶ 118

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

H O S iH 2 C H 2 SiH 2 OH

Silanol, 1,1′-methylenebis-

H 2 N SiH 2 C H 2 S iH 2 NH 2

Silanamine, 1,1′-methylenebis-

C lC H 2 C O O (C H 2 ) 2 OCOCH 2 Cl

Acetic acid, 2-chloro-,
1,1′-(1,2-ethanediyl) ester

S

S=

Methane, 1,1′-thiobis-

−

MeSMe

=

Carbamic acid, N,N′-silylenebis-−

H O 2 C N H S iH 2 N H CO 2 H

Phosphonothioic acid, P,P′-methylenebis-, OP,OP,OP′,OP′-tetramethyl ester

MeO −P −C H 2 −P −OMe
O Me

O Me

119. Locants for functional derivatives are always cited when there ismore than one occurrence of the principal functional group.
Examples:1

1,2-Benzenedicarboxylic acid,
3-methyl-,
1-methyl ester

CO2 Me

CO2 H

Me

a2

O

a3

120. Locants for indefinite compounds must often be omitted. In addition, such compounds can sometimes be named only by departing from the regular name selection policies, e.g., by citation of the principal group in themodification instead of as a suffix of the heading parent, citation of a functional
derivative in the modification rather than as a substituent, use of “mono” instead of the (unknown) locant, replacement of a numerical locant by the indefinite aromatic locant “ar-,” or inclusion of question marks in a set of otherwise
known locants.
Examples:Benzenediamine
Benzoic acid, dichloroNaphthalene, 2,2′-(1,4-phenylene)bis-,
disulfo deriv.
Benzeneacetic acid, 2-carboxy-,monomethyl ester
1,2-Ethanediol, 1-phenyl-,monocarbamate
Naphthalene, ar-chloro-1,2,3,4-tetrahydroBenzenemethanol, ar-amino[1,1′-Biphenyl]-ar,ar′-dicarboxylic acid
Benzene, 1,2,?-trimethylThe italic word “or” is used with substituent prefixes (but never with index
heading parents) when the number of alternative structures cannot be misinterpreted.
Examples:Quinoline, 2-chloro-3(or 4)-methylNaphthalene, 1(or 2)-ethyl-2(or 1)-methyl-

1

O||
C H2 —O —C—CH 3

6

2,3-Furandimethanol, α 3-chloro-,
α 2-acetate

C H —O H|
Cl

When one or more substituent prefixes are in known positions and the remainder in unknown positions, lowest locants are used for the former.
Example:Naphthalene, chloro-2-methyl-

MeOP(O) (OH)OP(O) (OH) OMep′P

Diphosphoric acid,
P,P′-dimethyl ester

H O 2 C (C H 2 ) 2 C O NHNH 2

Butanedioic acid,
1-hydrazide

MeC ( =N O H )C Me = NNHPh

2,3-Butanedione,
2-(phenylhydrazone), 3-oxime

MeO −C O

1,4-Benzenedicarboxylic acid,
1,4-dimethyl ester

CO− OMe

Locants are cited for esters of compounds named at an alcohol parent.
Examples:H 2 N− (C H 2 ) 2 O C O CH 3

Ethanol, 2-amino-, 1-acetate(the term ester is not cited
because a locant is present.)

PhC H 2 C H 2 O C O C H 3

Benzeneethanol, 1-acetate(for a conjunctive name, the ring
locant is used.)

An indefinite name like Piperidine, 2(or 4)-bromo-4(or 2)-chloro- cannot
be used because this name could be held to include the 2-bromo-2-chloro- and4-bromo-4-chloro-isomers; in such cases locants are usually omitted.
121. Alphabetization of substituent prefixes affects the position in the index where an inverted chemical substance name will be found. Simple prefixes
are placed in alphabetic order according to their names; only then are multiplicative prefixes (di-, tri-, etc.) placed in front of each as required, and locants
inserted; e.g., an index compound in which two nitro groups, three bromine atoms, and a chlorine atom are present receives the substituent name “tribromochlorodinitro,” and the substituents so arranged will be found together with anappropriate index parent, such as Naphthalene, alphabetized in accordancewith all the Roman letters in the complete name. The total name with locants,e.g., Naphthalene, 2,5,8-tribromo-3-chloro-1,6- dinitro-, will be preceded in
the list of index entries by both Naphthalene, nitro- and Naphthalene, tetrachloro-.
Compound and complex substituent prefixes (radicals) are constructed on
similar alphabetic principles and then arranged by their first letters (which may
have been derived from multiplicative prefixes within the radicals) in the total
name. This name is then placed in the index as described above, all letters being alphabetized. When the letters are all identical, arrangement depends on locants.
Examples:CO 2 HE t 2N ( CH 2) 2

Locants are used in modifications for index headings that express the same(or similar) functions in both the index parent and the substituents when the latter are not derivatized. This avoids confusion with former CA index names.
Examples:

1

6

Cl

(CH2) 2 NEt 2
Cl

Cl

CO2H
C O 2 Et

Benzoic acid, 3-sulfo-,
1-ethyl ester

HO3 S

Br

Br

CO 2 H

8a

51-Naphthalenecarboxylic acid, 4[bis(2-chloroethyl)amino]-6,7-dibromo- (the multiplicative prefix"bis-" is part of the name of the complex substituent prefix and this istherefore placed before "bromo")

14N [ ( CH 2 ) 2 Cl] 2

Benzoic acid, 3-(ethoxysulfonyl)(formerly Benzoic acid, 3-sulfo-,
3-ethyl ester)

E tO 3 S

NO2O2 N

The locant for an additive term such as “oxide” is an Arabic number whena nitrogen, phosphorus, sulfur, etc., atom of a ring in the index heading parent
is involved; otherwise a letter locant (N-, S-, etc.) is employed.
Locants are not employed for ionic modification terms, e.g., salts such as“sodium salt,” “hydrochloride.”

Benzoic acid, 3,4,5-trichloro-2,6bis[2-(diethylamino)ethyl]- (letter"c" is placed before "d", the initialletter of the complex radical)

8a

5

1

4

Naphthalene, 2-(2-nitrophenyl)-7(3-nitrophenyl)- (the radicals areplaced in order, according to the locants they contain, before locantsrelating to the heading parent are inserted)

7

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007122. Tautomeric compounds. Index names are normally based on the precise structures shown or described in the author’s original document. Tautomerism (ready interconvertibility of isomers) in certain types of compounds
causes a serious problem in index-name selection, the issue here being notwhich name to select for a given molecular structure but which diagram toname for a given tautomeric system if scattering at different names of information about what is essentially a single substance is to be avoided.
Common (trivial) names for most nitrogenous tautomeric systems arecross-referred to preferred systematic names.
Examples:Adenine.
Barbituric acid.
Caffeine.

See 9H-Purin-6-amine
See 2,4,6(1H,3H,5H)-PyrimidinetrioneSee 1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethylSee 2(1H)-Quinolinone
See 2(1H)-Pyrimidinone, 4-aminoSee 6H-Purin-6-one, 2-amino-1,9-dihydroSee 2,4-Imidazolidinedione
See 1,3,5-Triazine-2,4,6-triamine
See 1H-Purine-2,6-dione, 3,9-dihydro-1,3-dimethylSee 2,4(1H,3H)-Pyrimidinedione
See 1H-Purine-2,6,8(3H)-trione, 7,9-dihydroSee 1H-Purine-2,6-dione, 3,9-dihydro-

Carbostyril.
Cytosine.
Guanine.
Hydantoin.
Melamine.
Theophylline.
Uracil.
Uric acid.
Xanthine.

The necessity for many tautomeric structures to be redrawn to agree withselected CA index names is obviated by computer “normalization” algorithms
in the CAS Registry System. In the normalization process, the different structural diagrams for a single tautomeric system (of one of the types expressed in
the cross-references above) are recognized as equivalent and stored in identicalmachine-language representations. They share a single unique CAS Registry
Number and CA Chemical Substance Index name.
The structural requirements for the normalization process and the rules forselecting unique CA Chemical Substance Index names are as follows:
I. Requirements for normalization of structures. Tautomeric structures
represented by the following equilibrium:
HM −Q= Z

M= Q−ZH¶ 122

A unique CA Chemical Substance Index name is selected for each compound containing a normalized tautomeric structure by application of the rulesthat follow (see II, below). For tautomeric pyrazole derivatives and for tropolones, CA selects a single preferred structure and index name, and assigns a single CAS Registry Number, even though these systems do not conform to thegeneral equilibrium illustrated above and are not currently normalized by the
CAS Registry System. Lowest locants are employed successively in index parents and substituents in these cases.
Examples:
H1
N

Me

2

N

Me

N2

5

5

CH 2 O H

CH2 O H

1H-Pyrazole-3-methanol,
5-methyl(principle: lowest locant
for principal group)

1H-Pyrazole-5-methanol,
3-methyl-

NOT

O
1

1

NH

OH

OH

O

7

7

1

Br

2,4,6-Cycloheptatrien1-one, 3-bromo-2hydroxy(principle: lowest
locants for substituents)

Br

2,4,6-Cycloheptatrien1-one, 2-bromo-7-hydroxy-

NOT

For phosphonic-phosphorous and phosphinic-phosphonous acid tautomers, see¶ 197.
II. Rules for Choosing the Preferred Normalized Tautomer. These
rules are used to select the particular structure of a tautomer from which theunique CA Chemical Substance Index name is then derived. They are appliedin the order shown until a decision has been made.
Rule 1: The Stereo Retention Ruleare normalized, i.e., recognized as equivalent in the CAS Registry System,
when the following requirements are met:(a) Q = C, N, S, P, Sb, As, Se, Te, Br, Cl or I with any acceptable valency
for the individual elements.
(b) M and Z = any combination of trivalent N and/or bivalent O, S, Se or
Te atoms.
(c) The bonds involved in tautomerization may be in an acyclic chain or
in a ring system or partly in both.
(d) The end-points, M and Z, may be in adjacent rings of a fused ring system, but a nitrogen atom which occupies a fusion point in such a system cannot
take part in tautomerization.
(e) The hydrogen atom of the tautomeric system may be replaced by deuterium or tritium.
(f) Two or more systems of the form shown above may be linked througha common atom, whereby a proton can be considered to migrate along thechain.
Example:
|

|

|

|

|

CH3

Z
C

N

H
N

NO2

N
E

OH

Ethanimidic acid,N-nitro-, (1Z)-NH2

2(1H)-Pyridinone, hydrazone, (2E)-

Ph N HN

Z

MeN

1-Triazene, 1-methyl-3phenyl-, (1Z)-|—N= C −NH −C= N −C =N ——N H− C =N −C =N −C= N—||

When the original document reports the isolation of a normalized tautomer
with an E or Z double bond connecting the central atom Q to a terminal N, thepreferred tautomer retains the E or Z configuration.

|

|

|

|

—N= C −N= C −N= C −N H ——N =C −N =C −N H −C= N—

Replacement in the generalized formula above by specific elements affords
normalized tautomeric systems such as the following:

For any tautomer mobile group, if M is a chalcogen and Z is N, the preferredtautomer has the mobile H on N; and if M and Z are both chalcogens, the preferred tautomer has the mobile H on the chalcogen of higher atomic number.
The overall order of priority for attachment of the mobile H is thenN > Te > Se > S > O||—NH− C=N——N= C−ΝΗ —In other words, a double bond to oxygen is preferred above all others.

(amidine tautomerism)—NH− N=N—

Rule 2: The Oxo Rule

H
N

— N= N−NH—

O

N

NOT

OH

(diazoamino tautomerism)||—N H− C=O (S, Se , Te )—N = C−O( S, Se , T e ) H

2(1H)-Pyridinone

2-Pyridinol(lactam-lactim tautomerism)—NH− P= N——N = P− NH—SO||—S −NH 2||OOH|—S =NH
||
O

Ph

C

SH

NOT
NH2

Benzenecarbothioamide

Ph

C

NH

Benzenecarboximidothioic acid¶ 122

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

O

O

O

OH

NH

N

O

O

N

8
H
N

O

N

O

N

NOT
HO

P

NH

P

OH

OH

NOT

HO

P

OH

N

P

OH

Imidodiphosphoric acidOH

2H-Pyrrol-2-one, 5,5′iminobis-OH

2H-Pyrrol-2-one, 1,5-dihydro5-[(2-oxo-2H-pyrrol-5yl)imino]-

Phosphorimidic acid,N-phosphonoRule 5: The Alternating-Bond Rule

O
P

P

NOT

1H-Phosphole, 1-selenyl-,1-oxideFor a cyclic tautomer mobile group in which M and Z are both N and Q lies at
the junction of two rings, the preferred tautomer has one N in a ring with alternating single and double bonds and the mobile H on the other N.

Se

HO

SeH

1H-Phosphole, 1-hydroxy-,1-selenide

H
N

Rule 3: The Unsubstituted Imino Rule

N
H

N
H

6(5H)-Pteridinone,
7,8-dihydro-

For an acyclic tautomer mobile group, if M and Z are both N, the order of priority for attachment of the mobile H is

NH2

R−N > T−N > D−N > H−N

NH2

N
Et

NH

NH

O
N

N

8H-Purin-8-one, 6-amino7,9-dihydro-

8H-Purin-8-one, 6-amino1,7-dihydro-

N

NOT

C

O

H
N

HN

NOT

N
H

N

N

6(5H)-Pteridinone,
1,7-dihydro-

H
N

N

O

N

NOT
N

where R is any covalently attached atom or group other than H, D, or T. In other words, an unsubstituted imino group is preferred to a substituted one, and an
unlabeled imino group is preferred to a labeled one.

H
N

O

N

Et

N

C

H
N

N

NH2

O

H
N

N

O

N
H

N

O

NOT

1-Piperidinecarboximidamide,
N′-ethyl-

1-Piperidinecarboximidamide,N-ethylO
Ph

NH

Ph

NOT

Ph

NH

S

N

C

Et

NHNH2

Propanimidic acid,
hydrazide

C

NH 2
NH

Et

D

Propanimidamide-N-d

C

NH

Q

N

n

R′

b) both terminal N’s (those attached to R and R′) are acyclic or both are ina ring,the preferred tautomer has the mobile H on the terminal N of higher priority
based on the Cahn-Ingold-Prelog (CIP) sequence rule, the one used to assign
absolute configuration [R. S. Cahn, C. K. Ingold, and V. Prelog, Angew. Chem.
Int. Ed. Engl., 1966, 5, 385-415 (errata: 1966, 5, 511); V. Prelog and G. Helmchen, ibid., 1982, 21, 567-583.

NOT
C

R

a) R and R′ are any covalently attached atoms or groups, and

NNH2

PropanehydrazonamideNH
Et

For the isolated (n = 1) or extended (n > 1) tautomer

in which

NH 2
NOT

Et

Pyrazino[2,3-b]pyrazine-2,3dione, 5,8-dihydro-

Rule 6: The Tautomer CIP Rule

Benzenesulfonimidamide,
N′-phenyl-

NH

O

Ph

NH2

Benzenesulfonimidamide,N-phenyl-N
H

Pyrazino[2,3-b]pyrazine-2,3dione, 1,4-dihydro-

O

S

N

N

D

Propanimidamide-N′-dFor each tautomer, a tree diagram is constructed for the terminal N bearing themobile H. Then the following CIP-based rules are used:
Subrule 6.1: The Element Subrule

Rule 4: The Amino/Hydrazinyl Rule
For a tautomer mobile group in which M and Z are both N, but one N is in aring and the other is attached to the ring, the preferred tautomer has the mobile
H on the acyclic N.
N

NHNH 2
NOT

Pyridine, 2-hydrazinyl-

H
N

NH 2
N

1H-Imidazol-2-amine

H
N

NNH 2

2(1H)-Pyridinone,
hydrazone

NOT

Under subrule 6.1, at the first point of difference, the element with the higher
atomic number has priority. The terminal N for that branch is then assigned themobile H in the preferred tautomer.
N
HN
O2N

NH 2

NH

O2N

NH
NH 2

1H-1,2,3-Triazol-5-amine,
4-nitro-

Br

H
N

NH

2H-Imidazol-2-imine,
1,3-dihydro-N

NOT

1H-1,2,3-Triazol-4-amine,
5-nitro-

Br

H
N

N
N

N

NOT

P

P
N

1H-1,3,2-Benzodiazaphosphole,
6-bromo-NH

1H-1,3,2-Benzodiazaphosphole,5-bromo-9Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
NH2

unlike pair (R,S or S,R):

NH2
N

NOT

N

H
N

N

CO2H Me

N
H

N

N

N

9H-Purin-6-amine

¶ 124

NH
H

7H-Purin-6-amine

CH
S

CO2H Me

CH
S

Et
NOT

C
R
CH

N

S
CH

H

N

CH
S

CH
S

Et

NH

R
CH

S
CH

Et

C

Et

CO2H Me
HN

N

N

NOT

Me
O

NH
Me

Me

O

4H-Imidazol-4-one, 3,5-dihydro5,5-dimethyl-

L-Isoleucine, N-[[[(1R,2S)-1-

L-Isoleucine, N-[[[(1R,2S)-1-

carboxy-2-methylbutyl]imino]methyl]-carboxy-2-methylbutyl]amino]methylene]-Me

4H-Imidazol-4-one, 1,5-dihydro-5,5-dimethyl-

And finally, under subrule 6.5, an R chiral center has priority over an S one:
HN

HN

NHNH2

N

H2N

HN

Cl

2H-Pyrrol-2-one, 5-amino-,
hydrazone

N

Cl

N

NOT

N

CO2H

CO2H

1H-1,2,4-Triazole-5-carboxylicacid, 3-chloro-

Subrule 6.2: The Isotope Subrule
If a comparison of atomic numbers fails to reveal a difference in the tree diagrams, the CIP rule then compares mass numbers. Under subrule 6.2, at thefirst point of difference, the atom with the higher mass number has priority:
Me
Ph

15

NH

Me

C

N

NOT

Ph

Ethanimidamide-N-15N,
N,N′-diphenyl-

Ph

15

N

C

CH3

NH

C

N

Me

13

CH3

N

C

NH

Me

HN

NH2

N

NOT
35

S

35

S

S

3H-1,2,4-Dithiazol-1-35S-5-S

3H-1,2,4-Dithiazol-2-35S-5amine, 3-imino-amine, 3-imino-

Subrules 6.3-6.5: The Stereo Subrules
If a comparison of mass numbers also fails to reveal a difference, the CIP-based
rule then compares stereo elements. For example, under subrule 6.3, a Z double bond has priority over an E one if the structure is X−CH=CH−Y, where X
and Y are any covalently attached atoms or groups:
NH
Ph

CH

Z

CH

Me
NOT

C
N

CH

E

CH

Me

Benzenecarboximidamide,N′-(1E)-1-propen-1-yl-N(1Z)-1-propen-1-yl-

Ph

NH

N

S

R
H

Cl

NOT

Cl

S

R
H

H

2H-Pyrrol-5-amine, 3,4dichloro-3,4-dihydro2-imino-, (3S,4R)-Cl

H

2H-Pyrrol-5-amine, 3,4dichloro-3,4-dihydro-2imino-, (3R,4S)-

Z

N

CH

NH

CH

CH

123. Additive nomenclature embraces molecular structures whose several
component parts are considered to be added together without replacement(substitution) of atoms (usually hydrogen). It includes coordination names (¶215), conjunctive nomenclature (¶ 124) and binary names of inorganic compounds (¶ 219).
Examples:Copper, dichlorobis(methanamine)Benzeneethanol
Sodium chloride (NaCl)
The construction of additive names often involves indicated or added hydrogen (¶¶ 135, 136) in that part of the molecule known as the heading parent,
the addition of hydro “substituents”, or the use of additive terms such as “oxide” or “sulfide” in the modification. In a few cases, the additive term becomesa part of the heading parent.
Examples:9(10H)-Anthracenone
Naphthalene, 1,2,3,4-tetrahydroPyridine,
1-oxidePhosphine imide

Propanimidamide, N-methylN′-(methyl-13C)-

NH

N

Ph

Et
NOT

Propanimidamide, N′-methylN-(methyl-13C)-

H2N

NH

Ethanimidamide-N′-15N,
N,N′-diphenyl-

Et
13

H2N

NH
N

Cl

1H-1,2,4-Triazole-3-carboxylicacid, 5-chloro-

NH2

N

NNH2

N

NOT

2H-Pyrrol-2-imine,
5-hydrazinyl-

CO2H MeFor salts and molecular addition compounds, see ¶¶ 192, 198.
124. Conjunctive nomenclature allows a cyclic molecular skeleton to be
included as a part of the heading parent name even though the principal chemical group is separated from the ring by an acyclic chain. Larger molecules may
be named thereby as heading parents and more compounds of similar structure
can be collected at a given ring system name. Moreover, the major requirementof substitutive nomenclature, that the principal group be expressed in the heading parent as a suffix, is fulfilled.
A conjunctive name is employed when any ring system (including a polyhedral borane) is attached by single bonds to one or more saturated acyclic hydrocarbon chains, each of which bears only one functional substituent
corresponding to the principal chemical group of the compound. When a second or third such substituent is present on the chain, a conjunctive name may
still sometimes be employed so long as the resulting index heading parent does
not express more than a single function in each chain and other principles are
not violated (see the final example below). It is always implied that the chemical functional group is at one end of the acyclic chain and the ring system is at
the other.
ExamplesBenzenemethanol

Ph CH2 OH

Me

C
E

CH

CH M e CH2 O HβαMeCyclopentaneethanol, β-methyl-

Benzenecarboximidamide,
N-(1E)-1-propen-1-yl-N′(1Z)-1-propen-1-yl[1,1′-Biphenyl]-4-acetic acid
Ph

Under subrule 6.4, a like pair of chiral centers (R,R or S,S) has priority over an

CH 2 CO 2 H

¶ 124

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
Example:Pr|
C H N H2α33-Pyridinemethanamine,
α-propyl-

CO 2 HN

1′

C H C lC H2 CH2 CONH2
γ
β
α
N
S

1

1,3-Dithiolane-2-butanamide,
γ-chloro-α
C H C lC O 2 H

1,3-Benzenediacetic acid,
α1,α3-dichloroC H C lC O 2 H
α′Benzoic acid, 2,2′-thiobis-

6′

S

6

3

5

CO 2 H

1

1

S

In the example above, a simple one-part polyvalent radical, thio, was employed as a multiplier; other such radicals are oxy, -O-; methylene, -CH2-; 1,4phenylene, -1,4-C6H4-; imino, -NH-; nitrilo, -N=; and 1,3-disiloxanediyl, -SiH2OSiH2-. In general, any simple multivalent radical may be used as a multiplicative radical, and may itself be substituted; e.g., (methylimino), -N(CH3)-;(1-methyl-1,3-propanediyl), -CH(CH3)CH2CH2-.
Multicomponent radicals may be used as multipliers if they contain a central one-part multivalent radical (simple, compound, or complex) around which
all other multivalent radicals are so arranged that the sequence of atoms andbonds in each path is identical as one proceeds outwards. There is no restrictionin the number of components that may comprise the total multiplying radical,
so long as their use results in an unambiguous total name.
Examples of permissible multiplying radicals:[oxybis(methylene)]— CH 2 O CH 2 —
H
N

OH
|
C H C H2 CH2α

1H-Pyrrole-2-methanol, α−(2−phenylethyl)- (the heading parent which expresses the preferred ring system, not thepreferred acyclic chain, is chosen)

CH 2 − CH Cl—|— CH Cl− CH 2 −N −CH 2 −CH Cl—

1
10
6

CHO
|
C HCH 2 CHO
α3
C H 2 CHO
α4

Bicyclo[4.3.1]dec-7-ene-3,4-diacetaldehyde, α3-(2-oxoethyl) (not Bicyclo[4.3.1]dec-7-ene-3-propanal, βformyl-4-(2-oxoethyl)-; the preferred heading parent expresses the
maximum number of principal
groups and, because it also expresses a ring system, is preferred to Butanedial)

A conjunctive name is not permissible under the following conditions and theregular rules of substitutive nomenclature apply: 1) when a double bond joins
the ring to the functional acyclic chain; 2) when a conjunctive index parent
would express two or more functional groups in a single acyclic chain; 3) when
the acyclic chain is unsaturated, or contains hetero atoms; and 4) when a conjunctive name would fail to express the maximum number of principal chemical groups.
Examples:— SiH 2 CH 2 CH 2 C −SiH 2 —(1-propanyl-3-ylidynetetrasilylene)

SiH2|([1,1′-biphenyl]-2,4′-diyldiimino)—NH
NH—

The requirement for total symmetry in multiplication allows the use of“ylidene” in combination with other bivalent radicals.
Η 2C(cyclobutylidenemethylene)

CH2

H 2C
C

||

— C—

CH 2

Acetic acid, 2-cyclopropylidene-C H C O2 H

[nitrilotris(1-chloro-2,1-ethanediyl)][(1-chloro-1,2-ethanediyl)bis(oxy)]— O CH 2 CH ClO —
|
SiH 2

9

10

(methylenesilylene)||— Si —O
5

C H (O H )2

1

Methanediol, 1-(2-furanyl)-

Enclosing marks are used to distinguish certain combinations of multivalentradicals which would otherwise be ambiguous.
— C− O−C—O

C H= CHCH 2 NH 2

2-Propen-1-amine, 3-(2-benzofuranyl)-[oxybis(cyclopropylidenemethylene)]— CH 2 — C— O — C— CH 2 —[oxybis[(cyclopropylidene)(methylene)]]Examples of combinations of multivalent radicals which are not used as
multipliers:
N H C O2 H

Carbamic acid, N-cyclopropyl— CH 2 CH= N CH 2 C H =— CH 2 N H ——OS—— CH Cl CH 2 PH CH C l C H2 —OH
C H 2 OH

1,4-Naphthalenediol, 2-(hydroxymethyl)-OH125. Multiplicative nomenclature employs polyvalent radicals by whicha multiplicity of occurrences of an index heading parent in a compound may be
expressed.

— CH 2 O O —The naming of multiplying radicals is accomplished by citing first the central unit. This is followed by a prefix, e.g., “di” or “bis”, denoting the numberof “radial” series generated by the central unit. The remaining terms of thename, in the form of radicals, are cited in appropriate enclosing marks as necessary. The entire multiplying radical is set off by further enclosing marks,

11

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

which are preceded by locants “placing” the radical at the proper point of attachment on each index heading parent. Multivalent radicals other than central
units are numbered (if there is a choice) from the heading parents towards thecenter of the complete radicals, and the locant relating to the position closest to
the heading parent is cited last.
Examples:
1

2

1′

S—S

2

3

2

1

CH 2

6′

N

3

1

N

6

O Si H2 CH2 O CH2 CH2 O H

Ethanol, 2,2′-[[3-[[[(2-hydroxethoxy)
methyl]silyl]oxy]-1,5-trisiloxanediyl]bis(methyleneoxy)]bis- (notEthanol, 2,2′,2′′-[silylidynetris(oxysilylenemethyleneoxy)]tris-)(dithiodi-4,1-phenylene)(selenodi-2-propene-3,1-diyl)[methylenebis(1,3,5-triazine-6,2,4triyl)] (the 2- and 4-positions areequally close to the heading parent
and are therefore cited in normal sequence)

1′

N5

3N

N3′

5′N

Carbonyl groups which are part of carbon chains are expressed as oxo substituents; chalcogen, imino, and hydrazono analogs are expressed as thioxo, selenoxo, telluroxo, imino, and hydrazono substituents.
Examples:[(1,3-dioxo-1,3-propanediyl)bis(iminomethylene)]—C H2 N H C O C H 2 CONHCH2 —1

2

3(1,2-dioxo-1,2-ethanediyl)—C O C O ——C H2 C ( = N H )1

C( =ΝΗ) CH2 —

2

2′

1′

[1,4-phenylenebis(2-imino-2,1ethanediyl)]
When carbonyl groups and their analogs are not part of a larger acyclic carbon chain, the names carbonyl, carbonothioyl, carbonimidoyl, etc., are employed.
Examples:
1

1′

CO

6

(carbonyldi-4,1-phenylene)

6′—N HC ( = N H ) N H—

—N H C S(carbonimidoyldiimino)[1,4-phenylenebis(carbonothioylimino)]

CSNH—

Valid multiplying radicals are used only when the entire compound is symmetrical around the central unit of such a radical; i.e., the radical must be attached to the heading parent by bonds of the same type (single, double, or
triple) and at equivalent positions, and this parent must be identical with regard
to positions of principal groups (and their functional derivatives) and other substituents. Whether or not such other substituents are present, the terms “bis,”“tris,” etc., are employed after the multiplying radical, not “di,” “tri,” etc. Ifother substituents are present, they are cited as regular substitutive radicals after an opening bracket (which, perforce, is left unclosed).
Examples:Pyridine, 3,3′-thiobis[6-chloro- (notPyridine, 5,5′-thiobis[2-chloro-;
multiplicative radicals are given
lowest locants) (The uninverted
form of this name is 3,3′-Thiobis[6-chloropyridine].)

1′

1

N

N
6

6′

1

6′

S

1′

1

C= CH

NH2
6

1′′
6′′

Cl

NH 2

Me

Benzenamine, 3,3′,3′′-(1-ethenyl-2-ylidene)tris[6-methyl-MeThe principles of multiplicative nomenclature are applied only after the index heading parent has been chosen, and after other principles, e.g., centrality(¶ 138), have been applied. When more than one multiplicative name is possible, that one is used which multiplies the greatest number of index heading parents, and then, if a choice is still necessary, that one which appears earliest in
the alphabetic sequence of index entries. The number of occurrences of the parent is not increased by arbitrary breaking of the skeleton from which the multiplying radical is derived.

126. Radicofunctional nomenclature is used by CA in only a few cases,for disulfides, hydroperoxides, and peroxides (¶¶ 200, 196). Radicofunctional
names express the compound type, e.g., “peroxide,” usually as a separate word.
When inverted, the substituents are not followed by a hyphen unless multiplicative nomenclature (¶ 125) is used with Hydroperoxide; e.g., Disulfide, ethyl methyl; Hydroperoxide, 1-methylethyl; Hydroperoxide, cyclohexylidenebis-.
127. Replacement nomenclature (“a” nomenclature) is used for certain
heterocyclic ring systems (¶ 146) and also, sometimes, for heteroorganic acyclic compounds. This nomenclature is limited to cases in which carbon atoms
have been replaced in chains and rings by nonmetals and/or elements of which
the hydrides are CA index heading parents, i.e., P, As, Sb, Bi, Si, Ge, Sn, Pb,
and B.
Requirements for its use in expressing acyclic chains are as follows:(a) A minimum of four hetero units must be present, none of which may
be all or a part of a functional chemical group to be expressed in the index heading parent as the preferred functional compound class (i.e., as a functional suffix or as a functional index compound such as Carbonic or Phosphonic acid).
A hetero unit is defined as an isolated hetero atom or a series of consecutive
hetero atoms, alike or different, that may be expressed as a unit, such as by abivalent radical name. Examples: -S- (thio); -S-S- (dithio); -N=N- (1,2-diazenediyl); -SiH2-O-SiH2-(1,3-disiloxanediyl); -SiH2-NH-SiH2-(1,3-disilazanediyl). The above are all single hetero units, but -HP-NH-, -S-O-, and -OSiH2-O-, are not.
(b) The “a” name must not be lower in order of precedence than the nameobtained by regular substitutive nomenclature, i.e., it must express at least as
many principal functions of at least equal rank.
(c) All hetero atoms must be in their standard valency state, or else theabnormal valency must be expressible unambiguously by use of “oxide,” etc.,
terms.
(d) The chain may be terminated only by C, P, As, Sb, Bi, Si, Ge, Sn, Pb,
or B.
Acyclic “a” nomenclature is employed for organic chains containing siliconor metal atoms, polyesters, anhydrides, amides, polyamides, polyalkylene glycols, and condensed carbonic acid derivatives. It is not used for peptides orpolymers, or (if it can be avoided) for chains containing no carbon atoms. Otherwise, if the above criteria are met, an “a” name is always selected.
128. Replacement prefixes for the elements most frequently found in carbon chains are set out in descending order of precedence in Table I. (The orderis the reverse of that shown in ¶ 215 for coordinated elements.)
TABLE IREPLACEMENT PREFIXES IN DESCENDING
ORDER OF PRECEDENCE
Element
OxygenSulfurSelenium
Tellurium
NitrogenPhosphorus
Arsenic
Antimony
BismuthSiliconGermanium
Tin
Lead
Boron

Substitutive Valence
II
II
II
II
III
III
III
III
III
IV
IV
IV
IV
III

PrefixOxa
Thia
SelenaTelluraAza
Phospha
Arsa
Stiba
Bisma
Sila
Germa
StannaPlumbaBora

The replacement prefixes are placed in descending order of precedence
ahead of the name of the carbon skeleton with locants to indicate the positionsof the atoms replaced. Lowest locants are assigned to functional groups if
present, otherwise to the hetero atoms.
Replacement nomenclature is also employed for acyclic substituent prefixes (radicals) when the above requirements are fulfilled. In this case, lowest locants are assigned to free valency positions; i.e., the “a” names are based on the
carbon chain radical names, but the free valency locant (“1”) is always cited.
Examples:
~~~

1

Me

2

6′

—C Η 2 CΗ = C H Se CH= CHCH 2 —

H2 N

2′

|

CH3 − O−CH2 −CH2 −O− CH2 −CH2 − O —
14

~~~

6

Cl

1′

H O CH 2 CH 2 O CH 2 Si H 2 O Si H O Si H 2 CH 2 O CH 2 CH 2 O H

1

2

1

Example:[oxybis(1-chloro-2,1-ethanediyl)]—C H C l C H 2 O C H 2 CHCl—

¶ 128

13 12

11

10

9

8

7

— CH 2 − CH 2 −N H −CH 2 −CH 2 −CΗ 2 − O H
6

5

4

3

2

1

7,10,13-Trioxa-4-azatetradecan-1-ol

¶ 128

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

er by ≡N is denoted by nitrido. Peroxy acids are named by use of the affixes
peroxo, (thioperoxo), and (dithioperoxo).
These affixes are combined, in alphabetical order, with the functional suffix
of compound names based on molecular skeletons. The systematic names Benzenecarboxylic, Ethanoic, and Methanoic acids, not the trivial names Benzoic, Acetic, and Formic acids, are used as the parents for functional
replacement nomenclature.
Examples:(C H 2 ) 3 −S −(C H 2 ) 3 − O−CH 2 −CH 2 − CH 2 − SH
8
4
3
2
1
|
O 12
|
16
20 21
22
23
(C H 2 ) 3 −S − (C H 2 ) 3 − O−CH 2 −CH= CH 2

4,12,20-Trioxa-8,16-dithiatricos22-ene-1-thiol
C H 3 − N H− C H 2 −C H 2 −NH− CH 2 − CH 2 −ΝΗ−CH 2
1

2

3

4

5

6

7

14

13

12

11

10

9

8

12

Ethane(dithioic) acid (not Acetic
acid, dithio-)

M e CS 2 H

C H 3 − N H− C H 2 −C H 2 −NH− CH 2 − CH 2 −NH −CH 2
PhC( =NH) OH

3,6,9,12-Tetraazatetradecane1,14-diamine, N1,N14-dimethyl-

OH O

CH3 O

|

||

14

13 12

CH 3 O

|

||

11

10 9

|

||

8

7

CH3 O

|

||

5

4

NNH 2
||
CH2 S −O H
||
NH

CH3

|

C H 3 − C H− C−O− C H− C−O− CH− C−O− CH−C −O− CH−COOH
15

6

3

2

Benzenecarboximidic acid (thetautomeric Benzamide is preferred, except for esters andanhydrides; see ¶ 122)

1

3,6,9,12-Tetraoxapentadecanoic
acid, 14-hydroxy-2,5,8,11tetramethyl-4,7,10,13-tetraoxo-

Benzenemethanesulfonohydrazonimidic acid (derived fromthe conjunctive name Benzenemethanesulfonic acid)

O

||

O

||

In replacement names from phosphorus and arsenic functional parent compounds (¶ 197), all the affixes except hydrazono may be employed as part ofthe suffix. For Carbonic acid and its relatives (¶ 183) all but hydrazido and nitrido may be used.
Examples:C H 3 − C H 2 −O −(C H2 − CH 2 −O) 3 − CH 2 − CH 2 −O −C− ( CH 2 ) 10 − CH 3
12

2

1

Dodecanoic acid
3,6,9,12-tetraoxatetradec-1-yl
ester
CH3
+

CH 3

N 12 C H 2 − N H− CH 2 −NH −CH 2 − NH− CH 2 −NH −CH 2
9

8

7

6

5

4

3

2

1
2

1

3

N

+
−

2I

3

4

4

Quinolinium, 2,2′-(2,4,6,8-tetraazanonane-1,9-diyl)bis[1methyl-, iodide (1:2)
O||

C− N H−CH 2 −CH 2−S− CH 2 − CH2 −O −CH2 − CH2 − NH−C O O H
12 11

10

9

8

7

6

5

4

3

2

1

5-Oxa-8-thia-2,11-diazadodecanoic
acid, 12-oxo-12-phenyl-

C l P ( O ) ( O H )2

Phosphorochloridic acid

MeAs (NH2) OH

Arsonamidous acid, As-methyl-P(S)(NH2)3

Phosphorothioic triamide( H O ) 2 C= N N H 2

Carbonohydrazonic acid

( H O O ) 2 CO

Carbonodiperoxoic acid

In replacement names from other mononuclear acids and from condensed
nuclear acids (anhydrides), the affixes are used as nondetachable prefixes citedat the beginning of the heading parents. Because multiplicative prefixes are
rarely used for thio and other chalcogen prefixes, ambiguity is resolved by synonym line formulas in the boldface index headings.
Examples:
O

||

O

||

H O 2 CN H CO 2 H

Imidodicarbonic acidO||
H O− S− Se H||
O

Selenosulfuric acid (H2SO3Se)

P −C H 2 − CH 2 − C−NH− CH 2 − NH−C −C= CH 2

S
S
||
||
H S −C− S− C−SH

Thiodicarbonic acid ([(HS)C(S)]2S)

P −C H 2 − CH 2 − C−NH− CH 2 − NH−C −CH 2

Nondetachable prefixes are used in a few other cases.
Examples:

O

CH3 O

||

Imidotriphosphoric acid

COOH

Benzoic acid, 4-(3,5,7,9-tetraoxadec-1-yloxy)-

CH3 O

O

H O− P− N H− P−O −P −O H
|
|
|
OH
OH OH

C H 3 − O−C H 2 −O− C H 2 −O −CH 2 −Ο−CH 2 −CH 2 −ΟCH3 O

Ethane(dithioperoxoic) acid

CH 3 CSSH||||

CH3 O O

O

||

||

O

O

||

||

O

Phosphonic acid, P,P′-(8-methylene3,7,10,14-tetraoxo-4,6,11,13tetraazahexadecane-1,16-diyl)bis-, P,P,P′,P′-tetramethyl ester

ClSO 3 H
S( O ) (= N H ) ( N H 2 ) 2( H 2 N ) 2 CS
H 2 N SH

129. Replacement nomenclature for functions is a method of describing
the replacement of hydroxyl and oxo functional groups by nitrogen, chalcogens, halogens, or halogenoids such as isocyanato. The replacement may be
carried out in substituent suffixes, e.g., -thioic acid from -oic acid; in substituent prefixes, e.g., carbonimidoyl (¶ 134) from carbonyl, and phosphinothioylfrom phosphinyl (¶ 197); and in functional parent compounds (¶ 130), e.g.,
Phosphonimidodithioic acid from Phosphonic acid.
Replacement of hydroxyl in compounds and radicals is denoted by the following affixes (the final “o” is often elided): amido (for -NH2), azido (for -N3),
chlorido (for -Cl) (and similarly for other halo atoms), cyanatido (for -OCN),
hydrazido (for -NHNH2), isocyanatido (for -NCO), (isothiocyanatido) (for NCS), and (thiocyanatido) (for -SCN). Seleno and telluro analogs are named
analogously.
Replacement of oxo is denoted by the affixes hydrazono (for =NNH2), imido (for =NH), thio (for =S), etc. Replacement of a hydroxyl and an oxo togeth-

A c O SA c
E t O SH

Chlorosulfuric acid
Imidosulfamide
Thiourea
Thiohydroxylamine
Thioperoxide, diacetyl
Thiohydroperoxide, O-ethyl130. Substitutive nomenclature, in which hydrogen atoms are replacedby other atoms or chemical groups, is of paramount importance among nomenclature systems because of its versatility. Substitutive parent compounds,
which are real or hypothetical compounds whose names imply the presence of
replaceable hydrogen atoms, are of two kinds:(a) Functional parent compounds have names which express a chemicalfunction but are not based on a molecular skeleton. Substitutive examples
include Arsonic acid, Imidodicarbonic acid, Carbamic acid and Phosphonamidic chloride. Their substituents are always expressed as prefixes, neveras suffixes.

13

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007(b) Molecular-skeleton parent compounds are nonfunctional. They arechains or rings of atoms with only hydrogen atoms attached and possessing
names which express or imply the substitutive valency and bonding of the skeletal atoms. (Methane and monoatomic hydrides of the Group IVA elements
and the Group VA elements (except nitrogen) are treated as molecular skeletons.) Examples include Ethane, Distannane, Diazene, 3,6,9,12,15-Pentaoxaheptadecane, Cyclohexane, Morpholine, Phosphine, and Stannane. They
are transformed into index heading parents by appending, as a suffix, the substituent which represents the principal functional group of the compound; othersubstituents are expressed as prefixes.
131. Substituent suffixes of molecular-skeleton parent compounds arechosen to represent the principal chemical functional group (or groups) in accordance with the order of precedence of compound classes (¶ 106). When no
suffix is available to represent the preferred compound class, either a substitutive functional parent compound (¶ 130) is used as a heading parent, or anothersystem of nomenclature, e.g., coordination or radicofunctional, is adopted.
Examples:E tP(O ) (O H ) 2

Phosphonic acid, P-ethyl-(Phosphonic acid is a functional parent
compound.)P hS F 3

Sulfur, trifluorophenyl-, (T-4)(a coordination name)

F3COOCF3

Peroxide, bis(trifluoromethyl) (aradicofunctional name)

The particular suffixes used for various classes of compounds in descending order of precedence from acids through imines (¶ 106) are described in thesections of this Guide dealing with these classes. Only one class may be
expressed as a suffix in a single index heading parent; less preferred classes aredenoted by prefixes. Multiplicative prefixes are employed to indicate the number of principal groups present.
Examples (in descending order of compound classes):C O2 H

Benzoic acid, 2-(chlorocarbonyl)-

COCl
E tC O 2 H

Propanoic acid

MeC H MeSO 3 H

2-Propanesulfonic acid1

2

Examples:M e ( CH 2 ) 4 O —(pentyloxy)

NOT (pentylhydroxy)

ClCO —(chlorocarbonyl)

NOT (chloroformyl)

Ph O 2 C—(phenoxycarbonyl)

NOT (phenylcarboxy)( M e O ) 2 P( O ) — (dimethoxyphosphinyl)

2-Pentanone, 4-thioxo-

H O S iMe 2 O S iMe 2 OH

1,3-Disiloxanediol, 1,1,3,3-tetramethyl-

1

NOT (dimethylphosphono)(methoxythioxomethyl) NOT (methoxycarbonothioyl)

M e O CS—

All compound radicals are enclosed in parentheses. Simple radicals are so
enclosed when two locants of like type fall together; e.g., Benzoic acid, 3-(4pyridinyl)-; for clarity, when one locant has been omitted in the name of an indefinite compound; e.g., 1,2-Propanediol, 3-(thienyl)-; and when “bis” or“tris” has been employed to remove ambiguity (see ¶ 110); e.g., tris(decyl),bis(benzanthracenyl), bis(azepinyl). Brackets are used in complex radicals,e.g., [2-(dimethylamino)ethoxy]. Spaces in a name often permit the droppingof one set of enclosing marks around radicals in substituents and modifications;e.g., Disulfide, 2-chloroethyl ethyl; Propanoic acid, 2-ethylbutyl ester.
133.
Compound radicals. Selection of names for compound radicals is
usually simple, but, when chain branching is present, can sometimes become
perplexing. The following rules are successively applied; ((a) through (e) leadto selection of the preferred parent radical, (f) through (h) to a particular occurrence of this radical).
(a)Greatest number of acyclic hetero atoms.
(b)Greatest number of skeletal atoms.
(c)Greatest number of most preferred acyclic hetero atoms (see Table
I, ¶ 128).
(d)
Greatest number of multiple bonds.
(e)Lowest locants in the simple radical for replacement atoms in “a”
names, then for multiple bonds of any kind, and finally for double bonds.
(f)Greatest number of substituents attached to the simple radical.
(g)Lowest locants for such substituents.
(h)Earliest index position of the total radical as it appears within theindex name.
Examples (the italic letters on the left indicate the particular rule (above)that is exemplified):(a)CH 2 − CH 2 −CH 3|
CH 3 − O−CH −O− CH 2 − CH 2 −O− CH 2 − CH 2 − Ο − CH 2 − CH 2 —12

MeC O C H 2 C SMe

¶ 133

11

10

9

8

7

6

5

4

3

2

1

(10-propyl-3,6,9,11-tetraoxadodec-1-yl)

5

(a)

6

1

OH

Benzenemethanol, 2-hydroxy-CH3 − C=O|
CH 3 − CH= CH−CH —(1-acetyl-2-buten-1-yl)

CH 2||
CH 3 − CH 2 −C—(1-methylenepropyl)

CH 2 − CH 2−CH 3|
CH 3 − ( CH 2 ) 3 −CH −O —[(1-propylpentyl)oxy](not (1-butylbutoxy))(the selection principles
are applied before elision is performed; another example follows)—O([1,1′-biphenyl]-4-yloxy)(not (4phenylphenoxy))4(b)CH3CH2NH2(1-silyl-1-disiloxanyl)3(b)

C H 2OH

SiH3|
H3 Si −O− SiH —Ethanamine3(b)132. Substituent prefixes (commonly called “radicals”) are employed todenote atoms and chemical groups attached to an index heading parent. The
following substituents are never expressed as suffixes; they may be termed“compulsory” or “mandatory” prefixes: astato (At-), astatyl (AtO2-), azido(N3-), bromo (Br-), chloro (Cl-), chlorosyl (OCl-), chloryl (O2Cl-), diazo (N2), fluoro (F-), iodo (I-), iodosyl (OI-), iodyl (O2I-), isocyanato (OCN-), isocyano (CN-), nitro (O2N-), aci-nitro ((HO)(O)N=), nitroso (ON-), and perchloryl(O3Cl-). In addition, all thio, sulfinyl, and sulfonyl radicals, (RS-), (RS(O)-),and (RS(O)2-), and their seleno and telluro analogs, are mandatory substituent
prefixes; so are hydrocarbon radicals and other radicals derived from molecularskeletons, e.g., ethyl, furanyl, disiloxanediyl, when attached to a more
preferred heading parent.
Radicals may be simple, compound, or complex. A compound radical ismade up of two or more simple radicals, e.g., (chlorothio), (diaminomethyl). A
complex radical is composed of a simple radical to which at least one compound radical is attached; e.g., [(chloromethyl)amino], [1-(trichloromethyl)-2buten-1-yl]. In these examples, amino and 2-buten-1-yl are parent radicals, andmethyl (in both cases) is a subsidiary radical. This procedure may be repeatedindefinitely. (Chlorothio) is obtained by addition of the two components, (aminomethyl) by substitution of methyl by amino. Substitution is the preferred
method when a substitutive simple radical is available; e.g., (aminomethylene)is (NH2CH=), not (NH2CH2-). Substitution in certain radicals, including thefollowing, is not permitted: hydroxy, mercapto, selenyl, telluryl, hydroperoxy,sulfeno, formyl, carboxy, sulfo, phosphono, and carbonothioyl.

5

2

1

3

2

2

1

1

4-2

1

(b)

(b)

O
||
C—

(b)
Cl

CO —

([1,1′-biphenyl]-4-ylcarbonyl)(not (4-phenylbenzoyl))(thesimple radical benzoyl is retainedfor (phenylcarbonyl) only when
the rules lead to this name)(4-chlorobenzoyl)(not [(4-chlorophenyl)carbonyl])

(b)
1

1′
6′

3′ 1′′[1,1′:3′,1′′-terphenyl]-5′-yl¶ 133(c)(c)

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

S −S iH 3|
H 3 S i −O− S iH —[1-(silylthio)-1-disiloxanyl]

S −CH 2 − CH2 −Ο−CH2 − CH3|
C H 3 − C H 2 −O −CH 2 −Ο−CH 2 −CH −CH 2 − O−CH 2 −CH 2 −Ο−CH 2 −CH 2 —

14

13

12

11

10 9

8

7

6

5

4

3

2

H 2 N CH 2 CO —(2-aminoacetyl)(glycyl is permitted
in peptide nomenclature)

ClCO CO —(2-chloro-2-oxoacetyl)

AcNH—(acetylamino)

E tCO N H —[(1-oxopropyl)amino]

1[8-[(2-ethoxyethyl)thio]-3,6,10,12tetraoxatetradec-1-yl]

Ph C( =N H ) ( CH 2 ) 2 CS—(4-imino-4-phenyl-1-thioxobutyl)

M e C( =N H ) N H —[(1-iminoethyl)amino]

4

(d)

(d)

C H3 − C=O|
C H 2 = C H− C H —

6

5

4

3

2

1

[1-(1-hexen-3-yn-1-yl)-3,5-heptadien-1-yl] (double bonds are preferred over an equal number of
triple bonds)(e)

C H 3 − O−CH 2 −CH 2 − O−SiH 2 −Ο−CH 2 − CH 2|
C H 3 − C H 2 − Ο −CH 2 − CH 2 −Ο−SiH 2 −Ο−CH 2 − CH−CH 2 —

11

10

9

1

(1-acetyl-2-propen-1-yl)

C H 3− C H 2− C≡C− CH= CH|
C H 3 − C H= C H−CH =CH− CH 2 − CH—
7

8

7

6

5

4

3

2

1

[2-(3,5,8-trioxa-4-silanon-1-yl)4,6,9-trioxa-5-silaundec-1-yl]

Isolated carbonyl radicals, other than carboxy, are expressed as carbonyl (asa doubling radical, or when both free valencies are attached to a single atom),formyl (if unsubstituted), benzoyl (if attached to a phenyl group which is notitself attached to another phenyl), or as a compound radical in which carbonyl
is the parent.
Examples:H O 2 CCO —(carboxycarbonyl)

H 2 N CO —(aminocarbonyl)(not carbamoyl)

ClCO —(chlorocarbonyl)(not chloroformyl)— N H CO N H —(carbonyldiimino)

HCO

(e)

C H 3 − C H2 − C≡C− CH 2 −CH =CH|
C H 3 − C H 2 −C H 2 −CH =CH− C≡C −CH− CH 2 —
9

8

7

6

5

4

3

2

C H2 = C H−C ≡C− CH2|
H C≡ C−C H =C H− CH 2 − CH—

6

(f)

5

4

3

2

1

CF 3
|
C H 3 − C−C H 2 —
|
CF 3

(f)

CH 3− CH 2|
C H 2 − CH 2 − CH—(g)[1-(4-penten-2-yn-1-yl)-3-hexen5-yn-1-yl][3,3,3-trifluoro-2-methyl-2-(trifluoromethyl)propyl](1-ethyl-3-phenylpropyl)(not [1-(2phenylethyl)propyl])[1-(2-methylpropyl)-2-oxobutyl](not [3-methyl-1-(1-oxopropyl)butyl])

C H3|
C H 3 − C H− C H —|B rC H 2 − C H 2[1-(2-bromoethyl)-2-methylpropyl](not [3-bromo-1-(1-methylethyl)propyl])

C H3|
C H 3 − C H− C H —|C H3 − C=O(1-acetyl-2-methylpropyl)(not [1(1-methylethyl)-2-oxopropyl])

3

2

1

(g)

(h)

OC

(3-carbonylcyclohexyl)
Replacement analogs of isolated carbonyl groups (other than chalcogen analogs of carboxy) are named as thioxo, imino, etc., derivatives of methyl, unless both free valencies are attached to a single atom, or the radical is being
used multiplicatively (¶ 125), in which case carbonimidoyl, carbonohydrazonoyl, carbonothioyl, etc., are employed.
Examples:134. Carbonyl radicals which form part of a carbon chain are expressedby oxo substituents on the chain; the only exceptions are carboxy (-C(O)OH)
and acetyl (-C(O)CH3) radicals. The latter is used whenever (1-oxoethyl)would otherwise be called for. All chalcogen, imido and hydrazinylidene analogs of carbonyl in a chain are treated similarly by use of thioxo, selenoxo, telluroxo, imido, and hydrazinylidene radicals, except for chalcogen analogs (butnot imido, etc., analogs) of carboxy; e.g., (HS(S)C-) is named (dithiocarboxy).
Replacement analogs of acetyl are named (1-iminoethyl), (1-thioxoethyl), etc.
Acyl radical names other than acetyl and benzoyl, e.g., propanoyl, are not used
for substituents; neither are amido radicals, e.g., acetamido.
Examples:HO2CCH2—(carboxymethyl)

HCOCH2—(2-oxoethyl)(not (formylmethyl))

E tC O —(1-oxopropyl)

C lC O C H 2 —(2-chloro-2-oxoethyl)[(dithiocarboxy)amino]

H S 2 CN H —H CS

CH 3 − CH− CH3
|
O CH2
|| |
C H 3 − C H 2 −C −CH—4(4-formylbenzoyl)

CO —

1

[2-(1-hepten-4-yn-1-yl)-5-nonen-3-yn-1-yl](e)14[4-(thioxomethyl)benzoyl]CO —H O C(= N H ) —(hydroxyiminomethyl)

H 2 N C(= N H ) N H —[(aminoiminomethyl)amino]

H N= C=N —(carbonimidoylamino)

135. Indicated hydrogen is a designation comprising a locant followed
immediately by an italic capital H placed before a ring system name to express
the position of each of the saturated atoms necessary for formation of a definable, stable ring system. Thus, Pyrrole always has one saturated atom (an atom
not connected to either of its neighbors by a double bond) and, according to theposition of this atom, the compound is named as follows:1

1H-Pyrrole

1

1

H
N
5

N

N
5

5

2H-Pyrrole

3H-Pyrrole

In the Chemical Substance Index only a single illustrative structural diagram is provided for each ring system, viz., the diagram which shows the saturated center(s) in the lowest-numbered nonangular position(s).
Tetrahydropyrrole has the trivial name Pyrrolidine: dihydropyrroles are
named as derivatives of that pyrrole which has indicated hydrogen at the lowest
numberedpositionconsistentwiththestructure.Othermonocyclicheterosystems are named in the same way. Hydrogen on a single ring atom between two
bivalent hetero atoms is not indicated in the name.
Examples:HN
5

1

1H-Pyrrole, 2,5-dihydro- (not2H-Pyrrole, 1,5-dihydro-)

15

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 136

1

1

7a

2H-Pyran, tetrahydro- (not 4HPyran, tetrahydro-)O
63aH-Indene-3a-carboxylicacid, 1,4-dihydro-

3
4

CO 2 H1

S

4H-1,3-Dithiin (not 2H,4H-1,3Dithiin)

6

S3

9

1
10a O

10

O
6

4H,6H-Benzo[1,2-b:5,4-b′]dipyran4,6-dione, 2,3,7,8-tetrahydro-

45The lowest locants for nonangular positions of fused ring systems are normally cited for indicated hydrogen.
Example:OO

4H-3a,7-Methanoazulene-4,9dione, 1,2,3,7,8,8a-hexahydro(not 1H-3a,7-Methanoazulene-4,9(7H)-dione, 2,3,8,8a-tetrahydro-)(the ketone function on the bridge
is ignored in choosing indicatedhydrogen to accommodate thesingle remaining function)

1

4H-Indene, 3a,5-dihydro- (not3aH-Indene, 4,5-dihydro- or
5H-Indene, 3a,4-dihydro-)

1
7a
3

7

8a

O
9

3a

4

O

Indicated hydrogen is assigned to angular or nonangular positions whenneeded to accommodate structural features, e.g., a bridge, spiro junction or
ring-assembly junction, if that form of the ring system can exist.
Examples:

1
8a

S

2

(2,3-dihydro-4H-1,2,4-benzo
thiadiazin-4-yl)(not 2H-1,2,4benzothiadiazin-4(3H)-yl)

NH
4
5

H
N

7a

6

N

3a,6-Methano-3aH-indole,
1,4,5,6-tetrahydro-

1

8

O

3a

1
8a O

3

1
11a
11b

Spiro[7H-benz[de]anthracene7,1′-cyclohexane], 4,5,6,6atetrahydro-

4

7
8

6′

6

1′

7a

H
N

2

2′

3

3′

Ν

1

Ν

4

H
N

7′a

1′

2,2′-Bi-2H-indazole, 1,1′,3,3′tetrahydro4′

When a bridge requires hydrogen to be added, but indicated hydrogen of theparent system cannot be used for that purpose, the lowest locant, or a locant toaccommodate a principal function, is chosen for the parent ring, and additional
indicated hydrogen is cited in the name ahead of the bridge designation.
Example:

1
7a

6

O

S2

8
3a

4H-3a,6-Methano-3H-1,2-benzoxathiole, tetrahydro- (3aH-1,2Benzoxathiole cannot exist; thelowest available locant is therefore cited and the “extra” hydrogen for the bridge cited asadditional indicated hydrogen,not in the “added” hydrogenform (see below), 3a(4H),6Methano....)

After structural requirements have been met, indicated hydrogen is chosen
to accommodate principal functions or (in a cyclic radical) free valencies, solong as the number of indicated hydrogens cited equals or exceeds the numberof principal groups or free valencies that must be accommodated. For the usualcase of a ring which requires a single indicated hydrogen for its existence, asingle principal function or free valency is accommodated, but a polyfunctional
compound is named at the ring system with lowest nonangular indicated hydrogen. (Functions on bridges are disregarded in applying this rule.)
Examples:

5

4

O

O

2H-1-Benzopyran-4,5,8(3H)-trione,
6,7-dihydro- (not 4H-1-Benzopyran-4,5,8-trione, 2,3,6,7-tetrahydro-)136. Added hydrogen is hydrogen which is added to a ring system in thesame operation as, but in a position different from, hydrogen added to accommodate structural features of a ring system, e.g., bridges, or spiro or ring-assembly junctions, or principal groups of a heading parent, or free valencies of aparent radical, when indicated hydrogen (¶ 135) is either not needed for the ringsystem itself or cannot be chosen to accommodate them. It differs from indicated hydrogen in being expressed as a locant and capital italic H in parentheses immediately following the locant for the principal function or otheraccommodated structural feature, e.g., “2(1H)-.” Use of added hydrogen permits expression of a principal function, etc., in a heading parent instead of as a
substituent. Thus, 1-Naphthalenone cannot exist without partial hydrogenation of the naphthalene ring system; a name such as Naphthalene, 1,2-dihydro-1-oxo- violates the rule that the principal function be expressed as a suffix.
Therefore, two hydrogen atoms are added in one operation to provide the name1(2H)-Naphthalenone, in which the “added” (or “extra”) hydrogen is at the 2position.
O
8a5

4H-Pyran-4-one, tetrahydro-O

4

When principal functions or free valencies require added hydrogen, it is assigned to the lowest-numbered available angular or nonangular position; e.g.,
1(2H)-Naphthalenone, 3,4-dihydro- (not 1(4H)-Naphthalenone, 2,3-dihydro-);2(4aH)-Naphthalenone, 5,6,7,8-tetrahydro-. When the ring system requires
indicated hydrogen and it cannot be assigned to accommodate a principal
group or free radical, it has preference over added hydrogen for lowest locants.
When a pair of principal groups, e.g., “-dione,” are expressed by a heading parent, added hydrogen is not cited unless necessary, it being understood that only
sufficient hydrogen has been added to accommodate the functions.
Examples:
1

8a
1

1

5

6

4a(2H)-Naphthalenecarboxylicacid, 1,3,4,5-tetrahydro(a 4a(1H)-isomer cannot exist)

4

CO 2 H
O
H
N

O
6
2

9a

N (C H 2 ) 2 OH
65

2H-2-Benzazepine-2-ethanol,
1,3,4,5-tetrahydro-

1

3

NH

O

4,6(1H,5H)-Pyrimidinedione,
dihydro-¶ 136

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
H
N

8a

5

O

(3,4-dihydro-2(1H)-quinolinylidene)(not (1,4-dihydro-2(3H)-quinolinylidene))116(6-chloro-2,5-dioxo-3-cyclohexen1-yl)

4

Cl
O

1
3

9a

9b

1H-Benz[e]indene-3,5(2H,4H )dione, 3a,9b-dihydro-

O

5

4

2-Hexen-4-yne, 6,6,6-trifluoro(double bond given preference
over triple bond)M e CH= CH C≡CCF 3

1

6

6

O
OH
1

1

O

6

CO 2 H

8a

2H-Pyran-3(4H)-one, dihydro(3H-Pyran cannot exist)

2-Azulenecarboxylic acid,8-hydroxy-4,5-dimethyl-

3

O

4

Me

Me

O
8

10

10a

1

9a

9

9,10-Anthracenedione (not 9,10(9H,10H)-Anthracenedione)

4a

NHEt

1,3-Benzenediamine, N1-ethyl-N3,N3,4-trimethyl- (not 1,3Benzenediamine, N3-ethylN1,N1,6-trimethyl-; see ¶ 114)

1

4

5

O

3

NMe2
O

O
1

9b

9a

1H-Benz[e]indene-1,2(3H)-dione(not 3H-Benz[e]indene-1,2-dione)(low numbering of indicatedhydrogen is observed, even if added hydrogen must then be cited)

3
4

5

6

(2,3-dihydro-1,4-pyrazinediyl) (not(1,4(2H,3H)-pyrazinediyl))

1

4

N

Added hydrogen cited when hydrogen is required elsewhere for spiro andring-assembly junctions is assigned (in descending order of preference) (a) toaccommodate another spiro or ring-assembly junction, (b) to accommodate
principal groups or free valencies, or (c) to lowest-numbered available positions.
137. Numbering of molecular skeletons. Lowest locants for a set of principal groups, substituents, etc., are always preferred. The set, e.g., 5,6,1,2,1 iscompared with another (alternative) set, e.g., 1,2,5,6,5, by rearranging themboth in ascending numerical sequence: 1,1,2,5,6 and 1,2,5,5,6. The set whichcontains the lowest locant at the first point of difference when all sets are compared term by term is the lowest, i.e., 1,1,2,5,6 is lower than 1,2,5,5,6.
Example:NO 2

5Naphthalene, 5-bromo-6-chloro1,2-dihydro-1-nitro- (not Naphthalene, 1-bromo-2-chloro-5,6-dihydro-5-nitro-)

1

8a

Cl

4

Br

Lowest locants for various kinds of structural features in cyclic and acyclic
molecular skeletons are assigned, in order, to:(a) hetero atoms (except for “a”-named radicals, see ¶¶ 127, 161);(b) indicated hydrogen;(c) principal groups or (for radicals) free valencies;(d) multiple bonds;(e) substituent prefixes;(f) the substituent prefix cited earliest in the name.
Examples:C H 3 − O−C H 2 −C H 2 −O−CH 2 −CH 2 −Ο−CH 2 −CH 2 −Ο−CH 2 −CH 2 −Ο H
13

12 11

10

9

8

7

6

5

4

3

2

1

3,6,9,12-Tetraoxatridecan-1-ol
1

H O2 C

2H-Pyran-6-carboxylic acid, 3,4dihydro- (not 4H-Pyran-2-carboxylic acid, 5,6-dihydro-)

O
6

O
||
C H 2 = C H− C−C H 3

4

3

2

Br

Benzene, 1-bromo-3-nitro- (notBenzene, 3-bromo-1-nitro-)

N

6

Me

1

3-Buten-2-one (not 1-Buten-3-one)

NO2

138. Index name selection. Most organic compounds have names basedon molecular skeletons, e.g., Propanoic acid (from propane); 1,3-Dioxan-2amine (from 1,3-dioxane). Procedures for selecting the preferred name of thiskind for index use are described in this section (see also ¶ 105).
Selection of a heading parent name based on a molecular skeleton is madeby successive application of the following principles until a decision isreached.
(a)Greatest number of the principal chemical functional group.
(b)
Preferred atomic content of the molecular skeleton in accordancewith the order of precedence of compound classes (¶ 106). The heading parent
should express at least one occurrence of an atom appearing earliest in the following list: N, P, As, Sb, Bi, B, Si, Ge, Sn, Pb, O, S, Se, Te. (This principle isused to decide between a cyclic and an acyclic parent, but is not applied to
choices between ring systems. When acyclic and cyclic skeletons of the same
compound class are present, a cyclic parent is preferred.)(c)Preferred ring system. The choice between ring systems for use asheading parents is based on the following criteria, applied successively until adecision is reached. The senior ring system should:(1)
be a nitrogenous heterocycle;(2)
be a heterocycle;(3)
contain the largest number of rings;(4)
be a cyclic system occurring earliest in the following list of systems; spiro, bridged fused, bridged nonfused (Von Baeyer), fused;(5)
contain the largest individual ring (applies to fused carbocyclic
systems);(6)
contain the greatest number of ring atoms;(7)
contain the greater number of ring atoms common to two or morerings (applies to Von Baeyer ring systems); thusiss e n io rto(8)contain lowest locants for bridges;(9)contain the largest number of hetero atoms;(10)
contain the most preferred hetero atom other than nitrogen, according to the order in Table I, ¶ 128, i.e., O, S, Se, Te, N, P, As, Sb, Bi, Si, Ge, Sn,
Pb, B.
(11)
possess the most linear arrangement of rings (thus, Anthracene issenior to Phenanthrene);(12)
possess the lowest locants for hetero atoms assigned according to
the rules (¶¶ 146, 152);(13)
express the lowest state of hydrogenation; thus, Benzene is preferred over Cyclohexane, Pyridine over Piperidine;(14)
express the lowest locant for indicated hydrogen.
Note: These criteria differ from those employed in selecting basecomponents for fused systems (¶ 150).
(d)
Greatest number of acyclic hetero atoms.
(e)Largest index heading parent.

17Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

(f)
Greatest number of most preferred acyclic hetero atoms, according
to the order of precedence in ¶ 128, above; i.e., O, S, Se, Te, N, P, As, Sb, Bi,
Si, Ge, Sn, Pb, B.
(g)
Greatest number of multiple bonds.
(h)Lowest locants in the heading parent successively for hetero atoms, principal groups (suffixes), all multiple bonds, double bonds.
If the preferred heading parent occurs more than once in the total compound, further principles must be applied, as follows:(i)
Centrality. For three or more occurrences of the heading parent, atleast one of which must be nonterminal, the basis of the name is the central occurrence (or one of the central pair—both, when multiplicative nomenclature
is permitted—if the total number is even) in the linear arrangement which comprises all or part of the maximum number of occurrences.
(j)
Maximum number of substituent prefixes.
(k)Lowest locants for substituents on the heading parent.
(l)Multiplication of heading parents; when there is a choice of multiplicative names, that one is chosen which multiplies the largest number of occurrences of the index heading parent.
(m) Earliest index position of the total name.
Examples (the italic letters on the left indicate the particular rules(above) that are exemplified):
(a)

|

3

2

C H 3 − C H− C H−C H 2 −OH
4

(e)

5

4

HO

3

2

Hexane, 3-methylene- (not 1-Pentene, 2-ethyl-)1

CH ( O H ) CH 2 O H
β

1,3-Benzenediethanol, β1, 5-dihydroxy- (see ¶ 124)α( CH 2 ) 2 O H(f)

H 3 SiO SiH 2 SiH 2 SSiH 3

Disiloxane, 1-disilathianyl-

CH 3|
CH 2 =C −CH= CH 2

1,3-Butadiene, 2-methyl-

3 2 1

(g)

1

1,3-Butanediol, 2-pentyl-

1

CH 2
||
CH 3 −CH 2 −CH 2 −C− CH 2 −CH 36(g)

OH CH 2 − C H 2 − CH 2 −CH 2 −CH 3
|

(e)

2

C≡C− CH 2 − CH 2 −O H|
H O−CH 2 −CH =CH− CH 2 − CH−CH 2 −CH =CH− CH 2 −O H
9

8

7

6

5

4

3

2

1

2,7-Nonadiene-1,9-diol, 5-(4-hydroxy-1-butyn-1-yl)- (double
bonds are preferred over an equal
number of triple bonds)(a)
H O2 C¶ 138

CH( CO 2 H) CH 2 CO 2 H

Butanedioic acid, 2-(4-carboxyphenyl)(h)(b)
H O2 CNHNHCO 2 H
2

10 11

Hydrazinecarboxylic acid, 2-(4carboxyphenyl)-

1

9

(b)
O

S iH 2 SiH 3

Diazene, phenyl- (not Benzenamine,N-imino-) (homogeneous hetero
chains are never broken to obtaina higher function or more
preferred parent)

PhN=NH(C H 2 ) 6 −CH 3|
C H− C OOHα(b)2-Pyridinecarboxylic acid, 5-(2carboxyhydrazino)- (the numberof preferred hetero atoms in thecyclic and acyclic chains is disregarded)

CO 2 HN

H O2 C N H N H

6

5

2

3

4

5

6

7

8

9

10

11

12

13

14

3

2

1

ΟΗ
H O - CH2 - CH2 - CH 2||
H O−CH 2 −CH 2 −CH 2 − CH 2 −CH −CH 2 −CH− CH 3
1

2

3

4

5

6

7

8

1,7-Octanediol, 5-(3-hydroxypropyl)- (not 1,8-Octanediol,
4-(2-hydroxypropyl)-)(h)
CH 2 −CH =CH −CH 2 − O H|
H O−CH 2 −CH =CH− CH 2 − CH−CH =CH −CH 2 − CH 2 −O H
2

3

4

5

6

O− CH 2 − CH 2 −Ο−CH 2 − C H 3|
C H 3 − Ο −C H 2 − C H 2 −Ο−CH 2 − CH 2 −Ο−CH− CH 2 − NHNH− CH 2 −CH 2 −CH 3

1

4

(h)

1

(b)

7

4,6,8,10-Tetraoxadodecanoic
acid, 9-(methoxymethyl)- (not3,5,7,9-Tetraoxadodecan-12-oic
acid, 4-(methoxymethyl)-)Benzeneacetic acid, α-heptyl(not Nonanoic acid, 2-phenyl-)168Disilane, 2-furanyl-

(b)

(b)

12

O−CH2 −CH3|
CH 3 −O −CH 2 − CH− O−CH 2 − O−CH 2 −O− CH 2 − CH 2 −CO O H

7

8

9

2,6-Nonadiene-1,9-diol, 5-(4-hydroxy-2-buten-1-yl)- (not 2,7Nonadiene-1,9-diol, 5-(4-hydroxy-1-butenyl)-)15

2,5,8-Trioxa-11,12-diazapentadecane, 9-(2-ethoxyethoxy)(c)NH

N

3-Quinolinol, 2-(1,2-dihydro-2hydroxy-5-pyrimidinyl)-

OH
N

(i)

Benzene, 1,4-bis(phenylmethyl)-

Ph CH 2CH2 PhOH(d)
C H 2 − C H 2 − CH 2|
C H 3 − Ο −C H − Ο −CH 2 −Ο−CH 2 −Ο−CH 2 −Ο−CH 3
1

2

3

4

5

6

7

8

9

(i)

2,4,6,8,10-Pentaoxaundecane, 3propyl(e)HCO

Cl 2 CH CH 2 O ( CH 2 ) 2 O ( CH 2 ) 2 Cl

10 11

(i)

Ethane, 1-(2-chloroethoxy)-2(2,2-dichloroethoxy)-

NH2( CH 2 ) 8 CHO

Benzenenonanal, 4-formyl- (notBenzaldehyde, 4-(9-oxononyl)-)(e)
CH=CH −CH 2 − OH|
H O−C H 2 −C H 2 − CH 2 − CH 2 −CH −CH= CH− CH 2 − CΗ 2 −OH
9

8

7

6

5

4

3

2

1

3-Nonene-1,9-diol, 5-(3-hydroxy-1propen-1-yl)- (not 2,5-Octadiene1,8-diol, 5-(4-hydroxybutyl)-)

H2 N

N

NH

NH

NH2

1,4-Benzenediamine, N1,N1-bis(4aminophenyl)-N4-[4-[(4-aminophenyl)amino]phenyl]-¶ 138

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

(i,j)

18

(k)
H O2 C

Cl

Cl
1

CH3
CH 2

CH− CH2
|
CH 3

CH 2

CO 2 HO

6

CH3

Benzoic acid, 3-(4-carboxy-2chlorophenoxy)-2-chloro-

CH3

CH3

Benzene, 2-methyl-1-[1-methyl-2[4-[(3,4,5-trimethylphenyl)methyl]phenyl]ethyl]-4-(phenylmethyl)- (of the two central
occurrences of the preferredheading parent, the one with the
maximum number (three) of substituents is chosen; note that thecentrality principle prevents
choice of the tetrasubstituted parent on the right)

(i,l)

(l)
CH 2 − O−CH −O− CH 2

Benzene, 1,1′-[(phenylmethylene)bis(oxymethylene)]bis(note that all occurrences of benzene are terminal and that the
principle of centrality is therefore
not applicable)
(l,m)

Cl

CH 2

CH2

CH2

Cl

C−O−C−S−C

Benzene, 1,1′-methylenebis[4[(4-chlorophenyl)methyl]-

Benzene, 1,1′,1′′-[[[diphenyl(triphenylmethoxy)methyl]thio]methylidyne]tris- (notBenzene, 1,1′,1′′-[[diphenyl[(triphenylmethyl)thio]methoxy]methylidynetris-)

(i,l)
CH 2

CH 2

CH

CH2

Benzene, 1,1′,1′′-methylidynetris[4-( phenylmethyl)- (whenmultiplication of the heading parent is permitted, occurrences directly attached to the centralconnecting radical are includedin the same operation if possible)(m)
F 3 CCF( CCl 3 ) CO 2 H

Propanoic acid, 2,3,3,3-tetrafluoro- 2-(trichloromethyl)- (notPropanoic acid, 3,3,3-trichloro2-fluoro-2-(trifluoromethyl)-)O

Cyclohexanone, 2-[2-(2-oxocyclohexyl)ethylidene]- (not Cyclohexanone, 2-[2-(2-oxocyclohexylidene)ethyl]-)

1

3 2

(m)

(j)

CHCH 2CH− CH 2 − COOH

H2 N

Benzenepropanoic acid, 4-aminoβ-phenyl-O139. Subtractive nomenclature employs the suffixes “-ene” and “-yne”
to signify removal of hydrogen pairs from saturated molecular skeletons; removal of hydrogen atoms from an aromatic system is denoted by “dehydro.”
Examples:
1

(j)

6

CH 3
|
C C l 3− C− C O OH
|2 1
3
CCl 3

Propanoic acid, 3,3,3-trichloro2-methyl-2-(trichloromethyl)(not Propanoic acid, 2,2bis(trichloromethyl)-) (liketreatment of like groups is discontinued ( ¶ 255))

7

Bicyclo[2.2.1]hepta-2,5-diene

4
1
6

N

Pyridine, 2,3-didehydro- (not Pyridyne)

(k)
6
1

NH

Me

N

Me

Benzenamine, 2-methyl-N-(4methylphenyl)-

Functional class names such as “anhydride,” “ester,” “oxime,” imply lossof water and may strictly be regarded as subtractive terms. Prefixes such as“deoxy,” “nor,” and “anhydro,” are sometimes employed in names for classesof stereoparents (see Section E), but never in general index nomenclature.

19

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 143

B. MOLECULAR SKELETONSIntroduction
Acyclic hydrocarbons
Organic hetero chains
Homogeneous hetero chains
Heterogeneous hetero chains
Monocyclic hydrocarbons
Monocyclic hetero systems
Polycyclic systems
Fundamental fused carbocycles
Fundamental fused heterocycles
Selection of a base component
Index names for fused systems
Orientation and numbering of fused systems

¶ 140
141
142
143
144
145
146
147
148
149
150
151
152

140. Introduction. A molecular skeleton is defined for purposes of nameselection as a chain or ring of atoms in which the number of hydrogen atoms
attached to each skeletal atom is (usually) implied or (occasionally) explicitly
stated by citation of the substitutive valency and bonding of the skeletal atoms.
Monoatomic hydrides of Group IVA and VA elements (except nitrogen) arealso treated as molecular skeletons; so are boron hydrides, but because of their
unusual nature these are discussed separately (¶ 159).
Examples:CH4

MethaneA sH 5

Arsorane

H 3 S iO SiH 2 O SiH 2

Trisiloxane

H 3 S nS nH 3

Distannane

13

12 11

10

9

8

7

6

5

4

M e CH =CH CH 2 CH =CH 2

1,4-Hexadiene (not 2,5-Hexadiene)

H 2 C=C=CH 2

1,2-Propadiene

M e CH 2 C≡CCH 2 M e

3-Hexyne

H C≡ CC≡ CH

1,3-Butadiyne

1

1

3

2

4

1-Penten-4-yne

H C≡ CCH 2CH =CH 2
51

3,6,9,12 -Tetraoxatetradecane

¶ 153
154
155
156
157
158
159
160
161
162
163
163A

set of multiple bonds; when there is a choice, double bonds are preferred over
triple bonds. When principal groups (functional suffixes) are present, these andnot the multiple bonds are preferred for low numbering.
Examples:6

C H 3- C H 2- O- C H 2- CH 2 - O -CH 2- CH 2 - O - CH 2 - CH 2- O - CH 2- CH 3

14

Replacement (“a”) nomenclature for fused systems
Bridged fused systems
Von Baeyer nomenclature
Spiro systems
Ring assemblies
Hetero atoms with abnormal valencies
Boron molecular skeletons“Hetero” polyboranes
Substituent prefixes from molecular skeletons
Compound and complex radicals
Molecular skeletons as index heading parents
Fullerenes1

M e CH =CH ( CH 2 ) 3 C ≡ CH

6-Octen-1-yne (not 2-Octen-7-yne)

H 2 C=CH CH 2 O H

2-Propen-1-ol (not 1-Propen-3-ol)

1BenzeneH
N

Pyrrolidine

8

1

9
9a

4b

9H-Fluorene

142. Organic hetero chains containing at least four hetero units (¶ 127)
are given “a” names, i.e., replacement names based on the hydrocarbon
skeleton by use of “oxa,” “thia,” etc., prefixes. Lowest locants (¶ 137) are
assigned to all hetero atoms regardless of type and then to preferred hetero
atoms (Table I, ¶ 128). Locants for functional suffixes take precedence for low
numbering.
Examples:CH 3 - CH 2 - O - CH 2 - CH 2 - O - CH 2 - CH 2 - O - CH 2 - CH 2 - O - CH 3

4a

13

12

11 10

9

8

7

6

5

4

3

2

1

2,5,8,11-Tetraoxatridecane
Bicyclo[2.2.1]hept-2-ene
CH 3 −− O−− SiH 2 −− CH 2 −− CH 2 −− SiH 2 −− S−− CH 3

1

1′

6

S

S

4

5

6

7

8

CH 3 - CH 2 - SiH 2 - CH 2 - CH 2 - SiH 2 - CH 2 - CH 2 - SiH 2 - CH 2 - CH 2 - SiH 2 - C H 2 -C H 3
2

3

4

5

6

7

8

9

10

11

12

13

14

3,6,9,12-Tetrasilatetradecane

17

32-Oxa-7-thia-3,6-disilaoctane (not7-Oxa-2-thia-3,6-disilaoctane)
1

3′

4′

4

Spiro[cyclopentane-1,1′-[1H ]indene]

5

1

7′a

2

7λ4-[1,2]Dithiolo[1,5-b][1,2]di-S

thiole3

H 2 C=CH CH 2 [ O ( CH 2 ) 2 ] 3 O M e

2,5,8,11-Tetraoxatetradec-13-ene

H 2 C=CH ( O CH =CH ) 3 O CH =CH 2

3,6,9,12-Tetraoxatetradeca1,4,7,10,13-pentaene

14

14

Molecular skeletons are nonfunctional substitutive parent compounds. Substituents denoting a preferred compound class are generally cited as suffixes
and other substituents as prefixes. Molecular skeletons, alone or in combination with a substituent suffix, are index heading parents.
This part of the manual deals with the formation of index names forstructures that consist solely of one or more molecular skeletons.
141. Acyclic hydrocarbons. Saturated unbranched alkanes containing one
through four carbon atoms are named Methane, Ethane, Propane, andButane. Higher members of the class are named by adding the termination“-ane” to the appropriate multiplicative term, as, Nonane for C9H20, Hexadecane for C16H34, Eicosane for C20H42, Heneicosane for C21H44, and Tritriacontane for C33H68.
Unsaturated unbranched acyclic hydrocarbons (unbranched alkenes,
alkadienes, alkynes, etc.) are named by replacing the ending “-ane” by “-ene”(for a single double bond), “-adiene” for two double bonds, “-yne” for a single
triple bond, etc. Combinations, e.g., “-enyne,” “-trienediyne,” are employedwhen both bond types are present. Low numbering (¶ 137) is employed for the

12

13

2 1

3

1

143. Homogeneous hetero chains are considered to include the mononuclear hydrides Phosphine (PH3), Phosphorane (PH5), Arsine (AsH3),
Arsorane (AsH5), Stibine (SbH3), Bismuthine (BiH3), Silane (SiH4),
Germane (GeH4), Stannane (SnH4), and Plumbane (PbH4). Chains composed of two or more of these hydride residues are named by prefixing the hydride name with “Di,” “Tri,” etc.
Examples:H 2 BiBiH 2

Dibismuthine

H 4 PPH 4

Diphosphorane

H 3 Sn Sn H 2 Sn H 3

Tristannane

H 3 Si( SiH 2 ) 3 SiH 3

Pentasilane¶ 143Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Saturated nitrogen chains are named Hydrazine (not Diazane) for
H2NNH2, Triazane for H2NNHNH2, Tetrazane for H2NNHNHNH2, etc.
Unsaturation is denoted by use of the subtractive suffixes “-ene” and“-yne.” Locants are employed as for hydrocarbon chains (¶¶ 114, 141).
Examples:H A s=A sH

Diarsene

H 2 S i=SiH 2

Disilene

H 2 N N =N N H 2

2-Tetrazene

H N =N N =N H

1,3-Tetrazadiene

Trisiloxane

H3GeSeGeH3

Digermaselenane

H 3 SnSSnH 2 SSnH 3

Tristannathiane

1 2 3

1

1,3-Cyclohexadien -5-yne (notBenzyne)

4 5

2 3

1 2 3

1,3-Cyclopentadiene

Cyclohexene

144. Heterogeneous hetero chains in which any one of the Group IVA
elements (silicon, germanium, tin, or lead) alternates with chalcogen are given“oxane,” “thiane,” etc. names.
Examples:H 3 SiOSiH 2 OSiH 3

146. Monocyclic hetero systems.
(a) Rings of three through ten members containing nonmetallic hetero
atoms (except silicon) are named systematically by the (extended) HantzschWidman system or at trivial names. Table II supplies the stems for the systematic names, which are completed by adding replacement prefixes for the hetero
atoms in the order set out in Table I, ¶128, e.g., oxa, thia, aza, together withlocants and multiplicative prefixes denoting the position and number of each.
A locant for a single hetero atom is not cited. The preferred hetero atom is numbered “1.” This means the set of locants may not be the lowest possible, as defined in ¶137. The letter “a” of replacement prefixes is elided before anothervowel in Hantzsch-Widman names; e.g., Dioxazole, not Dioxaazole.
Examples:

4 5

1

O

Chains of alternating atoms of a Group IVA element and nitrogen, e.g.,
SiH3NHSiH3, SnH3NHSnH3, are not named Disilazane, Distannazane, etc.
Instead, the amine function is recognized; thus, Disilazane is indexed at
Silanamine, N-silyl-. However, substituent radicals derived from such heterogeneous chains containing nitrogen, e.g., 1-disilazanyl for SiH3NHSiH2 -, areemployed in the presence of higher functions (see ¶161).
“A” names for hetero chains are avoided unless carbon substituents can be
included in the chain. Otherwise the preferred parent is a homogeneous hetero
chain, hydride, or element name.
Examples:H 3 G eO SiH 2 S P bH 3

Silane, (germyloxy)(plumbylthio)-

H 3 G eO PbH 2 SeMe

2-Oxa-4-selena-1-germa-3plumbapentane

Oxirene

3

H
N

Aziridine

1

3
1

6

P

Phosphorin

1
1

2 3

4

20

Oxazole (not 1,3-Oxazole, because the
1,2 - isomer has the trivial name
Isoxazole)

O
5

N
3

145. Monocyclic hydrocarbons (cycloalkanes, cycloalkenes, etc.) are
named by attaching the prefix “cyclo” to the name of the acyclic hydrocarbon
with the same number of carbon atoms. Unsaturation is expressed by use of“-ene” and “-yne” in place of “-ane” as for the acyclic analogs. No locant is employed for a single multiple bond; lowest locants (¶ 137) are cited when two or
more multiple bonds are present. The trivial name Benzene is used for 1,3,5Cyclohexatriene.
Examples:1

1,2-Oxathiolane (all locants areplaced ahead of the name; cf.
¶146(c), below)

O
S2

5

2H-1,5,2-Dithiazine (not 1H-2,4,1Dithiazine; not 6H-1,3,6-Dithiazine;
not 4H-1,5,4-Dithiazine) (Thenumbering must begin with a sulfur
atom and proceed in the directionthat gives lowest numbers to theremaining hetero atoms.) (The“2H” signifies indicated hydrogen(see ¶ 135)).

1

S
6

2

NH

5S

Cyclohexane

TABLE II
HANTZSCH-WIDMAN STEMS FOR MONOCYCLIC HETEROSYSTEMS OF THREE THROUGH TEN MEMBERS1
No. ofmembers in
the ring
3
4
5
6
7
8
9
10

Rings containing nitrogen
Unsaturated-irine
-ete
-ole
-ine3
-epine-ocine-onine-ecine2

Rings containing no nitrogen

Saturated-iridine-etidine-olidine

4
4
4
4
4

1The symbols denoting the ring sizes for 3, 4, 7, 8, 9, 10 members are derived from numerical prefixes as follows: “ri” from tri; “et” from tetra; “ep”
from hepta; “oc” from octa; “on” from nona; and “ec” from deca.
2Corresponds to the maximum number of noncumulative double bonds
when the hetero atoms have the substituent valencies given in Table I, ¶ 128.
3When the Hantzsch-Widman prefixes “phospha,” “arsa,” or “stiba” areimmediately followed by the Hantzsch-Widman stems “-in” or “-ine,” they are
replaced by the prefixes “phosphor,” “arsen,” or “stibin,” respectively.

Unsaturated2-irene
-ete
-ole
-in3
-epin
-ocin
-onin
-ecin

Saturated-irane-etane-olane-ane5,6-epane-ocane-onane-ecane4Saturation is expressed by detachable prefixes such as “tetrahydro-,”“hexahydro-,” etc. The prefix “perhydro-” is not used.
5This stem is not used for saturated hetero systems based on the elements
silicon, germanium, tin, or lead. Saturation of these rings is indicated by detachable prefixes such as “tetrahydro-,” “-hexahydro-,” etc., when HantzschWidman names are used.
6Saturation of six-membered hetero systems based on the elements boronor phosphorus is denoted by the stem “-inane.”21

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Table II indicates those cases in which special endings are employed for fully
saturated monocyclic hetero systems: e.g., Azetidine, not Azete, tetrahydro-.
Special names for partially saturated ring systems are discontinued.
Example:(c) Rings of more than ten members not containing silicon atoms are indexed at organic replacement (“a”) names. Unsaturation is indicated by “-ene”
and “-yne” suffixes.
Examples:

1

4

¶ 148

H
N

11

NH

1

Azete, 1,2-dihydro- (not 2-Azetine)

Azacycloundecane

6

Certain five- and six-membered monocyclic hetero systems, both saturated andunsaturated, are indexed at trivial names. These names are set out in Table III
in the order of the corresponding Hantzsch-Widman names, which are not used
for indexing. Fully hydrogenated five-membered rings are given “-olidine”
names, as for systematically named systems. Special names for partially hydrogenated five-membered rings e.g., 2-Pyrroline, were discontinued in 1972;
they are now named as dihydro derivatives of the fully unsaturated rings. Indicated hydrogen (see ¶135) is necessary in some rings to describe the locationof the saturated skeletal atom, e.g., 1H-Pyrrole, 2H-Pyrrole, 3H-Pyrrole.
Presence of a triple bond in addition to the maximum number of noncumulative
double bonds is expressed by the subtractive prefix “didehydro.”
Example:N

Pyridine, 2,3-didehydro-

H
N

H
P

10

HN 9
HP

H
N

H
P

11

1

2P H

12
5

8
7

6

N
H

P
H

N
H

3

4

NH

P
H

O

1,6-Dioxacyclododec-3-yne
O(d) Rings containing silicon in general are indexed at replacement (“a”)
names based on the cyclic hydrocarbons. Systems comprising only silicon atoms or silicon atoms alternating with nitrogen or one of the chalcogens are given “Cyclosila-” names.
Examples:
H2
Si

Silacyclopropane

1

TABLE III
MONOCYCLIC HETERO SYSTEMSWITH TRIVIAL NAMES

3

H
N1

N2

5

Index name
Azine
Pyridine
Azine, hexahydroPiperidine
Azole
Pyrrole (1H-, 2H-, or 3H-)
Azolidine
Pyrrolidine
1,2-Diazine
Pyridazine
1,3-Diazine
Pyrimidine
1,4-Diazine
Pyrazine
1,4-Diazine, hexahydroPiperazine
1,2-Diazole
Pyrazole (1H-, 3H-, or 4H-)
1,3-Diazole
Imidazole (1H-, 2H-, or 4H-)
1,2-Diazolidine
Pyrazolidine
1,3-Diazolidine
Imidazolidine
2H-1,4-Oxazine, tetrahydroMorpholine
1,2-Oxazole
Isoxazole
Oxin
Pyran (2H- or 4H-)
Oxole
Furan
1,2-Selenazole
Isoselenazole
Selenole
Selenophene
Tellurole
Tellurophene
2H-1,4-Thiazine, tetrahydroThiomorpholine
1,2-Thiazole
Isothiazole
ThioleThiophene
1,3,5,2,4,6-Triazatriborine, hexahydro- Borazine
1,3,5,2,4,6-Trioxatriborinane
Boroxin
1,3,5,2,4,6-Trithiatriborinane
Borthiin

Hantzsch-Widman name(b) Rings of three through ten members containing antimony, tin, lead,
germanium or bismuth atoms in addition to carbon atoms are indexed at
Hantzsch-Widman names. Partially saturated and fully saturated six-membered ring systems of this type containing germanium, lead or tin are named on
the basis of the unsaturated rings. Heterocycles containing metallic atoms otherthan the above five are indexed by coordination nomenclature (¶ 215).
Examples:
1

O
6

2

Sn H 2

4H-1,3,2-Dioxastannin, dihydro-

O3

1

O

5

2

H2 Ge

Ge H 2H 2 GeGe H 2

3

4

H
Si
1

6

Silabenzene

H2
Si

5

Si H2

H2 Si

3

H
N

4

H2 Si

H 2Sn
5S

1

3

4

Cyclodisilazane

2

SiH2

N
H
H2
Si

1

O

10

H2 O
Si

11

O9
H 2 Si 8

12

O

6

7

Si
H2

O

4

Si
H2

Cyclohexasiloxane

O3

4
1
6
12b

2

10a

9

5

12c

S3

5

2

Si H 2147. Polycyclic systems may be subdivided into four classes as follows:(a) Fused systems contain at least two rings of five or more members andonly “ortho-” or “ortho- and peri-” fusions (see below).
(b) Bridged systems are monocyclic or fused systems with valence bonds,
atoms, or chains connecting different parts of the structure.
(c) Spiro systems have pairs of rings (or ring systems) with only one
common atom.
(d) Ring assemblies have pairs of rings (or ring systems) connected bysingle bonds.
In the following sections, methods of naming ring systems of all these types
will be described. The names of more complicated cases are built up from basecomponents which may be described as “fundamental” systems.
148. Fundamental fused carbocycles with ortho-fusions only, e.g.,
Naphthalene, have adjoining rings with only two atoms in common; they thus
have n common faces and 2n common atoms. An ortho- and peri-fused system
contains a ring which has two, and only two, atoms in common with each of
two or more rings, the total system containing n common faces and fewer than
2n common atoms.
Examples:Oxatetragermolane

8

1,3,5,2,4,6-Trithiatristannin

9

8

1

3
10c

10b

6

5

7

Sn H 2SnH2Cyclopentasilane

Si H2

4

12a

S

2

1

H 2 Si1
6

1,2,4-Triaza-3-silacyclopent-2-ene

Si H

HN

3

4

1,3,5,7,9,11-Hexaaza-2,4,6,8,10,12hexaphosphacyclododecane

4

An ortho-fused system
An ortho- and peri-fused system(3 common faces; 6 common atoms) (5 common faces; 6 common atoms)¶ 148

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Systems of five or more ortho-fused benzene rings are named by the“acene” system if the arrangement is linear, by the “phene” system if one
central angular site is present.
Examples:
11

12

13

14

8

7

6

5

14a

1

Pentacene

149. Fundamental fused heterocycles often have trivial names, e.g.,
Cinnoline, Xanthene. Others belong to one or another semisystematic system.
A linear set of three fused six-membered rings with the same hetero element inboth unfused positions of the central ring are given “-anthrene” names.
Example:

20a

4

20
5
17

16

C5-C5-C6-C6-C6-C6-C6
C6-C6-C6-C6-C6-C6-C6
C6-C6-C6-C6-C6-C6-C6
C6-C6-C6-C6-C6-C6-C6
C6-C6-C6-C6-C6-C6-C6
C6-C6-C6-C6-C6-C6-C6-C6
C6-C6-C6-C6-C6-C6-C6-C6-C6-C6

Rubicene
Coronene
Trinaphthylene
Heptaphene
Heptacene
Pyranthrene
Ovalene

4

1

15

19
18 18a6

Octaphene

18b

9

10

6

B

B 10a

1

7
11

12

10

9

Boranthrene

8Names ending in “-alene” are employed for bicyclic fused systems, and in“-phenylene” for systems built up from benzene rings fused to alternate sides
of a monocyclic hydrocarbon. (Analogous “-naphthylene” names have beenused for corresponding 2,3-fusion systems of naphthalene.)
Examples:1
6a

A similar set with different hetero elements in these positions is given a“Pheno-” name containing the organic replacement terms in the usual order(Table I, ¶128) and the ending “-in” (or “-ine” if nitrogen, phosphorus orarsenic is included).
Example:H
1
Si 10a93

45Pentalene
410

1H-Phenoxasilin

1
12a
12b
8b

4a

22

Triphenylene

O

8

4

5

4b
8a

Table IV lists the names of trivially-named fundamental fused carbocycles
in ascending order of preference for adoption as base components in the naming of more complex fused hydrocarbon systems. Also included are some of
the names discussed immediately above. (The order is based on the rules described in ¶¶138, 150.) The ring analyses describe the number of component
rings and the number of atoms each ring contains. Diagrams of these rings,
which show the preferred orientation and numbering, are displayed in the Ring
Systems Handbook. Diagrams justified by current entries are also provided in
the semiannual and collective Chemical Substance Indexes.
The following ring systems require citation of indicated hydrogen (¶ 135)
to complete the name: Indene, Fluorene, Phenalene, Trindene.
TABLE IV
FUNDAMENTAL FUSED CARBOCYCLES IN
ASCENDING ORDER OF PRECEDENCE FOR
USE AS BASE COMPONENTS IN FUSEDSYSTEMSAn exception is Phenazine for the analog that contains nitrogen in both central
positions.
Arsenic and phosphorus analogs of fused nitrogen heterocycles (Indole,
Quinoline, etc.) are named as follows: Arsindole, Isoarsindole, Arsinoline,
Isoarsinoline, Phosphindole, Isophosphindole, Phosphinoline, Isophosphinoline, Arsanthridine, Acridarsine, Acridophosphine, Phenarsazine,
Phenophosphazine.
The replacement of the oxygen in Xanthene by sulfur or selenium has been
denoted by the appropriate chalcogen functional replacement prefix: Thioxanthene, Selenoxanthene.
In the “benzo” system, bicyclic fused heterocyclic systems containing abenzene ring and a ring named by the Hantzsch-Widman system are indexedby prefixing the latter name by “Benz-” or “Benzo-.” Indicated hydrogen, if
necessary, and locants are placed in front of the complete name. Similar names
are used when benzene is fused to a monocycle with a trivial name (unless thebicyclic system itself has a trivial name).
Examples:1

8aRing analysis
C5-C5
C5-C6
C6-C6
C5-C7
C7-C7
C4-C6-C6
C5-C5-C6
C5-C5-C6
C5-C6-C6
C5-C6-C6
C6-C6-C6
C6-C6-C6
C6-C6-C6
C5-C5-C5-C6
C5-C6-C6-C6
C5-C6-C6-C6
C5-C6-C6-C6
C6-C6-C6-C6
C6-C6-C6-C6
C6-C6-C6-C6
C6-C6-C6-C6
C6-C6-C6-C7
C6-C6-C6-C6-C6
C6-C6-C6-C6-C6
C6-C6-C6-C6-C6
C6-C6-C6-C6-C6
C6-C6-C6-C6-C8
C6-C6-C6-C6-C6-C6
C6-C6-C6-C6-C6-C6

4H-3,1-Benzoxazine (not 4H-Benz[d]oxazine)

O3
4

5

Name
Pentalene
IndeneNaphthalene
AzuleneHeptalene
Biphenylene
as-Indacenes-Indacene
Acenaphthylene
Fluorene
Phenalene
Phenanthrene
Anthracene
Trindene
Fluoranthene
Acephenanthrylene
Aceanthrylene
Triphenylene
PyreneChrysene
Naphthacene
Pleiadene
PicenePerylene
Pentaphene
Pentacene
Tetraphenylene
Hexaphene
HexaceneN

1
7aBenzoxazole (locants are not cited; theisomers are named 1,2- and 2,1Benzisoxazole)

O
N3

4

1
7a

O

Benzofuran (the isomer is named
Isobenzofuran)

3
4

Such “benzo” names are not usually adopted as base components of fusedsystems when only hydrocarbon rings are fused to the benzene portion.
When benzene is fused to a heterocyclic ring containing more than ten
skeletal atoms, “Benzo-” or “Benz-” is placed ahead of the replacement (“a”)
name of the saturated ring and the ending changed to “-in” (or “-ine” ifnitrogenous) to indicate the maximum number of noncumulative double bonds.
(Saturated positions other than those occupied by indicated hydrogen are
denoted by hydro substituents.)
Example:

1
15a O
6
12

O

11

2H-1,11-Benzodioxacyclotridecin,
5,6-dihydro-

23

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Trivially named fundamental fused hetero systems are listed in Table V.
Also included are some of the systems discussed immediately above, as well
as a selection of monocyclic hetero systems to help illustrate the ascendingorder of priority for adoption as base components in complex fused systems.
Fused systems containing only silicon and carbon skeletal atoms areindexed at “Sila-” replacement names if the corresponding hydrocarbon has afundamental name (Table IV, ¶148).

TABLE VFUNDAMENTAL HETEROCYCLES IN
ASCENDING ORDER OF PRECEDENCE FOR
USE AS BASE COMPONENTS IN FUSEDSYSTEMS1
Index Name
Isoarsindole2
Arsindole2
Isoarsinoline
Arsinoline
Arsanthridine
Acridarsine
Arsanthrene
Isophosphindole2
Phosphindole2
Isophosphinoline
Phosphinoline
Tellurophene
Selenophene
Selenanthrene
Thiophene
Thianthrene
Furan
Pyran2
Isobenzofuran
Xanthene2
Phenoxastibinin
Phenoxarsine2
Phenoxaphosphine2
Phenoxatellurin
Phenoxaselenin
Phenoxathiin
Pyrrole2
Imidazole2
Pyrazole2
Isothiazole
Isoxazole
Pyridine
Pyrazine
Pyridazine
Pyrrolizine2
Indolizine
Isoindole2
Indole2
Indazole2
Purine2Isoquinoline3
Quinoline3
Quinolizine3
Phthalazine
Naphthyridine4
Quinoxaline
Quinazoline
Cinnoline
Pteridine
Carbazole2
Phenanthridine
Acridine
Perimidine2
Phenanthroline5
Phenazine
Anthyridine
Phenarsazine
Phenophosphazine
Phenotellurazine2
Phenoselenazine2
Phenothiazine2
Phenoxazine2
Thebenidine
Quindoline2
Quinindoline2
Phthaloperine2
Acrindoline2
Triphenodithiazine

Ring Analysis
C4As-C6
C4As-C6
C5As-C6
C5As-C6
C5As-C6-C6
C5As-C6-C6
C4As2-C6-C6
C4P-C6
C4P-C6
C5P-C6
C5P-C6
C4Te
C5Se
C4Se2-C6-C6
C4S
C4S2-C6-C6
C4O
C5O
C4O-C6C5O-C6-C6
C4OSb-C6-C6
C4AsO-C6-C6
C4OP-C6-C6
C4OTe-C6-C6
C4OSe-C6-C6
C4OS-C6-C6
C4N
C2N2
C3N2
C3NS
C3NO
C5N
C4N2
C4N2
C4N-C4N
C4N-C5N
C4N-C6
C4N-C6
C3N2-C6
C3N2-C4N2
C5N-C6
C5N-C6
C5N-C5N
C4N2-C6C5N-C5N
C4N2-C6
C4N2-C6
C4N2-C6
C4N2-C4N2
C4N-C6-C6
C5N-C6-C6
C5N-C6-C6
C4N2-C6-C6
C5N-C5N-C6
C4N2-C6-C6
C5N-C5N-C5N
C4AsN-C6-C6
C4NP-C6-C6
C4NTe-C6-C6
C4NSe-C6-C6
C4NS-C6-C6
C4NO-C6-C6
C5N-C6-C6-C6
C4N-C5N-C6-C6
C4N-C5N-C6-C6
C5-C4N2-C6-C6-C6
C4N-C5N-C6-C6-C6
C4NS-C4NS-C6-C6-C6

Triphenodioxazine
Phenanthrazine
Anthrazine¶ 151

C4NO-C4NO-C6-C6-C6
C4N2-C6-C6-C6-C6-C6-C6
C4N2-C6-C6-C6-C6-C6-C6

1The order of precedence is based first on the presence or absence ofnitrogen, then upon the nature of the (other) hetero atoms (see Table I, ¶ 128).
For fused heterocycles, this order (for base-component selection) is distinct
from that used to determine seniority of a total ring system in an index name(¶ 138).
2Citation of indicated hydrogen (¶ 135), e.g., 1H-Pyrrole, 2H-Pyrrole, isnecessary when these component names are used alone.
3Because of established usage, Quinolizine is favored over Isoquinoline
and Quinoline as a base component.
4Naphthyridine requires the locants 1,5-, 1,6-, 1,7-, 1,8-, 2,6- or 2,7- todefine the position of the nitrogen atoms.
5Phenanthroline requires the locants 1,7-, 1,8-, 1,9-, 1,10-, 2,7-, 2,8- or
2,9- to define the positions of the nitrogen atoms.

150. Selection of a base component is facilitated by use of Tables IV,¶ 148 and V, ¶149; the appropriate component listed latest in these Tables isused. The system must contain at least two rings of five or more atoms,
although such rings need not be directly fused to one another; i.e., they may bejoined by a smaller ring, as in Cyclobutadicyclopentene. The criteria for basecomponents differ markedly (in the case of heterocyclic systems) from thosedescribed (¶ 138) for a preferred ring system in a compound containing morethan one. A base component of lower preference is used if the fusion procedure
is not possible on the preferred component; as a last resource, an organic
replacement (“a”) name based on the fused hydrocarbon is employed.
The preferred base component should:(a) be a heterocycle;(b) be a nitrogenous heterocycle;(c) be a nonnitrogenous heterocycle containing a hetero atom of highest
precedence (see Table I, ¶ 128);(d) contain the greatest number of rings;(e) contain the largest individual ring; Benzindene (not Cyclopentanaphthalene) is an exception based on established usage;(f) contain the greatest total number of hetero atoms;(g) contain the greatest variety of hetero atoms, e.g., one nitrogen and one
oxygen rather than two nitrogens;(h) contain the greatest number of hetero atoms of highest precedence;(i) possess the most linear structure;(j) have the lowest locants for hetero atoms (before fusion).
151. Index names for fused systems, other than fundamental systems
which possess their own names (Tables IV, ¶ 148 and V, ¶149), are formulated
from the names of the components. Cycloalkanes may be adopted as basecomponents by invariant use of the “-ene” suffix. This denotes a maximum
number of noncumulative double bonds; e.g., Cyclooctene as part of a fusedsystem is not meant to imply the presence of a single double bond; instead,saturated carbon atoms are indicated by “hydro” prefixes. Fusion locants forthe base component comprise lower case italic letters assigned sequentially toall sides, beginning with the side “1,2” as denoted by the usual peripheral
locants. (See the Ring Systems Handbook for a complete set of ring system
diagrams, including base components, complete with such locants.) If morethan twenty-six letters are required, subsequent alphabets of the form a1, b1,
c1,... etc., are adopted. Locants for the fusion prefixes (derived from the lesspreferred fundamental ring systems) comprise the normal peripheral numericallocants. When a choice is possible, lowest alphabetic and numerical locants arecited. When one or both types of locants are unnecessary they are usuallyomitted. Numerical and letter locants are separated by a hyphen, and the locant
set is bracketed.
Example:Benzene

+
j

k

l

m

n

1

1
11

12
12a

a
2
b

i
h

g

f

e

d

c

Anthracene (basecomponent)

4
12b
5

8

7

6

Benz[a]anthracene

In this example, a locant defining the fusion site on Benzene is unnecessary.
The “1,2” side of Anthracene is lettered “a” and the lettering proceeds aroundevery side back to the 1-position. The fused system is then oriented (¶ 152) andrenumbered.

¶ 151

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Angular positions of base components involved in fusion are not cited.
Example:

1′ 2
2′
3

5′
4′

8
a

+

b

4

8a

Cyclopenta[a]cyclopropa[4′,5′]cyclopenta[1′,2′:2,3]cyclopropa[ 1 , 2 -f ] n a p h t h a l e n e ( n o t
Cyclopenta[a]cyclopropa[3′,4′]cyclopenta[2′,1′:1,3]cyclopropa[2,1-f ]naphthalene.) (The locants
1,2 in the preferred name are lower
than 2,1 in the incorrect name. It
should be noted that the use of 1′,2′
requires that the cyclopentane ring
be numbered the long way around.)aNaphthalene
f
1

NOT

1

c
d

2

a

e

3′
4′

f

Perylene

2′ 1
1′
3

f

2′

Naphtho[8,1,2-bcd]perylene(not “[8,8a,1,2-bcd]”)

a′
1′

2

3′
3
5′′
1′′
4′′ 2′′
4
4′

2
a
1

Benzo[1′′,2′′:3,4;5′′,4′′:3′,4′]dicyclobuta[1,2-a:1′,2′-a]diindene(Note that a semicolon separates
locant sets which already containcolons.)When a hetero atom is shared by two or more rings, it is expressed in all thecomponents. When the order of lettering of the base component proceeds in the
direction opposite to numbering in the fusion-prefix component, numericallocants for the latter are reversed.
Example:O1 2

I s o i n d o l o [ 2 , 1 -a ] q u i n o x a l i n e(not “[2,3-a]”; not “[1,2-c]”)

2

N
a

3′

Fusion prefixes are placed in alphabetical order and the earliest cited prefix
is given preference for lowest letter locant. When two or more fusion prefixes
are identical, as in “Dibenzo-” systems, the letter locants are separated bycommas, e.g., “[a,j].”Example:j

Benzo[a]cyclopent[j]anthracenea

A form of multiplicative name is employed for fused systems different fromthat described for general substitutive nomenclature. Multiplication proceeds
in steps, with “di,” “tri” repeated as necessary (not “bis,” “tris,” etc., except to
avoid ambiguity). Serially primed letters are used for fusion sites on thesecond, third, etc., base components and the locant sets are separated by colons.
When a base component is fused to a central component and to anothercomponent, lowest letters (when a choice must be made) relate to the central
fusion site.
Examples:O

152. Orientation and numbering of fused systems.
(a) Hydrocarbons. The component rings are normally drawn as regularpolygons. The cyclopropane ring may point left or right, and cyclopentane andcycloheptane rings may point up or down. The total system is oriented so that(a) a maximum number of rings are in a horizontal row, and (b) a maximum
number are above and to the right. If further choice is necessary, then (c) a minimum number of rings should be in the lower left quadrant. Numbering begins
at an atom not engaged in fusion in the most counterclockwise position of theuppermost ring furthest to the right. Angular positions are not counted; theirlocants, when needed, are derived from those of the preceding nonangular
positions by addition of the lower-case Roman letters, “a,” “b,” etc. Interior
atoms are numbered last by addition of letters to the highest available numerical locant in a continuous pathway, a clockwise route being followed whenevera choice presents itself; any remaining interior atoms are then numbered similarly from the next highest available numerical locant.
Examples:
10

11

12

7

6

5

10c

4

1

10a

9

Benzo[1,2-c:3,4-c′:5,6-c′′]trifuran

2
3
c′

6

1

5c

3

10b

NOT

8

3

5b

4

c

4

10a

9
8

1

1

12a

Naphthacene

O
6
c ′′
5

Pyrrolo[2′′,3′′:4′,5′]pyrano[2′,3′:5,6]pyrano[4,3-b]pyrrole

N

1′′
2′
2′′ 4′
3′′ 5′ 6′ 1′

N

1 b

O

3
b
5 4

6

N

24

4

5a

5

Pyrene
O
4

1

4

1

2

d′

b′

b

2′

S 5′

1

d

S

Dinaphtho[1,2-d:1′,2′-d′]benzo[1,2-b:5,4-b′]dithiophene (notDinaphtho[2,1-b:2′,1′-b′]benzo[1,2-d:5,4-d′]dithiophene)

13a

1

16a
16b

13b

11

N

3

N

16b

5

8d
8c

16a

13

8
10

6

8b

Pyrido[1′,2′:1,2]imidazo[4,5-b]quinoxaline

8a

11

9

10

7
8

9

Naphtho[1′,8′:3,4,5]cyclohepta[1,2-c]phenanthrene
When a further choice is needed for orientation and numbering, carbon
atoms at angular positions are assigned lowest numbers.
Examples:
2

1
3

8b

N

14

NOT

7

1

1
2

6

16c

8a

5
b 4

5

16d

2

Ring systems fused to base components are designated primary components; a ring system (other than a base component) fused only to a primary
component is a secondary component, and primed numerical locants are used
to denote its fusion sites. Primed and unprimed locant sets are separated bycolons. Lowest locants are used for the site closest to (or fused directly to) thebase component. Doubly primed locants are needed (a) when the secondary
component is centrally located with identical primary and base components on
both sides, and (b) when tertiary components are present.
Examples:

N

4

1

NOT

3

8a
8b

4
5

6

5

6

Acenaphthylene (Note: 2a,5a,8a,8b is lower
than 3a,5a,8a,8b)

25Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Indicated hydrogen is assigned the lowest locant.
Example:17a

1H-Indene (not 3H-Indene)
3
4

The following fused carbocyclic compounds have special numberingsystems: Anthracene, Phenanthrene, Cyclopenta[a]phenanthrene (steroid
numbering) and the Cyclopropacyclopenta[a]phenanthrenes.
(b) Heterocycles. The ring systems are oriented as for hydrocarbons. Whena choice is necessary, lowest locants are assigned to (a) all hetero atoms; (b)most preferred hetero atom (Table I, ¶ 128); (c) carbon atoms common to two
or more rings; (d) positions bearing indicated hydrogen; (e) an angular rather
than a nonangular atom of the same hetero element. The ring is then numbered
as for hydrocarbons, except that hetero atoms common to two or more rings arecounted. Interior atoms are numbered last, following the shortest path from thehighest previous number.
Examples:153. Replacement (“a”) nomenclature for fused systems is employedwhen fusion names fail to express all interfaces (fusion sites) between
component systems. This occurs when two or more components that are expressed as prefixes are fused to one another as well as to the base component.
“A” names are also used for silicon replacement in a carbocycle that has atrivial name. Indicated hydrogen of the parent carbocycle is ignored, but iscited, if needed for the “a” name, ahead of the replacement prefixes.
Examples:1O

6H−1,7−Dioxacyclopent[cd]indene(not 1,7-Dioxa-6H-cyclopent[cd]indene)

2

7a

7b

3

7O

4
5

1

3

9a

9b

B

4

9b-Boraphenalene

6

7

1

O

7a

¶ 154

8a

H
Si
1

Cyclopenta[b]pyran

1-Silanaphthalene, 3,4-dihydro-

5
5

4

1

N

9a

4,1-Benzothiazepine
6

S

5

4

1

6

S 6a O

Thieno[2,3-b]furan
4

3

6

1

N 6a O

4H-1,3-Dioxolo[4,5-d]imidazole
O3

HN
4

8

1

8

N

N

N
5N

4a

1
8a

1

8

N

N

N

8a

NOT

NOT

N

N
5

4

N

N

4

4

Saturation of double bonds in fused systems is denoted by hydro prefixes
which are given lowest locants; e.g., Naphthalene, 1,2,3,4(not 5,6,7,8)tetrahydro-. Triple bonds are indicated by “didehydro.”154. Bridged fused systems are fused ring systems that possess atomic
bridges or valence bonds which connect two or more parts of the system
without creating or extending a fused system. They are named by adding bridge
prefixes (in alphabetical order if different types are present) to the fused systemnames.
Simple bivalent bridges include methano (−CH2−), ethano (−CH2−CH2−),etheno (−CH=CH−), propano (−CH2CH2CH2−), 2-buteno (−CH2CH=CHCH2−), and benzeno (−C6H4−). Trivalent bridges, e.g., metheno (−CH=),
1-propanyl-3-ylidene (−CH2CH2CH=), and tetravalent bridges are also employed; locants for positions of attachment on the fused system are cited in thesame order as free-valency locants of the radicals. Bridges from monocyclichydrocarbons other than benzene are named as for the fusion prefixes, exceptthat “endo-” is used with them to avoid ambiguity, e.g., “endo-cyclopenta.”
Simple hetero bridges include epoxy (−O−), epithio (−S−), imino (−NH−),
epidioxy (−O−O−), and -silano- (−SiH2−). Heterocyclic rings may also be usedas bridges.
Example:N

5

43,4-furano (cf. “furo” for the fusion
prefix)O

Imidazo[1,2-b][1,2,4]triazine

1112

10a 10b

12a

11

10

1
NOT

N

5a

N

7

6a

4a

5

12

N
6

12a 12b

5a

N
5

6

1

4

Pyrrolo[1,2-a:5,4-b′]diindole

8a−NH(CH2)2−(iminoethano)−OSO−(epoxythioxy)

2

1
7O

When locants are used for the bridge itself, e.g., 2-buteno, 3,4-furano-, they areplaced in brackets within the bridged system name.
Compound bridges are named by combination of simple bridges beginningat the terminal position which gives the preferred (a) cyclic bridge (¶ 138), (b)hetero atom (Table I, ¶ 128), (c) chain, (d) alphabetic order.
Examples:

8b

9

N

F u r o [ 3 , 4 -a ] p y r r o l o [ 2 , 1 , 5 -c d] indolizine

3

O

5a

5b

The following heterocyclic systems have special numbering systems:
Acridine, Carbazole, Purine, Xanthene, and Epoxy- and Epithiocyclopenta[a]phenanthrenes (steroid numbering).
Indicated hydrogen for fused carbocyclic and heterocyclic systems isnormally cited, if there is a choice, at the lowest nonangular position, unless asaturated angular atom is required to accommodate a principal function or freevalency (see ¶ 135). Indicated hydrogen of component systems is ignored inconstructing a fused ring name, and is reassigned if it is still needed in the final
system.
Example:(epoxy[1,2]benzeno)

Indicated hydrogen of a fused system is cited, if possible, to accommodate
a bridge. When this is unnecessary or impossible, the lowest-numbered nonangular indicated hydrogen is cited for the fused system, and additional indicatedhydrogen, when needed, is cited ahead of the bridge locants.
Examples:1
6a

1,4-Methanopentalene, 1,4-dihydro7
3

4
1
11

12

O 12a

4

12b
5

8

O

O

7

6

5H-[2]Benzopyrano[3,4-b][1,4]benzodioxin (Note: The locants“2” and “1,4,” which relate to thecomponents, are bracketed toindicate that they do not conformto the peripheral numbering of
the total system)

1

2

6a
6
5

3

7 6b
8

4

6,1,3-Ethanylylidenecyclopenta[cd]pentalene¶ 154

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

21

22

18

17

11

12

1,7-Ethano-1H-pyrano[3,2-c]pyridazine, octahydro- (not 4,6(Epoxymethano) -1H -pyrido[1,2 b]pyridazine, octahydro-)(The fusedring system Pyranopyridazine ispreferred to Pyridopyridazine;see ¶ 138.)

1

15

N

8a
9

10

O

4

16
14

13

14a

1

5

6,13[2′,3′]-Naphthalenopentacene

2

NH

7

NOT
8

5

6

7

4

H
N

9
14
12
8

1

O 11

11
1

9

4a
10

4
1

6

O

6a

3,2,6-(Epoxyethanylylidene)furo [3,2-b]furan

2

4O 7

3

4

5

9,10[1′,2′]-endo-Cyclobutanthracene

9a

10a
5

N

10

Fused carbocyclic and nonnitrogenous heterocyclic systems with simple
imino bridges are named by use of the termination “-imine” with appropriate
locants. Such a name requires addition of a regular functional suffix whenappropriate. (Nitrogen heterocycles with imine bridges are named as bridged
fused heterocycles in the usual manner.)
Example:

O

8

9

1

Br

8a
1

3

10a
10

9 NCO2 H

10b

4

7 , 1 0 -E t h e n o c y c l o h e p t a [ d e ]naphthalene

11
12
6
7

1

5H-4a,7-Ethano-2H-1-benzopyran(4aH-1-Benzopyran cannot exist)

O

8a
7

26

9
10
4a

Numbering of bridged fused systems is based on the regular numbering of
the parent fused system. Lowest locants are assigned to bridgehead positions
and the bridge atoms are numbered from the end nearest the highest numberedposition of the parent fused system. In cyclic bridges, e.g., benzeno, endocyclobuta, the shorter bridge is first numbered, and then the rest of the ring inthe same direction. If possible, hetero atoms in bridges are numbered low.
Examples:5

6

Bicyclo[4.3.2]undecane

10

1,4-Ethenonaphthacene

14

For tricyclo- and higher hydrocarbon systems, superscripts are employed toindicate the positions of secondary bridges.
Example:

13
7

9
1

6
11

12a

Br

155. Von Baeyer nomenclature. This was first developed to name alicyclic hydrocarbons containing two rings. It has been extended to all bridged systems which cannot be treated as fused or bridged fused systems. Von Baeyer
names for hydrocarbons are formed by prefixing to the name of the acyclic hydrocarbon with the same number of carbon atoms “Bicyclo-,” “Tricyclo-,” etc.,
terms, followed by a set of numerals, separated by periods and bracketed,which describes in descending sequence the number of atoms in each bridge.
The system is numbered from one bridgehead via the other bridgehead(s) andback, always choosing the longest route. The system is numbered along thesame route, ending with the smallest bridge, numbered from the bridgehead
with the highest locant.
Example:

1

12

11

10

4a

N a p h t h a l e n -4 a , 8 a -i m i n e -9 carboxylic acid, 2,3-dibromooctahydro-

41

8a,4a-(Iminomethano)naphthalene( n o t 4 a , 8 a -( I m i n o m e t h a n o )naphthalene)

8a
9 NH
10

1
2

10

Tricyclo[5.3.1.12,6]dodecane

11

12

4a
7
6
15
11

12

11H-5,10[1′,2′]-endo-Cyclopent5H-oxazolo[3,2-b]isoquinoline191010a ON
6

5

4The exceptional numbering employed for bridged cyclopenta[a]phenanthrenes is shown in the following example. Steroid numbering is used
for positions 1 through 17. When the methyl groups normally numbered 18 and
19 are transformed into methano bridges, their locants are retained. Other
bridges are numbered 20 and upward.

When more than one Von Baeyer name is possible for a hydrocarbon, thechoice is determined by the following principles, applied successively until adecision is reached.
(a) The main ring contains the maximum number of atoms, two of whichmust serve as bridgeheads for the main bridge.
(b) The main bridge is as large as possible.
(c) The main ring is divided as symmetrically as possible by the main
bridge.
(d) Lowest superscripts (regardless of order of citation) are cited.
Examples:
1
2

7
17
19

11

13

1

9
10

20 O

9
4

18

5

15
8

1

8

6

Criteria for the naming of bridged fused systems are applied successively
as follows:(a) The unbridged system contains the maximum number of (i) rings, (ii)skeletal atoms.
(b) The bridges are as simple as possible; e.g., two simple bridges are
preferred to one compound bridge, and saturated bridges are preferred tounsaturated ones.
(c) The unbridged system has the highest precedence according to ¶ 138(c).
Examples:Tricyclo[3.2.1.0 2,7]octane (not Tricyclo[2.2.2.02,6]octane)

7

5
4

Tricyclo[3.2.2.02,4]nonane (not Tri−
cyclo[2.2.2.12,3]nonane)

8

2
16
14

18 17
19

1

Tricyclo[12.2.2.11,14]nonadecane

10
5

10
1
8a
9
5

4

1

1,4-Methanonaphthalene, 1,2,3,4tetrahydro- (not 1,3-Ethano1H-indene, 2,3-dihydro-)

12

11
6

5

Tricyclo[4.4.1.11,5]dodecane(not Tricyclo[5.3.1.11,6]dodecane)27

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
Pentacyclo[4.4.0.02,5.03,8.04,7]decane(not Pentacyclo[4.4.0.04,9.05,8.07,10]d e c a n e ; n o t P e n t a c y c l o[4.4.0.0 2,5 .0 3,10 .0 4,9 ]decane; notPentacyclo[4.4.0.0 2,9 .0 3,8 .0 7,10 ]decane)

10
1

2

6

5

8

3
4

7

Unsaturation is denoted by “-ene” and “-yne” suffixes. A second locant inparentheses is cited for a double bond at a bridgehead when it does not proceed
to the next atom in the numbered path. Multiple-bond locants are determinedby the following criteria applied successively:(a) The numbering proceeds in a clockwise sequence.
(b) The cases in which both locants for a double bond are cited areminimized.
(c) Lowest locants are employed.
Examples:
8
9
10

8

156. Spiro systems contain pairs of rings or ring systems having only one
atom (a “spiro atom”) in common. In the simplest monospiro systems, in which
two alicyclic rings share an atom, the name is formed by prefixing to the acyclic hydrocarbon name the term “Spiro” and numerals (separated by periods)
in ascending sequence to define the number of atoms in each ring linked to the
spiro atom. The numbering begins at the atom next to the spiro atom in thesmaller ring and proceeds around that ring, through the spiro atom and aroundthe larger ring.
Example:1

8

Spiro[3.4]octane

4This system is extended to dispiro and higher systems. Numbering begins
next to a terminal spiro atom and proceeds in such a way as to give the spiro
atoms lowest locants.
Example:Tricyclo[3.3.2.02,8]deca-3,6-diene

1

5

16 17

15

2

Bicyclo[4.2.0]oct-6-ene (not Bicyclo[4.2.0]oct-1(8)-ene)

6
1

16

15
11

Heterocyclic analogs are named by “a” nomenclature. The hetero atoms are
given locants as low as are compatible with the ring numbering.
Example:Tricyclo[9.3.1.1 4,8 ]hexadeca -1 (15),4,6,8(16),11,13-hexaene (notTricyclo[9.3.1.14,8]hexadeca-4,6,8(16),11(15),12,14-hexaene)

4

14

8

Von Baeyer names for heterocyclic systems are formed from the hydrocarbon names by use of replacement (oxa, thia, aza, etc.) prefixes and lowest
locants for hetero atoms in the order of Table I, ¶ 128. Unsaturation is denoted
as for hydrocarbons.
Examples:Dispiro[5.1.7.2]heptadecane (notethat the numbering path corresponds
to the bracketed sequence)

1
6

8

1

¶ 156

10

1

6-Oxaspiro[4.5]decane

5O
6

Unsaturation is expressed by “-ene” and “-yne” suffixes.
Example:

9

10 O
6

N 12

5,10-Dioxa-12-azadispiro[3.1.3.3]dodec-11-ene

1

4

O

3-Oxatricyclo[2.2.1.02,6]heptane(not 5-Oxatricyclo[2.2.1.02,6]heptane;
not 2-Oxatricyclo[2.2.1.03,5]heptane)(low numbering for bridge takes
precedence over hetero atom)

6

4

1

7

3O

2

2

6-Oxa-2-thia-4-azabicyclo[3.1.0]hexane (not 6-Oxa-4-thia-2azabicyclo[3.1.0]hexane)

S

1
6O

NH

5

O
H 2 Si 10

H2
Si

1

O

2

Si 6
8

Si
H2

4

O7 O

O3

Spiro[5.7]hexasiloxane

Si
H2

5

1

2,4-Dithia-3-stibabicyclo[3.3.1]nona-1(9),5,7-triene (not 2,4Dithia-3-stibabicyclo[3.3.1]nona1(8),5(9),6-triene)

S2
S

5

4

Saturated bridged systems containing only silicon atoms, or silicon atoms
alternating with nitrogen or one of the chalcogens, are given Bicyclosilazane,
Tricyclosiloxane, etc., names. Regular Von Baeyer numbering is employed.
Examples:H 2 Si

Si
7
Si H
H2

H2 Si
8

HN
H2 Si

5
SiH2
Si 4
H2

HN
6

Si 5 NH
H 4

6′

2

3

H
Si 15
16O

O
O H
11 Si
10 O 9

HSi

H
Si

O 18

1 O

2

3 Si
O H
20

Pentacyclo[9.5.1.1 3,9 .1 5,15 .1 7,13 ]octasiloxane

7

4a

H
N1

4

O

1

9a

Added hydrogen (¶ 136) is cited in parentheses in the usual way, but with aprimed locant if it does not relate to the component cited first. It is assigned thelowest available locant unless a different one can be used to accommodate aprincipal group.
Example:

Si H

8′a

5

8O

H Si

S 2′

4b

O
17

8

Bicyclo[3.3.1]tetrasilazane

Spiro[9H−fluorene-9,3′-[2]thiabicyclo[2.2.2]oct[5]ene]

1′

7′
8′
3′
9

4′

14

12

Spiro[cyclopentane-1,1 ′-[1H ]indene] (not Spiro[cyclopentane−
1,1′-1′H-indene])

5

1′

4′

NH
NH
Si H 277′aBicyclo[4.4.0]decasilane

3′

6

H
Si 1

8

Monospiro systems containing at least one fused or bridged component are
named by placing the component names in brackets in alphabetical order andprefacing them with “Spiro.” The position of the spiro atom is denoted by two
locants, separated by a comma, related to the two components. Primes are used
for the component cited second. Indicated hydrogen (¶ 135) is assigned, where
possible, to accommodate the spiro unions. Locants related to the components
but not to the total spiro system are bracketed to avoid ambiguity.
Example:1

H2
H2
Si H Si 3
10 Si 1 2
Si H2

9

19 O

H2
Si 13
12 O

11

9O

9 3
Sb H

13

Saturated spiro systems containing only silicon atoms or silicon atoms
alternating with nitrogen or one of the chalcogens are given Spirosilazane,
Spirosiloxane, etc., names.
Example:

4

8

H Si

5

H 5
N
1′

O6
5′

N
4′

2′

4

NH
3

Spiro[imidazolidine-4,2′(1′H)quinoxaline]¶ 156

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Monospiro systems containing identical fused components are given“Spirobi-” names. The component name is bracketed if it is preceded bylocants or is itself made up of fusion components. Added hydrogen is cited inparentheses following the spiro locants.
Examples:

1

8a

1′

5

4

4′

1′

3,3′-Spirobi[3H-indole]

3

5′

1
6′

3′

8′a

2,2′-Binaphthalene

1′
7′a N
4

28

5,5′-Bibicyclo[2.2.1]hept-2-ene (not2,2′-Bibicyclo[2.2.1]hept-5-ene)

6

7′

7

4′

4

4′
7a

N
1

3′

1,1′:2′,1′′-Tercyclopropane

1′
3′′
8′a
1

2′

H
N

H
N

3

4′

2

2,2′(1H,1′H)-Spirobinaphthalene
2

5

1

5′

1′

8

1′′

HN

4

5 5′′

1

NH

4,4′:4′,4′′-Terpyrazolidine

Di-, tri-, etc., spiro systems containing at least one fused or bridged
component are named by extension of these policies. If terminal components
are identical, citation is determined by earliest index position of the complete
name. Serially primed locants are used for successive components.
“Branched” polyspiro systems in which a single component is surroundedby three or more identical components are named by citing the centralcomponent (which is assigned plain locants) first and multiplying the identical(terminal) components. When two terminal components of a “branched” spirosystem are identical, and one different, they are cited in alphabetical order (asusual) and the term “bis” is applied as appropriate.
Examples:
1
8
3 1′

9

Dispiro[bicyclo[3.3.1]nonane−3,1′−cyclobutane−3′,1′′− cyclo−butane]3′ 1′′
4′′

4′

5′

NH

HN

1′

2′

1

5′

Indicated hydrogen (¶135) is assigned, where possible, to points of attachment. When indicated hydrogen is cited in different positions for different
components, a ring-assembly name is not used. Added hydrogen (¶ 135) iscited immediately after the locant to which it relates.
Example:
1′

O

6′′
3′′

5′

3′

5′′

1′

4′′

1

2′

2

2′

N

N
N

3

3′

H
N

6

N

N

5

Trispiro[cyclohexane-1,1 ′- cyclopentane−3′,3′′(2′′H)−cyclopenta−[b]pyran−6′′(4′′H),1′′′− cyclo−
hexane]1′′3,3 ′:5′,3′′:5 ′′,3 ′′′-Quatercyclopentene

1′′

1

7′′a

1′′′
5′′′

1′

N

6′′′

5′′

5

5

1′′′

2′′

1′′

5′

H
N

2 3

2,2′-Bi-2H-1,2,3-triazole

1H-Benzotriazole, 1-(1,3−dihydro2H -benzotriazol -2 -yl) -2,3 -di hydro- (not 1H-Benzotriazole,
2-(2,3-dihydro-1H-benzotriazol-1yl)-2,3-dihydro-; not 1(3H),2′B i -2 H -b e n z o t r i a z o l e , 1 ′ , 3 ′ dihydro-)

H
N

N N1
NH

4′
3′

O
2′

1′′′

1

O

7′′′a

O

O

2′′

3′′′′
4′′′

N

3′′

O

7′′a

1′′

Trispiro[cyclopropane-1,2′:2,2′′:3,2′′′-tris[1,3]benzodioxole]
5′′
3′′′

O

2′

O

4′

1′

1

5′′′
2′′′

2′′

3′′ O
7a

1′′

O

O
1′′′

Trispiro[1,3-benzodioxole-2,1′cyclohexane-2′,2′′:4′,2′′′-bis[1,3]dioxolane]

2
6′

O3

2(1H),4′-Biisoquinoline

4′′

O

2

N

7′a

1′

3

2′′′

Linear benzene assemblies (polyphenyls) are named by prefacing “phenyl”
with the appropriate term (Bi-, Ter-, etc.). Arabic numeral locants are cited in
all cases for points of attachment. Two-component assemblies of monocyclichydrocarbons and of hetero systems with “cyclo” names, e.g., Cyclopentastannane, Cyclotrisiloxane, and monocycles with one silicon using “sila”
names, are named from the radicals, and locants for the points of attachment
are cited only when the radical has no locant for the free valency. Two-component ring-assembly names from unsaturated (“-enyl”) radicals are formed only
when the unsaturation is symmetrical with respect to the points of attachment.
Examples:
6

4

1 1′

157. Ring assemblies contain a multiplicity of the same cyclic systemjoined by single bonds, not necessarily in equivalent positions. They aretreated as molecular skeletons in substitutive nomenclature and rank just above
the component ring. Except for assemblies of benzene, and two-component
assemblies of cycloalkanes, cycloalkenes, and hetero systems with “cyclo”
names (see below), they are named by prefixing the component names with theterms Bi-, Ter-, Quater-, Quinque-, Sexi-, Septi-, Octi-, Novi-, Deci-,
Undeci-, etc.
Locants are placed ahead of the name to define the points of attachment.
These locants are as low as possible, compatible with fixed numbering (expressed or implied) of the components, including “-ene” and “-yne” suffixes.
Examples:

1,1′-Biphenyl
6′

6′′′′

6′′′
1′′′′

6′

1′

1

N
H

N
H

6

6′
1′′

1′ 1
6

1,1′:4′,1′′:4′′,1′′′:4′′′,1′′′′- Quinquephenyl
62,2′-Bipiperidine

6′′
1′′′

1,1′-Bicyclohexyl (not Bicyclohex−
1-yl)

1 1′
6′

29

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 158

6′

Bi-2-cyclohexen-1-yl (not 1,1′-Bi2-cyclohexen-1-yl)

1′ 1

Te

6′

H2
Si
O

1′

1

O

8

7

Cl

H 2Si 6

4

H
2 Si

H
Si 2′

3O

O 3′

Si
H2

O

5

O

H 2 8′
Si

5,5-dichloro-

O 7′
6′
4′

Si
H2

Bicyclotetrasiloxan-2-yl

Si H2• A radical is formed according to the established rules–including the use ofadded hydrogen to accommodate an “ylidene” radical–when the free valenceis on the nonstandard heteroatom.

O
5′

3

Cyclohexene, 1- (3-cyclohexen-1yl)- (not Cyclohexene, 4-(1cyclohexen-1-yl)- (lowest locant
for the substituent prefix is preferred(¶ 138))1 1
6

6158. Nonstandard heteroatoms in CA ring nomenclature. Additive
terms are used to describe oxides, sulfides, selenides, and tellurides of ring heteroatoms:
7a

O2
S

Benzo[b]thiophene, 3,5-dimethyl1,1-dioxide

1
3

Me

4

O
N
6

1

Cl

5H-5λ4-Dibenzotellurophene,

N
Me

SO 2

Me

S

Me

Benzenesulfonamide,
N-(3,4-dihydro-5,6-dimethyl1λ4-thiopyran-1(2H)-ylidene)-

Me
H
N

Acetic acid, 2-[(1-oxido-2-pyridinyl)thio]-

SCH2 CO 2H

For all other neutral ring heteroatoms with nonstandard bonding numbers(hereafter referred to as nonstandard heteroatoms), the IUPAC lambda convention (Pure Appl. Chem. 1984, 56, 769-778) is used, regardless of the heteroatom in question, its bonding number, or the kinds of bonds joining it to otherskeletal atoms.

H
N

Me
P

N
H

P
N
H

Me

2λ5-1,3,2-Diazaphospholidine,
2-methyl-2-(2-methyl-2λ5-1,3,2diazaphospholidin-2-ylidene)-N

The rules are as follows:• The λ term is prefixed to the name for the ring parent, preceded by the locant
for the nonstandard heteroatom–in a fusion name, that locant is for the fusedring system, not a component ring–and followed by a superscript denoting thenonstandard valence. (In the IUPAC recommendations, the λ is usually inserted within the ring name, after the locant for the nonstandard heteroatom.)
Me
O

Me

S
O

HP

PH

N

N
P
H2

2λ5,4λ5,6λ5-1,3,5,2,4,6-triazatriphosphorine-2,4-diyl• After the established rules for low numbering have been applied–for heteroatoms, indicated hydrogen, an onium center, and so on–low numbering is assigned to a nonstandard heteroatom in preference to the same heteroatom
with the standard bonding number.

2λ4-1,3,2-Dioxathiane,
2,2-dimethyl-

S
6

5

4

1

2

3

H
N

S
H

NEt 2
I

P
N
H

1λ4-1,5-Benzodithiepin

NEt 2

2λ5-1,3,2-Diazaphospholidine-2,2-diamine,
N,N,N′,N′-tetraethyl-2-iodo-• In a bridged fused ring system, the name of the bridge (including its locants
and any indicated hydrogen required by the bridge) is prefixed to the fusionname with its λ term.

F

F

S

F
I

N

O
N

Me

Me

1λ5-1,2-Benziodoxole,
1,1,1-trifluoro-1,3-dihydro-3,3-dimethylH
S
5N

1,4-Methano-5,11-nitrilo-11H-5λ4,11λ4dibenzo[c,f][1,5,2]dithiazepine• In a ring assembly or spiro name, the component name is always cited with
its own λ term.

1 2
4 3N

1λ4-Pyrido[2,3-e]-1,3-thiazine• For a ring parent with the maximum number of noncumulative double bonds,
indicated hydrogen is used with a nonstandard heteroatom if that atom isjoined to other skeletal atoms only by single bonds–unless the other atoms are
divalent, in which case indicated hydrogen is not used. Indicated hydrogenalways precedes the λ term.

S

Cl

Cl

Et
N
P6 1 2PMe

N5 4 3 N
P

N 3′ 4′ 5′ N
P

Cl

Cl

Cl

Cl
N
P 2′ 1′ 6′ P Cl

Cl

2,2′-Bi-2λ5,4λ5,6λ5-1,3,5,2,4,6-triazatriphosphorine,
4,4,4′,4′,6,6,6′,6′-octachloro-2-ethyl-2′-methyl-¶ 158

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
O1
4

N
2 P 2′

3

1′

N

N

Spiro[2λ5-1,3,2-benzoxazaphosphole-2,2′[2H-2λ5-1,3,2]diazaphosphole]SS

3′2 Te 2′
3
1′
1

S

S

2,2′-Spirobi[2λ4-1,3,2-benzodithiatellurole]• In a replacement name for a saturated ring parent, both the lambda convention
and subtractive suffixes are used to describe a nonstandard heteroatom joined
to cumulative double bonds.

30

Until structures have been determined, author terms such as “iso” and “neo”
are cited in index modifications to differentiate isomers.
Numbering of polyboranes in CA indexing is based on “Nomenclature of
Boron Compounds” adopted by the American Chemical Society, and“Nomenclature of Inorganic Boron Compounds”, published by theInternational Union of Pure and Applied Chemistry,1 which may be consulted
for further details. For “closed” polyboranes (those whose boron skeletons arepolyhedra with triangular faces throughout) the numbering begins with theboron atom at the head of the largest axis of highest order, then proceeds
sequentially to the planes which intersect this axis. Boron atoms in each plane
are numbered clockwise unless lowest locants for substituents demand
anticlockwise numbering. On succeeding planes, numbering begins at theboron atom immediately “below” the lowest-numbered one on the previous
plane, or the one nearest to it in the direction of numbering.
Example:
H1
B

S

5

6 1 2
5 4 3

2

B
H

4

HB

H
B

BH

BH

HB

3BH

1λ4-1-Thia-4-silacyclohexa-1,6-diene
H
HB
5• To describe all other nonstandard heteroatoms joined to cumulative double
bonds, the lambda convention is used together with the IUPAC delta convention (Pure Appl. Chem. 1988, 60, 1395-1401). The terms are combined intoa single expression, prefixed by the locant for the nonstandard heteroatom.
The number of cumulative double bonds to the nonstandard heteroatom is
specified by a superscript Arabic numeral after the δ.
2N
3

N

1λ4δ2-1,2,3-Thiadiazole
N

S

6

5

7

N8 1
S

B

5

1

3

HB

BH

BH

9

B
H7

BH
6

BH

HB

7

8

B 10
H

4B

Decaborane(10)planar projection

H(Note that atom “6” (in the lower plane) is nearest to atom “2” in the
direction of numbering.)

S
1

6

2

9

Si
H2

2

For “open” polyboranes (those with incomplete polyhedral boron
skeletons) the rules are more complex. A planar projection, as viewed from theopen side, is numbered so that interior boron atoms have lowest locants,
beginning at the “center” or “apex.” Each atom set is numbered in the same
direction.
Examples:

4N
3

H2
B
SH

N

Diborane(6)

1

H

H

2

B
H2

1λ4δ2,3λ4-1,3,5,2,4,6,8-Trithiatetrazocine

H
B
1

1 2N
4 3

N

S 1′

HB

BH

6δ2-1,3,2,4-benzodithiadiazine-3,1′-[1H-1λ6]thiophene]

HB

H

H

H

H

2

2

5

HB

Spiro[3λ

H
B

H

S

H 3
B
BH

5

1

4

4

3

H

BH

H

Pentaborane(9)HB
H

planar projection

1159. Boron molecular skeletons. Because the number of hydrogen atoms
in neutral and anionic boron hydrides often bears no simple relationship to thenumber of boron atoms, borane names must express the number of both. (Thesingle exception is Borane itself, which represents BH3.) The Ring Systems
Handbook should be consulted for structural diagrams of the neutral
polyboranes of established structure. Diagrams justified by current index
entries are displayed in the Chemical Substance Indexes. (In these diagrams,
the lines do not represent electron-pair bonds but indicate the geometry of thestructures.) Neutral boron hydrides, real or hypothetical, are treated as
molecular skeletons in substitutive nomenclature, Borane and the diboranes asheteroacyclic compounds, and the higher hydrides as heterocyclic compounds.
Borane(1) is BH, Borane(2) is BH2. In higher boranes, the number of boron
atoms is expressed by multiplicative prefixes.
Examples:

BH
H

H

H
B

H

H

2

HB 6
BH
HB

6

2

HB 5

4

3

BH

H

BH

H

H

Hexaborane(10)

3 BH

1

BH
5

4

B
H

B
H

H

planar projection

Some polyboranes can be named as derivatives of simpler polyboranes.
Thus, a bimolecular polyborane, i.e., a two-component “ring” assembly inwhich both skeletons are identical, can be named as follows:

B2H4

Diborane(4)1,1′-Bipentaborane(9)B2H6Diborane(6)B3H7Triborane(7)B4H10Tetraborane(10)B5H9Pentaborane(9)When the various parts of the structure are not identical, the general principles
of substitutive nomenclature are applied, and a polyborane radical is used forthe less preferred skeleton, e.g., Decaborane(10), 2-octaboran(8)-1-yl-.
Polyboranes joined along an edge, or with a triangular face in common, arenamed like fused ring systems; e.g., Decaborano(14)[5′,6′:5,6]decaborane(14), Undecaborano[2′,7′,11′:1,2,3]dodecaborane(17).

B6H10Hexaborane(10)B10H14

Decaborane(14)1Inorg. Chem. 1968, 7(10), 1945-65; Pure Appl. Chem. 1972, 30(3-4),
683-710.

31

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

160. “Hetero” polyboranes are boron hydride skeletons in which boron
atoms have been replaced by those of other elements, notably carbon.
Replacement prefixes, e.g., “carba,” “phospha,” are employed with the
polyborane name, and the number of hydrogen atoms attached to the skeleton
expressed in parentheses after the name. Structural diagrams for compounds ofestablished structure can be found in the Ring Systems Handbook and, when
justified by current entries, in the Chemical Substance Index. Numbering is as
for the parent polyboranes, with lowest compatible locants assigned to thereplacement atoms.
Examples:
H
C
1

BH
6

HB
5

HB 9

CH

H
B

H
B

4

3

H
B

H
B

10

11
7

H8
B

1,2-Dicarbadodecaborane(12)

2

BH

12

B
H
H
B
1

B

HB

H

6
5
4C

H
3

H
B

2

CH

2,4-Dicarbaheptaborane(7)¶ 161multiple) in one or two positions of an acyclic chain are always terminal, otherwise a compound radical name is employed. When three or more positions
have free valencies, two of them must be terminal.
Examples:
MeCH2−ethyl

H2C= CHCH2−

2-propen-1-yl (not allyl)

EtCH=

propylidene

PrC≡butylidyne

H2C= C=ethenylidene

H2C= CHCH=

2-propen-1-ylidene

MeC≡CCH2CH= CHCH=

2-hepten-5-yn-1-ylidene−(CH2)2−

1,2-ethanediyl−CH2CH=1-ethanyl-2-ylidene−CH=CH−

1,2-ethenediyl−(CH2)3−

1,3-propanediyl=C=C= C=

1,2-propadiene-1,3-diylidene|—CH2CHCH2—

1,2,3-propanetriyl||—CH2CCH2—

1,3-propanediyl-2-ylidene(c) Organic heteroacyclic (“a”) radicals are used when the requirements( ¶127) are met. The numbering of the parent radical is retained. A single freevalency is hence always in the 1-position, and this locant is always cited. When
there is still a choice, lowest locants are assigned to hetero atoms, then to most
preferred hetero atoms(Table I, ¶ 128), then to unsaturation (with double
bonds preferred).
Examples:7

BH

161. Substituent prefixes (radicals) derived from molecular skeletons
are used very frequently in substitutive nomenclature. Their names are basedon the skeleton names and may be classified accordingly as radicals from (a)monoatomic skeletons, (b) hydrocarbon chains, (c) organic hetero (“a”-named)
chains, (d) homogeneous hetero chains, (e) heterogeneous hetero chains, (f)carbocycles, (g) heterocycles, (h) ring assemblies, (i) polyboranes. Combination of simple radicals to form compound and complex radicals is performed
by application of principles described earlier (¶ 133). (See also “Illustrative
List of Substituent Prefixes,” which constitutes Section H (¶ 294).
(a) Monoatomic radicals from borane, methane, silane, germane, stannane,and plumbane are named by replacing “-ane” by “-yl,” “-ylene,” and“-ylidyne” to denote the loss of one, two, or three hydrogen atoms. The final“e” of the hydrides arsorane and phosphorane may be replaced by “-yl,”“-ylidene,” and “-ylidyne.” Stibine and bismuthine may have the “-ine” ending
replaced by “-ino,” “-ylene,” and “-ylidyne.” Phosphine and arsine may havethe “-ine” replaced by “-ino,” “-inidene,” and “-inidyne.” The -tetrayl suffixes
indicate loss of all hydrogen from Group IVA monoatomic hydrides.
Examples:Me[O(CH2)2]3 OCH2CH2−

3,6,9,12-tetraoxatridec-1-yl (not[2-[2-[2-(2-methoxyethoxy)ethoxyl]ethoxy]ethyl])

MeSiH2CH2SiH2CH=CHSiH2CH2SiH2CH=
10 9

7

4

2

1

2,4,7,9-tetrasiladec-5-en-1-ylidene—CH2CH2[S(CH2)2]2SCH=CHNHCH2CH21

2

9

12

14

3,6,9-trithia-12-azatetradec-10-ene1,14-diyl(d) Homogeneous heteroacyclic radicals are named analogously to acyclichydrocarbon radicals, except that only the “e” of “ane” suffixes of heteroacyclic skeleton names is replaced by “-yl.”
Examples:HN= N−

diazenyl (also used for the substituted
radical, rather than azo)

H2NNHNH−

triazanyl

HN= NNH−

2-triazen-1-yl

H2NN=NN= N−

1,3-pentazadien-1-yl

H2PPH−

diphosphinyl−PHPH−

1,2-diphosphinediyl=AsAs=

1,2-diarsinediylidene

H2B−

boryl

HC≡

methylidyne

H2C=

methyleneHSi≡silylidyne=Sn=stannanetetrayl

HAs=arsinidene

H2P−

phosphinoAs≡arsinidyne

HP=phosphinidene

H2Sb−stibinoP≡

phosphinidyne

HSb=stibylene

H4P−

phosphoranylSb≡

stibylidyne

H3P=

phosphoranylidene

H2Bi−

bismuthino−Sb=Sb−1,2-distibenediyl

H2P≡

phosphoranylidyne

HBi=bismuthylene

H2NNH−

hydrazinyl (not hydrazino)

H2As−

arsinoBi≡

bismuthylidyne

H2NN=

hydrazinylidene (not hydrazono)−NHN=

1-hydrazinyl-2-ylidene−NHNH−

1,2-hydrazinediyl (not hydrazo or
hydrazi)−N=N−

1,2-diazenediyl (not azo or azi)=NN=

1,2-hydrazinediylidene (not azino)(b) Acyclic hydrocarbon radicals are named from the skeletons byreplacing “-ane,” “-ene,” and “-yne” suffixes by “-yl,” “-enyl,” and “-ynyl,”(for monovalent radicals); by “-diyl,” “-triyl,” “-enediyl,” “-ynediyl,” etc., fordivalent radicals with hydrogen removed at more than one position; and by“-ylidene” and “-ylidyne” to indicate two or three hydrogen atoms lost at one
position. (Methylene is an exception.) Locants are not cited for monovalentradicals (the free valency position is always “l”), but unsaturated positions arealways indicated for chains of three or more atoms. Free valencies (single or¶ 161

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007(e) Heterogeneous heteroacyclic radicals are named analogously tohydrocarbon radicals.
Examples:

32

1

7a

1H-inden-2-yl
3

4

H3SiOSiH2−

1-disiloxanyl

H3SiOSiH=

1-disiloxanylidene

H3SnOSn≡

1-distannoxanylidyne−SiH2NHSiH2−

1,3-disilazanediyl

3aH-inden-3a-yl (a hydro derivative
would be named, e.g., 2,3-dihydro3aH-inden-3a-yl, not 2H-inden3a(3H)-yl)

1

7a

3
4

|
—SiH2OSiHOSiH2—

10

1,3,5-trisiloxanetriyl

195H-dibenzo[a,d]cyclohepten-5-ylidene

11a(f) Cyclic hydrocarbon radicals. Loss of one or two hydrogen atoms froma single cycloalkane carbon atom is denoted by replacement of “ane” of thering name by “-yl” and “-ylidene,” respectively. The implied locant (“l” in allcases) is not expressed. In radicals from cycloalkenes, cycloalkadienes, etc.,
only the final “e” is replaced by the radical suffix, and locants for unsaturationand the free valency (always “l”) are all cited. Loss of hydrogen at more than
one position is expressed by the suffixes “-diyl” (not “-ylene”), “-diylidene,”“-enylylidene,” etc. All locants are cited, and locants for free valencies are
assigned lowest locants.
Examples:

4

6

9
10a 1

8

cyclohexyl

16

53-naphthalenyl-1(4H)-ylidene (not2-naphthalenyl-4(1H)-ylidene)

1

8a

1

2,7-phenanthrenediyl

4b 4a

4

2-cyclopropen-1-yl

3

Von Baeyer and spiro radicals follow similar principles. Free valency
locants are assigned lowest locants compatible with ring-system numberingand are preferred over locants for unsaturation.
Examples:1

2,4-cyclopentadien-1-yl

5

bicyclo[2.2.2]oct-5-en-2-yl (not bi cyclo[2.2.2]oct-2-en-5-yl)
1

1,5-cyclohexadien-3-yn-1-yl

6

1

8

bicyclo[3.3.1]nonane-2,3-diyl-4ylidene

95
12,4-cyclohexadien-1-ylidene

6

11

1

1,3-cyclopentanediyl (not 1,3-cyclopentylene)

6

7 2

1

1-cyclohexanyl-2-ylidene (not 1cyclohexyl-2-ylidene)

16-cyclohexen-1-yl-2-ylidene

6

6

8a

5

1′
6′

(g) Heterocyclic radicals from ring systems not named by organic
replacement (“a”) nomenclature are named analogously to fused-hydrocarbon
radicals (above). The shortened form thienyl is used for thiophene radicals andall their fused derivatives; selenophene-yl (not selenophenyl) is the name of theseleno analog.
Examples:1
6

Radicals from benzene are named phenyl (C6H5-), 1,2-, 1,3-, and 1,4phenylene (-C6H4-), 1,2,3-benzenetriyl, 1,2,3,4-benzenetetrayl, etc.
Fused hydrocarbon radicals are assigned the lowest locants compatible withthe fixed numbering of the ring system. Indicated hydrogen (¶ 135) necessary
for the existence of the ring is assigned to the lowest nonangular position unless
it can be located to accommodate a monovalent radical in an angular positionor an “ylidene” radical in a nonangular position. Added hydrogen (¶ 136) iscited immediately after the radical locant and is assigned the lowest available
angular or nonangular position.
Examples:spiro[bicyclo[2.2.1]hept-5-ene-2,1′[3,5]cyclohexadien]-2′-yl (note:
lowest locants are assigned, inorder, to spiro atoms, free valencies,
all multiple bonds, double bonds)

1

4

dispiro[4.1.4.1]dodec-2-yl

5

7

5

1

12

6

N

3-pyridinyl (not 3-pyridyl)N1(2H)-pyridinyl

1

1

O

6

4-morpholinyl (not morpholino)

4

N

1
1

2-naphthalenyl (not 2-naphthyl)

7a

S
3

4
4

benzo[b]thien-2-yl (not benzo[b]thiophen-2-yl)

33

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
1
7a N

4

1

O

5

6′

3H-indol-2-yl-3-ylidene (a hydro derivat
would be named, e.g., 1,2-dihydro3H-indol-3-ylidene, not 1H-indol3(2H)-ylidene)

32,5-furandiylidene

¶ 162

1′ 1

[bi-2,5-cyclohexadien-1-yl]-4,4′diylidene
6(i) Polyborane radicals are formed from polyborane and hetero polyborane
names by citing the usual radical suffixes after the parenthetical designation of
the number of hydrogen atoms, with elision of the final “e” before “y.”Requirements for locant citation with diborane radicals are the same as for the
analogous acyclic hydrocarbon radicals.
Examples:1
7aN

2H-benzimidazol-5-yl-2-ylidene
N3

4
1

O

6

1-pentaboran(9)yldiboran(6)yl

1,2-dicarbadodecaboran(12)-1-yl

diboran(4)ylidene

6,9-decaborane(10)diyl

2

H Si

SiH

5O

O3

4

cyclotrisiloxane-2,4,6-triyl

1,2-diborane(4)diyl
162. Compound and complex radicals from molecular skeletons are
named by principles described earlier (¶ 133).
Examples:Si H“A”-named cyclic radicals are named like the hydrocarbon parents fromwhich they have been derived by atom replacement. The hetero atoms receive
lowest locants (cited or implied), then the free valencies (cited just ahead of theradical suffix).
Examples:H2
Sisilacyclohex-2-yl (not 2-silacyclohexyl)

16diboran(4)yl

Me2CH−(1-methylethyl)

H2C= CMe−(1-methylethenyl) (the unsaturated
parent radical is preferred)

CH= CH−C≡C−CH3|
CH3−CH= CH−CH=CH−CH−CH= CH−CH=CH−CH2—
11

10

9

8

7

6

5

4

3

2

1

[6-(1-penten-3-yn-1-yl)-2,4,7,9-undecatetraen-1-yl]

13-oxabicyclo[3.1.0]hex-6-ylidene

O36

PhCH=CH−(2-phenylethenyl) (not styryl)

PhC≡(phenylmethylidyne) (not benzylidyne)

5Me(h) Ring-assembly radicals are derived by bracketing the assembly name,eliding a final “e” if “y” is to follow, and appending the radical endings “-yl,”“-ylidene,” “-diyl,” etc., as appropriate. The free valencies need not be on theterminal rings of the assembly.
Examples:(2-methylphenyl) (not o-tolyl)

1
6

1

6′

[1,1′-biphenyl]-4-yl (not 4-biphenylyl)

1 1′

4-methyl-1,2-phenylene) (not 4methyl-o-phenylene)

6

6

Me
6

[1,1′-biphenyl]-2,4′-diyl (not 2,4′biphenylylene)

1 1′
6′

6′

[1,1′-biphenyl]-3,4-diyl (not (4phenyl-1,2-phenylene))

1′ 1
6
6′

[1,1′:3′,1′′-terphenyl] -4,4 ′-diyl (not(2-phenyl[1,1′-biphenyl]-4,4 -diyl))′

1′ 1Radicals from branched polyphenyls are chosen by application of thefollowing principles successively until a decision is reached:(a)longest chain of rings containing all of the free valencies, which
need not be on terminal rings;(b)lowest locants in the radical name for (1) ring junctions, and (2)free valencies;(c)maximum number of substituent prefixes;(d)lowest locants for substituent prefixes;(e)earliest index position of the radical name.
Examples (the letters on the left refer to the principles above):
(a)

6
6′′

1′′

1′′′′

6′′′′

(3′′,6′′-diphenyl[1,1′:4′,1′′:2′′,1′′′:4′′′,1′′′′-quinquephenyl]-4′′,5′′-diyl)

1′′′
1′′

6′′′

1′

6′

8′a
1
4′

5′

[1,2′-binaphthalene]-4′,5-diyl

1′

1

8a
5

1′

S

4

6′′

1

[5,5′-bithiazol]-2-yl (not [5-(5-thiazolyl)-2-thiazolyl])

S

5′ 5

3′ N

6

(b) (1)

6
1
1′

6′′

N3

6′

1′′

6′

1′

1

N

N

6

1′′′

[2,2′-bipyridine]-4,6-diyl (not [6-(2pyridinyl)-2,4-pyridinediyl])

6′′′(4′′,5′-diphenyl[1,1′:2′,1′′:2′′,1′′′quaterphenyl]-3′-yl)¶ 162

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007(b) (2)[6′-(4-methylphenyl)-4′,5′-diphenyl[1,1′:2′,1′′-terphenyl]-3′-yl]

6
1

Example:1′′ 6′′

1′

34

6′
Me

CO2H

6’

1’
1

Br

1’’

[1,1′:2′,1′′-Terphenyl]-3 ′-carboxylicacid, 4′′-bromo-3-fluoro-4′,6′diphenyl- (a decision is reached bychoosing lowest locants for theTerphenyl skeleton and then for the
principal group)

6’’

6

(c)

[6′-(2-bromophenyl)-4-(3-chlorophenyl)-2′′,4′′-diiodo[1,1′:2′,1′′terphenyl]-4-yl]

Cl

Br
6′′
1′′

I

1′
1

I

6′

6

(d)

[2′′-chloro-6′-(4-chlorophenyl)-4′phenyl[1,1′ :2′ ,1′′ -terphenyl]-4-yl]

6′′
1′′

6′

Cl

F

163A. Fullerenes. The even-numbered, closed spheroidal structures of 20
or more carbon atoms, in which every atom is bonded to three other atoms andof which the C60 “buckminsterfullerene” is the prime example, as known generically as “fullerenes”.2,3 “Fullerene” has been adopted as the class name and to
it are added ring sizes, number of carbon atoms, and point group symmetries toname specific members of the class. For example, in the name [5,6]FullereneC60-Ih, “[5,6]” indicates the presence of ring sized 5 and 6, “C60” the numberof carbon atoms, and “Ih” the point group symmetry.4 When a fullerene is modified (e.g., by addition, replacement, or deletion of atoms), the ring sizes, thenumber of carbon atoms, and the point group symmetry remain those of the parent fullerene. Incompletely described fullerenes, i.e., where ring sizes and/or
point group symmetries are not known or disclosed are named with only the
number of carbon atoms, e.g., Fullerene-C60. Existing nomenclature practices
are followed as closely as possible when naming derivatives. Anions, cations,
protonated fullerenes, and free radicals are named as follows:[5,6]Fulleride(3-)-C60-Ih

1′
1[5,6]Fullerene-C60-Ihion(1+)

Cl 6[5,6]Fulleren-C60-Ih-1(2H)-ylium[5,6}Fulleren-C60-Ih-1(2H)-yl
(e)
Cl
6′′
1′′

[2′′-bromo-6′-(2−chlorophenyl)-4′phenyl[1,1′:2′,1′′-terphenyl]-4yl](not [6′-(2−bromophenyl)-2′′chloro-4′-phenyl[1,1′:2′,1′′-terphenyl]-4-yl])

Metallofullerenes are compounds in which one or more metals are either
trapped inside the fullerene or located outside without bonding directly to it.
They are given fullerene names, with the metals cited by name in alphabeticalorder
Example:6′[5,6]Fullerene-C60-Ih
compd. with potassium (1:1), ion(1+)

1′
1
6

Br

163. Molecular skeletons as index heading parents. These two entities
coincide when no suffix, expressing a principal group, is added to the skeleton
name, either because such a group is absent, or because it is attached to a hetero
atom of the skeleton which changes it from a functional into a nonfunctionalgroup.
Examples:H3C−CH3

EthanePhNO2Benzene, nitro- (“nitro” is a mandatory prefix (¶ 132))OH
N

Piperidine, 1-hydroxy- (“hydroxy”
is considered nonfunctional when
attached to a hetero atom other thansilicon)

Me3SiCOMe

Partial hydrogenation of a fullerene is described by terms such as “hexatriacontahydro-”, while full saturation is implied by the name “fullerane”, e.g.,[5,6]Fullerane-C60-Ih.
Fullerenes containing substituents require that hydrogen be added before thesubstituents can be named.5 For example, C60F60 is named [5,6]FulleraneC60-Ih, hexacontafluoro- (the hydrogen being part of the parent name). C60Br2
is named as a dibromodihydrofullerene, and C60H6Ph6 is named as a dodecahydrohexaphenylfullerene.
Addition of hydrogen is not necessary when a fullerene contains two functional groups, as in [5,6]Fullerene-C60-Ih-1,60-diamine.
Modification of the fullerene network such that some carbon atoms nolonger have a connectivity of 3 are named by using “homo”, “nor”, and “seco”,
e.g., 1,2(2a)-Homo[5,6]fullerene-C60-Ih-2a-carboxylic acid.
Replacement of a carbon atom by a trivalent hetero atom such as boron or
nitrogen results in a free radical, e.g., 1-Bora[5,6]fulleren-C60-Ih-2- yl.5

Ethanone,1-(trimethylsilyl)-

Choice of a preferred index heading parent has already been described(¶ 138). In the case of a branched polyphenyl, the criteria are the same as forthe derived radicals (¶ 162), except that principal groups replace free valencies.

2Science 1988, 242, 1017-22; 1139-1145.
3“Fullerene” has also been defined as a closed, hollow network of 12 pen-tagonal and m hexagonal faces for a C20+2m molecule (Science 1991, 254,
1768-1770), but CAS also includes structures with 3-, 4-, and 7- through 10sided faces as fullerenes for purposes of naming.
4“Character Tables for Chemically Important Symmetry Groups”. In: F. A.
Cotton, Chemical Applications of Group Theory. 3rd ed., John Wiley & Sons,
1990. Appendix IIA, pp. 426-435.
5International Union of Pure and Applied Chemistry, Nomenclature ofOrganic Chemistry, Sections A,B,C,D,E,F, and H, 1979 ed., Pergamon Press,
Oxford (England), 1979. Rules C-0.1 and C-32.

35

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 165

C. PRINCIPAL CHEMICAL GROUPS (SUFFIXES)

¶ 164
165
166
167
168
169
170

Introduction
Acids expressed as substituent suffixes
Acyclic acids with cyclic substituents
Order of precedence of acids
Acid radicals
Functional derivatives of acids
Acid halides

164. Introduction. In substitutive nomenclature, a principal chemicalgroup is that substituent of a molecular skeleton which is selected for expression as a suffix. Only one kind of substituent may be cited as a suffix, viz., themost senior one as determined by the Order of Precedence of Compound Classes (¶ 106); all other substituents are expressed as prefixes (radicals) which may
be simple, compound, or complex (¶¶ 132, 133). For functional compounds,
the molecular skeleton name together with its suffix constitutes an index heading parent. The locants for suffixes are placed in front of the heading parent
name unless locants for indicated hydrogen, hetero atoms (in “a” names), unsaturation, fusion sites, etc., are present, in which case they are placed just before the suffix.
In the following paragraphs, compound classes expressed as substituent
suffixes are discussed in descending order of precedence.
165. Acids expressed as substituent suffixes on molecular skeletons include carboxylic, sulfonic, sulfinic, selenonic, and telluronic acids and theirfunctional replacement analogs, such as peroxy, imidic and thio acids. For
Carbonic acid and its relatives (including Carbamic acid and Formic acid)see ¶ 183.
(a) Carboxylic acids are named by the Geneva (“-oic”) or “-carboxylic”
system. The “-oic acid” suffix is employed for acyclic mono- and dicarboxylic
acids of carbon chains, including “a”-named acids; the “-carboxylic acid” suffix is used for acyclic polycarboxylic acids and compounds in which the carboxyl group is attached to a ring, a monoatomic hydride, or a heteroacyclic
chain. The trivial names Acetic acid and Benzoic acid are retained for these
two acids and their substituted derivatives. (The amides, acid chlorides, etc.,
are named similarly, but organic replacement analogs are named systematically, e.g., Benzenecarboximidic acid (not Benzimidic acid.)
Examples:Phosphinecarboxylic acid (notFormic acid, phosphino-)

H 2 PCO 2 H

H O 2 CSn H 2 O Sn H 2 CO 2 H
1

2

3

Propanoic acid (not Propionic acid)

Me(C H 2 ) 3 C O 2 H

Pentanoic acid (not Valeric acid)

1,3-Distannoxanedicarboxylic acidH
H2B

Diborane(6)-1-carboxylic acid

BH CO 2 H
H
CO 2 H
1

2,6-Cyclohexadiene-1,2-dicarboxylic
acid (lowest locants for principal
groups are preferred)

CO 2 H6

CO 2 H891

1-Anthracenecarboxylic acid

4a

10a

5

9a

10
1

N

8a

4-Quinolinecarboxylic acid
4

5

MeC H 2 C O 2 H

¶ 171
172
173
174
175
176
177

AmidesNitrilesAldehydes
Ketones
Alcohols (and phenols)
AminesIminesCO 2 H
5
O

1

5

3O

1′

Spiro[1,3-dioxolane-2,2′(1′H)naphthalene]-5′-carboxylic acid8 ′a2-Propenoic acid (not Acrylic acid)H 2 C =C H C O 2 H
3

1

2

1

5′

4′

CO 2 H

Me(C H 2 ) 4 C H =C HCH 2 CH= CH( CH 2 ) 7 CO 2 H
18

13

1

9

HO2C
1 1′
6′

Ethanedioic acid (not Oxalic acid)

HO2CCO2H

CO 2 H

12

Pentanedioic acid (not Glutaric acid)H O 2 C (C H 2 ) 3 C O 2 H
1[1,1′-Biphenyl]-2,2′-dicarboxylicacid

69,12-Octadecadienoic acid

1,4(4H)-Pyridinedicarboxylic acid(the added hydrogen is expressed
after the final locant but relates tothe 1-carboxyl group; see ¶ 136)

CO 2 H
N

5

1

~~~

6

H 3 C− C H 2 −O −C H 2 − CH 2 −O −CH 2 − CH 2 −O −CH 2 −CH 2 − O−CH 2 −CH =
21

18

~~~

23

15

12 11

10

=CH −( CH 2 ) 7 − COOH

CO 2 H1

912,15,18,21-Tetraoxatricos-9-enoic
acid (lowest locants are assigned tofunctional suffixes, not replacement
prefixes)−C O OHH O O C− C H 2 − C H−CH 2 −COOH
12

3

1,2,3-Propanetricarboxylic acid(numbering excludes the carboxylgroups)(H O 2 C ) 2 C =C (C O 2 H) 2

1,1,2,2-Ethenetetracarboxylic acid

HO2CNHNHCO2H

1,2-Hydrazinedicarboxylic acid (notBicarbamic acid)

1

HO2C

2

CO 2 HB 1 0H 1 0

1,2-Dicarbadodecaborane(12)-1,2dicarboxylic acid (the 1,2-bonddoes not possess single-bondcharacter)(b) Sulfonic, sulfinic and sulfenic acids and their selenium and tellurium
analogs are expressed by appending the appropriate suffix to the name of themolecular skeleton. Mono- and diacids of these series, unlike “-oic acids,”
above, do not need to occupy terminal positions on a chain.
Examples:Ethanesulfonic acidE tSO 3 H

1

2−

SO 3 HCH 3 −CH 2 −CH 2 − CH− CH 3
5

4

3

2

1

2-Pentanesulfonic acid¶ 165

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
1

Benzenesulfonic acid

P hS O 3 H

36

3-Pyridinecarbohydrazonic acid

N
6

N
6

1

3-Pyridinesulfinic acid

C( =N N H 2 ) O H

SO2H

6

Methanesulfenic acid

MeSO H1

H O C(=N H )C( =N H ) O H

1,4-Benzenedicarboximidic acidH 2 N N =N S O 3 H

1-Triazene-1-sulfonic acidH 2 N N H SO 2 HHydrazinesulfinic acid

3 2

8a

1

S(=N H ) O 2 H

2-Naphthalenesulfonimidic acid

1

5

−

SO 3 HC H 3 − C H 2 −O −C H 2 − CH 2 − O−CH 2 −CH 2 − O−CH 2 −CH 2 −Ο−C Η 2 −CH −CH 3

15

13

10

7

4

3

2

4

4,7,10,13-Tetraoxapentadecane2-sulfonic acid (principal
groups are preferred over heteroatoms for lowest locants)
Phosphinesulfonic acidH2PSO3H

Benzeneselenonic acid

P hS eO 3 H

Ethanesulfonodiimidic acid

E tS(= N H ) 2 O H

1S(=N H ) (= Ν N H 2 ) O H

2-Naphthalenesulfonohydrazonimidicacid
E tS(= N H ) O H

Ethanesulfinimidic acid

Ph Se (=N H ) O 2 H

Benzeneselenonimidic acid

−

SeO2H

C H 3 − C H 2 −C H 2 −CH 2 −CH− CH 3
6

5

4

3

2

2-Hexaneseleninic acid

1

−

TeO2H

CH3− CH2− CH−CH3

2-Butanetellurinic acid

P hT eO H

Benzenetellurenic acid

3

2

1

Ο

Ethaneperoxoic acid (notPeroxyacetic acid)=

4(d) Peroxy acids are named by use of the suffixes “-peroxoic acid” (from“-oic acid”) and “-carboperoxoic acid” (from “-carboxylic acid”). Acetic acidand Benzoic acid afford systematically named peroxy acids. Sulfonic, sulfinic,
and sulfenic acids and their selenium and tellurium analogs are named by useof the suffixes “-sulfonoperoxoic acid”, etc. Combinations with imidic and hydrazonic suffixes are made, in alphabetic order, by the normal rules.
Examples:(c) Imidic and hydrazonic acids. Names for these are formed from theparent carboxylic, sulfonic, sulfinic, selenonic, etc., acid names by functional
replacement nomenclature (¶ 129). Some modification of the formal endings ismade; thus, an “-oic acid” becomes an “imidic acid”, not an “-imidoic acid”.
Acetic acid affords systematically named Ethanoic acid replacement analogs,
while Benzoic acid is treated as Benzenecarboxylic acid in a similar manner.
The suffixes appended to the molecular skeleton name in each case are as follows:
Parent Acid-oic-carboxylic-sulfonic-sulfinic

Imidic acid
-imidic-carboximidic-sulfonimidic-sulfinimidic

Hydrazonic acid
-hydrazonic-carbohydrazonic-sulfonohydrazonic-sulfinohydrazonic

The group -S(:NH)2OH is named by the suffix “-sulfonodiimidic acid,” and-S(:NH)(:NNH2)OH by “-sulfonohydrazonimidic acid.” Selenium and tellurium acids are named analogously.
Note: Imidic acids are tautomeric with amides; except for derivatives inwhich an acid proton has been replaced, e.g., esters and anhydrides, amides
are preferred for index entries; see ¶ 122. Hydrazonic acids are tautomericwith hydrazides, which are preferred as index entries.
Examples:Ethanimidic acid (not Acetimidic acid)

P hC (=N H )O H

Benzenecarboximidic acid (notBenzimidic acid)

Cyclohexanecarboperoxoic acid

CO 3 HH O 3 C( CH 2 ) 2 CO 3 H

Butanediperoxoic acid

M e C( =N H ) O O H

Ethanimidoperoxoic acid (notPeroxyacetimidic acid)

Ph C( =N H ) O O H

Benzenecarboximidoperoxoic acid(not Peroxybenzimidic acid)

Peroxy analogs of acids expressed as heading parents, e.g., Carbonoperoxoic acid (¶ 183), Phosphoroperoxoic acid (¶ 197), are ranked with the acids,e.g., Carbonic acid, Phosphoric acid, from which they are derived.
(e) Thio acids derived from carboxylic, sulfonic, sulfinic, and sulfenic acids and their imidic, hydrazonic, and peroxy replacement analogs are named byincorporating “thio” (or “dithio”) into the suffixes of the oxygenated acidnames. The terms “seleno” and “telluro” are used similarly when appropriate.
Selenonic, telluronic, etc., acids are handled like sulfonic acids. The names do
not distinguish between replacement of oxygen in =O and -OH groups in theunesterified acids. This information is usually given in the ester name, or by a
substituent prefix.
Examples:Ο

Benzenecarbothioic acid,S-methyl ester=

MeC (= N H )O H

CH 3 −C− O O H

C− SCH 3
Me(C H 2 ) 4 C (= N H ) OH
61SC (=N H) OH

1H-Pyrrole-2-carboximidic acid

CH 3 CH 2 O−CCH 2 CH 2 C− O H
4 3

H O C (=N H )(C H 2 ) 4 C(= NH) OH

Hexanediimidic acidH 2 N N H C (= N H )O H

Hydrazinecarboximidic acid

MeC (= N N H 2 )O H

Ethanehydrazonic acid

O
=

H
N

Hexanimidic acid

=

5

1

2

1

Butanoic acid, 4-ethoxy-4-thioxo- (fororder of precedence of acid groups,
see ¶ 167)

When a specific name for a single form is imperative, an italicized element
symbol is used in the heading parent, e.g., Ethanethioic O-acid for CH3C(S)OH.
Replacement by two sulfur atoms in a monocarboxylic acid named by thesuffix “-oic acid” is denoted by the suffix “-(dithioic) acid” and by one sulfur
atom in each of the two groups in a “-dioic acid” by “-bis(thioic) acid.” Ambiguity is absent from “-carboxylic” names, and parentheses are therefore not
employed for the analogous “-carbodithioic acid” and “-dicarbothioic acid”
suffixes.

37

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Examples:Butanethioic acid

Me(C H 2 ) 2 C O SH

166. Acyclic acids with cyclic substituents may usually be named by conjunctive nomenclature (¶ 124).
Examples:Ph CH 2 CH 2 CO 2 H
βBenzenepropanoic acid (notHydrocinnamic acid)α2-Propene(dithioic) acidH 2 C= C H C S 2 H
3

¶ 167

1

CH 2

=

Benzeneacetic acid, α-methylene- (notAtropic acid)

C- CO O H
αBenzenecarbothioic acid (notBenzoic acid, thio-)

P hC O SH

CS2HN

1-Piperidinecarbodithioic acid
CH= C−CO O H

Benzeneacetic acid, α-(phenylmethylene)- (not Benzene-2-propenoic acid,α-phenyl-; conjunctive nomenclature is
not used with unsaturated acyclic acids(¶ 124))αPropanebis(thioic) acidH O S C C H 2 C O SH

CH 3−

CH 2 − CH− SO 3 H
H S 2 C C H 2 C H =C H CH 2 CS 2 H
1

6

1

5

C O SH

1,2-Naphthalenedicarbothioic acid

4

5

HSSO2

4

2

9-Anthracenepropaneperoxoic acid

( CH 2 ) 2 CO 3 H

S O 2 SH

MeC H [S(S)SH ]Me

1-Naphthalenemethanesulfinic acid18a

1,3-Benzenedisulfonothioic acid1

Benzeneethanesulfonic acid, α-methyl-

CH 2 SO 2 H

C O SH8aαβ3-Hexenebis(dithioic) acid8

2-Propanesulfinodithioic acid

5

9

1

9a

4a

10a

10

3
6

Methanesulfenothioic acid

MeSS H
1S

5C (=N H )SH

E tS( =N H )O S H

Ethanesulfonimidothioic acid

( CH 2 ) 2 CO 2 H

1,4-Benzenedipropanoic acid

2-Thiophenecarboximidothioic acid

When different numbers of sulfur atoms replace oxygen in the functionalgroups of polyacids, the groups of higher sulfur content are expressed as substituent prefixes.
Examples:Η ΟS C CΗ 2 C H 2 C O 2 H1

H O 2 C( CH 2 ) 2

When conjunctive names are impermissible, e.g., for unsaturated and polyfunctional acyclic acids, acids attached to rings by a double bond, and acids ofnoncarbon chains, the cyclic group is expressed as a substituent.
Examples:1

N

N H N H CO 2 H

6Hydrazinecarboxylic acid, 2-(2pyridinyl)-

Propanoic acid, 3-(thiocarboxy)−

CH 2 CO 2 H

E tO SC C O 2 H

CH CO 2 H

Acetic acid, 2-ethoxy-2-thioxo8

Thio peroxy acids are named by similar principles; the replacement affixes“(thioperoxo)” and “(dithioperoxo)” are placed, in alphabetic order with otherterms such as “imido” and “hydrazono,” in the “-oic,” “carboxylic,” “sulfonic,”
etc., suffixes of the appropriate parent acids.
Examples:
MeC O S S H

9
4b

9a

Butanedioic acid, 2-(9H-fluoren9-yl)-

1

4aEpoxy derivatives of acids are named as oxirane and oxetane derivatives.
Example:Ethane(dithioperoxoic) acid
2,3-Oxiranedicarboxylic acid (notButanedioic acid, 2,3-epoxy-)O
P hC ( =N H )O S HBenzenecarboximido(thioperoxoic)
acid

HO2C

CO 2 H

6

HS3CN

1 NCS3H

P hS O 2 S S H

1,4-Piperazinedicarbo(dithioperoxo)thioic acid
Benzenesulfono(dithioperoxoic) acid

SSSH
N
1

6

MeC H MeSS O H
1

1-Piperidinesulfeno(dithioperoxic)acid
2-Propanesulfeno(thioperoxoic) acid2

MeC SeO H

Ethaneselenoic acid

P hC S eSH

Benzenecarboselenothioic acid167. Order of precedence of acids. Acid suffixes are the most preferredprincipal group of all non-cationic substituent suffixes (¶ 106), but only one
type of acid suffix may be expressed in a heading parent. Less preferred acidfunctions are cited as substituent prefixes. The choice is made in accordancewith the following hierarchy, listed in order of descending precedence:(a) Peroxy acids. (Among peroxy acids, the choice depends on the natureof the parent acid as described in (b) through (i), below.) (See also the separate
ranking of peroxy carbonic and peroxy phosphorus acids at ¶¶ 183, 197.)(b) Carboxylic acids, followed by thio, seleno, and telluro analogs, in thatorder. The preferred acid group contains the maximum number of preferredchalcogens, oxygen being the most preferred. (For Carbonic acid, Formic acid, etc., see ¶ 183.)(c) Carbohydrazonic acids, followed by chalcogen analogs (see (b)).
(d) Carboximidic acids, likewise.
(e) Sulfonic acids, followed by chalcogen and nitrogen analogs in the order of (b), (c), and (d).
(f) Sulfinic acids, likewise.
(g) Sulfenic acids, likewise.
(h) Selenonic, seleninic, and selenenic acids, as for sulfonic acids.
(i) Telluronic, tellurinic, and tellurenic acids, likewise.

¶ 167

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

HO2C

SO 2 OOH==SSH O− C−C H 2 −C H 2 − C− SH12(2-hydroxy-1,2-diiminoethyl)

H O C(= N H ) C(=N H ) —Examples:3

Benzenesulfonoperoxoic acid, 4carboxy-

38

CO —

(2-naphthalenylcarbonyl)

CO —Propanethioic acid, 3-(dithiocarboxy)-(1,2-phenylenedicarbonyl)

4

CO —
CO2H
1
6

Benzoic acid, 3,4-disulfo-O=([1,1′-biphenyl]-4-ylcarbonyl) (not(4-phenylbenzoyl) (see ¶ 133))

—C —

SO3H
SO3H

=

NH
O− C−C H 2 −COOH
2

Propanoic acid, 3-imino-3-phenoxy-

When two or more like acid groups are attached to different molecular skeletons, or when one or more are attached to a branched skeleton, the preferredindex name is selected according to the usual rules (¶ 138).
Examples:
6
1

HO2C

CH( CO 2 H) 2

NHNHCO 2 H

HO2C

P hC H (C O 2 H )C H 2

Propanedioic acid, 2-(4-carboxyphenyl)- (principle: maximum numberof the principal group)

Hydrazinecarboxylic acid, 2-(3-carboxyphenyl)- (principle: heteroacyclic parent preferred)

Benzeneacetic acid, α-(cyclopentylmethyl)- (principle: preferred ringsystem)1

O
3(C H 2 ) 3 CO 2 H

Ph

CO2H

3

−

−

CH3
F 3 C−C−
COOH
2
1

CF3

2-Oxiranebutanoic acid, 2-carboxy3-phenyl- (principle: largest heading parent)
Propanoic acid, 3,3,3-trifluoro-2-methyl-2-(trifluoromethyl)principle: maximum number ofsubstituent prefixes)

Aldehydic, amic, anilic, hydroxamic, hydroximic, nitrolic, and nitrosolic
acids are indexed as compounds of mixed function (see ¶ 228). So are triviallynamed hydroxy and oxo acids, e.g., Glycolic acid, Acetoacetic acid, and aminoacids, e.g., Sulfanilic acid, other than those which are of biological significance(¶ 205).
168. Acid radicals derived, by removal of hydroxyl groups, from acids expressed as suffixes are named as compound and complex radicals. Acyl radicals, e.g., propionyl, naphthoyl, acetimidoyl, are no longer used as substituent
prefixes; the only exceptions in general index nomenclature are acetyl(CH3CO-) and benzoyl (C6H5CO-). Amino acid radicals, e.g., glycyl, L-alanyl,
are restricted to use in peptide and depsipeptide names (¶ 206).
Radicals derived from monocarboxylic acids are in general named as (1oxoalkyl) or (arylcarbonyl); carboximidic acids afford (1-iminoalkyl) and(aryliminomethyl) radicals; carbothioic acids give (1-thioxoalkyl) and (arylthioxomethyl) radicals (carbonimidoyl and carbonothioyl are used only as multiplicative radicals (¶ 125) and in cases where both bonds are attached to thesame atom); sulfonic, sulfinic, and sulfenic acid radical names are based on theparent radicals “sulfonyl,” “sulfinyl,” and “thio.”
Examples:
E tC O —(1-oxopropyl)

MeC S—(1-thioxoethyl) (not thioacetyl)(1,4-phenylenedicarbonothioyl)— CS —— CS —

1N(3,5-pyridinediyldicarbonimidoyl)C( =N H )C( =N H )Ph SO 2 —(phenylsulfonyl)

Ph SO —

(phenylsulfinyl)

Ph S( =N H ) —(S-phenylsulfinimidoyl)

Ph S—(phenylthio)

169. Functional derivatives of acids. In the absence of higher functions ormore preferred compound classes (¶ 106), esters are indexed in the modification, usually at the acid name, sometimes at the alcohol (see ¶ 185). Hydrazides
are likewise indexed at the acid name (¶ 189). Hydrazones, azines, and semicarbazones are named at hydrazonic acid parents (RC(OH):NNH2) (¶ 165).
Oximes of carboxylic acids are given N-hydroxy imidic acid names; hydrates
and acetals (ortho carboxylic acids and their diesters) are indexed as alcohols(or thiols).
Examples:M e C( O H ) 3

1,1,1-Ethanetriol (not Orthoacetic acid)

M e C( O M e ) 2 O H

Ethanol, 1,1-dimethoxy-

170. Acid halides. In this category are now included the halogenides, inwhich the hydroxyl groups of acids are replaced by -NC, -NCO, -NCS, -NCTe,-N3, and (in acids other than carbon acids) -CN groups. They are named byplacing the halide (etc.) term in the heading as a separate word following anacid term which ends as follows for various acid classes:
Acid suffix-carboxylic-carbohydrazonic-carbothioic-carboximidic-oic-hydrazonic-thioic-imidic-sulfonic-sulfonimidic

Acid halide suffix-carbonyl-carbohydrazonoyl-carbothioyl-carboximidoyl-oyl-hydrazonoyl-thioyl-imidoyl-sulfonyl-sulfonimidoyl

Examples:Pentanoyl isothiocyanate

M e ( CH 2 ) 3 CO N CS

O

=

3

CH 3 − CH 2 −O −CH 2 −CH 2 − O−CH 2 −CH 2 − O−CH 2 −CH 2 −O− CH 2 −C− F

14

H N= C H —(iminomethyl) (not formimidoyl)—C O C O C O —(1,2,3-trioxo-1,3-propanediyl)H O 2 C (C H 2 ) 2 C O —(3-carboxy-1-oxopropyl)

13

12 11

10

9

8

7

6

5

4

3

2

1

3,6,9,12-Tetraoxatetradecanoyl
fluoride

H 2 N N H CO Cl

Hydrazinecarbonyl chloride

39

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
O=

Benzoyl isocyanide¶ 171

Examples:— C− N C
M e CO N H 2

Acetamide

H N= N H CO N H 2

Diazenecarboxamide

M e CSN H 2

Ethanethioamide

2

Benzenecarboximidoyl bromide

P hC ( =N H )B r

Benzenecarbothioyl chloride

P hC S C l

C H 3 − C H 2 −C H 2 −C H 2 −SO 2 −NCO
4

3

1

2

1

1-Butanesulfonyl isocyanate

Hexanedithioamide

H 2 N CS( CH 2 ) 4 CSN H 2
16

H 2 N C(= N H ) CH 2 C( = N H ) N H 2
N′1

N1

Benzenesulfonimidoyl chloride

P hS (O )( =N H )C l

2

1

Butanedioyl dichloride (notButanedioyl chloride)4

Propanediimidamide

N3

Ph C( =N N H 2 ) N H 2

Benzenecarbohydrazonamide

M e S(= N H ) 2 N H 2

MethanesulfonodiimidamideN′

C lC O (C H 2 ) 2 C O C l

N′3

3

N

SO 2 N H M e18a

O C N S O 2 C H 2 (C H 2 ) 4 CH 2 SO 2 NCO
61

1,5-Naphthalenedisulfonamide,
N1,N 5-dimethyl-

1,6-Hexanedisulfonyl diisocyanate
54

M e N H SO 2
P hC H 2 C H 2 C O N 3

Benzenepropanoyl azide
Benzenecarbothioamide, N-phenyl-

Ph CSN H Ph

Halides, etc., of peroxy acids are generally indexed as anhydrides, anhydrosulfides, etc., with halogen or halogenoid “oxo” acids such as Hypochlorousor Thiocyanic acid. Halides, etc., of (thioperoxy)sulfenic acids are indexed atDisulfide.
Examples:

7a

H
N

1H-Indole-3-ethanimidamide1
3

CH 2 C( =N H ) N H 2

4Carbonochloridothioic acid,anhydrosulfide with thiohypochlorous acid

C lC O SC lαN′

Acetamide, N-acetyl- (not Diacetamide)

M e CO N H CO M e2

1NBenzenesulfonamide, N-(phenylsulfonyl)- (not Dibenzenesulfonamide)

Ph SO 2 N H SO 2 Ph=S
C− O−C N

Benzenecarbothioic acid,anhydride with cyanic acid

Amides of peroxy acids and thio peroxy acids are indexed as azanyl esters(¶ 193).
Amide radicals are named as compound or complex radicals based on “amino” or “imino,” with acid radicals (¶ 168) as substituents.
Examples:AcNH—

S S ClFSO2
C OCl

Bz N =(benzoylimino)

M e ( CH 2 ) 4 CO N H —[(1-oxohexyl)amino] (not hexanamido)

Ph SO 2 N H —[(phenylsulfonyl)amino] (notbenzenesulfonamido)

Ph C( =N H ) N H —[(iminophenylmethyl)amino]

Benzoyl chloride, 3,5-bis(fluorosulfonyl)-FSO2
F C O (C H 2 ) 2 C O I(acetylamino) (not acetamido)

Disulfide, chloro 2-naphthalenyl

When more than one acid halide residue is present in a compound, only one
type is named in the heading parent. This is chosen by consideration first of thehierarchy of the parent acids (¶ 167) and then, if a further choice is necessary,of the following list of halides and halogenides (in descending order of precedence): -F, -Cl, -Br, -I, -N3, -NCO, -NCS, -NCSe, -NCTe, -NC, -CN.
Examples:Butanoyl fluoride, 4-iodo-4-oxo-

Functional derivatives of acid chlorides are indexed similarly to those of theparent acids (¶ 169).
171. Amides are named by modification of the parent acid suffixes, thus:

The radicals above are employed as substituents when a more preferredamide or a higher function, e.g., an acid or acid chloride, is present in part ofthe molecule attached to the amide by way of the nitrogen atom. Other attachments call for use of amino and oxo, or (aminocarbonyl), (aminosulfonyl), etc.,
radicals.
Examples:becomesbecomesbecomesbecomesbecomesbecomes-amide-carboxamide-carbohydrazonamide-carbothioamide-carboximidamide-sulfonamide

Butanoic acid, 4-amino-4-oxo-

H 2 N CO ( CH 2 ) 2 CO 2 H
4-oic acid-carboxylic acid-carbohydrazonic acid-carbothioic acid-carboximidic acid-sulfonic acid

N

6

1

1

CO 2 H

Benzoic acid, 2-(aminocarbonyl)CO N H 2
6Secondary and tertiary amides are named as primary amides with N-substituents. Anilides, toluidides, etc., are indexed as N-aryl amides.

H 2 N SO 2

1

CO N 3

Benzoyl azide, 4-(aminosulfonyl)-¶ 171

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

H 2 N C SC H 2 C O N H M e

Propanamide, 3-amino-N-methyl3-thioxo-

A cN H S O 2 P h

Acetamide, N-(phenylsulfonyl)-

3

N

1

+

−

The zwitterionic nitrilimines (R C ≡Ν −Ν −R ′) are named as substituted hydrazinium inner salts (¶¶ 201, 267).
Examples:Acetonitrile

M e CN

H C≡ CCH= CH CN

Replacement (“a”) nomenclature is employed where applicable (¶ 127) for
naming polyamides, but not peptides (¶ 206).
Example:H 2 N C O C H 2 C O N H( CH 2 ) 2 NHCOCH 2 CONH( CH2) 2 NHCOCH 2 CO N H 2
4

7

11

14

17

4,7,11,14-Tetraazaheptadecanediamide,
3,8,10,15-tetraoxoAmides incorporated in a ring system are indexed at the ring name andranked according to the nature of the suffix, if any (¶ 106), not as amides.
Examples:
Me

H
N

6

O

1

7a

5

N CCN

Ethanedinitrile (not Cyanogen)

H 3 G e CN

Germanecarbonitrile

H 2 N N H CN

Hydrazinecarbonitrile( N C) 2 C=C( CN ) 2

1,1,2,2-Ethenetetracarbonitrile

Ph CN

Benzonitrile
CH 2 − CH 2 −CH 3

2-Piperidinone, 6-methyl- (ranked asa ketone)O2S

1,2-Benzisothiazole, 2,3-dihydro1,1-dioxide (ranked as a nonfunctional cyclic nitrogen skeleton)

2NH
32-Penten-4-ynenitrile

1

Benzeneacetonitrile, α-propyl-

−

1

40

CH− CNαIn the presence of higher functions, nitriles are always expressed as cyano
radicals.
Examples:4OH

1,3-Dioxolo[4,5-c]pyridin-4(3aH)one, tetrahydro-7-hydroxy-2phenyl-

1

O

7

HN

5

Ph
2

O

4

N CCH 2 CO N H 2

Acetamide, 2-cyano- (notPropanamide, 3-nitrilo-)

M e CH ( CN ) CO Cl

Propanoyl chloride, 2-cyano-

2

1

3

O

CO 2 H

Amides of which only the nitrogen atom forms part of a ring, formerly referred to as “unexpressed amides”, are named according to the highest function
present.
Examples:
HO
4 NCO

1O

Methanone, (2-hydroxyphenyl)4-morpholinyl-

1

Benzoic acid, 2-cyanoCN

173. Aldehydes, RCHO, are named from “-carboxylic” and “-oic” acids byuse of “-carboxaldehyde” and “-al” suffixes, respectively.
Examples:A c H ( M e CH O )Acetaldehyde

M e CH =CH CH O

2-Butenal

6

6

A cN 1Ethanone, 1-(4-hydroxy-1-piperidinyl)-OH

6

H CO CH 2 CH =CH C≡ CCH 2 CH O

3-Octen-5-ynedial

H 2 P( O ) CH O

Phosphinecarboxaldehyde
oxide

1

1

E tC O N
51

SO 2 NH 2

Benzenesulfonamide, 4-[1-(1-oxopropyl)1H-pyrrol-3-yl]Amides of amino acids with trivial names are named systematically except
in peptide nomenclature (¶ 206).
Example:

3

5

8

6
1

Me

6

1

CH O

CH O

Benzaldehyde, 4-methyl-

1,2-Benzenedicarboxaldehyde

CH O
H2NCH2CONH2

Acetamide, 2-amino- (not Glycinamide)

Oximes of amides (amidoximes) (R-C(:NOH)NH2) are tautomeric with Nhydroxy carboximidamides (R-C(:NH)NHOH) and are indexed at imidamide
names:
Example:Me(C H 2 ) 4 C (=N H )NHOH

Hexanimidamide, N-hydroxy-

172. Nitriles (RC≡N) are indexed at names derived from “-carboxylic” and“-oic” acid names by use of “-carbonitrile” and “-nitrile” suffixes, respectively.

Ph CH 2 CH O

Benzeneacetaldehyde

Chalcogen analogs of aldehydes are given “-thial,” “-selenal,” “-carbothioaldehyde,” etc., names.
In the presence of more highly ranked compound classes (¶ 106) or more
preferred aldehydes, the -CHO group is expressed by formyl (if it does notform part of an acyclic carbon chain) or by a terminal oxo radical. For thio aldehydes, the equivalent radicals are (thioxomethyl) and a terminal thioxo radical.
Examples:H CO CH 2 CO 2 H

Propanoic acid, 3-oxo-41

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
Benzenepropanal, 3-formyl(principle: largest heading parent)O=(C H 2 ) 2 C H O¶ 174

Methanone, phenylphosphino-

C− PH 2

CHO

Benzonitrile, 2-(thioxomethyl)-

CN

Methanone, 1-piperidinyl-1H-pyrrol-1-yl-

N CO NCHS

Butanethial, 4-telluroxo-

T eC H (C H 2 ) 2 C H S

E tCO SiH 2 O H

1-Propanone, 1-(hydroxysilyl)-

H 2 P( S) CSPh

Methanethione, phenylphosphinothioyl-

Substitution of the aldehydic hydrogen atom is not permitted.
Examples:MeC ( =N O H )N O

Ethanone, 1-nitroso-, oxime(not Acetonitrosolic acid)=

O

Methanone, nitrophenyl(not Benzaldehyde, α-nitro-)

C −N O 2174. Ketones, RC(:O)R′, and their chalcogen analogs are named by use of
the characteristic suffixes -one, -thione, -selone, and -tellone. (The last twoclasses must be differentiated from selenones and tellurones, which contain the
noncarbon groups -SeO2- and -TeO2-, respectively.) The carbonyl group may
be attached to carbon or other elements with the exception of hydrogen andthose that could form an acid, acid derivative, or amide name. Conjunctive
names are not employed for acyclic ketones attached to ring systems; instead,the cyclic portion is expressed as a substituent of the acyclic ketone parent (inwhich the oxo group may occupy the 1-position). When an acyclic ketone withtwo cyclic substituents consists only of a single carbon atom with a chalcogenattached, the heading parents Methanone, Methanethione, Methaneselone
and Methanetellone are employed.
Examples:2-Propanone (not Acetone)

MeC O Me1

Cyclic ketones (including those with neighboring hetero atoms) are namedby appending “-one,” “-thione,” etc., suffixes to the ring names. Indicated hydrogen (required to form the ring system itself) is often chosen (where possible) to accommodate a single ketone group (¶ 135). In other cases, addedhydrogen (¶ 136) is introduced at some other position of the ring system when
the ketone suffix is attached.
Examples:

1

1

4
5

O
1

S

6

4H-Thiopyran-4-one, 2,3-dihydro(not 2H-Thiopyran-4(3H)-one)

4O

MeC H 2 O SiH 2 (C H 2 ) 2 CO( CH 2 ) 2 SiH 2 OCH 2 Me1

4H-1-Benzopyran-4-one, 2-phenyl(not flavone)

Ph

O

8a

3

2

3-Cyclohexen-1-one

O
6

34

7

10

11

13

S

3,11-Dioxa-4,10-disilatridecan-7-one

7a1

1H-Indene-1,3(2H)-dithione

35-Hexene-2,4-dione (not 1-Hexene3,5-dione)

MeC O C H 2 C O C H =CH 2
6

1

S

4
1

S
H 2 C =C =O

Ethenone (not Ketene)

Me(C H 2 ) 3 C H =C =O

1-Hexen-1-one

MeC SeC H 2 Me

2-Butaneselone

4-Thiazolidinone

5
3

NH
O

6

1

1

4

O

7a

1

6

4

O

O
8

2-Butanone, 4-cyclohexyl-C H 2 C H 2 COMe
4

1

9
10

10a

1-Hexanone, 1-phenyl- (not Hexanal,
1-phenyl-)

P hC O (C H 2 ) 4 Me

Methanone, cyclohexylidene-

C =O

Methanone, diphenyl- (notBenzophenone)

Ph2CO

6

1

1′

N

N

P hC O —— COPhN

N—COCO —

6′

Methanone, 1,1′-[2,2′-bipyridine]5,5′-diylbis[1-phenyl- (a multiplicative name (¶ 125))

1
3O

2-Hexanone, 4-thioxo- (not 2,4Hexanedione, 4-thio-)

MeC O C H 2 C SC H 2 Me

1H-Indole-5,6-dione, 2,3-dihydro(the two oxo substituents can be
added as a pair without hydrogen
being added elsewhere to the ringsystem)HN

9a1,9,10(2H)-Anthracenetrione, 3,4dihydro- (the added hydrogen iscited in the lowest-numberedavailable position)

1

4a

5

O

In the presence of higher functions or more preferred ketones, oxo, thioxo,
selenoxo, and telluroxo radicals, are used. The = CO group, when not part ofan acyclic chain or a ring, is expressed as carbonyl; the chalcogen analogs (carbonothioyl, carbonoselenoyl, and carbonotelluroyl) are used when they are notpart of a chain, and when, in addition, they are either bonded to a single atom
or used as multiplicative radicals. The trivially named radicals benzoyl, for(oxophenylmethyl), and acetyl, for (1-oxoethyl), are used when appropriate.
Examples:Butanoyl bromide, 3-oxo(not Acetyl bromide, acetyl-)

M e CO CH 2 CO Br

M e COCO E t1-Propanone, 1-(4-acetylphenyl)-

1,2-Ethanedione, 1,2-di-2-pyridinylS
CO 2 HA cN =N N H

Ethanone, 1-(1-triazen-1-yl)-

S

2H-Thiopyran-3-carboxylic acid,
3,4-dihydro-4-thioxo-¶ 174

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
Butanoic acid, 2,4-dioxo- (notPropanoic acid, 3-formyl-2-oxo-)

HCOCH2COCO2H
4

1

CH =CH CH 2 O H

1OHHydrazinecarboxylic acid, 2-(cyclopropylcarbonyl)-C O N H N H CO 2 H
461

O ( CH 2 ) 9 O HOHNBenzonitrile, 3-(2-pyridinylthioxomethyl)- (not Benzonitrile, 3-(2pyridinylcarbonothioyl)-)

CN
—CS —

CO2H

S =C

Cyclopentanecarboxylic acid, 3carbonothioyl-

Phenol, 2-(3-hydroxy-1-propen-1-yl)(not 2-Propen-1-ol, 3-(2hydroxyphenyl)-)Phenol, 2-[(9-hydroxynonyl)oxy](principle: a cyclic parent ispreferred (¶ 138))
Ethanol, 2-mercapto-

H SCH 2 CH 2 O H
2

42

1

Hydroxy derivatives of thiophene, selenophene, and tellurophene are indexed at Thiophene-ol, etc., (the final “e” of the parents being left unelided to
avoid confusion with chalcogen analogs of Phenol). The locant is placed immediately before the suffix.
Example:1

1
8a

N
N C H 2 COCH 2 COPh

4

4

5

1

O

1,3-Butanedione, 4-(4-oxo-3(4H)quinazolinyl)-1-phenyl- (principle: maximum number of theprincipal chemical functionalgroup (¶ 138))

175. Alcohols (and phenols) and their chalcogen analogs (thiols, selenols,
and tellurols) are expressed by the suffixes -ol, -thiol, -selenol, and -tellurol, attached to a carbon or silicon atom of a molecular skeleton name. The only trivial name employed in CA indexes for a compound of this class is Phenol (forBenzenol). Phenols as a class are treated precisely like alcohols, the choice ofindex name for a compond containing alcoholic and phenolic groups depending on the usual rules (¶ 138). Alcoholic groups and their analogs are expressedas hydroxy, mercapto, selenyl, and telluryl prefixes on more preferred heading
parents.
Examples:HTe

Thiophene-3-ol, 5-tellurylOH

Hydroxy, mercapto, selenyl, and telluryl groups attached to hetero atoms
other than silicon are always expressed as prefixes (unless they form part of anacid functional parent compound (¶ 130)). “Esters” of such groups are also expressed as prefixes.
Examples:H 2 N N H SH

Hydrazine, mercapto-

M e 2 BO H

Borinic acid, B,B-dimethyl-

8aEthanol (not Ethyl alcohol)

E tO HH 2 C =C H C H 2 O H

2-Propen-1-ol (not Allyl alcohol)

MeC H (O H )Me

2-Propanol (not Isopropyl alcohol)

3

3

1

2

1

H 2 C =C H C H 2 C H (S H) CH 2 Me

5-Hexene-3-thiol

MeSiH 2 O H

Silanol, 1-methyl-

Me(C H 2 ) 2 C H 2 T eH

1-Butanetellurol

6

3

2

1

S

5

OH
N

3-Quinolinethiol, 1,2-dihydro-1hydroxy-

1

SH

5

4

H O−

O
P = OH

2-Phosphorinol, 1,2-dihydro-1hydroxy-,1-oxide6

4

Acetic acid, 1-piperidinyl ester(not Piperidine, 1-(acetyloxy)-)

1 NOAc

1

12 11

10

9

8

7

6

5

4

3

2

−

SSO 2 PhC H 2 -(C H 2 ) 11 -S-C H 2 - CH 2 - O- CH 2 - CH 2 - O- CH 2 - CH 2 - O- CH 2 - CH 2 - O H

24

9

1

As 10a1

Benzenesulfonothioic acid, S-10Hphenoxarin-10-yl ester (not10H-Phenoxarsine, 10-[(phenylsulfonyl)thio]-)10

3,6,9-Trioxa-12-thiatetracosan-1-ol
O

6

4

5

Benzeneselenol

P hS eHO

OH

1-Naphthalenol (not 1-Naphthol)

1

8a

7a

1

N O CO CH 2 CO 2 H

3
5

O

4

4

Propanedioic acid, 1-(1,3-dihydro-1,3-dioxo-2H-isoindol2-yl) ester (not Propanoic acid,3-[(1,3-dihydro-1,3-dioxo-2Hisoindol-2-yl)oxy]-3-oxo-)

—

—

SH SH

C H 3 -C H -C H -C H 3
423

2,3-Butanedithiol

1

H O -SiH 2 -S iH 2 -O H

1,2-Disilanediol

OH

Methanamine (not Methylamine)

MeNH2

1

1,3-Benzenediol

6

1

CH2OH
OH

2-Propanamine (not Isopropylamine)M e CH ( N H 2 ) M eOH

6176. Amines are always named as primary amines, RNH2, or their N-derivatives, by attaching the suffix “-amine” to the name of a molecular skeleton,
cyclic or acyclic. Attachment may be at a carbon or hetero atom. Trivial names,e.g., Aniline, and radicofunctional names, e.g., Methylamine, are not used.
Examples:1

Benzenemethanol, 2-hydroxy(not Phenol, 2-(hydroxymethyl)-)(principle: largest parent)

23

H 2 C=CH CH ( N H 2 ) M e

3-Buten-2-amine

H 3 Pb N H 2

Plumbanamine

4

2

1

43

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

H2PPHNH2

Diphosphinamine

P hN H 2

Benzenamine (not Aniline)

1

NH2

6

¶ 177

H 3 SiN H Sn H 3

Silanamine, N-stannyl- (principle:
preferred hetero atom)M e ( CH 2 ) 7 N H 2

Cyclohexanamine, N-octyl- (principle:
a cyclic parent is preferred)

Bicyclo[2.2.1]hept-5-en-2-amine

7

1

6

NH 2

4

NH 2

NH

Bismuthinediamine

H 2 N B iH N H 2

H2N

1,2,4-Benzenetriamine, N 2 -(3,5-diaminophenyl)- (principle: lowest
locants for principal groups)

NH 2

1

O
5

2 A sN H 2

1,3,2-Dioxarsolan-2-amine

Me2NONMe2

1H-Pyrrol-2-amine

MeNH

Methanamine, N,N′-oxybis[Nmethyl- (principle: multiplication)

O3
H
N

5

NH2

1

1

1,2-Propanediamine

H 2 N C H 2 C H (N H 2 )M e
6

1

2

1

NH2

3

1,2-Benzenediamine (not 1,2-Phenylenediamine)

NH2

Benzeneethanamine, α-methyl-

P hC H 2 C H MeN H 2
β

NH

α

Replacement names are employed for acyclic secondary and tertiary amines
provided that the “-amine” suffix of the “aza” name expresses at least the same
number of such groups as the conventional name and that other requirements(¶ 127), e.g., the presence of a minimum of four hetero units in the molecularskeleton, are satisfied.
Examples:
E tN H CH 2 CH 2 N H [ ( CH 2 ) 2 N H ] 3 CH 2 CH 2 N H E t
N1

1

13

3

1

N

6

14

N14

3,6,9,12-Tetraazatetradecane-1,14diamine, N1,N 14-diethyl-

5-Pyrimidinemethanamine
N3

H2NCH2

CH 3 - N H - CH 2 - CH 2 - N H - CH 2 - CH 2 - N H - CH 2 - CH 2 - N H - CH 2 - CH 2 - NH -C H 3
N1When higher functions (¶ 106) or more preferred amine parents are present,
the prefix “amino” is employed.
Examples:

H2N

CH 2 CH(NH 2 )CH 2 NH 2

6
1

H 2N

1,2-Propanediamine, 3-(4-aminophenyl)- (principle: maximum
number of the principal group)αBenzenemethanamine, 4-amino(principle: largest heading parent)

CH 2 NH 2

NH 2

2

N2

Schiff bases (anils, azomethine compounds) contain the -N=C- grouping
and are therefore both amines and imines. They are indexed as amines in theabsence of higher functions.
Example:Benzenamine, N-(phenylmethylene)-

Ph N =CH Ph

NH 2

NH 2

Me

1

1,2-Ethanediamine, N1-[2-(methylamino)ethyl]-N 2-[2-[[2- (methylamino)ethyl]amino]ethyl](not 3,6,9-Triazaundecane-1,11diamine, N1,N 11-dimethyl-; thisorganic replacement name expresses
only three hetero units) (not2,5,8,11,14-Pentaazapentadecane;
this name does not express theamino groups as a substituent suffix)

Silanamine, 1-(5-aminopentyl)(principle: hetero atom parent
preferred)

H 2 N (C H 2 ) 5 SiH 2 N H 2

Me
CH 2

CH 2

Me

Me

Benzenamine, 2,6-bis[(2-amino3,5-dimethylphenyl)methyl](principle: centrality)
Secondary and tertiary amines, RR′NH and RR′R′′N, are named as derivatives of primary amines by application of the usual criteria (¶ 138).
Examples:MeC H 2 N H C H 2 Me

Ethanamine, N-ethyl- (not Diethylamine)(Me 2 C H ) 3 N

2-Propanamine, N,N-bis(1methylethyl)- (notTriisopropylamine)

2

NHMe

1,4-Benzenediamine, N1,N 4 -bis[4-(methylamino)phenyl](principle: centrality)

1,2-Ethanediamine (not Ethylenediamine)

H2NCH2CH2NH2
2

NH

1

N

N-Hydroxy amines are named as such, not as hydroxylamine derivatives.
Amine oxides are named by citation of the additive term “N-oxide” in the modification.
Examples:Ph N H O HBenzenamine, N-hydroxy-

E tN ( O ) E t 2

Ethanamine, N,N-diethyl-,N-oxide177. Imines are ranked as the lowest compound class named by use of afunctional suffix. The “-imine” suffix is attached to a cyclic or acyclic molecular skeleton (at a carbon or hetero atom). Indicated and added hydrogen (¶¶135, 136) for cyclic imines are assigned as for the analogous ketones (¶ 174).
N-Alkyl, N-aryl, etc., imines are indexed as amines (¶ 176). Conjunctive nomenclature is used for imines when the molecular skeleton to which a single
function is attached is itself connected to a ring system by a single bond.
Examples:Ethanimine (not Ethylideimine)M e CH= N H
2OO

2-Furanamine, N-2-furanyl-

NH

2

1

2

H P =N H

H 2 N -C H 2 -C H 2 -C H 2 - NH- CH 2 - CH 2 - CH 2 - NH 2N1

3

2-Propanimine
Phosphinimine

NH

1-(3-

1,3-Propanediamine, Naminopropyl)-N

M e C( =N H ) M e
1

N3 3

1

5

1

2,4-Cyclopentadien-1-imine¶ 177

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
4H-Pyran-4-imine, tetrahydro- (not2H-Pyran-4(3H)-imine, dihydro-)

1

O

6

NH
H N= C=N H

Methanediimine (not Carbodiimide)

Me 2 C H N= C=N C H M e 2

2-Propanamine, N,N′ -methanetetraylbis- (not Methanediimine,
N,N′-bis(1-methylethyl)-)In the presence of any other chemical function expressible as a suffix, imines are described by substituent prefixes. The =NH group is named imino; the=C=NH group is expressed as carbonimidoyl in a multiplying radical or when
attached to a single atom; the -CH=NH group is named (iminomethyl) (notformimidoyl) unless the methyl group is part of an acyclic carbon chain.
Examples:
Ph C(= N H )

2

1

Et
N

6

Ethanimine, N-chloro-,N-oxideN

SO 2 N H 2

2

1

OHC

C( = N H )2(1H)-Pyridinimine, 1-ethyl-

CH O

Benzaldehyde, 3,3′-(1,4-phenylenedicarbonimidoyl)bis-

1
7a

NH
8

1
9
10a

C( =N H )

NH

1

5

Benzenesulfonamide, 3-(iminophenylmethyl)-

Propanenitrile, 3-imino-

H N= CH CH 2 CN
3

MeC H= N (O )C l

44

10

9a

NH

O

9,10-Anthracenediimine

S
4

1,3-Benzoxathiol-4-ol, 2-imino-

3

OH

4a

NH
P h 2 C=N SS N =C P h 2

Benzenemethanimine, N,N′ -dithiobis[α-phenyl- (principle: multiplication of a conjunctive name)

E tC(=N H )OH

Phenol, 3-(1-iminopropyl)-

45

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 179

D. COMPOUND CLASSES

CH 3

−

CH 3 − SO 2 −O− SO 2 − CH− CH 2 −CH 2 −SO H
3

O

11

−

Propanoic acid,
1,1′,1′′,1′′′-tetraanhydride withboric acid (H4B2O5)

O

=

=

O

=

O

=

O

1

2′

2

C−O−C−C H 3O
H O O C −CH 2 − CH 2 − C−O− CN

Butanedioic acid,1-anhydride with cyanic acid

O
=

HOOC
=

= =

O
O
S−O−C−C H 3
O1′

Acetic acid, 2,2′-oxybis-,
1,1′-dianhydride with 2-chloroacetic acid (principle: centrality(¶ 138))Benzoic acid, 4-chloro-,
1,1′-anhydrideBenzoic acid,anhydride with acetic acid
(The parent is not multiplied sothere are no locants.)O

Cl −CH 2 −C− O−C− CH 2 − O−CH 2 −C− O−C− CH 2 − Cl=

Cl

O−C −CH 2 − CH 3
O
=

O

C−O−C

−

CH 3 − CH 2 −C −O
O
=

O

=

1

=

4

=

=

Cl

O

=

O

CH 3 − CH 2 − C−O− Β− O −B− O−C− CH 2 − CH 3

O

Propanoic acid,
1,1′-anhydride(Locants are used because theparent is multiplied.)OO
C H 3 −C H 2 −C− O−C −CH 2 − CH 3

Benzoic acid,anhydride with phosphoricacid (1:1)

OH−

Symmetrical anhydrides of monobasic organic acids are indexed at the acidheading parent with the term “anhydride” in the modification. Locants are used
when the parent is multiplied. Unsymmetrical anhydrides of monobasic acids,
at least one of which is organic, are indexed at the name of the preferred acid(¶¶ 167, 138) with an “anhydride with” phrase in the modification. Anhydridesof Hydrazinecarboxylic acid and related compounds are given special treatment (see the final example below).
Examples:O

C− O−P −O H

4,8-Dioxa-5,7-dithiaundecanedioic
acid, 3,9-dioxo-,
5,5,7,7-tetraoxide

=

8

1

=

7

2

1,3-Butanedisulfonic acid,
3-anhydride with methanesulfonic acid (not “3-monoanhydride with...”)=

4 5

Propanedioic acid,1-anhydride with acetic acid

=

3

=

O
O
O
CH 3 − C−O −C− CH 2 −C −O H

H O 2 C C H 2 C O O SO 2 CH 2 SO 2 OCOCH 2 CO 2 H
1

¶ 190
191
192
193
194
195
196
197
198
199
200
201

Anhydrides of monobasic organic acids with polybasic acids are indexed at
the name of the preferred acid. The terms “di,” etc., are used to indicate thenumber of molecules of water lost in anhydride formation. Locants are cited forpolybasic organic acids or when the parent is multiplied. A ratio is cited for anhydrides of an unmultiplied monobasic acid with an unmultiplied mononuclear
polybasic acid and for anhydrides of two different unmultiplied polybasic
mononuclear acids.
Examples:=178. Introduction. Previous sections have dealt with general principles andwith the naming of specific compounds by combination of a molecular skeleton name with a suffix which describes the principal chemical function. The
present section discusses nonfunctional compound classes (those that fall below imines in order of precedence (¶ 106)), and classes of compounds such as
esters, free radicals, ions, addition compounds, oxo acids, and carbonic acidrelatives, which are named by application of principles already discussed. The
order is alphabetic by class.
179. Anhydrides of acid groups, at least one of which is expressed as afunctional suffix (“-oic acid,” “-carboxylic acid,” “-sulfonic acid,” etc.), areindexed, if cyclic, at heterocycle names and, if acyclic, either at “a” names(¶ 127) or at acid heading parents with the term “anhydride” in the modification. (Acyclic anhydrides of certain mononuclear “oxo” acids, e.g., Carbonicacid, Phosphonic acid, are indexed at such headings as Dicarbonic acid,
Triphosphonic acid.)
Replacement (“a”) names are used for acyclic anhydrides when the suffix
expresses no lower functionality than the heading parent of the regular substitutive name and the other requirements (¶ 127), e.g., that the molecular skeleton contain at least four hetero units, are satisfied.
Example:Hydrazones
ImidesMolecular addition compounds
Nitrogen compounds
Organometallic compounds
Oximes
Oxygen compounds
Phosphorus and Arsenic compounds
Salts
Silicon, Germanium, Tin, and Lead compounds
Sulfur, Selenium, and Tellurium compounds
Zwitterionic compounds

=

¶ 178
179
180
181
182
183
184
185
186
187
188
189

=

Introduction
Anhydrides
AnionsAntimony and Bismuth compounds
Boron compounds
Carbonic acid and relatives
Cations
Esters
Ester-anhydrides
Free radicals
Halogen and Halogenoid compounds
Hydrazides

4

1

Acetic acid,anhydride with benzenesulfonicacid

C−O−SO 2 − O H

1,4-Benzenedicarboxylic acid,1-anhydride with sulfuric acid

Acyclic anhydrides of different polybasic acids require locants.
Examples:O

O

O

C−O−C−O−COO

H O− SO 2 −O− C−CH 2 −C−O −SO 2 −O H

Dicarbonic dihydrazide, 2-methyl(see also ¶ 183)

CO O H

1,4-Benzenedicarboxylic acid,
1,1′-dianhydride with carbonic
acid

=

=

=

O

=

=

=
=

O
O
H 2 N N H C −O− C N H NHCH 3

Benzoic acid,anhydride with methyl hydrogencarbonate (the ester name isgiven in its uninverted form (¶ 185);
not Benzoic acid, anhydride withmethoxyformic acid)

1

=

O
O
C− O−C− O−CH 3

4

=

HOOC

=

Acetic acid,anhydride with nitrous acidC H 3 −C −O N O

Propanedioic acid,
1,3-dianhydride with sulfuricacid¶ 179Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

46

O

O

O

H 3 C −N− CH 3

=

=

=

=

=

=

H O −C− ( C H 2 ) 4 −C− O−C −(CH 2 ) 4 −C− O−C −(CH 2 ) 4 −C −OΗ

=

=

=

Benzoic acid,
O
O
O
anhydride with 2-[(acetyloxy)C−O−C−C H 2 −SO 2 −O−C−CH 3
sulfonyl]acetic acid

Benzenecarbothioic acid,
1,1′-anhydride (not “anhydrosulfide”)

=

=

O

S

Thiodiphosphonic acid((HO)HP(O)SHP(S)SH)

H− P− S− P− H
−

=

=

S
S
C−O−C

Anhydrosulfides of “oxo” acids are generally named analogously by use of“anhydrosulfide” terms. Other chalcogens are treated similarly. When sulfur,
etc., replaces oxygen in Diphosphonic acid and similar compounds, the nondetachable prefixes “Thio,” etc., are employed. The number of sulfur atoms is
not indicated in the name; instead, a synonym line formula is always cited.
Example:−Chalcogen analogs of acyclic anhydrides are indexed like anhydrides.
When the oxygen atom connecting the acid residues has been replaced, theterms “anhydrosulfide,” “anhydroselenide,” and “anhydrotelluride” are used,
and the sulfur, selenium, or tellurium is indicated in the names of both acidcomponents.
Examples:Phosphinic cyanate, P,P-dimethyl-

H3C

OH

SH

The peroxy analogs of this kind of “oxo” acid are indexed (with synonym line
formulas) at such headings as Thioperoxydiarsonic acid ([(HO)HAs(S)]2S2).
Anhydrides of mononuclear peroxy “oxo” acids are generally named at Peroxide, Disulfide, etc.
Examples:O

O=

Benzoic acid, 4-[(acetyloxy)sulfonyl]-

=

COO H

O

CH 3 −P −O− CN=

C H 3 −C−O−S O 2

Phosphonocyanatidic acid, P-methyl-

OH

−

=

O

O

CH 3 −P −O− CN−

When the acid group which has undergone anhydride formation would havebeen expressed (in its unmodified form) as a substituent of the preferred heading parent, the anhydride is likewise expressed as a (more complex) substituentof the same parent. Anhydride formation of an acid group expressed as a substituent in an “anhydride with” phrase is treated similarly.
Examples:

O

O

=

−

−

OH

OH

H− P− S− S− S− Ο H=

C−Se−C−CH 3

=

=

O
Se
C H 3 − C H 2 −C−S−P−CH 2 −CH 3−

O− CH 2 −CH 3

Benzenecarboselenoic acid,anhydroselenide with ethaneselenoic acid

Disulfide, hydroxyphosphinyl sulfo

O
7a

1

1,3-Isobenzofurandione (not 1,2Benzenedicarboxylic acid, cyclic
anhydride)

2O
3

4

Propanethioic acid,anhydrosulfide with O-ethylhydrogen P-ethylphosphonoselenothioate

O
1

O2

O2S
3

9b

9a

SO 2

4

MeC(=NOH)SCN

Ethanimidothioic acid, N-hydroxy-,anhydrosulfide with thiocyanicacid

Symmetrical anhydrides of the monobasic “oxo” acids Formic, Phosphinic, Arsenic, Phosphinous, and Arsinous acids (and their substituted derivatives) are indexed by citation of the simple term “anhydride” in themodification. Symmetrical anhydrides of the dibasic “oxo” acids Phosphonic,
Arsonic, Phosphonous, and Arsonous acids and their substituted derivatives
are indexed at Di-, Tri-, etc., acid headings.
Example:MeA s(O H )O A s(O H) Me

Diarsonous acid, dimethyl-

Anhydrides of boron acids are named as anhydrides.
Examples:Borinic acid, B-methyl-B-phenyl-,
B,B′-anhydride(not Borane, oxybis[methylphenyl-)

Naphth[1,2-c][1,2,5]oxadithiole,
1,1,3,3-tetraoxide (not 1,2Naphthalenedisulfonic acid,cyclic anhydride)

5

6

O
7a

PhB MeO B MePh

Peroxide, carboxy formyl

Cyclic anhydrides, anhydrosulfides, etc., are indexed like other heterocyclic compounds.
Examples:O=

O

Benzenesulfonotelluroic acid,
1,1′-anhydrotelluride=

H C −O− O−C− Ο H

S O 2 − Τe −SO 2

Boronic acid, B-[4-(dimethylamino)butyl]-, B,B′:B′,B′′-,dianhydride(formerly Boronic acid, [4(dimethylamino)butyl]trimol. dianhydride)

Unsymmetrical anhydrides of “oxo” acids in general are indexed by use of“anhydride with” phrases at the preferred acid component heading parents, but
cyanic acid anhydrides with mononuclear arsenic and phosphorus acids are expressed by means of “cyanatido” replacement affixes or by the class term “cyanate.”
Examples:=Hexanedioic acid,
1,1′:6′,1′′-dianhydride(formerly trimol. dianhydride)

−

O

−

O

CH 3

O H (CH 2) 4

CH 3

CH 3
O

−

CH 3

−

1 2 3
4

H 3 C −N− (CH 2 ) 4 −B−O − Β− O−B− ( CH 2 ) 4 −N− CH 3
−

2′

=

O
O
C−O−C

=

1′

1,2-Benzenedicarboxylic acid,
4-methyl-,
1,2′-anhydride(formerly bimol. 1,2′-monoanhydride)

−

OH

COOH

COOH

1

Benzo[c]thiophene-1,3-dione

S2
3

4

O

180. Anions. Index names for anions are required as sole entries when anions themselves are being studied, and as additional entries in the indexing ofsalts (¶ 198). Anions are often expressed differently as modification terms at
cationic heading parents.
Anions from unsubstituted Ethyne, Arsine, Phosphine, Stibine, Silane(Si4− only), and Hydrazine are named Acetylide, Arsenide, Phosphide, Antimonide, Silicide, and Hydrazide. Synonym line formulas are used, e.g.,
Acetylide (C22− ), except for Hydrazide (which is H2NNH− ) and Silicide, andfor Arsenide, Phosphide, and Antimonide when all hydrogens have been lost.
Anions derived from compounds with names based on substitutive parent
compounds (¶ 130) other than those just described are named at the heading
parent for the neutral compound with a modification term such as “ion(1−),”“ion(2−),” or (if indefinite) “ion (neg).” Anions from esters of “oxo” acids are
named similarly.

47

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Examples:Radical ions are named at the neutral compound heading with “radical ion”
terms in the modification.
Examples:

1,3-Cyclopentadiene,ion(1−)1−HC

MeC H 2 C H 2 O −3•−

1-Propanol,ion(1−) (not Propoxide)

1

NO2

Phenol, 2,4,6-trinitro-,ion(1−)

CO2−

1

2,5-Cyclohexadiene-1,4-dione,
radical ion(1−)
O−

NO2
6

O•
6

1

6

Naphthalene,radical ion(1−)

1

−
O
O2N

1,2-Benzenedicarboxylic acid,ion(2−)CO2−
Me 2 A s −Arsine, dimethyl-,ion(1−)EtP(O)(OH)O−

Phosphonic acid, P-ethyl-,ion(1−)

At cationic index headings, e.g., Ethanaminium (see ¶¶ 184, 198), anions
are expressed by “-ide” or “-ate” terms, as described below, or by “salt with”
phrases. The “salt with” phrase is followed by a ratio, e.g., (1:1).
Modification terms for unsubstituted carbanions from acyclic and monocyclic hydrocarbons are derived by adding “-ide” to the hydrocarbon name after
elision of the final “e,” e.g., “benzenide,” “cyclopentadienide.” Unsubstituted
acids expressed as principal groups (e.g., carboxylic and sulfonic acids) affordanions which are named by “-ate” terms in the modification, e.g., “acetate,”“1,2-benzenedicarboxylate.” Phosphonic acid, Carbamic acid, and othersubstitutive functional parent acids, whether substituted or not, also provide
anions which are named in modifications by means of “-ate” terms, e.g., “phosphonate,” “dimethylcarbamate.” Similar terms are used for anions from partial
esters of polybasic “oxo” acids.
Examples:
O

O−

NOT

Propanimidic acid,ion(1−)

3
7aO−

Ph N H —

N
Cl

NOT

1H-Benzimidazole,
5-chloro-,ion(1−)

Negative ions from tautomeric pyrazole and tropolone systems are not normalized by the CAS Registry System; their preferred structures and names are
based on nomenclature rules, such as low numbering for principal functionalgroups, low numbering for substituents, etc.
1

2

Me

5

CN

1H-Pyrazole-3-carbonitrile, 5-methyl-,ion(1−)

N
−N1

N2

NOT

salt with benzenamine

O2N

O−

3

4

salt with 4-methoxyphenol (not“4-methoxyphenoxide”)

NO2

N
−

N

−1

1H-Benzimidazole,6-chloro-,ion(1−)

N−

P-methyl phosphate

Anions from the unsubstituted alcohols and phenols Methanol, Ethanol,
1-Propanol, 1-Butanol, and Phenol are named by “-oxide” terms, e.g., “propoxide,” “phenoxide”. Loss of hydrogen from the mercapto group of unsubstituted Benzenethiol is expressed as “benzenethiolate”.
In all other cases, anion names at cation headings are replaced by “salt with”
phrases; it is to be understood that, in a complete salt name, a ratio would always be added when known.
Examples:

1

N
7a

O
CH 3 −O−P− O −EtC= NH

Propanamide,ion(1−)Cl

CO 2 M e

MeO

−

=

−
E tC −NH

1-methyl 1,2-benzenedicarboxylateO−in which Q = C, N, S, P, Sb, As, Se, Te, Br, Cl, or I, and M and Z represent any
combination of trivalent N and/or bivalent O, S, Se, or Te atoms are normalized
in this way. The formula is analogous to that for normalized tautomeric compounds (¶ 122), with a negative charge replacing the hydrogen atom, and therequirements described for them apply equally to normalized anions. The
names are derived by the same structural rules, and are identical except for addition of the index modification term “ion(1−)”.
Examples:4

CO 2 −− M −Q= Z

O

O-methyl carbonothioate−

M= Q−Z −O

CH 3 −O−C−S −=Certain resonance-stabilized anions and cations containing hetero atoms areindexed by CA at names corresponding to preferred canonical structures. In thesame manner as the analogous tautomeric compounds (¶ 122), anions are normalized, i.e., recognized as equivalent, by machine programs, regardless of
how the structures are shown in the original documents. Each ion is assigned asingle CAS Registry Number and a unique CA index name.
Resonance-stabilized anions of the general formula

O− CH 3=

1,2-Ethanedisulfonic acid,
1-methyl ester, ion(1−)

2

CH 3 −P−O −−Sulfuric acid,monophenyl ester, ion(1−)

MeO 3 SC H 2 C H 2 SO 3 −MeP-methyl O-methylphosphonate=

P hO SO 3 −

1

¶ 181

CN

1H-Pyrazole-5-carbonitrile, 3-methyl-,ion(1−)

salt with 2,4,6-trinitrophenol (not“picrate”)

NO2

181. Antimony and Bismuth compounds, are conveniently discussed together because of the close similarity in the indexing treatment of their derivatives. Antimony and bismuth are metals (¶ 215), and their salts are named assuch, not as cyclic or acyclic molecular skeletons. (Prior to CA Volume 95 (see¶ 101), antimony was classed as a nonmetal for indexing purposes; now, it andbismuth are treated alike.)
Hydrides of trivalent antimony and bismuth are named Stibine and Bismuthine, respectively; polymolecular saturated and unsaturated hydride
chains have names such as Distibine, Distibene, Tribismuthine. The mononuclear oxide heading parents Stibine oxide and Bismuthine oxide are employed, as are also the analogous names for the sulfides, etc., and imides. In
heterocyclic compounds the valency is understood to be three unless an abnormal valency can be expressed in the name (¶ 158).
Examples:E t 3 Bi

Bismuthine, triethyl-¶ 181

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

E tSbC l 2

Stibine, dichloroethyl-P h 2 B iI

Bismuthine, iododiphenyl-

Acyclic carbon chains containing boron atoms are given “a” names if therequirements (¶ 127) are met.
Example:MeB(Me)CH 2 O(CH 2 ) 2 OCH 2 B(Me)Me
1

Distibine, 1,1-dimethyl-2,2-bis(trifluoromethyl)-(F 3 C ) 2 S bS bMe 2
2

1

P hS b=SbP hDistibene, 1,2-diphenyl-

P h 2 Sb(O )O H

Stibine oxide, hydroxydiphenyl-

2

4

7

9

1

N

E tB iH 2 =N Me
1

N

H
Sb

Bismuthine imide, 1-ethyl-Nmethyl-

6

H
N

2

HB

1

BH

HN

4

NH

5

B
H

3

Borazine

1

O

7a

2

B( CH 2 ) 2 CN

1
7a

S

2

O3

1,3,2-Benzodithiabismole

B iH

4,7-Dioxa-2,9-diboradecane,
2,9-dimethyl-

1H-Borole

1

Stibinamine,
1-oxide5

1H-Stibole

1

5

10

Heterocyclic boron compounds and their derivatives are named by the usual
procedures (¶ 146). Intramolecular coordination bonds between boron atoms
and other hetero atoms are ignored in naming; thus, a zwitterionic ring bond
between boron and phosphorus in the last example below is disregarded, andthe monocyclic system is named. (A monocycle entirely dependent on such abond is named as an acyclic compound.)
Examples:H
B

H 2 S b(O )N H 2

481,3,2-Benzodioxaborole-2-propanenitrile

4

S3

8
1

4

Heterocyclic antimony and bismuth compounds without functional suffixes
are ranked in accordance with the seniority of ring systems (¶ 138). Nonfunctional acyclic antimony substitutive parent compounds follow arsenic compounds in order of precedence (¶ 106) and are followed in turn by bismuth andthen boron parents. Within each class the order is determined by the number ofhetero atoms, then unsaturation, size and additive hetero atoms, as illustrated
by the following descending order of antimony compounds: Tristibine, Distibene, Distibine, Stibine oxide, Stibine sulfide, Stibine imide, Stibine. In thepresence of more preferred compound classes, the following substituent prefixes are employed. (The substituent prefixes stiboso (−SbO), stibo (−SbO2), stibinico (=Sb(O)OH), and stibono (−Sb(O)(OH)2) were used prior to CA
Volume 95 (see ¶ 101).)
Substituent
PrefixSubstituent
Prefix−SbH2

stibino−BiH2

bismuthino=SbH

stibylene=BiH

bismuthylene≡Sbstibylidyne≡Bibismuthylidyne−Sb=Sb−1,2-distibenediyl

P
5

Boron molecular skeletons fall between nonfunctional bismuth and siliconcompounds in the order of precedence of compound classes (¶ 106). Within theboron class, the descending order is carbapolyboranes, hetero polyboranes, polyboranes, heterocyclic boron compounds, and finally Borane. When more
preferred groups or molecular skeletons are present, boron substituent prefixes(¶ 161) are used.
Examples:Me3B

Borane, trimethyl-

H 2 Sb BH 2

Stibine, boryl-

M e 2 BN H M eBoranamine, N,1,1-trimethyl(principle: heteroatom molecularskeleton preferred)

1N

N BPh N

Examples:P hN =B iI
N

1′

1

3

HO2CCH2S

1,5-Phosphaborocine

B

H
SbI 2

Acetic acid, 2-[[4-(diiodostibino)phenyl]thio]-

Benzenamine, N-(iodobismuthylene)-

Trihydroxy and hydroxy oxo derivatives of Stibine, Bismuthine, Stibineoxide, Bismuthine oxide and their chalcogen analogs are given binary oxide,hydroxide, etc., names (with synonym line formulas) such as Antimony hydroxide (Sb(OH)3), Bismuth hydroxide (Bi(OH)3), Antimony hydroxide
oxide (Sb(OH)O) and Bismuth hydroxide oxide (Bi(OH)O). (Antimonicacid headings were used prior to CA Volume 95 (see ¶ 101).)
Halo, alkoxy, and aryloxy derivatives of Stibine, Bismuthine and their oxides are so named; amino derivatives are named at Stibinamine, Stibinediamine, Bismuthinamine, etc.
Examples:MeO S bC l 2

Stibine, dichloromethoxy-(H O ) 2 Sb(O )N H 2

Stibinamine, 1,1-dihydroxy-,1-oxide3′

Aziridine, 1,1′-(phenylborylene)bis-

Cl

H2B

B
H

H

Diborane(6), 1-chloro-

When the position of substituent suffixes or prefixes cannot be related to theaccepted numbering of polyboranes and hetero polyboranes (as illustrated in
the Ring Systems Handbook and current Chemical Substance Index), no numerical locants are used, but capital italic letters may be cited to denote substitution
on a “hetero” atom in a hetero polyborane.
Examples:
1,2-Dicarbadodecaborane(12),
B-(acetyloxy)-

B10H9
AcO
B10C2Me2H10

Dicarbadodecaborane(12), C,C ′dimethyl-

Substitution of bridging hydrogen of a polyborane or hetero polyborane isindicated by the prefix “µ” (mu); when necessary, the locants of the boronatom bridgeheads are cited.
Examples:H

Arsenic compounds. See Phosphorus and Arsenic compounds (¶ 197).
182. Boron compounds. For the naming of neutral boron hydrides and replacement (“a”) analogs (hetero polyboranes) see ¶¶ 159, 160. Except for hydroxyl groups attached to boron (¶ 175), principal groups on such hydrides are
expressed as suffixes in the regular way, and conjunctive names are adopted
with those known to have closed polyhedral structures; e.g., Diborane(4)1,1,2,2-tetramine and 1,2-Dicarbadodecaborane(12)-1,2-diethanol.

H2B

BH 2

Diborane(6), 1,2-[µ-(phenylamino)]-

N
Ph

H

H

H
B NH2

H2B 4
H

1
2 BH 2B H
3
H

Tetraborane(10), 1,2-µ-amino-

49

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Cyclic derivatives of polyboranes (other than Diborane(4)) and hetero polyboranes formed by replacement of non-bridging hydrogen atoms by bivalentradicals are named by citing such radicals as substituents.
Examples:Diborane(6), 1,1-(1,4-butanediyl)-

H
H2B 2

1 B

H
O
1

1,2-Dicarbadodecaborane(12),1,2-[oxybis(methylene)]-2

B 10 H 10

Hydroxy derivatives of Borane have acid names as follows:
B (O H ) 3

Boric acid (H3BO3)

H B (O H ) 2

Boronic acidH 2 B (O H )Borinic acid

Boronic acid, B-methyl-,
ethyl methyl ester

P hB MeO H

Borinic acid, B-methyl-B-phenyl-

P hB (SH ) 2

Boronodithioic acid, B-phenyl-

A cO B Me 2

Acetic acidanhydride with B,B-dimethylborinic acidBr 2 BBBr 2

M e −NN−H
B
Br 2 M e

Borazine, 2,2,4,4,6,6-hexabromo1,2,3,4,5,6-hexahydro-1,3,5trimethyl-

Ionic boron compounds are indexed by coordination nomenclature (see ¶215) at such names as Borate(2−), decahydrodeca- (for [B10H10]2−), and Boron(1+), diamminedihydro- (for [BH2(NH3)2]1+). Acidic polyboranes andhetero polyboranes are named as complex acids (¶ 215); e.g., Borate(2−),
decahydrodeca-, hydrogen (1:2) (not Decaborane(12)). Prior to the EleventhCollective Index period, the special term “borata” denoted a tetrahedral borateanion attached to carbon atoms in a heterocyclic ring system. Now, compoundsof this type are named by coordination nomenclature at such index headings as
Borate(1−).
183. Carbonic acid and relatives, with a few trivially named exceptions,
are indexed by the principles of replacement nomenclature for functions (¶129), based on the names Carbonic acid (for (HO)2C=O) and Formic acid(for HCO2H). Trivial names employed in CA indexes are: Formyl halides andhalogenides (except the cyanide, which is indexed at Acetonitrile, 2-oxo-),
Formamide, Formaldehyde, Hydrocyanic acid, Urea, Guanidine, Cyanicacid, Thiocyanic acid, Selenocyanic acid, and Tellurocyanic acid. These
trivially named compounds are ranked with the appropriate class (acid, amide,etc.) as Carbonic acid derivatives, which fall below derivatives of acids
named as principal groups (carboxylic, sulfonic, etc.) and above inorganic“oxo” acids (Hypochlorous acid, Phosphonic acid, etc.) (see ¶ 106).
Examples:O
H− C−N COO

Formyl isocyanate

H− C−O CN

Formic acid,anhydride with cyanic acid

H CΟ Ν H M eFormamide, N-methyl-=

MeB (O Me)O E t

N=Boronic and borinic acids have replaceable hydrogen atoms attached to boron
and are used as substitutive parent compounds. Their esters, anhydrides andsalts are named in the usual way, but their acid halides, amides and hydrazides
are named as Borane, Boranamine, and Hydrazine derivatives, respectively.
Chalcogen analogs are named by use of afffixes thio, seleno, and telluro.
Hydroxy derivatives of Diborane(4), are now indexed at that index heading
parent.
Examples:

Me

H

H

¶ 183

Analogs (imidic, hydrazonic, peroxy, chalcogen) of Formic acid, Formamide, etc., are named systematically as methanoic acid analogs, but are ranked
as compounds related to Formic acid.
Examples:O=

Methaneperoxoic acid

P hB (N H N H 2 ) 2

Hydrazine, 1,1′-(phenylborylene)bis-

H− C−O− O H(H O ) 2 B B (O H ) 2

Diborane(4), 1,1,2,2-tetrahydroxy(prior to CA Volume 95
the name Hypoboric acidwas used)

H− C−SH

Methane(dithioic) acid (not Formic
acid, dithio-)

H CSN H 2

Methanethioamide (not Formamide,
thio-)H C( =N H ) N CO

Methanimidoyl isocyanate

H CS 2 CN

Methane(dithioic) acid,anhydrosulfide with thiocyanic
acid

S

Boric acid (H3BO3) is not a substitutive parent. Esters and anhydrides areindexed as functional derivatives; hydrazides are indexed at Hydrazine.
Examples:Boric acid (H3BO3),
monopropyl ester(H 2 N N H ) 3 B

Hydrazine, 1,1′,1′′-borylidynetris-

Addition compounds of neutral boranes are named as molecular coordination compounds (see ¶ 215). (Prior to CA Volume 95 (see ¶ 101), they were indexed at the component names (¶ 192).)
Example:B (N Me 3 )H 3

Boron, (N,N-dimethylmethanamine)trihydro(T-4)- (preferred index name)(formerly indexed at
Methanamine, N,N-dimethyl-,
compd. with borane (1:1), and at
Borane, compd. with N,N-dimethylmethanamine (1:1))

Oligomeric boranamines which are linear or unspecified are indexed at themonomer name with “dimer,” “trimer,” etc., in the modification. Cyclic dimers
are named as µ-derivatives of Diborane(6). Monocyclic trimers, tetramers,
etc., are given ring names in which the abnormal valencies of hetero atoms are
expressed (see ¶ 158).
Examples:
Me 2
N
F2B

BF2
N
Me 2

Diborane(6), bis[µ-(dimethyl
amino)]tetrafluoro-

S=(H O ) 2 B O P r=

Boranetriamine

B (N H 2 ) 3

H O− C−CO 2 H

Formic acid, 1-(thiocarboxy)(not Methanethioic acid,carboxy-)

Replacement of the nuclear hydrogen atom in formic acid compounds byradicals derived from molecular skeletons leads to carboxylic acids, carbothioamides, etc., expressed as suffixes on the skeleton names.
Formaldehyde analogs have systematic names based on Methane, e.g.,
Methanimine (for CH2=NH) and Methanethial (for CH2=S). (Methanethione (¶ 174) is employed only as the index heading parent for thio ketones withtwo cyclic substituents and for cyclic thio ketenes.) Replacement of hydrogenin formaldehyde by carbon skeletons leads to larger aldehydes and to ketones;
they and their analogs are named by the usual principles of substitutive nomenclature (¶¶ 173, 174). Replacement by nitrogen, halogen, etc., leads to compounds which are often named as Formic or Carbonic acid derivatives.
Examples:N

3-Pyridinecarboxaldehyde
CH O
Ph 2 CO

Methanone, diphenyl-

Ph C( =N H ) M e

Benzenemethanimine, α-methyl-

H CO N H 2

Formamide

H 2 N CO Cl

Carbamic chloride

Cl 2 C=N H

Carbonimidic dichloride¶ 183Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Carbonic acid analogs in which oxygen is replaced by halogen, halogenoid,chalcogen, or nitrogen atoms or groups (¶ 129) (except cyano or a single hydrazino) are given functional replacement names. The replacement of one hydroxyl by amino leads formally to Carbonamidic acid, H2NC(O)OH, but it andits analogs are named at the approved abbreviated forms Carbamic acid, Carbamothioic acid, etc.
Examples:(H O ) 2 C =N H

Carbonimidic acid (the tautomeric
Carbamic acid is preferred inindexing unless both acid hydrogenatoms have been replaced.)

H 2 N C (=N H )O H

Carbamimidic acid (not Carbonamidimidic acid) (Urea is preferredin indexing in the absence of acovalent acid derivative.)

C lC O 2 H

Carbonochloridic acid

NCCO2H

Carbonocyanidic acid

(H O O ) 2 C O

Carbonodiperoxoic acidH 2 N C (=N H )S S HCarbamo(dithioperox)imidic acid

Cl2CS

Carbonothioic dichloride

C lC O B r

Carbonic bromide chloride

Carbonic diamide is named Urea, and its chalcogen analogs are indexed at
Thiourea (not Urea, thio-), etc. The monohydrazide of carbonic acid is Hydrazinecarboxylic acid, but the dihydrazide is named Carbonic dihydrazide.
The monocyanide of Carbonic acid is Acetonitrile, 2-oxo-; the dicyanide is
Propanedinitrile, 2-oxo-; the trivial name Guanidine is employed for Carbonimidic diamide.
Examples:
N′ ′

N′

O

N H CO 2 H

H O 2 CN H

=

=

NH

NH

NH

=

=

=

Dicarbonic acid

H O− C−O −C−O H

Tricarbonimidic acid

H O− C−O −C−O −C− OHOOCarbamodithioic acid, N,N dimethyl-

Pr N H C( =N H ) O E t

Carbamimidic acid, N-propyl-,
ethyl esterHO3S

N H CO 2 H

=

=

NH
=

Diimidotricarbonimidic acidS

S

Thioperoxydicarbonic acid([(HO)C(S)]2S2)=

H O− C−N H −C− N H−C −OH

=

=

NH

=

NH

H O− C−S −S −C− O H

=

=

O

O

=

=

C l−C −O− C−C l

Cyanic acid and its chalcogen analogs are treated as mononuclear “oxo”
acids; their esters and anhydrides are named in the usual way. Isocyanic acidand its analogs are not used in general index nomenclature; their esters and anhydrides are named like halogen compounds. The acids themselves, and theirsalts, are indexed at Cyanic acid, Thiocyanic acid, etc. The amide, H2NCN,
is named Cyanamide.
Examples:Cyanic acid,methyl ester

M e O CN

Imidodicarbonic bromide chloride

H 2 N N H C O N H C O NHNH 2

Imidodicarbonic dihydrazide

C lC O N H C O 2 H

Benzoic acid, 4-cyanatoBenzene, isocyanato- (not Isocyanicacid, phenyl ester)

H 2 C=CH CO N CO

2-Propenoyl isocyanate

Ph N H CN

Cyanamide, N-phenyl- (not Benzenecarbamonitrile)

Numerical and italic letter locants are used with carbonic acid relatives toplace substituents. Locants are employed with monosubstituted Guanidine
and Carbamimidic acid.
Examples:M e N H CO N H 2

Urea, N-methyl-

Carbamic acid, N-(chlorocarbonyl)-

M e N H CSN H M e

Thiourea, N,N ′-dimethyl-

N

O

O

O

5

6

7

N′

=

=

=

=

=

4

N′

O

N H 2 − C−N H −C− N H− C−NH −C− NH−C− NH 2
3

CO 2 H

Ph N CON

2

Ethanethioic acid,anhydrosulfide with thiocyanicacid

H 3 CC( O ) SCN

Dicarbonic dichloride

C l−C −N H− C−B r

1

Benzenesulfonic acid, 4-(carboxyamino)-

Peroxydicarbonic acid

HO2COOCO2H

O

Carbamic acid, N,N′-1,4phenylenebis(not Carbamic acid, 1,4phenylenebis- (see ¶ 118))

M e 2 N CS 2 H

N CO

O

N H CO 2 H

Dicarbonodiperoxoic acid

H O− O−C −O−C −O− OH

O

Carbamic acid, N-2-naphthalenyl(not 2-Naphthalenecarbamic acid)N

Carbonic acid linear polyanhydrides are named at Dicarbonic acid, Tricarbonic acid, etc. Carbonimidic, carbonoperoxoic, and carbonimidoperoxoicacid anhydrides are named in the same manner. When all the anhydride oxygens have been replaced by -OO- or -NH- groups, nondetachable “peroxy-”and “imino-” prefixes are cited ahead of the name along with multiplicative
prefixes. Chalcogen analogs are treated similarly, except that synonym line
formulas form part of the name, and multiplicative prefixes are not cited. Whenboth acid groups have been replaced by amide or acid halide functions, appropriate names are derived, but when only one hydroxyl group has been replaced,or different functions are present, choice of a simpler parent is made. Longer
chains can often be indexed by replacement (“a”) nomenclature (¶ 127).
Examples:O

Carbonic acid and its relatives are placed in the order of precedence of compound classes just below acids expressed as suffixes attached to molecularskeleton names, e.g., sulfonic acids (¶ 106). Within this subclass of acids, they
are ranked by the following criteria, applied successively until a decision isreached: (a) number of acid groups; (b) number of nuclear carbon atoms; (c)precedence of atoms directly attached to nuclear carbon atoms (see Table I, ¶128); (d) number of most preferred hetero atoms directly attached to nuclear
carbon atoms; (e) order of priority of other atoms or groups attached to nuclear
carbon atoms. A partial list in descending order is: Peroxydicarbonic acid, Dicarbonic acid, Imidodicarbonic acid, Carbonoperoxoic acid, Carbonic acid, Carbonimidic acid, Carbonochloridic acid, Carbamic acid, Formic
acid, Cyanic acid, and Thiocyanic acid. (Chalcogen analogs of each acid immediately follow it in descending order of increasing replacement of oxygenby sulfur, selenium, and tellurium.) Acid chlorides, amides, etc., are ranked
within their own classes in a similar order.
Carbamic acid derivatives with cyclic substituents are not assigned conjunctive names. In the presence of higher functions, including any acid expressed as a suffix, the carbamic acid residue is indicated by a (carboxyamino)
radical. Its replacement analogs are named in the usual manner. Its hydrazides
are indexed at Hydrazinecarboxamide.
Examples:Guanidine, N-ethyl-N′-methyl-

MeN H C (=N H )N H Et

50

8

9

2,4,6,8-Tetraazanonanediamide,
3,5,7-trioxo-

H 2 N N H C( =N H ) SE t

Hydrazinecarboximidothioic
acid,
ethyl ester

51

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

H2NNHCONHNH2

Carbonic dihydrazide

H 2 N C (= N H )N H 2

Guanidine

1′

2 1

N′ ′

N

2′

N′

N′ ′

N′ ′ ′

=

NH

=

NH

Imidodicarbonimidic diamide

H 2 N− C−N H −C− N H 2
2

3 N′

N′ ′

N′ ′ ′=

NH

N′ ′ ′ ′

NH

NH
=

1

=

N

N H 2 − C−N H −C− N H− C−NH 2
N

1

2

3

4

Diimidotricarbonimidic diamide

Pr 3 N + ( CH 2 ) 2 N + Pr 3

1,2-Ethanediaminium, N1,N1,N1,N 2,N 2,N 2hexapropyl- (principle: maximum numberof the preferred substituent suffix)

MeC≡ N+Me

Methanaminium, N-ethylidyne-

Quaternary ammonium cations not included in the heading parent are expressed as substituted ammonio, +NH3−, iminio, +NH2=, and nitrilio, +NH≡,
radicals.
Example:5 N′−

Pyridine,
conjugate acid (1:1)

−

• H+

+

−

N

−

Hydrofluoric acid,compd. with methanol (1:1)

CH 3

CH 3

CH 3

Ethane,protonated (1:1)

Orthodox carbonium compounds are named from the hydrocarbon (or otherparent) radical by addition of “-ium.”
Examples:MeC H 2 +EthyliumMe 2 C H +Ethylium, 1-methyl- (not 2Propylium

MeC O +

Ethylium, 1-oxo- (not Acetylium)

2

1

Methylium, cyclopropyloxo- (notCyclopropylcarbonylium)CO+

1,6-Hexanediaminium, N1-[3-[(6aminohexyl)dimethylammonio]propyl]-N1,N1,N6,N 6,N 6-pentamethyl- (principle: largest
heading parent)
Aminium and diaminium names may be derived from amines named by replacement (“a”) nomenclature. In addition, cationic centers in the “a” name ofa molecular skeleton may be expressed, if such a name is permitted (see ¶ 127),
by use of the “azonia” replacement prefix.
Example:
CH 3
CH 3
CH 3
CH 3
CH 3
CH 3
|+
|+
|+
|+
|+
|+
| 2)6−N−CH2−CH3
CH3−CH2−N−(CH2)6−N−(CH2)6−N−(CH2)6−N−(CH2)6−N−(CH
N′ |
N|
7|
14 |
21 |
28 |
CH 3
CH 3
CH 3
CH 3
CH 3
CH 3

+

Iminium names are employed when the quaternary nitrogen atom is attached to one or more bivalent radicals derived from a molecular skeleton, andanalogous monovalent radicals are absent. The names are derived from thoseof the preferred imines (¶ 177).
Example:Diazonium compounds contain the −N2+ group attached to a substitutive
parent compound. When such a parent is a molecular skeleton, the suffix “-diazonium” is employed; otherwise Diazonium is the heading parent. The corresponding substituent prefix is “diazonio.”
Examples:3-Pentanediazonium, 2,4-dioxo-

M e CO CH ( N 2 + ) CO M e
3

4

+N

5

Benzenediazonium, 4-chloro-

N2+

Cl

2+

Benzenemethaniminium, N(diphenylmethylene)-α-phenyl-

Ph 2 C=N + =CPh 2

1,3-Dioxan-5-yliumOO

7,14,21,28-Tetraazoniatetratriacontane-1,34-diaminium, N1,N34diethyl-N1,N1,N34,N34,7,7,14,14,21,21,28,28-dodecamethyl-

1

H

+

H 3 C− N− (CH 2 ) 6 −N − (CH 2 ) 3 −N − (CH 2 ) 6 −N H 2

Carbon cations formally derived by addition of a proton to a saturated carbon atom are named at the molecular skeleton name by use of a modification
term such as “protonated”.
Example:MeC H 4 +

CH 3

+

−

MeO H • H F (not [Me OH 2 ] + F − )

CH 3

−

CH 3

184. Cations, including carbonium ions (which possess an electron-deficient, tricoordinate carbon atom), “ium” ions (defined for index nomenclature
purposes as resulting from addition of a proton to a saturated carbon atom or of
one covalent substituent other than hydrogen to a fully substituted hetero atom), and radical cations related to these two classes are described here. (Forsalts of which they are components, see ¶ 198.) When a proton is added to ahetero atom, the resulting compound is named as a salt (if the anion is known)
or by such modification phrases as “conjugate acid” or “conjugate monoacid”
at the neutral component followed by the appropriate ratio.
Examples:

1,4-Benzenebis(diazonium)

N2+

2

Naphthalenediylium, dihydroDiazonium, (methylamino)-

MeNHN2+

Acyclic nitrogen cations derived from amines attached to parent molecularskeletons are named by converting the preferred “-amine” name (¶ 176) to“-aminium” and expressing the remaining quaternizing groups as substituent
prefixes.
Examples:
Me 4 N +Methanaminium, N,N,N-trimethyl-

Me 2 N + O

Methanaminium, N-methyl-N-oxo-

C − CH 3−

C H= N+−−CH 3 CH 3
CH 3

O

¶ 184

(C H 2 ) 2 N + Et 2 Me

2-Propanaminium, N,2-dimethyl-N-(phenylmethylene)(principle: largest amine parent)

Cl
+N

NMe

2

Benzenediazonium, 3-chloro-4[(4-diazoniophenyl)methylamino]-

Cations from acyclic nitrogen molecular skeletons are named in a similarmanner by use of the “-ium” suffix. Lowest locants are given to cationic centerswhen a choice is necessary.
Examples:Ph N + M e 2 N H 2

Hydrazinium, 1,1-dimethyl-1phenyl-

H2NN+Me2NH2

Triazanium, 2,2-dimethyl-

M e N =N N + M e 3

2-Triazenium, 1,1,1,3-tetramethyl-

Me3N+N+Me3

Hydrazinium, 1,1,1,2,2,2-hexamethyl-

1 2

2-Furanethanaminium, N,N-diethyl-N-methyl- (from a
conjunctively-named amine)

N2+

3

3

2 1

¶ 184

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Acyclic cations from nonnitrogenous hetero atoms are indexed at Phosphonium, Arsonium, Stibonium, Bismuthonium, Oxonium, Sulfonium, Iodonium, etc. The corresponding substituent prefixes are phosphonio, arsonio, etc.
Diphosphine, H2P-PH2, affords Diphosphinium.
Examples:
Me 3 P + (C H 2 ) 2 P + Me 3

Phosphonium, 1,1′-(1,2-ethanediyl)bis[1,1,1trimethyl- (analogous compounds with
one or more noncarbon attachments tophosphorus are indexed at Phosphorus(1+)(see ¶ 215))

C l 2 P P + Me 3

Diphosphinium, 2,2-dichloro1,1,1-trimethyl-

Me 4

As+

52

In all the examples above, the charge of the cationic atom was derived froman additional covalent substituent at a ring hetero atom already saturated to thecovalency limit. Similar names are used (for rings other than those with “a”
names) when the covalency limit is exceeded within the ring system itself, no“external” substitution being involved. The “-ium” name is derived from theuncharged heterocycle, indicated hydrogen, if present, being removed. If indicated hydrogen is needed for the cationic system, it is added at the lowest available nonangular position. The trivial names Furylium, Pyrylium, Thiopyrylium (and their benzo analogs), and Xanthylium (from Xanthene) areused. When other hetero atoms are present in the ring system, a locant before
the “-ium” suffix defines the position of the cationic center.
Examples:1

9aArsonium, tetramethyl-

Quinolizinium+N5

Me 3 S +Sulfonium, trimethyl- (the corresponding
S-oxide is named Sulfoxonium, trimethyl-)

Ph2I+

Iodonium, diphenyl- (the corresponding
I-oxide is named Iodonium, diphenyl-,I-oxide)

6

MeO —

MeO

OMe
9a

Cyclic cations from rings with “a” names are named by replacing the aza,oxa, thia, etc., terms by the cationic prefixes azonia, oxonia, thionia, etc. They
are cited in the same order as the corresponding neutral terms (Table I ¶ 128);
when the same element is present in neutral and cationic forms, alphabetic order of the terms is followed, but the cationic center is preferred for lowest locants if a choice is available.
Examples:1

9bDibenziodolium, 1,9-dimethoxy-

+
I

6

4

5
1

O
+

5

Me

1,3-Dioxol-1-ium, 2-methyl-

O3

1

8

2

1O

9

+NEt

9

N 1Oa

5-Aza-2-azoniabicyclo[4.2.2]decane, 2,2-diethyl-

106Pyrylium, 4-methoxy- (from 2Hor 4H-Pyran)

+O 1

HN

Me2N

5

+
S

6

4

5

1

1

NMe2

Phenothiazin-5-ium, 3,7-bis(dimethylamino)-P
6O

2,6,7-Trioxa-1-phospha-4-phosphoniabicyclo[2.2.2]octane,
4-methyl-

O2

7O
8

4
+ P

Me

1
7

8-Thioniabicyclo[3.2.1]octane,
8-methyl-

+
8 SMe
5

Me
Me

1

9

O
5

1-Oxa-4-azoniaspiro[4.4]nonane,
2,2,4,4-tetramethyl-

4Cationic heterocyclic monospiro compounds, other than those from “a”named rings, have the “-ium” term placed in the name in accordance with thenature of the component rings. When the cationic hetero atoms are in nonspiro
positions, the “-ium” suffix is appended to the appropriate component. If the
spiro and cationic centers coincide, or if both component rings contain such a
center, the “-ium” is attached only to the second component (if the components
are different). For “a”-named components, “azonia,” “oxonia,” etc., terms areused as appropriate; in addition, an “-ium” suffix is attached to the second component if the spiro atom is cationic and the second component does not have an“a” name.
Examples:
1

Me

N+
Me 2

S

7a

MeN +
3

5′

1

9

+
P 5

1′

5-Phosphoniaspiro[4.4]nonane
1′8′aCationic monocyclic and fused ring systems, other than those with “a”
names, are indexed at heading parents derived from the heterocycle name byaddition of an “-ium” suffix. Lowest locants are preferred for indicated hydrogen, e.g., 1H (never 3H)-Benzimidazolium; a cationic center is numbered
lower than a neutral hetero atom of the same element if a choice is available.
Examples:

6

O

6′

2

5

O

4′

5′

4′

2N

6′

5

1O

N 1O a

9a

6

4

Br

Phenazinium, 3,7-dibromo-5methyl- (not Phenazinium, 2,8dibromo-10-methyl-)

Me
+N 2

Spiro[isoquinoline-2(1H), 2′-[2H]
pyrido[1,2-a]pyrazinium]

4

1

5

+N
Me

9 ′a

1′

Pyridinium, 1,3-dimethyl-

1′

9b

5

6
4′

P+

5′

9′b

1

Spirobi[5H-dibenzophospholium]

4
6′

9′a

1
4

Piperazinium, 1,1,4,4-tetramethyl-

+N
Me 2

1′
1
+

Me2N 3

+ Et
O
5

5′

+

8a

1

9

Spiro[1,3-dioxolane-2,6′(2′H)isoquinolinium], 2′,2′-dimethyl-

3

N

Me

6

2′

+N M e 2

1

+ Me
N

Br

Spiro[benzothiazolium-4(5H),1′cyclopentane], 6,7-dihydro-2,3dimethyl-

4

1

6 9′

4′a
4′b

Furanium, 1-ethyltetrahydro-

8′

Spiro[3-azoniabicyclo[3.1.0]hexane6,9′-[9H]fluorene], 3,3-dimethyl-

53

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
1

Spiro[3-azoniabicyclo[3.2.2]nonane-3,3′(2H)-oxazolium]5′+

3 N 3′

8

7

O 1′

9
5

Dispiro compounds with other than “a”-named components and containing
two cationic spiro atoms have the “ium” suffix appended to the terminal, i.e.,
the first and third, component names.
Several classes of resonance-stabilized cations containing nitrogen atoms
are either normalized by the CAS Registry System or treated as though they
were; i.e., to avoid scattering of information in CA indexes, each such cation,
regardless of how its structure is drawn, is assigned a unique CAS Registry
Number and unique CA Chemical Substance Index name (cf. ¶¶ 122, 180). A
normalized cation is any cyclic cation with the substructure
—

—

+

−

R′

R

Me

where (a) the terminal N’s are in the same ring or adjacent rings (but not at aring junction) and (b) the bonds to R and R′ are not part of the ring.
Examples:
Me
N

7a

4

3

1

Me
N

1

NPh

Me

1H-Benzimidazolium, 1methyl-3-phenyl(principle: positive
charge on the CIP-preferred nitrogen)

NOT

5

N
N

4

9

3

6

8

1

6

N
2

N

O

3

N

+
5

N7

4

9

Ph

CH 3 CH 2

CH 3

CH 3 CH 2

CH 3

CH 3 CH 2

CH 3

NOT

Methanaminium, N-[(diethylamino)methylene]N-methyl-N1-azoniabicyclo[3.3.1]non-1-yl

N

4

4

NOT

+

methyliumyl+
MeC H —

1-ethylium-1-yl

O
6 1 2

(tetrahydro-4H-pyran4-ylium-4-yl)+(octahydro-8a(1H)azulenylium-1-yl)

1

1

3

+
4

1H-Imidazo[1,2-a]pyridin4-ium, 1-ethyl-

NHPh

+
H2C —

+ 8a

When at least one canonical form of a resonance-stabilized cation represents a hydrogen atom as being attached to a positively charged nitrogen atom,
it is named as a neutral compound with an index modification term such as“conjugate acid” or (if the anion is known) as a salt such as “hydrochloride”
followed by the appropriate ratios.
Example:MeN

Carbon cationic prefixes are named by addition of “-yl” to the cation name.
Locants are cited (except for methane prefixes) for both the cationic center andthe point of attachment, with lowest locants for the latter.
Examples:

Et
N

8a

+

N

NHPh

N+
9

+
−
−
N−CH=N−
−

1 Et

Me

1

5

CH 3

+N

piperidinium-1-ylidene

8

1H-Purinium, 2,9-dihydro-1,7-dimethyl2-oxo-9-phenyl-− +−N=CH−N−−

Imidazo[1,2-a]pyridinium,
1-ethyl(principle: the neutral
ring, quaternized bysubstitution, is preferred)(1,1,4,4-tetramethyl-2-tetrazenium1-yl)

N

CH 3 CH 2

8a

1

8

Ph

NOT

2 1

+
N

6

For resonance-stabilized cations that are not normalized, the unique CA Chemical Substance Index name is derived by regular nomenclature rules (see¶ 138).

Ethanaminium, N-[(dimethylamino)methylene]-N-ethyl(principle: preferredindex parent)

4

+

4 3

Me

1H-Purinium, 2,7-dihydro-1,7-dimethyl2-oxo-9-phenyl(principle: positive
charge on the CIP-preferred nitrogen)(5-methyl-10H-phenothiazinium10-yl)

5

+S
Me

M e 2 N N= N N M e 2 −

+

2

1

10

1H-Benzimidazolium, 3methyl-1-phenyl-

Me

N7

N 10a

1

Me
6

9

NPh

7a

3

O

(1,4-dimethylpiperazinium-1,4-diyl)

4

N
+

+

4

1

+
N

6

+

Me

(1-methylpyridinium-2-yl)

1

−

R′

R

Me
+N

−N−C(or N) =N−−−−N=C(or N) −N−

Cationic prefixes are used when more preferred compound classes (¶ 106)are present, or when different cations, or additional occurrences of the samecation, cannot be included in the heading parent. Heteroacyclic cationic prefixes are based on “-onio” radicals such as ammonio and iminio (for singly anddoubly bound nitrogen, respectively), diazonio, sulfonio, phosphonio, and iodonio. Cyclic cationic radicals from rings, not named by “a” nomenclature,containing a single hetero atom at which the free valency is located are namedby changing the “-ium” ending of the cation name to “-io”; e.g., pyridinio, 2Hpyranio, phenanthridinio. In all other cases, heteroacyclic and heterocyclic cationic prefixes are derived from the cation name by adding “-yl,” “-diyl,” etc.,
to the “-ium” suffix with locants (low-numbered if there is a choice) to indicate
the points of attachment.
Examples:

6

+

¶ 184

Me
N

Cationic compounds are ranked in the following descending order of precedence of elements: C, N, P, As, Sb, Bi, O, S, Se, Te, F, Cl, Br, I. When morethan one cationic center is present, the general rules of substitutive nomenclature (¶ 138) are applied, the cationic centers being considered as principal
chemical groups for this purpose.
Examples:

+
MeN

+

Cycloheptatrienylium, (1-methylpyridinium-4-yl)- (principle:
carbon cation preferred)

NPh• Cl −• Cl −• HCl

CO 2 MeCO 2 MeCO 2 Me(The hydrochloride salt is the preferred structure.)M e 3 N + ( CH 2 ) 3 S + M e 2

1-Propanaminium, 3-(dimethylsulfonio)-N,N,N-trimethyl(principle: nitrogen cationpreferred)¶ 184

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
Me
+N

Me
N
+
CH 2

6

Pyrazinium, 1,4-dimethyl-2-[(1methylquinolinium-6-yl)
methyl]- (principle: maximum
number of cationic centers)

4

+N
Me

6

+
(CH 2 ) 2 NMe 3+N

Pyridinium, 1-[2-(trimethylammonio)ethyl]- (principle:
ring parent preferred)

1

Me
N
+

1

(C H 2 ) 2
Me

S
MeN
3

Me

7a

+
4

Benzothiazolium, 3-methyl-2[2-(1,3,3-trimethyl-3Hindolium-2-yl)ethyl](principle: preferred ring)
Cationic compounds of indefinite structure are named by use of alternative
locants if possible, e.g., Quinazolinium, 1(or 3)-methyl-, iodide (1:1); otherwise as molecular addition compounds of the neutral compounds with a termsuch as “compd. with iodomethane (1:1)” (not “monomethiodide”) in the modification.
Cationic free radicals from carbonium ions are named like the carbon cationic prefixes (above); e.g., Methyliumyl; 4-Cyclohexylium-1-yl. When thefree radical and cationic centers are separated, the “-yl” suffix is preceded by alocant, if known. When the free radical and cationic center are in different parent molecular skeletons, the free radical supplies the heading parent.
Examples:Piperidinium-4-yl,
1,1-dimethyl-•

are modified for esters. The chemical functionality (¶ 106) of certain very common acids (“Class I” acids) is disregarded for the purpose of naming their esters, unless the “alcoholic” component is also very common, and the entry ismade instead at the uncommon alcohol, despite its lower functionality. The“Class I” acids comprise: Acetic acid; Benzenesulfonic acid; Benzenesulfonicacid, 4-methyl-; Benzoic acid and its monoamino, mononitro, and dinitro derivatives; Boric acid (H3BO3); Carbamic acid; Carbamic acid, N-methyl-;
Carbamic acid, N-phenyl-; Carbonic acid; Formic acid; Methanesulfonicacid; Nitric acid; Phosphoric acid; Phosphorodithioic acid; Phosphorothioic acid; Phosphorous acid; Propanoic acid; Sulfuric acid; and Sulfurous acid. All other acids, including isotopically labeled forms of “Class I” acids,
belong to “Class II.”
Esters of “Class I” monobasic acids with “Class II” alcohols and thiols areindexed at the latter. Esters of “Class I” acids with “Class I” alcohols and thiols
are indexed at the acids. “Class I” alcohols are: Benzeneethanol; Benzenemethanol; 1-Butanol; 1-Butanol, 2-ethyl-; 2-Butanol; Cyclohexanol; 1Decanol; 1-Dodecanol; Ethanol; Ethanol, 2-(diethylamino)-; Ethanol, 2(dimethylamino)-; Ethenol; 1-Heptanol; 1-Hexanol; 1-Hexanol, 2-ethyl-;
Methanol; 1-Nonanol; 1-Octadecanol; 1-Octanol; 1-Pentanol; Phenol andits monochloro, monomethyl, and mononitro derivatives; 1-Propanol; 1-Propanol, 2-methyl-; 2-Propanol; 2-Propanol, 2-methyl-; and 2-Propen-1-ol.
The list of “Class I” thiols is completely analogous to the “Class I” alcohol list;
the individual index names are also analogous, e.g., Benzeneethanethiol; 2Propanethiol, 2-methyl-; except that the Phenol analog is Benzenethiol. All
selenols and tellurols belong to “Class II.”
Esters formed from hydroxy derivatives of nitrogen, phosphorus, arsenic,
antimony, bismuth, germanium, tin and lead are named as such. They are always indexed at the acid regardless of the type of acid. The acyclic nitrogenradicals used in ester names are azanyl, diazanyl, diazenyl, triazanyl, etc.
Examples:A c O ( CH 2 ) 2 Ph

Acetic acid,2-phenylethyl ester

M e O SO 3 H

Sulfuric acid,monomethyl ester (the uninverted
name is methyl hydrogen sulfate)

Ph SP( S) ( O M e ) O H

Phosphorodithioic acid,O-methyl S-phenyl ester+NO
CH 3 −C− O−N Ph 2

Me
•

N

+
N

CH2

Me

Me

Me

2-Pyrrolidinyl,
2-[(1,1-dimethylpyrrolidinium-2-yl)methyl]-1-methyl-

Delocalized radical cations are described at the index name of the corresponding neutral compound by the modification term “radical ion” followed bya cationic Ewens-Bassett number in parentheses.
Example:•+Azulene,radical ion(1+)

In each of the examples above, a “Class I” acid is esterified by a “Class I”
alcohol or thiol. When the acid belongs to “Class I” and the alcohol or thiol to“Class II,” the entry is found at the alcoholic component name, except when
the acid is polybasic and the alcohols differ from one another, in which case theacid heading is chosen. When the ester is named at the alcohol heading a locant
is always cited for the “ate” or “ite” term. This eliminates the need for the parenthetical expression “(ester)”.
Examples:Cationic free radicals formally derived by loss of an electron from a hetero
atom of a molecular skeleton or of an isolated chalcogen atom are named similarly (¶ 270).
Example:SO 2 −O −CH 2 − CH 2 − Ο H

CH 3

6

1

1

185. Esters, other than cyclic esters, of principal functions are named assuch for indexing purposes, usually at the acid component name. Cyclic esters
are named as heterocyclic ring system derivatives. Esters of hydroxy, mercapto, carboxy, sulfo, etc., groups expressed as substituents of heading parents are
expressed as compound or complex substituents, not as modification terms at
the same heading parent. To be recognized as an ester in CA indexing, a C-O,
C-S, C-Se, or C-Te bond must be present. Thus, ethyl cyanate and ethyl perchlorate are considered to be esters, but ethyl azide, ethyl isocyanate, and ethyl
chloride are not.
Examples:E tO C N

Cyanic acid,
ethyl ester

E tO C lO 3

Perchloric acid,
ethyl ester

E tN 3Ethane, azido-

E tN C O

Ethane, isocyanato-

E tC lEthane, chloro-

To permit information on esterified alcohols and thiols to be more readilyfound in the Chemical Substance Index, the usual rules of index name selection

OAc

1,2-Cyclohexanediol,
1-acetate 2-benzoate

H CO 2 CH 2 CH 2 O 2 CH

Methanamine, N,N-dimethyl-,
radical ion(1+)

21,2-Ethanediol,
1-(4-methylbenzenesulfonate)

O Bz

1

+
Me 3 N •Acetic acid,diphenylazanyl ester

=

Me

54

2

1,2-Ethanediol,
1,2-diformate (the uninverted nameis 1,2-ethanediyl diformate)

O 2 CN H M e

O2N

OH

1,3-Benzenediol, 5-nitro-,
1-(N-methylcarbamate)

AcO

OH

1,3-Benzenediol, 4-amino-,
1-acetate

NH2[ Cl( CH 2 ) 2 O ] 3 P( O )Ethanol, 2-chloro-,
1,1′,1′′-phosphate (3:1) (all the “Class II”
alcoholic components are alike here; theratio is necessary to indicate a neutral esterof known composition; the mono- anddiesters are named with “dihydrogen
phosphate” and “hydrogen phosphate”,
respectively in the modification)

H O ( CH 2 ) 2 O P( O M e ) 2

Phosphorous acid,
2-hydroxyethyl dimethyl ester(the entry is made at a “Class I” acid, not atthe “Class II” alcohol 1,2-Ethanediol, because the alcoholic components are unlike)55

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

When an ester of the type illustrated immediately above has a more preferred acid residue present in the molecule, the “Class I” polybasic acid becomes a substituent.
Example:Acetic acid, 2-[[(2-hydroxyethoxy)methoxyphosphinyl]oxy]- (notAcetic acid, hydroxy-, 2-hydroxyethyl methyl phosphate)

=

O

−

C H 3 −O −P− O−C H 2 −COOH
O− C H 2 −C H 2 −OH

Esterified substituents of the index heading parent are expressed as substituents, not as modification phrases.
Examples:H O− CH 2 − CH 2 −O− SO 2 −O− CH 2 −CH 2 −O H
2

1

1′

2′

1,2-Ethanediol,
1,1′-sulfate
Esters are named by replacement (“a”) nomenclature if the requirements (¶127) are met.
Example:H O CH 2 CH 2 O SO 2 O ( CH 2 ) 2 O SO 2 O CH 2 CH 2 O SO 3 H
12

10 9

8

54

3

1

3,5,8,10-Tetraoxa-4,9-dithiadodecane-1,12-diol,
1-(hydrogen sulfate),
4,4,9,9-tetraoxide

A cO

Benzenesulfonic acid, 3-(acetyloxy)-,
methyl ester (not Benzenesulfonicacid, 3-hydroxy-, methyl ester
acetate)S O 3 MeMultiplicative radicals in modifications are cited ahead of nonmultiplicative.
Example:Boric acid (H3BO3),
B,B′-(1,3-propanediyl) B,B,B′B′tetramethyl ester( M e O ) 2 BO ( CH 2 ) 3 O B( O M e ) 2

=

O
HOOC

O− C−Ο

4′

4

1

COOH

Benzoic acid, 4,4′-[carbonylbis(oxy)]bis- (not Benzoic acid,
4-hydroxy-, carbonate (2:1))
The phrase “ester with” is usually avoided in general index nomenclature
for compounds of known structure, even when the alcoholic component contains a function higher than alcohol, but it is employed when an acid which requires a line formula is cited in a modification; a ratio is included if the alcohol
is monohydric and has a single occurrence, and locants are used if the alcohol
is polyhydric or has multiple occurrences.
Examples:¶ 185

Although locants to differentiate between principal and subsidiary groups
are strictly not necessary in ester modifications (because esterification of thelatter is not expressed in the modification), they are nevertheless cited to preclude misinterpretation.
Examples:HO3S

Benzoic acid, 3-sulfo-,
1-phenyl ester
CO 2 PhPh O 3 SΟΗ
C l−C H 2 −C H 2 − O−B −OH−

Ethanol, 2-chloro,
ester with boric acid
(H3BO3) (1:1)

1

2

ΟΗ
−

−

OH

H O− B−O −C H 2 − C H 2 − O−B− OH
1

2

1,2-Ethanediol,
1,2-diester with boric acid
(H3BO3)

Benzoic acid, 3-(phenoxysulfonyl)-

CO 2 H

Esterification of an alcoholic component cited in the index modification isexpressed as a substituent of the esterifying radical.
Example:
Ο

=

Ο

=

=

Ο

=

−

CH 3 Ο

CH 3 − CH− C−O− CH 2 − C−CH 2 −O− C−CH 2 − C−O −CH 2 − CH 3

ΟΗ

3

2

1

−

H O− C H 2 − C H 2 −O −B− O−CH 2 − CH 2 − OH
1′

1

Propanedioic acid,1-ethyl 3-[3-(2-methyl-1-oxopropoxy)-2-oxopropyl] ester (notPropanedioic acid, ethyl 3-hydroxy-2oxopropyl ester, 2-methylpropanoate)2′

1,2-Ethanediol,
1,1′-diester with boric acid
(H3BO3)The choice of a preferred index name for a complex ester depends on thenormal criteria (¶ 138), first on the preferred acid class (peroxoic, carboxylic,carboximidic, sulfonic, carbonic, etc.) then on the preferred heading parent andthe particular occurrence of such a parent if it occurs more than once. If there
are three or more occurrences, the principle of centrality is invoked; if there are
only two, often the preferred name is the one appearing earliest in index sequence.
Example:O=

The word “hydrogen,” with multiplicative prefixes if necessary, is usedwith an “-ate” (or “-ite”) term derived from a polybasic acid cited in a modification to denote unesterified acid groups. One or more “hydrogen” terms may
be replaced by radicals to denote further esterification not expressed in theheading parent. When all acid groups of a polybasic acid have been esterified,“hydrogen” cannot be cited; therefore, if the precise structure is known, a ratio
is placed after the “-ate” term. If more than one such term is necessary, thecomplete “-ate” phrases are cited (without commas) in alphabetical order.
Examples:C− Ο − C Η 2

Br

1

2

ΟΗ

1,2-Ethanediol,
1-(dihydrogen phosphate) 2-(hydroxyethyl hydrogen phosphate)(principle: maximum number offunctional derivatives)

=

Ο

−

H O− P− Ο −C H 2 −C H 2 − O−SO 2 − OH
ΟΗ

4

Br

1

2

1,2-Ethanediol,
1-(dihydrogen phosphate) 2-(hydrogen sulfate)

When functions higher in precedence than acids are present, all esters are
expressed as substituents.
Example:

6

Me
N 1
+

Cl −

CO 2 E t−ΟΗ

H O− C H 2 − C H−C H 2 −O− SO 2 −OH
31

Benzoic acid, 4-bromo-,
4-[[(4-bromobenzoyl)oxy]methyl]phenyl ester (not Benzoic
acid, 4-bromo-, [4-[(4-bromobenzoyl)oxy]phenyl]methyl ester)−−

H O− P− Ο −C H 2 −C H 2 − O−P −O −CH 2 − CH 2 − OH
ΟΗ

O− C

=

Ο

=

Ο

O
=

2

2

1

1,2,3-Propanetriol,
1-(hydrogen sulfate)Pyridinium, 3-(ethoxycarbonyl)1-methyl-,chloride (1:1)

Peroxy acid esters and their chalcogen analogs are named in the usual way,with “OO,” “OS,” “SeO,” “SS,” etc., locants used when necessary along withthe usual “O,” “S,” etc., locants.

¶ 185

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

56

O
=

Examples:O− C− (CH 2 ) 1 6 −CH 3

CH 3

CH 3

O

O

=

O

CH 3 − ( CH 2 ) 1 6 −C− O−CH 2 −CH −CH 2 − O−C − (CH 2 ) 1 6 −CH 3

Octadecanoic acid,
1,1′,1′′-(1,2,3-propanetriyl) ester

CH 3

−

−

CH 3

−

=

CH 3

−

−

O

−

CH3

=

=
=

Ethanediperoxoic acid,
1,2-bis(trichloromethyl) ester=

O O

C l 3 C− O−O− C−C −O−O −CCl 3

C H 3 − C H− O−C− O−O −C− CH 2 −CH 2 −C− O−O− C−O −CH− CH 3

=

O

=

O

=

Carbonoperoxoic acid,
OOc,OO c ′-(1,1,4,4-tetramethyl1,4-butanediyl) Oc,O c ′-bis(1methylethyl) esterO

CH 2 − O−C− ( CH 2 ) 1 6 −CH 3
CH 3 − ( CH 2 ) 7 −CH =CH− (CH 2 ) 7 −C− O−CH −CH 2 − O−C − (CH 2 ) 1 6 −C H 3
1 7 −1 1

18

10

9

8 −2

1

9-Octadecenoic acid,2-[(1-oxooctadecyl)oxy]-1[[(1-oxooctadecyl)oxy]methyl]ethyl ester (principle: unsaturated
acid preferred)=O

Benzenecarbo(thioperoxoic) acid,OS-(trichloromethyl) esterC− Ο −S− CCl 3

Ethanesulfeno(thioperoxoic) acid,
SO-methyl ester

E tSS O Me

Carbono(dithioperox)imidic acid,N-methyl-,O-ethyl SS-(trichloromethyl)
ester

=

N− CH 3

C H 3 − C H 2 −O −C− S− S− CCl 3

Esters of boric acids and their chalcogen analogs are indexed regularly, except for those of Hypoboric acid and cyclic metaboric acids, (HBO2 ) n , which
are named as derivatives of the molecular skeletons.
Examples:Diborane(4), 1,1-diethoxy-2,2dimethoxy-(E tO ) 2 B B (O Me) 2

Urethanes are esters of Carbamic acid and its derivatives. Xanthic acids
are O-esters of Carbonodithioic acid.
Examples:Ph N H CO 2 E t

Carbamic acid, N-phenyl-,
ethyl ester

Ph O CS 2 H

Carbonodithioic acid,O-phenyl ester

Cyclic esters and lactones are indexed as heterocycles.
Examples:
1

1
6

5

O

O3

O

2

4

O

MeO B

Me

O

6

O

B O MeO

Boroxin, 2,4,6-trimethoxy-

3

Me

B
O Me

1

O
(B uS) 2 B O Me

Thioboric acid ((HO)(HS)2B),
S,S-dibutyl O-methyl ester

Esters of ortho acids and their peroxy and chalcogen analogs are indexed
like ethers, sulfides, peroxides, hydroperoxides, alcohols, etc. Ortho acidnames are not used as heading parents.
Examples:MeC (O Me) 3

Ethane, 1,1,1-trimethoxy- (notOrthoacetic acid, trimethyl ester)

P hC (SMe) 3

Benzene, [tris(methylthio)methyl]-

MeC (O E t) 2 O H

Ethanol, 1,1-diethoxy-

MeC (O E t) 2 O O C Me 3

Peroxide, 1,1-diethoxyethyl 1,1dimethylethyl

11,2-Oxaphosphorinane, 2-ethoxy-,2-oxide (not Phosphonic acid,(4-hydroxybutyl)-, monoethyl ester,δ-lactone)

O

O

6

2(5H)-Furanimine (not 2-Butenimidic acid, 4-hydroxy-,γ-lactone)

NH

5

2P

OEt

1

O− C H 3−−

O− C H 3

Oxides of thio esters are named not as ester derivatives but at the preferredmolecular skeleton or other heading parent with sulfinyl or sulfonyl prefixes.
Examples:
=
=

O O
S −S

4

1

8a

5

O

O

2H-1-Benzopyran-2-one (notCoumarin; not 2-Propenoic acid,3-(2-hydroxyphenyl)-, δ-lactone)

4

Methanesulfenic acid, trimethoxy-,
methyl ester

C H 3 − O−C −S −O− CH 3

H 3 C− O

1,3-Dioxane-4,6-dione, 2,2-dimethyl(not Propanedioic acid, cyclic 1methylethylidene ester)=

O−CH 3186. Ester-anhydrides are named by combining the policies for anhydrides and esters (¶¶ 179, 185). Cyclic anhydride and cyclic ester components
are named in accordance with heterocyclic nomenclature. Anhydride terms
precede ester terms where this can be done unambiguously (but see the last example, below). Esters cited in modifications are named in the uninverted form
unless the acid is one for which a synonym line formula is required.
Examples:O
O

Benzene, 1-methoxy-4-[[(4-methoxyphenyl)sulfinyl]sulfonyl]O
=

α

O
7a

O

C− S− C H 3=

Methanone, (methylsulfinyl)phenyl-,oxime

N− O HO

4

Glycerides, esters of 1,2,3-Propanetriol (glycerol), are indexed at the nameof the preferred acid unless only “Class I” acids are present.
Examples:
=

O
1

O
=

−

=

O− C−CH 3

8a

C H 3 − C−O −C H 2 − CH− CH 2 −O− C−CH 3
1

2

S

N

3

1,2,3-Propanetriol,
1,2,3-triacetate

O

2

O

5-Isobenzofurancarboxylic acid,
1,3-dihydro-1,3-dioxo-,
5,5′-(1,2-ethanediyl) ester

N

O

1

3

CO 2 ( CH 2 ) 2 O 2 C

4
5

O

O3

4H-3,1-Benzoxathiin-4-one,2-(cyclohexylimino)- (notCarbonimidothioic acid,
cyclohexyl-, anhydride with
2-mercaptobenzoic acid, cyclic
ester)

57

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
O=

Acetic acid,anhydride with ethylhydrogen phosphonate−

E tO −P −O A c
H

−

=

O −B

−

C H 3 −C H 2 − C−C= C

Nitroxide, dimethyl

Me2N O •O

O− C−CH 3
O− C−CH 3=

CH3

The heading parent Nitroxide is employed for the free radical H2N −O •.
Example:=CH 2 − CH 3

O

¶ 188

O

Acetic acid,anhydride with boric acid
(H3BO3) mono(1-ethyl-2methyl-3-oxo-1-penten-1-yl)
ester (2:1)

Free radicals from hydroxyl and hydroperoxy groups that are attached to amolecular skeleton, including (acyloxy) radicals (see below), are indexed at “oxy” and “-dioxy” heading parents with systematically named nondetachable
prefixes. Chalcogen analogs are named similarly at “-thio” and “-dithio” heading parents.
Examples:Methoxy (not Oxy, methyl-)

MeO •

O

C lC H 2 − C H 2 − Ο −C− CH 2 − CH 2 −C

CH 3 − C− Ο O •Ethyldioxy, 1-oxo-=

C lC H 2 − C H 2 − Ο −C− CH 2 − CH 2 −C

=

−

=

O

−

Butanedioic acid,
1,1′-anhydride, 4,4′-bis(2O
chloroethyl) esterO

Methoxy, oxo- (not Formyloxy)

H C− O •

=

=

O

=

O

O

=

O

Ethoxy, 1-oxo- (not Acetyloxy)

CH 3 − C−O •

O

Cl

=

=

O

=

O

N= N O •Diazenyloxy, 2-(4-chlorophenyl)-C H 3 − Ο −C −C H 2 − CH 2 − C−Ο−C−CH 3
4

3

2

1

Butanedioic acid,1-anhydride with acetic acid,
4-methyl ester−CH 3

O− CH− CH 3

−

O

=

=

O

Methylthio

MeS •Acyl free radicals (derived from aldehydes or acids) are named as α-oxo derivatives of the alkyl parents.
Examples:Ο − C− CH 2 −C−Ο−B −O− CH 3O

Ethyl, 1-oxo- (not Acetyl)=

Propanedioic acid,1-anhydride with boric acid
(H3BO3) monomethyl mono
(1-methylethyl) ester, 3-phenyl
ester

CH 3 −C•

Methyl, cyclopropyloxo- (notCyclopropylcarbonyl)CO•

H 2 N CO •187. Free radicals, highest in the order of precedence of compound classes(¶ 106) and functional groups, if present, are named as substituents. Most, but
not all, free radical names coincide with the names of substituent prefixes (¶¶132, 133).
Examples:
Et •

Ethyl

P hC H 2 •Methyl, phenyl-•CH2

CH 2 •

B rC •••

Methyl, 1,1′-(1,4-phenylene)bisMethylidyne, bromo-

E tO 2 C C O •Ethyl, 2-ethoxy-1,2-dioxo- (notAcetyl, ethoxyoxo-)

H2P•

Phosphino

F 2 S i ••Silylene, difluoro-

P h 2 N N (C H O )•Hydrazinyl, 1-formyl-2,2-diphenyl-

2 1

Methyl, aminooxo- (not Aminocarbonyl)

Free radicals from sulfonic and sulfinic acids are named as derivatives ofalkyl and aryl sulfonyl and sulfinyl radicals and the analogous oxy radicals.
Examples:CH 3 − SO 2 − O •Me(Methylsulfonyl)oxy
S( O ) •The following chalcogen hydride free radicals are employed: Hydroxyl,HO•; Hydroperoxo, HOO•; Mercapto, HS•; and Selenyl, HSe•.
188. Halogen and halogenoid compounds. (See also Acid halides, ¶ 170).
The halogen and halogenoid “oxo” acids are hypohalous acids, HOX (e.g., Hypochlorous acid, HOCl); halous acids, HOXO; halic acids, HOXO2; perhalicacids, HOXO3; Cyanic acid, HOCN; and Fulminic acid, HONC. Their esters
and anhydrides are named in the regular way. They rank below acids, e.g., carboxylic, sulfonic, expressed as suffixes on molecular skeleton names (¶ 106),and in their presence are expressed as cyanato, (iodyloxy), (chloryloxy), etc.,
radicals.
Examples:
Ph O F

Hypofluorous acid,phenyl ester

M e CO ( CH 2 ) 2 O Br O 2

Bromic acid,3-oxobutyl ester

2 1

Free radicals that might be considered as derived from Borane are indexedat Borane(1) and Borane(2).
Examples:FH B •

Borane(2), fluoro- (not Boryl, fluoro-)

FB ••Borane(1), fluoro- (not Boron
fluoride (BF))

O CN

Cyanic acid,
3-methylphenyl ester
MeCl

CO 2 IFree radicals from ammonia, amides, or amines are named as Amidogen,
H2N•, Imidogen, HN:, and their derivatives.
=

O

F2N•

Amidogen, difluoro- (not Nitrogen
fluoride (NF2))

P hC H (C O 2 H )N ••Imidogen, (carboxyphenylmethyl)-

Phenylsulfinyl, 4-methyl-

CH 3 −CH 2 − C−S −Cl

N CO CH 2 CO 2 H

Benzoic acid, 4-chloro-,anhydride with hypoiodous acid(not Benzoyl hypoiodite, 4-chloro-)
Propanethioic acid,anhydrosulfide with thiohypochlorous acid (not Propanoyl
thiohypochlorite)
Acetic acid, 2-cyanato-¶ 188

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

O 2 C lO

Benzoic acid, 4-(chloryloxy)-

CO 2 HThe groups −X, −XO, −XO2, −XO3, −NC, −NCO, −N3, and their chalcogenanalogs, e.g., −XSe; −NCS, are normally expressed as substituent prefixes
when attached to a molecular skeleton; the radicals chloro, chlorosyl, chloryl,
perchloryl, isocyano, isocyanato, isothiocyanato, azido, etc., are used (see theIllustrative List of Substituent Prefixes in Section H (¶ 294)).
Examples:CHCl3

Methane, trichloro- (not Chloroform)

P hIO 2

Benzene, iodyl-

NC
N

6

190. Hydrazones of ketone and aldehyde principal groups are expressed byhydrazone terms in the index modification, except for hydrazones of carbonylgroups of acids, acid halides, and amides; these are usually indexed as hydrazonic acids (¶ 169) and their halides and amides. Azines are indexed as“-ylidene” hydrazones; osazones as dihydrazones (of adjacent carbonylgroups); and cyclic hydrazones as heterocycles. In the presence of compoundclasses more preferred than the aldehyde or ketone bearing the hydrazone, ahydrazono substituent is cited.
Examples:M e 2 C=N N H 2

2-Propanone,
hydrazone

Ph ( CH 2 ) 2 CH =N N H

N H N= CH ( CH 2 ) 2 Ph

Piperidine, 1-isocyano-

Benzenepropanal,
1,1′-[2,2′-(1,4-phenylene)dihydrazone]

1

H2 H2
C−C
H2C

Groups such as −I(OH)2, −ClBr2, are not expressed by (dihydroxyiodo) and(dibromochloro) radicals; instead, coordination nomenclature (¶ 215) based on
the central halogen atom is employed.
Example:C=N− N=C − (CH 2 ) 4 −CH 3

Cyclohexanone,
2-(1-methylhexylidene)hydrazone(not 2-Heptanone, azine withcyclohexanone) (principle: ring
preferred to chain)

Iodine, dihydroxyphenyl-

P hI(O H ) 2

189. Hydrazides of principal acid groups are expressed by hydrazide terms
in the index modification except for (a) sulfenic acid hydrazides, R−S−NHNH2,
which are indexed at Hydrazine with a “thio” substituent prefix; and (b) hydrazides of Hydrazinecarboxylic acid, for which the heading parent Carbonic
dihydrazide, (H2NNH)2CO, (¶ 183) is employed. Hydrazides of subsidiarygroups, e.g., of carboxyl substituents on aminium compounds, are indexed as
substituents by use of hydrazino radicals. Cyclic hydrazides are indexed as heterocycles. Replacement (“a”) names are used when the requirements (¶ 127) aresatisfied.
Examples:Ph N H N= CH SCH 2 CO 2 H

Acetic acid, 2-[[(2-phenylhydrazinylidene)methyl]thio]- (not Acetic
acid, mercapto-, formate, phenylhydrazone)

M e N H N= CPh CPh= N N H M e

1,2-Ethanedione, 1,2-diphenyl-,
1,2-bis(2-methylhydrazone)

10

P hC S N H N H 2

Benzenecarbothioic acid,
hydrazide

A cN H N H A c

Acetic acid,2-acetylhydrazide (not Hydrazine,
1,2-diacetyl-)

H O 2 C C H 2 C O N H N HPh

Propanedioic acid,
1-(2-phenylhydrazide) (notPropanoic acid, 3-oxo-3-(2phenylhydrazino)-)1

A cN H N H

C−C
H2 H2

CH 3

−

Silane, diisocyanatodimethyl- (notIsocyanic acid, dimethylsilylene
ester)

Me 2 Si(N C O ) 2

2

N− Ν

6

5

Acetic acid,
1,1′ -[2,2′-(1,2,4,5-tetrazine-3,6diyl)dihydrazide]

NHNHAc

N−− Ν

4

H2N

SO 2 NMe NH 2

Benzenesulfonic acid, 4-amino-,
1-methylhydrazide

7

11

12

N − Ν 12a 1
N−Ν

6

5

NHNHCON= N

Phosphazines, which contain the fragment =C=N−N=P, are indexed as
phosphoranylidene hydrazones.
Example:M e CH= N N=PPh 3

M e 2 C=N N H CSN H 2

Hydrazinecarbothioamide, 2-(1methylethylidene)- (not 2Propanone, thiosemicarbazone)

Ph CH =N N H CN H O E t

Hydrazinecarboximidic acid,2-(phenylmethylene)-,ethyl ester (not Benzaldehyde,
3-ethylisosemicarbazone)

O2N
H 2 N N H SO 2

7a

H
N

CO 2 H

2

1

O

CH=N N H CO N H N =CH Ph

Carbonic dihydrazide, 2-[(5-nitro2-furanyl)methylene]-2′-(phenylmethylene)- (not 2-Furancarboxaldehyde, 5-nitro, carbohydrazone with benzaldhyde)

Benzoic acid, 4-(hydrazinylsulfonyl)-

3H-Indazol-3-one, 1,2-dihydro- (notBenzoic acid, 2-hydrazino-, cyclic
hydrazide)

NH
3

O

4

Ph CH =N N H CO CO N H 2
=

O

=

O

=

O

=

O

=

O

Acetaldehyde,
2-(triphenylphosphoranylidene)hydrazone

Semicarbazones, isosemicarbazones, carbohydrazones, and semioxamazones of systematically named compounds are expressed, not by these modification terms or as substituted hydrazones, but by the general principles ofsubstitutive nomenclature on the basis of the highest function present.
Examples:CO 2 H

Diazenecarboxylic acid,2-(4-carboxyphenyl)-,
1-[2-(4-carboxyphenyl)hydrazide] (principle: heteroacyclic parent preferred)

Dibenzo[c,g][1,2,5,6]tetrazocine(not 3,5-Cyclohexadiene-1,2-dione,
bimol. cyclic azine)

4

2 1

HO2C

58

Acetic acid, 2-amino-2-oxo-,
2-(phenylmethylene)hydrazide(not Benzaldehyde, semioxamazone)

H O− C−N H −C H 2 −C− NH−NH −C− NH−NH −C− NH− CH 2 −C −OH
1

2

3

4

5

6

7

8

9

10 11

12

13

2,5,6,8,9,11-Hexaazatridecanedioic
acid, 4,7,10-trioxo-

191. Imides are indexed as heterocycles with “-one” suffixes and are accordingly ranked as ketones; in the presence of higher ranking compounds, the59

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

imide is expressed as a heterocyclic radical. The “diimide” of orthocarbonic acid, HN=C=NH (“carbodiimide”) is indexed at Methanediimine, and its derivatives are often to be found at amine or amide headings.
Examples:
H
N

O

O

1H-Azepine-2,7-dione, 3,4-dihydro(not 2-Hexenimide)

7 1

H
N

O

2

1
9a

O

1H-Benz[de]isoquinoline-1,3(2H)-dione (not 1,8-Naphthalenedicarboximide)

3

9b

4

7

6

O

O

1

1′

HN

NH
5

5′

O

6

[3,3′ -Bipyrrolidine]-2,2′ ,5,5′tetrone (not 1,2,3,4-Butanetetracarboxylic 1,2:3,4-diimide

O

O2
S 2
1 NH
3

4H-1,3,2-Dithiazine, dihydro-,
1,1,3,3-tetraoxide (not 1,3Propanedisulfonimide)

SO 2

O

Butanamide, N-(2,4-dioxo-1-azetidinyl)-

P rC O N H N
NO
6E tN =C= N (C H 2 ) 2 N 4

4-Morpholineethanamine, N(ethylcarbonimidoyl)-

O1

N

P hN =C= N SO 2
N

MeBenzenesulfonamide, 4-methylN-(phenylcarbonimidoyl)-

For sulfur imides, see ¶ 200; for Phosphine imide, see ¶ 197.
192. Molecular addition compounds of neutral components are generallyindexed in the Chemical Substance and Formula Indexes. The preferred nameappears at the formula of each component. (The formula headings used arethose of the components.) Ratios are used in the name to express stoichiometry.
Some common components are not indexed unless all other components arealso “common” or cannot be related to compound classes described in the “Order of Precedence of Compound Classes” (¶¶ 106); however, unesterified acidsin the following list are indexed when not components of salts withbases.These common components are:Acetic acidAcetic acid, 2,2,2-trifluoroAcetonitrile
BenzeneBenzene, methyl- *Benzene, 1,3,5-trinitro1,3-Benzenediol, 2,4,6-trinitroBenzenesulfonic acid *Benzenesulfonic acid, 4-methylBenzoic acid
Borate(1−), tetrafluoro-, hydrogen (1:1)
Butanedioic acid, 2,3-dihydroxy- (all stereoisomers)
2-Butenedioic acid (of defined or undefined stereochemistry)
Carbamimidothioic acid, phenylmethyl ester *Cyclohexanamine *Cyclohexanamine, N-cyclohexylEthanamine, N,N-diethyl- *Ethanedioic acid
Methane, dichloro- *Methanesulfonic acid *Phenol, 2,4,6-trinitro1,2,3-Propanetricarboxylic acid, 2-hydroxy3H-Pyrazol-3-one, 2,4-dihydro-5-methyl-4-nitro-2-(4-nitrophenyl)- *Pyridine* The preferred name is printed at the molecular formula for these compounds.

¶ 193

In addition, compounds with water and ammonia are not indexed at thesenames; they are expressed as “hydrate” and “ammoniate”. Fractional hydrates
and ammoniates, such as hemi- and sesquihydrate, are named by use of a ratio
as hydrate (2:1) and hydrate (2:3), respectively. Other solvates are indexed as
molecular addition compounds. Often the solvate component receives the only
entry; e.g., Ethanol, compd. with pyridine (1:1). Crystal forms of organic
compounds containing solvents of crystallization are indexed only as the unsolvated species except when properties of the crystals themselves are being
studied. “Hydrates” of carbonyl compounds are indexed as gem-diols; e.g.,“acetaldehyde hydrate” is indexed as 1,1-Ethanediol.
Ozonides of known structure are indexed by regular nomenclature; ozonides of unsaturated compounds are indexed at the compound headings with“ozonide” modification terms when the structures are unknown; “ozonides” ofother compounds, e.g., phosphorus acid esters, are expressed as “compd. withozone” and a ratio.
Bisulfite addition compounds are named as salts of specific hydroxy sulfonic acids when the structures are known or can reasonably be assumed, otherwise as a molecular addition compound of the carbonyl compound with aphrase such as “compd. with sodium hydrogen sulfite” and a ratio in the modification. (This is an exception; an “oxo” acid salt ranks higher than an aldehyde or ketone (¶ 106) and would normally receive the preferred index entry.)
Diels-Alder adducts (diene adducts) of unknown constitution are indexed
like molecular addition compounds, except that the “compd. with” phrase is replaced by “adduct with.”
Catena compounds (cyclic compounds with interlocking rings) are indexedat the components with a “catena compd. with” phrase and a ratio.
Rotaxane is the term given to a linear molecule threaded through a cyclic
molecule. The cyclic molecule is usually large, and the linear molecule usually
has bulky end groups that prevent unthreading. These are indexed at the component names with a “rotaxane compd. with” phrase and a ratio.
The “preferred” index name is the name given precedence in the CAS Registry System, and therefore the name which, after uninversion of the index
heading if necessary, may be used among CA users in general discussions andreports. (To the index user in search of information, all the index names for anindividual compound are of equal value.) For molecular addition compoundsof stereoparents and their derivatives (¶ 203 I) with nonstereoparents, the preferred index entry appears at the former heading. In the absence of a stereoparent, the preferred index name is that which describes, in order of decreasing
preference:(a) a component other than a common component (see list above) selected according to the Order of Precedence of Compound Classes (¶ 106);(b) a common component highest in the same order;(c) a component which does not belong to any compound class described in the “Order of Precedence of Compound Classes,” according to theearliest alphabetic position of the index name.
Examples ((a) is the preferred index name in each case):
1. (a) 2,5-Cyclohexadiene-1,4-dione, 2,3,5,6-tetrachloro-,
compd. with coronene (1:?) (The question mark indicates an unknown ratio; a functional compound is preferred to cyclic hydrocarbon)
2. (a) Anthracene,
compd. with 2,4,6-trinitrophenol (2:1)(The cyclic hydrocarbon is preferred to a common compound of
higher rank)
3. (a) Methane, 1,1′-sulfinylbis-,
compd. with iodine (1:1) (by “iodine,” the molecular form I2 is
implied; atomic forms are indicated, when necessary, by phrases
such as “compd. with at. chlorine (1:2)”)

193. Nitrogen compounds. Cyclic nitrogen compounds, including lactams, sultams, and cyclic hydrazones, oximes, etc., are indexed at heterocyclic
molecular skeletons (see Section B). Nitrogen-containing functional derivatives include imidic acids, amides, amines, imines, etc., for which the appropriate paragraph should be consulted. Hydroxylamine (see below) is a substitutive functional parent compound (¶ 130). Acyclic nitrogen skeletons, alone
or with principal groups expressed as suffixes, are employed as heading parents
for indexing purposes. Some groups, including azido, nitro, nitroso, and isocyano, are always expressed as substituent prefixes (¶ 132). aci-Nitro, HON(O)=,may be substituted; e.g., (propyl-aci-nitro) is CH3CH2CH2ON(O)=.
Diazene, HN=NH; 1-Triazene, NH=N−NH2; Triazane, NH2−NH−NH2,
etc., are molecular skeleton heading parents to which the principal groups except hydroxy (and its chalcogen analogs), amino, and imino can be suffixed.
Hydrazine is used as a trivial name for Diazane and its derivatives. Except forhydrazides (¶ 189) and hydrazones (¶ 190), alkyl and aryl are indexed at thesenitrogen parents, which rank just below nitrogen heterocycles as the highest
class of nonfunctional compounds (¶ 106). Within the class, seniority depends
first on the number of hetero atoms, then on maximum unsaturation. When
more preferred compound classes (including all those expressed by means offunction suffixes) are present, the nitrogen skeletons are named as substituent
prefixes, some of which have trivial names.

¶ 193Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Examples (See also ¶ 161):

Br

N= N N ( CH O ) N ( CH O ) N=N
1

H N =N−diazenyl− N=N −

1,2-diazenediyl− N=N (O )−1-oxidodiazenyl

60

2 3

4

5

Br

6

1,5-Hexazadiene-3,4-dicarboxaldehyde, 1,6-bis(4-bromophenyl)62-oxidodiazenyl
Η 2 N N H−

hydrazinyl

Η 2 N N=hydrazinylidene−NHNH−

1,2-hydrazinediyl−N H N =1-hydrazinyl-2-ylidene=N N =

1,2-hydrazinediylidene

Η 2 N N H N H−

triazanylΗ 2 N N =N−

1-triazen-1-yl

ΗN= N NΗ −2-triazen-1-yl−N =N NΗ −1-triazene-1,3-diylΗ 2 N N H N H N H−

tetrazanyl=N N H N H N=

1,4-tetrazanediylidene

H 2 N C(= N H )Hydrazinecarboxylic acid

HO2CNHNHCO2H

1,2-Hydrazinedicarboxylic acidH 2 N N H C O N H Me

Hydrazinecarboxamide, N-methyl-

Et2NNHEt

Hydrazine, 1,1,2-triethyl-

H2NNHOH

Hydrazine, hydroxy-2

2 1

C( =N H ) N H 2

Benzenecarboximidamide, 4,4 ′(1-triazene-1,3-diyl)bis-

Formazan is a trivial name that describes the tautomeric compound H2N−
N=CH−N=NH. Beginning with the Thirteenth Collective period, the use offormazan and its associated prefixes, formazano and formazanyl, has been discontinued and compounds containing the formazan residue are named systematically.
Examples:H 2 N −N=CH −N =N H

Diazenecarboxaldehyde,
hydrazone (formerly Formazan)

H 2 N −N=C( CH 3 ) −N= N−CH 3

Ethanone, 1-(2-methyldiazenyl)-,hydrazone

H 2 N −N=C( CH 2 O H )−N =N− CH 3

Ethanone, 2-hydroxy-1-(2-methyldiazenyl)-,hydrazone

I
CH= N−N =C− N=N− CH 3

Diazenecarbohydrazonyl iodide,2-methyl-N-(phenylmethylene)-

2 1

1

1

N H N =N
6′

Hydrazides (¶ 189) and hydrazones (including azines) (¶ 190) are excluded
from the following examples.
Examples:H2NNHCO2H

1′Cl
N H −N= CH−N =N

HOOC

CO O HN

Benzoic acid, 4-[2-[[2-(4-carboxyphenyl)diazenyl]methylene]hydrazinyl]-2-chloroCl

S

NHNH2

Hydrazine, (3-nitro-2-thienyl)(principle: preferred hetero atom inheading parent (¶ 138))

NO2

N H −N= CH−N =N

HOOC

Benzoic acid, 4-[2-[[2-(4-carboxyphenyl)hydrazinylidene]methyl]diazenyl]]-2-chloro-

N H N Me 2
8

9

10a
5

1

9a

Acridine, 9-(2,2-dimethylhydrazinyl)-

CH= N−N =C( CH 3 ) −N =N− CH 3

4aN

Benzaldehyde,
2-[1-(2-methyldiazenyl)ethylidene]-,hydrazone

10

P hN =N SO 3 H

Diazenesulfonic acid, 2-phenyl-

P hN =N C O N H 2

Diazenecarboxamide, 2-phenyl-

2

N

1

CO O H6

PhN =N (O )

1

HOCO

N( O) =

CO 2 H

Benzoic acid, 4-(1-oxido2-phenyldiazenyl)-

Benzoic acid, 4,4′-(1,2-dioxido1,2-diazenediyl)bis2

Hydroxylamine, H2NOH; Thiohydroxylamine, H2NSH, etc., are substitutive parent compounds; i.e., substituent prefixes but (usually) not substituent
suffixes may be attached to them. N-Ylidene derivatives are oximes (¶ 195),
imidic acid derivatives (¶ 165), etc.
In general, N-alkyl and N-aryl derivatives of Hydroxylamine are indexedas amines; N-acyl derivatives as amides; and S-amino derivatives of Thiohydroxylamine are indexed as sulfenamides. When the nitrogen atom is unsubstituted, O-derivatives are usually indexed at Hydroxylamine, etc.
Examples:H 2 N O SO 3 H

Sulfuric acid,monoazanyl ester

H2NOAcAcetic acid,azanyl ester

H 2 N O CO 2 H

Carbonic acid,monoazanyl ester

H 2 N O CO N H 2

Carbamic acid,azanyl ester

Bu O N H 2Hydroxylamine, O-butyl-

N (O )=N F
1

2

Diazene, 1-(2-chlorophenyl)2-fluoro-, 1-oxideCl
H 2 N N =N A c

Acetic acid,
1-triazen-1-yl ester

MeSO 2 N H N H N H C(=NH) Me
3

2

1

Ethanimine, 1-[3-(methylsulfonyl)triazanyl]-

61

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

H 2 N O (C H 2 ) 2 O N H 2Hydroxylamine, O,O ′-1,2-ethanediylbis-

E tSN H 2

Ethanesulfenamide

P hN H O HBenzenamine, N-hydroxy-

N SCO SH

1
6

A cN H S HAcetamide, N-mercapto-

HONHCO2H

Carbamic acid, N-hydroxy-

HONHCONH2

Urea, N-hydroxy-

P hS O 2 N H O HBenzenesulfonamide, N-hydroxy-

Hydroxylamine and its chalcogen analogs rank lowest among the nonfunctional nitrogen parents. In the presence of more preferred compound classes,
the radicals (aminooxy), (aminothio), (hydroxyamino), etc., are employed.
Examples:Br

196. Oxygen compounds include a wide range of compound classes: acids,
anhydrides, esters, alcohols, salts, metal oxides, etc. These are discussed in other sections and paragraphs. Cyclic oxygen compounds are indexed as heterocycles; these include cyclic esters, anhydrides, ethers, and oximes, as well as
lactones, sulfones, etc.
Examples:1

H2NOCH2NHNHNH2123

Triazane, 1-[(aminooxy)methyl]-

Oxirane, 2,2-diethyl- (not Butane,
1,2-epoxy-2-ethyl-)

Et

O

Et

Acetic acid, 2-(hydroxyamino)2-oxo-

HONHCOCO2H

Hydroxylamine-O-sulfonic acid,N-ethylidene-,
methyl ester

M e CH=N O SO 3 M e

3

1

O

4

Et

194. Organometallic compounds. Organic derivatives of germanium, tin,lead, antimony, and bismuth are indexed at hydride heading parents (see ¶¶181, 199).
Cyclic derivatives of these metals with standard substitutive valencies areindexed as heterocycles.
Example:7a2,5-Cyclohexadiene-1,4-dione,
2,6-dibromo-,
4-[S-(thiocarboxy)thiooxime]

Br
O

¶ 196

2-Oxetanone, 4-ethyl- (not Pentanoic acid, 3-hydroxy-, β-lactone;see ¶ 185)

O

1
7a

O

O

1,3-Benzodioxol-2-one (not Carbonicacid, cyclic 1,2-phenylene ester; see¶ 185)

O

3

4
1

1

2

G eH

1H-2-Benzogermole

7-Oxabicyclo[4.1.0]heptane (a Von
Baeyer ring system; see ¶ 155)

7 O
6

3

L i-P hLithium, phenyl-

Me 3 P + C H =C H C H 2 HgBr • B r −Phosphonium, [3-(bromomercurio)-1-propen-1-yl]trimethyl-,
bromide (1:1)

195. Oximes contain a bivalent hydroxylamine residue, =N−OH. When thisresidue has replaced oxygen in carboxylic acids, acid halides, and amides, thecompounds are named as N-hydroxy derivatives of imidic acids (¶ 165), imidoyl halides (¶ 170), and imidamides (¶ 171). Cyclic oximes are indexed at heterocyclic parents, e.g., Isoxazole.
Acyclic oximes derived from aldehydes and ketones expressed as principalgroup suffixes are expressed by “oxime” terms in the index modifications at the
carbonyl-containing heading parents. When the carbonyl group is expressed asa substituent, it is replaced by the (hydroxyimino) radical, HO−N=. O-Alkyl,
O-aryl, and O-acyl oximes are named as such in the modification or as an“-oxyimino” radical. Oximes derived from Hydroxylamine-O-sulfonic acid(¶ 193) are named as substituents of that heading parent.
Examples:H 2 C= N O HFormaldehyde,
oxime

Ph 2 C=N O H

Methanone, diphenyl-,oxime

Acyclic ethers (including acetals and ortho esters) are indexed by replacement(“a”) nomenclature if the requirements (¶ 127) are satisfied.
Example:
CH 3

CH 3

−

Acyclic metal derivatives, other than acetylides (¶ 219) and those indexed
at metal hydride names, are indexed at the metal element name. Such names
are ranked as neutral coordination compounds (¶ 215) and all functional compounds are expressed as substituent prefixes. When all metal atoms cannot be
expressed by the heading parent, elements other than those of Groups IVA and
VA are expressed as “-io” radicals, e.g., sodio, magnesio, aurio, lithio, whenthe metal replaces a single hydrogen. No hydrogen or other “substituent” is implied by these radical names, and atoms or groups attached to them must be expressed.
Examples:−4

CH 3 −CH 2 − Ο − CH −O− CH 2 − CH 2 − Ο − CH− O−CH 2 −CH 2 −O H

12

11

10

9

8

7

6

5

4

3

2

1

3,5,8,10-Tetraoxadodecan-1-ol,
4,9-dimethyl- (not Acetaldehyde,
1,2-ethanediyl ethyl 2-hydroxyethyl
diacetal)
When “a” names are not permitted, acyclic ethers are indexed at heading
parents (functional parent compounds, hydrocarbons, etc.) by use of “oxy” radicals, including the elided radicals (¶ 107) methoxy, ethoxy, propoxy, butoxy,and phenoxy.
Examples:E tO M e

Ethane, methoxy- (not Ether, ethyl
methyl)Et2O

Ethane, 1,1′-oxybis- (not Ethyl ether)CH 2 − Ο − CH 2

1

Benzene, 1,1′-[oxybis(methylene)]bis-

1′

Naphthalene, 2-(dodecyloxy)(principle: ring preferred to chain(¶ 138))

Ο (CH 2 ) 1 1 M e

Me

NOH
1

3

1,3-Isobenzofurandione,
monooxime

O2
3

1

Ethene, 1,1 ′-[(1-chloroethylidene)bis(oxy)]bis- (principle:
unsaturation)−

Ο − CH= CH 2

CO2H

Benzoic acid, 3-[(hydroxyimino)methyl]-

6ClCH 3 −C− Ο −CH =CH 2

O4

CH 2 Ο (CH 2 ) 2 O−

7aOxirane, 2-[[2-(2-methylphenoxy)ethoxy]methyl]- (principle:
preferred ring)

1

O

O

4

1

O

1′

O

C H=N O H

MeC H= N O Me

Acetaldehyde,
O-methyloxime

Benzene, 1,1′-oxybis[4-phenoxy(principles: centrality and multiplication)

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

C H 3 − C H 2 −O −C H 2 −CH 2 − S− S− CH 2 −CH 2 −O− CH 2 −CH 3

O=

Diazene, [3-(benzoyldioxy)-3oxopropyl]ethyl-

O Me

−

−

−

−

−

−

−

−

CH2−CH3 CH2−CH3 CH2−CH3 CH2−CH3OO

H O −C− CH 2 − CH 2 −C− O−O −C− CH 2 −CH 2 −C− O H

Butanoic acid, 4,4′-dioxybis[4-oxoO

Peroxyhypofluorous acid,methyl ester

MeOOF

1

9a

Hydroperoxide, 1,1′-(9H-fluoren-9ylidene)bis-

9
4a

4b

H O O C H 2 C O Ph

Ethanone, 2-hydroperoxy-1phenyl-

NOOH

Piperidine, 1-hydroperoxy-

=

=

O

O
=

OOH

8

O

F −C− O−O −C− F=

HOO

Ethaneperoxoic acid,
ethyl ester

CH 3 − C−O −O− CH 2 −CH 3

O

Hydroperoxide, ethyl (the uninverted
name is Ethyl hydroperoxide)

E tO O H

O
=

O

=

Hydroperoxide, 1,1′-[dioxybis[(1ethylpropylidene)dioxy(1-ethylpropylidene)]]bis=

Hydroperoxides, ROOH, follow alcohols (including phenols) in order ofprecedence (¶ 106). They are indexed at the radicofunctional heading parent
Hydroperoxide. No hyphen follows the substituent radical (¶ 108) unless theheading parent is being multiplied by a prefix such as “bis”. In the presence ofmore preferred compound classes, or when the HOO− group is attached to ahetero atom other than silicon, a hydroperoxy radical is employed. The chalcogen analogs R−S−OH and R−S−SH are indexed as sulfenic acids and sulfenothioic acids, respectively (¶ 165). Thiohydroperoxide is the heading parent for R−O−SH compounds.
Hydrotrioxide, Hydrotetraoxide, etc., heading parents are treated in asimilar manner, and hydrotrioxy and hydrotetraoxy radicals can be used as substituent prefixes.
Examples:CH2−CH3 CH2−CH3 CH2−CH3 CH2−CH3

HOO−C−O−O−C−O−O−C−O−O−C−ΟOH=

Benzene, 1-methoxy-2-(4-methoxyphenoxy)- (principle: lowest
locants for substituent prefixes)

=

OMe

O

C− O−O −C− CH 2 −CH 2 −N= N−CH 2 −CH 3

Disulfide, bis(2-ethoxyethyl) (an “a”
name cannot be used; only threehetero units (¶ 127) are present)

O

Peroxydicarbonic difluoride
Thioperoxide, S-acetyl O-benzoyl

CH 3 −C− S− O−C

The heading parents Trioxide, Tetraoxide, etc., are treated analogously
and, in the presence of more preferred compound classes, radicals such as (methyltrioxy), CH3−O−O−O−, are used.
Example:Trioxide, dimethyl

MeOOOMe−CH3

Thiohydroperoxide, O-(1-methyl-1phenylethyl)−

C− O−SH
CH3−

CH3

H 3 C−C −O− O−O H−

Hydrotrioxide, 1,1-dimethylethyl

CH3Acyl hydroperoxides are peroxy acids (¶ 165).
Peroxides, R−O−O−R ′ (R and R ′ = alkyl or acyl), are named at the radicofunctional heading parent Peroxide unless a replacement (“a”) name (¶ 127) isappropriate. Cyclic peroxides are indexed as heterocycles and are ranked in accordance with the seniority of ring systems (¶ 138). Acyclic peroxides rankwith the nonfunctional oxygen parents (¶ 106) and in the presence of a more
preferred compound class are expressed by “dioxy” radicals. Acyl alkyl (andacyl silyl) peroxides are esters of peroxy acids. Symmetrical diacyl peroxides
derived from “oxo” acids are named at acid, acid halide, etc., heading parents
such as Peroxydiphosphonic acid. Dithio peroxides are indexed at Disulfide(¶ 200); R−S−O−R′ compounds are named as esters of sulfenic acids (¶ 165).
The corresponding diacyl compounds are indexed at Thioperoxide.
Examples:CH3−C−O−O−C−O−CH2−CH2−O−CH2−CH2−O−C−O−O−C−CH3
6

7

CH3

8

9

10

11

12 13

14 15 16

CH 3

−

4 5

CH3

−

3

−

2

−

1

TABLE VI
FUNDAMENTAL MONONUCLEAR
PHOSPHORUS AND ARSENIC OXO ACIDS“Trivalent” acids(HO)3P

Phosphorous acid(HO)3As

Arsenous acid(HO)2HP

Phosphonous acid(HO)2HAs

Arsonous acid(HO)H2P

Phosphinous acid(HO)H2As

Arsinous acid

HOPO

Phosphenous acid
Metaphosphorous acid
(HPO2)

HOAsO

Arsenenous acid

17

CH3

3,4,6,9,12,14,15-Heptaoxaheptadecane, 2,2,5,5,13,13,16,16-octamethyl1197. Phosphorus and arsenic compounds. The fundamental phosphorus
and arsenic “oxo” acids are shown in Table VI. By use of replacement nomenclature (¶ 129) in which oxo and hydroxyl groups are replaced by other chalcogen atoms or nitrogen groups, a large number of acids, acid halides, amides,
etc., can be named. Phosphorous acid is the heading parent when all three hydroxyl groups are involved in anhydride, ester, or salt formation; otherwise thetautomeric Phosphonic acid is the preferred heading parent. Similarly, Phosphinic acid is preferred over the tautomeric Phosphonous acid. Metaphosphorous acid is the name used for the unsubstituted acid and its ester and salts,
but Phosphenous acid is the fundamental name from which replacement analogs are derived. Metaphosphoric and Phosphenic acids stand in the same relationship, except that the special names Metaphosphimic acid, Thiometaphosphimic acid, etc., are used for (HO)P(O)(=NH) (or (HO)2P ≡ N) and its
chalcogen analogs.

CH3

−

−

CH 3

−

CH3

−

CH3

4

12 a 12b

O
5

8
9

O6

“Pentavalent” acids

Dibenzo[d,f ][1,2]dioxocin-5,8-dione

O(HO)3PO

Phosphoric acid(HO)3AsO

Arsenic acid
(H3AsO4)(HO)2HPO

Phosphonic acid(HO)2HAsO

Arsonic acid(HO)H2PO

Phosphinic acid(HO)H2AsO

Arsinic acid

HOPO2

Phosphenic acid
Metaphosphoric acid
(HPO3)

HOAsO2

Arsenenic acid

7O

Me 2 C H O O C H Me 2

Peroxide, bis(1-methylethyl)

E tO O Me

Peroxide, ethyl methyl (the uninverted name is Ethyl methyl peroxide)

O

=

=

O

C H 3 − C−O− O−C− CH 3

62

=

¶ 196

Peroxide, diacetyl
Examples:=O
C−O −O− SO 3 H

Peroxide, benzoyl sulfo( Ph N H ) 2 P( O ) O H

Phosphorodiamidic acid, N,N′ -diphenyl-

63

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Me 2 N N H P(O )(O H ) 2

Phosphorohydrazidic acid, 2,2dimethyl-

MeN H P(O H )(= N H ) NHMe

Phosphorodiamidimidic acid, N,N′-dimethyl-

2 1

N′ ′

N

N′

Cl 2 HAs

Arsonous dichloride(NC)H 2 As

Arsinous cyanide

ClAs=NH

Arsenenimidous chloride¶ 197

P h 2 A sO H

Arsinous acid, diphenyl-

BrAsO

Arsenenous bromide

E tN H A s(O )(O H ) 2

Arsenamidic acid, N-ethyl-

Cl 3 PO

Phosphoric trichloride

ClF 2 PO

Phosphoric chloride difluoride(OCN) 3 PO

Phosphoric triisocyanate

Cl 3 PS

Phosphorothioic trichlorideOP≡ N

Phosphoric nitride

Esters and anhydrides are indexed by the usual rules. Phosphorous, Phosphoric, Phosphorothioic and Phosphorodithioic acids are “Class I” acids;
their esters with a single alcohol or thiol of “Class II” (¶ 185) are indexed at thealcohol name, but “mixed” esters are indexed at the phosphorus acid unless amore preferred compound class (e.g., carboxylic acid, aminium compound) ispresent. All cyclic esters are indexed as heterocycles.
Examples:(E tO ) 2 P O (C H 2 ) 2 N H 2

Phosphorous acid,
2-aminoethyl diethyl ester[C l(C H 2 ) 2 O ] 3 P

Ethanol, 2-chloro-,
phosphite (3:1)

H P (O )(O H )O Me

E tP (O )(O E t)SE t

Phosphonic acid,monomethyl ester

Esters and anhydrides of cyclic oligomers of metaphosphorus acids are indexed as heterocycles.
Examples:
Me
N

Ph O
O

−

−

CH3

Phosphonothioic acid, ethyl-,
O,S-diethyl ester−

H 3 C−A s −S −A s =S
CH3

Arsinodithioic acid, dimethyl-,anhydrosulfide with dimethylarsinothious acid

Nonacidic mononuclear arsenic and phosphorus names are derived from theacid names in the usual way by expressing the highest function as a class term,e.g., “amide,” “chloride,” and the other replacement terms in alphabetical order
within the main part of the name. The descending order of precedence for classterms is: hydrazide, halide (all considered equivalent, and cited in alphabeticalorder), azide, amide, cyanide, isocyanide, cyanate, thiocyanate (etc.), isocyanate, isothiocyanate (etc.), nitride, imide. Nonacidic analogs of phosphoric acidin which an oxo and hydroxyl group have been replaced by ≡ N, are named at
Phosphonitrile headings.
Examples:

2P

3

N
Me
Me
N

6

CH3

O

1

P4

2

1

MeOP
MeN 5

O Ph

PO M e3

4

1,3,2,4-Diazadiphosphetidine, 1,3dimethyl-2,4-diphenoxy-,
2,4-dioxide

NMe

P
OMe

1,3,5,2,4,6-Triazatriphosphorine,
1,2,3,4,5,6-hexahydro-2,4,6trimethoxy-1,3,5-trimethyl-

1

O

O

O

P6

2P

E tO
O
5

O3

4

P

O

O P( O ) ( O E t) 2

1,3,5,2,4,6-Trioxatriphosphorinane,2-[(diethoxyphosphinyl)oxy]4,6-diethoxy-,
2,4,6-trioxide

OEt

Phosphorus and arsenic molecular skeletons other than those named as acids and acid analogs are indexed as heterocycles or at acyclic hydride names:
Phosphine, PH3; Arsine, AsH3; Phosphorane, PH5; Arsorane AsH5; Diphosphine, H2P−PH2; Triarsine, H2As−AsH−AsH2; etc. Oxo, thio (etc.), andimino derivatives of Phosphorane and Arsorane are indexed at additive heading parents.
Examples:(H 2 N) 3 P=NH

Phosphorimidic triamide

Cl 3 P=NH

Phosphorimidic trichloride(H 2 N)Cl 2 PS

Phosphoramidothioic dichloride(H 2 N)BrClPO

Phosphoramidic bromide chloride

H 3 PO

Phosphine oxide(OCN)ClFPO

Phosphorisocyanatidic chloride
fluoride

H 3 AsSe

Arsine selenide(H 2 N) 2 (N 3 )PO

Phosphorodiamidic azide

H 3 P=NH

Phosphine imide(H 2 N) 2 (NC)PO

Phosphorocyanidic diamide

HPO 2

Phosphine oxide, oxo- (not Phosphorane, dioxo-)(H 2 NNH)F 2 PO

Phosphorodifluoridic hydrazide(H 2 N) 3 P

Phosphorous triamide

Cl 3 P

Phosphorous trichloride

ClF 2 P

Phosphorous chloride difluoride(NC)H 2 P

Phosphinous cyanide(SCN)H 2 P

Phosphinous isothiocyanate

H 2 NPS

Phosphenothious amide

ClP=NH

Phosphenimidous chloride(H 2 N)ClHP=NH

Phosphonamidimidic chloride

Cl 2 P≡N

Phosphonitrile chloride (notPhosphoronitridic dichloride)(H 2 N) 3 AsO

Arsenic triamide(H 2 N)ClHAs=NH

Arsonamidimidic chloride(NCS) 2 HAsO

Arsonic dithiocyanate(H 2 N)H 2 As=NH

Arsinimidic amide

Cl 3 As

Arsenous trichloride

Oxides, etc., of Diphosphine, Diarsine, Triphosphine, etc., are indexed byuse of “oxide” and “sulfide” terms, with locants if necessary, in the modification. Acid derivatives of one of the phosphorus atoms are indexed at acid parents when names based on the phosphorus chains are impracticable.
Example:
PhPHP(O)H 2

Diphosphine, phenyl-,2-oxideEt 3 P(Cl)P(O)Cl 2

Phosphonic dichloride, P-(chlorotriethylphosphoranyl)-

Derivatives of Phosphine and other phosphorus and arsenic molecularskeleton parents are named substitutively by use of suffixes and prefixes.
Examples:(HO) 2 P(O)CO 2 H

Phosphinecarboxylic acid, 1,1-dihydroxy-,oxide

F 4 PNHMe

Phosphoranamine, 1,1,1,1-tetrafluoro-N-methyl-

Me 2 AsCO 2 H

Arsinecarboxylic acid, 1,1-dimethyl-

EtAsMe 2 =NH

Arsine imide, As-ethyl-As,As-dimethyl-¶ 197

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

(EtO) 5 P

Phosphorane, pentaethoxy-

Ph 3 As(OAc) 2

Arsorane, bis(acetyloxy)triphenyl-

HPO

Phosphine, oxo-

MeAsS

Arsine, methylthioxo-

MePHPHMe

Diphosphine, 1,2-dimethyl-(Me)(Ph)As−As(Ph)(Me)

Diarsine, 1,2-dimethyl-1,2-diphenylDiarsene, 1,2-dimethyl-

MeAs=AsMe

Polyphosphorus acids (anhydrides of the mononuclear acids) and their replacement analogs do not follow the rules described for the mononuclear acids.
They are given traditional inorganic names, and many cross-references will befound at mononuclear names (see also ¶ 219). (Polyarsenic acids are named
analogously.)
Examples:64

In the presence of more preferred compound classes, phosphorus and arsenic acids and hydrides are expressed by the following substituent radicals(*denotes a radical which requires bis, tris, etc., (and parentheses) instead of di,tri, etc., when more than one is present):
H2P−*phosphino

H2As−*arsinoH2P(O)−*phosphinyl

H2As(O)−*arsinyl

H2P(S)−

phosphinothioyl

H2As(S)−

arsinothioyl

H2P(=NH)−

phosphinimyl

H2As(=NH)−

arsinimyl

HP(≡N)−

phosphononitridyl

HAs(≡N)−arsononitridyl

H4P−*phosphoranyl

H4As−*arsoranylHP=phosphinidene

HAs=arsinidene

HP(O)=*phosphinylidene

HAs(S)=

arsinothioylidene

P(O)≡*phosphinylidyneAs≡arsinidyne(HO) 2 P(O)OP(O)(OH) 2

Diphosphoric acid(HO) 2 P(O)P(O)(OH) 2

Hypophosphoric acid(HO)HP(O)OP(O)(OH) 2

Isohypophosphoric acidP(O)−phosphoroso

As(O)−

arsenoso(HO) 2 POP(O)(OH) 2

Diphosphoric(III,V) acid

P(O)2−

phospho

As(O)2−arso(HO) 2 POP(OH) 2

Diphosphorous acid(HO)2P(O)−phosphono(HO)2As(O)− arsono(HO) 2 P(O)NHP(O)(OH) 2

Imidodiphosphoric acid

−P(O)(OH)−phosphinico(multiplying
radical only)−As(O)(OH)− arsinico(multiplying
radical only)

The above are substitutive; the following are not, and can be used only as
simple radicals (¶ 132):(HO) 2 P(O)OP(O)(OH)NHP(O)(OH)OP(O)(OH)2P′-Imidotetraphosphoric acid(H 2 N) 2 P(O)NHP(O)(OH) 2

P,P-DiamidoimidodiphosphoricacidLine formulas are used with thio, seleno, and telluro analogs of polyphosphorus acids to indicate the number and positions of sulfur (etc.) atoms. Thio, etc.,
prefixes are placed at the beginning of the name without multiplicative terms;
e.g., Thiodiphosphorous acid ([(HO) 2P] 2S); Thiodiphosphoric(III,V) acid((HO) 2POP(S)(OH) 2); Thioperoxydiphosphoric acid ([(HO) 2P(S)] 2S 2);
Thioimidodiphosphoric acid ([(HO) 2P(S)] 2NH).
When all acid groups have been replaced, the compounds are named as halides, amides, etc. The phosphoric halides and halogenoids are named by phosphoryl terms, the phosphoric amides by single-word heading parents. The
phosphorous analogs of both classes are indexed at Phosphorous binary heading parents with a multiplicative prefix for the class term.
Examples:Cl 2 P(O)OP(O)Cl 2

Diphosphoryl chloride (the phosphorous analog is named Diphosphorous tetrachloride)(H 2 N) 2 POP(NH 2 ) 2

Diphosphorous tetraamide (thephosphoric analog is named
Diphosphoramide)

O

−

−

−

NH3

NH3

NH 3

H 2 PPH−diphosphinyl−PHPH−

1,2-diphosphinediyl=PP=

1,2-diphosphinediylidene−P=P−

1,2-diphosphenediyl−As=As−1,2-diarsenediyl−PH(PH) 2 PH−

1,4-tetraphosphinediyl

198. Salts. Metal salts of acids and of other compounds having replaceablehydrogen on chalcogen atoms (whether expressed in the heading parent, in thesubstituents, or in a previous modification phrase) are indexed by use of salt
terms in the modification. Ratios and Ewens-Bassett numbers are used, but locants are never cited. In the presence of hetero atom groups capable of forming
chelate rings, salts of aluminum, beryllium, gallium, indium, magnesium, thallium, and the transition metals with acids (except polybasic hydroxy acids) are
named by coordination nomenclature (¶ 215).
Examples:Acetic acid,sodium salt (1:1)

AcOH • Na

=

O
=

=

O

H 2 N −P− N H− P− N H−P −NH 2

Radicals from polynuclear arsenic and phosphorus hydrides are formed likethe carbon analogs.
Examples:Diimidotriphosphoramide
OH • 2KHO

In the order of precedence of compound classes (¶ 106), phosphorus and arsenic acids are functional heading parents, which fall below the acids expressed
as principal functions (carboxylic, sulfonic, etc.) but above the highest nonacidgroup (acid halides). Phosphorus acids as a group rank just above arsenic acids.
Within each group, seniority is dependent on (a) the greatest number of acidgroups; (b) the greatest number of nuclear phosphorus or arsenic atoms; (c) the
highest oxidation state (5+) of these atoms; (d) the most preferred atoms (Table
I, ¶ 128) attached to the nuclear atoms; (e) the greatest number of such preferred atoms; (f ) the nature of less preferred atoms. A partial list of acids in descending order of precedence is: Triphosphoric, Diphosphoric, Imidodiphosphoric, Diphosphorous, Phosphoroperoxoic, Phosphoric, Phosphorothioic, Phosphorodithioic, Phosphorous, Phosphorochloridic, Phosphorohydrazidic, Phosphoramidic, Phosphonic, Phosphinic, Phosphinous acid.
(Chalcogen analogs of each acid immediately follow it in descending order ofincreasing replacement of oxygen by sulfur, selenium, and tellurium.) For the
choice between tautomeric pairs such as Phosphorous and Phosphonic acids,
also see above.
Nonacid analogs are ranked according to their class, e.g., halide, amide;
then on the multiplicity of their class, e.g., a diamide is preferred over a monoamide; then on the remaining criteria set out above for the acids.

Ph P( O ) ( O H ) O E t • K

3 M e O H • Bi 3+

ClCO 2 ( CH 2 ) 2 O H • L i

1,4-Benzenediol,potassium salt (1:2)
Phosphonic acid, P-phenyl-,monoethyl ester, potassium
salt (1:1)
Methanol,bismuth(3+) salt (3:1)
Benzoic acid, 2-chloro-,
2-hydroxyethyl ester, lithium
salt (1:1)

When a metal (except Sb3+, Bi3+, Ge4+, Sn4+, or Pb4+) has replaced hydrogen atoms attached to nitrogen, phosphorus, arsenic or antimony in molecularskeletons, they also are named as salts, e.g., Piperidine, potassium salt (1:1);
Acetamide, sodium salt (1:1); Phosphine, cyclohexyl-, lithium salt (1:1);
but unsubstituted Hydrazine, Phosphine, and Arsine afford the binary heading parents Sodium hydrazide (NaN2H3); Lithium arsenide (LiH2As); Aluminum phosphide; etc.

65

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Except for those cyclic derivatives of germanium, tin, lead, antimony, andbismuth which are treated as heterocycles (¶ 194), cyclic metal salts of two or
more compounds, as well as mixed acyclic salts, are named by coordination nomenclature (¶ 215). Metal salts of radical anions and of certain delocalized
structures, e.g., β-dicarbonyl compounds and nitro alkanes, are indexed by citing the ion term in the modification followed by the metal name and a ratio.
Examples:
•

−

• Na+

−

O 2 N−C H −N O 2 • N a+

Naphthalene,radical ion(1−), sodium (1:1)

Methane, dinitro-,ion(1−), sodium (1:1)• H 2 Se O 4

M e CH 2 CH ( N H 2 ) CH 2 O H • H O 2 CCO 2 H
2

=

=

−

For salts of amines, etc., with alcohols and thiols, the phrase “compd. with”
and a ratio are used.
Examples:Ethanol,
compd. with 2-methylpyridine
(1:1)

CH 3
• E tO H

2,4-Pentanedione,
ion(1−), potassium (1:1)

Uninverted names for metal salts of acids and esters depend on the structureand name of the acid or ester. The metal is cited first when there is a free acidgroup remaining in the parent that can take an “ate” or “ite” suffix. If there isno acid group available in the parent, e.g., all acid functions of the parent areesterified, the metal follows the acid name. When the acid is one that requires
a line formula, the acid name is placed first.
Examples:sodium acetate (1:1)
potassium carbonate (1:1)
calcium ethyl phosphate (1:1)
zinc methyl sulfate (1:2)
1,4-diethyl 2-sulfobutanedioate sodium salt (1:1)
potassium 2-hydroxybenzoate (1:1)
calcium 4-aminobenzoate (1:2)
perboric acid (HBO(O2)) sodium salt (1:1)
In uninverted names of alcohol or amine metal salts, the alcohol or amine
is cited first, e.g., 2,6-dimethylphenol lanthanum(3+) salt (3:1) or 2-ethoxybenzenamine sodium salt (1:1).
Amine, phosphine, etc., salts of acids, alcohols, thiols, etc., in general are indexed in the Chemical Substance Index at the preferred name. The preferredname is also cited at each of the component formulas in the Molecular FormulaIndex. Exceptions are salts of ammonia, indexed only as ammonium salts at theacid headings, and the “common components” of molecular addition compounds (¶ 192) together with the following common acids: hydriodic, hydrobromic, hydrochloric, hydrofluoric, nitric, nitrous, perchloric, phosphoric,
phosphorous, sulfuric, and sulfurous. Entries are not made for these components except for salts that contain only “common components,” in which casea single entry based on the rules for molecular addition compounds (¶ 192) ismade. At the acid heading, a “compd. with” phrase appears in the modification.
Example:1-Butanol, 2-amino-,ethanedioate (1:1)
Phenol, 4-amino-,
1-acetate, acetate (1:1)

NH2 • AcOHO

C H 3 − C−C H −C− C H 3 • K +

1

AcO

N
O

Selenic acid,compd. with pyridine (1:1)

N

4

¶ 198

Salts of aminium compounds and other substitutive cations are indexed by
combining the “-ium” heading and the anion term, named according to therules already described, (¶¶ 180, 184). The preferred name appears in theChemical Substance Index and at each of the components in the Formula Index
except for the following common anions:(a) halide and halogenide simple anions, e.g., bromide, cyanide, thiocyanate, azide;(b) chalcogenide anions, e.g., hydroxide, sulfide;(c) anions derived from acetic acid, benzenesulfonic acid, 4-methylbenzenesulfonic acid, 1,1,1-trifluoromethanesulfonic acid, methanesulfonic acid,carbonic acid, phosphoric acid, nitric acid, nitrous acid, sulfuric acid, sulfurousacid, and 2,4,6-trinitrophenol;(d) methyl sulfate (MeOSO3− ), and ethyl sulfate (EtOSO3− );(e) tetrafluoroborate(1−) (BF4− ), tetraphenylborate(1−) (BPh4− ), andhexafluorophosphate(1−) (PF6−).
Ternary salts of this kind are indexed by citing the terms in alphabetical order in the modification, cations first, then anions. In molecular addition compounds, the “-ium” salt is cited in uninverted form.
Examples:M e 4 N + • Br −Methanaminium, N,N,N-trimethyl-,
bromide (1:1)

M e 4 N + • M e CO S −Methanaminium, N,N,N-trimethyl-,ethanethioate (1:1)

Et4As+ • −O2C

Arsonium, tetraethyl-,
cyclohexanecarboxylate (1:1)

Me

CO 2 −+N

Pyridinium, 1-methyl1,2-benzenedicarboxylate (1:1)•
CO 2 HN H 2 • Ac OH

Acetic acid,compd. with cyclohexanamine(1:1)

At index headings for nitrogenous substances, and those containing trivalent
phosphorus or arsenic, an “-ate”, “-ite”, or “-ide” term is normally cited in themodification, but when the acid has a synonym line formula, or is an acid ester
indexed at a “Class II” alcohol name, a “compd. with...” phrase is used instead.
Examples:Me 2 A sH • H C l

PhN H 2 • H 3 P O 4

Arsine, dimethyl-,hydrochloride (1:1)
Benzenamine,
phosphate (1:1)

−

Me2N+

+N M e 2 • 2Piperazinium, 1,1,4,4-tetramethyl-,
cyclopentadienide (1:2)

M e 4 N + • − N H Ph

Methanaminium, N,N,N-trimethyl-,salt with benzenamine (1:1)

M e 3 N + CH 2 O H • ClO 4 −Methanaminium, 1-hydroxy-N,N,Ntrimethyl-,
perchlorate (1:1)+N M e 2 • F 3 CCO 2 − • H Cl

HN

Piperazinium, 1,1-dimethyl-,
2,2,2-trifluoroacetatehydrochloride (1:1:1) (¶ 281A)−•N
C H− C H 2 −NEt 2 • HO 2 CCO 2 H+

Me4P • Me4As • 2−

CH3

C l ( C H 2 ) 2 O P ( O ) ( O H ) 2 • H2N+( N C) 2 C

2-Pyridineethanamine, N,Ndiethyl-β-methyl-,ethanedioate (1:1)

Phosphonium, tetramethyl-,
tetramethylarsonium, salt with
2,2′-(2,5-cyclohexadiene-1,4diylidene)bis[propanedinitrile](1:1:2)

CONH 2

Benzamide, 4-amino-,
compd. with 2-chloroethyl
dihydrogen phosphate (1:1)

C( CN ) 2Cl

N 2 + • C l − • x Co Cl 2

Benzenediazonium, 4-chloro-,chloride, compd. with cobalt
chloride (CoCl2) (1:1:?)

¶ 199Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

199. Silicon, germanium, tin, and lead compounds are indexed (a) as heterocyclic compounds, (b) as derivatives of acyclic hydride parents such as
Germane or Disilane, (c) as special acyclic parents such as Tristannathianeor Tetrasiloxane, or (d) as silicic acids.
Heterocyclic compounds are indexed by the usual methods (¶¶ 146, 149).
Examples:1

O

6

Examples:SiCl 4

Silane, tetrachloro-

M e 3 SiCN

Silanecarbonitrile, trimethyl-M e 3 Sn CN

Stannanecarbonitrile, trimethyl-M e 3 SiO H

Silanol, 1,1,1-trimethyl-E t 3 SiO SiE t 2 O H

1-Disiloxanol, 1,1,3,3,3-pentaethyl-

H3GeNH2

Germanamine( H O SiM e 2 ) 2 CH 2

Silanol, 1,1′-methylenebis[1,1-dimethyl-

4H-1,3,2-Dioxagermin

2 G eH 2

O3

6

H2
Sn

H2Sn

1

S nH 2H2Sn

4S nH 2

5

66

2Hexastannin, hexahydro-

3

Sn
H2

1

O

6

M e 2 Si

H2
Si

Me

Silacyclopentane

1

5

O

4

Si
Me2

10 O

H2Si
9

2

1

O

11 O

7

O

Si
H

H2
Si
3

O

Distannoxane, 1,3-dichloro1,1,3,3-tetramethyl-

Ph Pb ( O ) O Pb ( O ) Ph

Diplumboxane, 1,3-dioxo-1,3-diphenyl-

2 34Bicyclo[5.3.1]pentasiloxane

1

SiH 2

2 3

5

O
6

8

Acyclic linear chains of tetravalent hydrides of silicon, germanium, tin, andlead are molecular skeletons with names derived from the mononuclear hydrides: Silane, SiH4; Germane, GeH4; Stannane, SnH4; Plumbane, PbH4.
Examples:H3SiSiH3

Disilane

H3GeGeH2GeH3Trigermane

H3Sn(SnH2)11SnH3

Tridecastannane

H3SiSiH2SiH(SiH3)SiH2SiH3

Pentasilane, 3-silyl-( M e 3 Si) 2 Se

Disilaselenane, 1,1,1,3,3,3-hexamethyl-M e 2 Pb O

Plumbane, dimethyloxo-

F 3 SiSiH 3

Disilane, 1,1,1-trifluoro-

1 2

E t 3 Pb Pb E t 3
1

When a single element of this series alternates with a single chalcogen in a
linear acyclic chain, “-ane” names which express the nature of the alternating
elements and number of silicon (etc.) atoms are employed.
Examples:Plumbane, hydroxyoxophenyl-

HOGeH2OGeH2OH

Digermoxane, 1,3-dihydroxy-1(H3Ge)2Se

Digermaselenane(H3Sn)2Te

Distannatellurane(H3SnO)2SnH2

Tristannoxane

H3Si(OSiH2)2OSiH3

Tetrasiloxane

An acyclic chain of alternating silicon and nitrogen atoms is not named as a silazane; instead the functionality of the nitrogen is recognized. Thus, disilazane,
H3SiNHSiH3, is indexed at Silanamine, N-silyl-. However, silazanyl radicals(see below) are employed in the presence of higher functions.
Replacement (“a”) names are used as parents when the chain contains carbon atoms and the other requirements (¶ 127) are met.
Example:MeO (C H 2 ) 2 O C H 2 SiMe 2 OSiMe 2 CH 2 O( CH 2 ) 2 OMe
5

7

8 9

11

14 15

2,5,8,11,14-Pentaoxa-7,9-disilapentadecane, 7,7,9,9-tetramethylDerivatives of all these parents are named by the usual substitutive methods
except for silicic acids and germanium, tin, and lead hydroxides and salts (seebelow). A hydroxyl group on a germanium, tin, or lead atom is expressed as ahydroxy prefix, but by the suffix “-ol” on a silicon atom when it is a principal
group. O-Acyl derivatives of silanols or of hydroxy germyl, stannyl, and plumbyl are named as esters.

2 3( M e O ) 3 SiM e

Silane, trimethoxymethyl-M e 3 SiO A c

Silanol, 1,1,1-trimethyl-,1-acetate

−

CH 3

O

H 3 C− G e− O−C −CH 2 − CH 3−

Disilathiane

2

Ph Pb ( O ) O H

Disiloxane(H3Si)2S

Diplumbane, 1,1,1,2,2,2-hexaethyl-

2

CH 3

Propanoic acid, trimethylgermyl
ester

Substituent prefixes (radicals) from silicon, germanium, tin, and leadmononuclear hydrides are formed by adding the suffixes “-yl,” “-ylene,” and“-ylidyne” to the appropriate stem, or “-tetrayl” to the hydride name: silyl,
H3Si−; germylene, H2Ge=; stannylidyne, HSn≡ ; plumbanetetrayl, =Pb=. Radicals from polynuclear hydrides and “oxanes,” etc., are derived as for hydrocarbons.
Examples:H 3 SiSiH 2 −disilanyl−G e H 2 G e H 2 −1,2-digermanediyl (formerly
digermanylene)

21

H 3 Sn Sn H 2 Sn H =tristannanylidene≡ Sn Sn ≡1,2-distannanediylidyne

12

H 3 SiO SiH 2 −1-disiloxanyl

H 3 SiN H SiH 2 −1-disilazanyl−Pb H 2 O Pb H 2 −1,3-diplumboxanediyl

1

2 3

−

(H3Si)2O

1

O3

ClSn M e 2 O Sn M e 2 Cl
1HSi

2-Cyclotrisiloxanol, 2,4,4,6,6-pentamethyl-

=

5

OH
2 Si

−SiH 2 O SiH O SiH 2 −1

3

5

1,3,5-trisiloxanetriyl

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Benzenamine, 4-disilanyl-

SiH 2 SiH 3

F

Disiloxane, 1-(silylthio)-

H 3 SiO SiH 2 S S iH 3
3 2 1

−

=

S
C H ( C O 2H)2N

Propanedioic acid, (1-sulfido-2pyridinyl)-

Oxides of doubly-bound sulfur atoms in principal groups are named in themodification with an “S” locant.
Examples:Ethanethioamide,
S-oxide1

Germanium, tin, and lead analogs of silicic acids are named at binaryhydroxide and hydroxide oxide heading parents. Symmetrical derivatives ofGermane, Stannane, and Plumbane, in which all hydrogen atoms have been
replaced by groups derived from alcohols, thiols, etc., or acids, are named as
metal salts.
Examples:G e(O H ) 4

Germanium hydroxide (Ge(OH)4)

S nO (O H ) 2

Tin hydroxide oxide (Sn(OH)2O)
Co 2 H • Pb 4

4Me+

Benzoic acid, 4-methyl-,lead(4+) salt (4:1)

200. Sulfur, selenium, and tellurium compounds are often named similarly to oxygen compounds, but sometimes, e.g., in sulfonic and sulfenic acids(¶ 165), the sulfur, etc., acts as a nuclear atom in a functional group of whichno oxygen analog is known. Because sulfur, selenium, and tellurium are treated
identically, “thio,” “sulfur,” “sulfide,” etc., in the following discussion may invariably be replaced by the corresponding selenium or tellurium term.
Cyclic sulfur compounds are named as heterocycles; sulfur alternating withsilicon, germanium, tin, or lead atoms forms the silathianes, etc. (¶ 199). Sulfur
analogs of anhydrides are usually named as anhydrosulfides, but the anhydrosulfides of acids named as functional parent compounds are often indexed atpolynuclear acid headings, e.g., Thiodicarbonic acid.
Examples:
S
=

=

S

CH 3 − S− CH 2 − S− CH 2 −S −CH 2 −S −CH 3−

N−C−S−C−N−

CH 3
CH 3

Thiodicarbonic diamide,([H2NC(S)]2S), N,N,N′,N′-tetramethyl-

2

3

4

5

6

7

8

9

2,4,6,8-Tetrathianonane
O

O

O

O
=

4

=

O

6

CH 3 − CH 2 −S − CH 2 −CH 2 −S −CH 2 − CH 2 − S− CH 2 −CH 2 −S −CH 2 −CH 3
1

2

3

4

5

6

7

8

9

10

11

12 13

14

3,6,9,12-Tetrathiatetradecane,
3,6,9,12-tetraoxide

M e Se CH 2 ( CH 2 ) 2 CO 2 H

Butanoic acid, 4-(methylseleno)-

Ph CO CH 2 CH 2 T e Ph

1-Propanone, 1-phenyl-3(phenyltelluro)-41

H 2 N CH 2 CH 2 Se CH 2 CH 2 N H 2
1

2′

2

O

1′

CH 3 O

=

Si 5
O

=

1,4,6,9-Tetraoxa-5-silaspiro[4.4]nonane(not 1,2-Ethanediol, cyclic diesterwith silicic acid (H4SiO4))

Phosphine sulfide, Arsine sulfide, and Stibine sulfide (¶¶ 181, 197) aresubstitutive parent compounds, but the sulfides of Diphosphine, Triarsine,etc., are named by modification terms.
Acyclic sulfides, sulfoxides, and sulfones, containing one or more isolated
sulfur atoms, including thio acetals and thio ortho esters, are named (like ethers(¶ 196)) as substituents of hydrocarbons and other heading parents by use ofthio radicals, unless a replacement (“a”) name (¶ 127) is permissible. In the latter, oxide terms in the modification are employed to express sulfinyl (−S(O)−)
and sulfonyl (−S(O)2−) groups. The analogs of “thio” are “seleno” and “telluro”; those of “sulfinyl” are “seleninyl” and “tellurinyl”; those of “sulfonyl”
are “selenonyl” and “telluronyl.”
Examples:−1O

3-Heptanethione,
S-oxide

7

=

9

O

4

3

−

Thiosilicic acid (H4SiO3S),
O,O,O-tris(1-methylethyl) ester

1=(Me 2 C H O ) 3 SiS H

M e CH 2 C( =S= O ) CH 2 ( CH 2 ) 2 M e=

Silicic acid (H4SiO4),
tetraethyl ester

3

OMe
O3

O

CH3 O

CH3−CH2−S— C— S−CH2−CH3O=(E tO ) 4 Si−
H C

1,3,2-Dioxaphosphorinane,2-methoxy-,2-sulfideP

M e C( =S = O ) N H 2

Silicic acids are silanes and siloxanes (and chalcogen analogs) in which allhydrogen atoms have been replaced by hydroxyl and oxo groups (or their chalcogen analogs). Their esters and anhydrides are named as usual. Cyclic derivatives are named as heterocycles.
Examples:

H3C −

2

=

1

S

O

=

6

Silanol, 1-[[4-(acetyloxy)phenyl]methyl]-,
1-benzoate (not Phenol, 4-[[(benzoyloxy)silyl]methyl]]-, acetate)

1-Hexanamine, 6-(triethylgermyl)-E t 3 G eC H 2 (C H 2 ) 4 CH 2 NH 2−

The additive term “sulfide” is used in modifications when sulfur is attachedto saturated Group VA elements in molecular skeletons. The locant relating to
the parent is used when the parent contains the heteroelement sulfide; otherwise, an element symbol provides the locant.
Examples:
1

OAc

=

−

F

6

B z O S i H2CH2

Thioperoxydiphosphoric tetrafluoride, ([F2P(S)]2S2)

=

=

S

F−P−S−S−P−F

=

H2N

S

−

Methanol, 1-(1,1,3,3,3-pentamethyldisiloxanyl)- (not 3-Oxa-2,4-disilapentan-1-ol, 2,2,4,4-tetramethyl-)

Me 3 SiO SiMe 2 C H 2 OH

S

¶ 200

1-Piperidinecarbodithioic acid,anhydrosulfide with N,N-diethylcarbamodithioic acid

H2 H2
C−C
N−C−S−C−N 1
4 CH 2−
CH 3 −CH 2
C−C
H2 H2
S

CH 3 −CH 2−−

The nonfunctional germanium, tin, and lead hydrides fall (in that order) between boron and oxygen heading parents in order of precedence of compoundclasses (¶ 106). The heading parent Silane is an exception. It now ranks below
cyclic carbon parents and above acyclic carbon parents. This ranking does not
apply to any other silicon parents, cyclic or acyclic, functional or nonfunctional. When a principal group is expressed as a suffix, the compound is classed
accordingly. Silanol is ranked with the alcohols, and is placed above all carbon-chain monohydric alcohols, cyclic or acyclic (¶ 138).
Examples:−67

CH 3 − CH 2 −T e − CH 3

Ethanamine, 2,2 ′-selenobis-

Propane, 2,2-bis(ethylsulfonyl)(principle: largest heading parent(¶ 138))Ethane, (methyltellurinyl)- (principle: largest heading parent)¶ 200Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Me(C H 2 ) 6 S O 2 P hBenzene, (heptylsulfonyl)- (principle: ring preferred over chain)

P hC H 2 S e O 2

Benzene, [(cyclohexylselenonyl)methyl]- (principle: preferred ringsystem)Ethene, 1,1 ′-[methylenebis(thio)]bis- (principles: largest heading
parent and multiplication)

H 2 C= C H SC H 2 S CH= CH 2
2

1

1′

2′

Ethene, [(1-ethoxyethyl)thio](principle: maximum number ofunsaturated bonds)

H 2 C= C H SC H MeOEt

68

Cl( CH 2 ) 2 SSSCl

Trisulfide, chloro 2-chloroethyl

FC( O ) SSCN

Disulfide, cyano fluorocarbonyl(not Formyl fluoride, (cyanodithio)-)

The heading parents Disulfoxide, Trisulfone, etc., are employed for chalcogen compounds in which the same number of oxygen atoms is attached toeach skeletal atom. When all oxide atoms are on one sulfur, the compounds are
named whenever possible as esters or anhydrides of thio analogs of sulfur acids. When different numbers of oxide atoms are attached to skeletal sulfur atoms, substitutive nomenclature is employed in which thio, sulfinyl, andsulfonyl radicals are cited separately.
Examples:C l 2 C H C H 2 S C H 2 C H 2 SCH 2 CH 2 SCH 2 CHCl 2

Ethane, 1,1′ -thiobis[2-[(2,2-dichloroethyl)thio]- (principles:
centrality and multiplication)

Disulfoxide, dimethyl[ M e S( O ) ] 2

ClClBenzene, [(2-phenylethyl)thio](not Benzene, [2-(phenylthio)ethyl]-) (principle: earliest index
position)Ph(C H 2 ) 2 S P hHydrodisulfides are named as dithioperoxoic acids, as sulfenothioic acids,
or as thio analogs of mononuclear peroxy “oxo” acids. The oxides R−S(O)−SH
and R−S(O)2−SH are named as sulfinothioic and sulfonothioic acids.
Examples:2

Benzenesulfonothioic acid,S-phenyl ester

Ph SO 2 SPh

Cl

SS( O ) SCl

Thiosulfurous acid, (H2S3O),
S,S-bis(4-chlorophenyl) ester
S

O

S
=

SCH 2 OPh

Disulfone, bis(4-chlorophenyl)

SO 2

=

Cl

Benzene, 2,4-dichloro-1-[(phenoxymethyl)thio]- (principle:
maximum number of substituent
prefixes)

H O− C−S −S −S −C −O H

Carbonodithioic acid,bis(anhydrosulfide) withthiosulfuric acid (H2S3O2)

=

1

=

6

O

PhC(O)SSH

Benzenecarbo(dithioperoxoic) acid

EtSSH

Ethanesulfenothioic acidMeO

SO 2 S( O )Benzene, 1-methoxy-4-[[(4-methoxyphenyl)sulfinyl]sulfonyl](not Benzene, 1-methoxy-4-[[(4methoxyphenyl)sulfonyl]sulfinyl]-)(principle: earliest index position)

Thioperoxymonosulfuric acid((HO)(HSS)SO2)

HOSO2SSH

The compounds R−S−S−SH, R−S(O)−S−SH, R−S(O)2−S−SH, are named
as sulfeno(dithioperoxoic) acids and their sulfino and sulfono analogs.
Example:PhSSSH

Benzenesulfeno(dithioperoxoic)
acid

Hydrotrisulfide is a radicofunctional heading parent for acyl derivatives,and Hydrotetrasulfide, etc., for alkyl and aryl derivatives.
Example:EtSSSH

Cyclic sulfides, etc., are ranked according to the rules for ring systems; acyclic sulfur, selenium, and tellurium heading parents follow, in that order, theoxygen heading parents (Peroxide, etc.). Within each element group, the descending order is illustrated as follows: Trisulfide, Disulfone, Disulfoxide,
Disulfide. In the presence of more preferred compound classes, dithio, trithio,
diseleno, disulfonyl, etc., radicals are used as substituents.
Examples:Hydrotrisulfide, ethyl

Acyl substituted polysulfides are named as Ketones

1

1′

N

N
SS

6

Cyclic polysulfides are named as heterocycles; acyclic sulfides fulfilling
the requirements (¶ 127) of replacement nomenclature are indexed at “thia”
names. Other acyclic disulfides, trisulfides, etc., are indexed at Disulfide andsimilar heading parents unless they are esters of dithioperoxoic acids or chalcogen analogs of peroxy condensed mononuclear acids. (Examples of these exceptions are illustrated below.) Hydrogen polysulfides in which both of theterminal hydrogen atoms have been replaced by sulfo groups constitute thepolythionic acids; thus, Tetrathionic acid is HO3S−S−S−SO3H.
Examples:
MeCH 2 S(CH 2 ) 2 OSSO(CH 2 ) 2 SCH 2 Me

6,9-Dioxa-3,7,8,12-tetrathiatetradecane

Me 2 C H S S C H Me 2

Disulfide, bis(1-methylethyl)

P hC H 2 SeSeC H 2 Ph

Diselenide, bis(phenylmethyl)(E tS S C H 2 ) 2

Disulfide, 1,1′-(1,2-ethanediyl)bis[2ethyl

3

Pyridine, 3,3 ′-dithiobis6′

Ethanone, 1-trithio-

678 9

12

14

P hS S S P h

Trisulfide, diphenyl

A cS S A cEthanone, 1,1′-dithiobis-[E t 2 P(Se)S e] 2 Se

Triselenide, bis(diethylphosphinoselenoyl)

E tO S S O E t

Disulfide, diethoxy

A cS S C lEthanone, 1-(chlorodithio)-SSSPh

H O 3 S CH 2 CH 2 SS( O ) ( CH 2 ) 2 SO 3 H
1

2

Thiophene, 3-(phenyldithio)(principle: preferred ring system)

Ethanesulfonic acid, 2-[[(2sulfoethyl)sulfinyl]thio]- (notEthanesulfonic acid, 2-[[(2-sulfoethyl]thio]sulfinyl]- (principle:
earliest index position)

Acyl alkyl and acyl aryl disulfides are named as esters of either dithioperoxoic acids or peroxy mononuclear “oxo” acids.
Examples:O=

AcSSSH1

OMe

Phosphoro(dithioperoxoic) acid(HO)2P(O)SSH

CH 3 −C− S− S− CH 3

Ethane(dithioperoxoic) acid,methyl ester

Ph SO 2 SSPh

Benzenesulfono(dithioperoxoic)
acid,
phenyl ester

H O SO 2 SS M e

Thioperoxymonosulfuric acid,((HO)(HSS)SO2),
SS-methyl ester

69

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Symmetrical diacyl disulfides derived from polybasic mononuclear “oxo”
acids (except Sulfuric acid and Sulfurous acid; see above) are named at Thioperoxy headings.
Example:
S

=

=

S

H O− C H 2 − C H 2 −N H −C− S− S− C− NH −CH 2 − CH 2 − OH

Thioperoxydicarbonic diamide,([(H2N)C(S)]2S2), N,N′ -bis(2hydroxyethyl)Sulfilimine, H2S=NH, and Sulfoximine, H2S(O)=NH, are substitutive
heading parents. The selenium and tellurium analogs are named Selenilimine,
Tellurilimine, Selenoximine and Telluroximine. They are ranked just below
imine suffix compounds (¶ 106). Higher functions in chalcogen-linked derivatives can be recognized by use of other chalcogen-nitrogen parents or by sulfonimidoyl, sulfinimidoyl, etc., radicals.
Examples:¶ 201

Mixed sulfide-selenides, etc., with three contiguous chalcogen atoms areusually named by compound and complex radicals; e.g., [selenobis(thio)] for−S−Se−S−. When only two different contiguous chalcogen atoms are present,
the compound is an ester of a sulfenic (etc.) acid analog.
Example:PhSSePhBenzenesulfenoselenoic acid,phenyl ester

Acyclic tetravalent and hexavalent sulfur compounds containing at least
one substituent derived from a molecular skeleton (¶ 130) that cannot be named
by general index nomenclature as described above, or as “oxo” acid derivatives, are given coordination names (¶ 215).
Examples:PhSF5

Sulfur, pentafluorophenyl-,(OC-6-21)-

Ph2TeCl2

Tellurium, dichlorodiphenyl-,(T-4)-

Sulfilimine, S,S-diethyl-E t 2 S=N H

MeS (O )(=N H )C H 2 CH 2 CH( NH 2 ) CO 2 H
421

Butanoic acid, 2-amino-4-(Smethylsulfonimidoyl)N-derivatives containing higher chemical functions are named at these functions by using the following newly introduced radical names:
λ4-sulfanylidene, λ6-sulfanylidene

201. Zwitterionic compounds have internally compensating ionic centers.
When the cationic center is known, the compound is named either as an “innersalt”.
M e 3 N + CH 2 −Methanaminium, N,N,N-trimethyl-,
inner salt

Ph CO C − H S + M e 2

Sulfonium, dimethyl(2-oxo-2-phenylethyl)-,
inner salt

and their selenium and tellurium analogs
Benzenesulfonamide, N-(diethylλ4-sulfanylidene)-E t 2 S =N S O 2 P h

Me

S(O)Me=NCONHBu

Urea, N-butyl-N′-[methyl(4-methylphenyl)oxide-λ4-sulfanylidene]-

PhS (O H )= N Ph

Benzenesulfinimidic acid,N-phenyl-(MeO ) 2 S= N P hImidosulfurous acid, N-phenyldimethyl ester

Sulfur diimide, HN=S=NH, and Sulfur triimide, HN=S(=NH)=NH, aresubstitutive heading parents and are ranked with the sulfur parents. The above
mentioned radical names are used when higher functions are present.
Examples:HO2C

N= S= N=(C H 3 ) 3 S i− N=S =N− Si( CH 3 ) 3

Phosphorane, triphenyl(phenylmethylene)(preferred index name)Ph 3 P= CH Ph

Zwitterionic compounds are usually named at the “-ium” heading with “inner salt” as the phrase in the modification. “Inner salt” (¶ 293A) indicates acompensating anion located in the same molecule as the cation. The expression“bis(inner salt)” at a “-diium” heading indicates two compensating anions inthe same molecule. A phosphonium compound of this type is indexed as aphosphonium inner salt only when such a zwitterionic structure is emphasizedor discussed by the author. Otherwise only a neutral Phosphorane entry is
made.
Examples:Methanaminium, 1-carboxy-N,N,Ntrimethyl-,
inner salt

M e 3 N + CH 2 CO 2 −
N

1

+
Me3N

O P( O ) O M e
O−Silanamine, N,N′,N′′-λ6-sulfanetriylidenetris[1,1,1-trimethylAcN−
N+

Sulfimide, O2S=NH, and Thionyl imide, OS=NH, are substitutive heading
parents. They follow the imines in order of precedence (¶ 106) and, when necessary, are expressed by sulfonyl (O2S=) (sulfinylamino) (OS=N−), etc., radicals.
Examples:O2S=NMe

Methanamine, N-sulfonyl-

PhSO2N=SO

Benzenesulfonamide, N-sulfinyl-

6

PPh 3
HO

Amidosulfenyl chloride (H2N−S−Cl) is ranked with mononuclear “oxo”
acid halides and can be expressed by (chlorothio) and [(chlorothio)amino] radicals when necessary.
Example:Amidosulfenyl chloride, N-methylN-(phenylsulfonyl)- (not Benzenesulfonamide, N-(chlorothio)-Nmethyl-)Me

Benzenaminium, 3-[(hydroxymethoxyphosphinyl)oxy]-N,N,Ntrimethyl-,
inner salt

Quinolinium, 1-(acetylamino)-,inner salt

O
1

PhSO2NMeSCl

Pyridinium, 1-[2-ethoxy-1-(ethoxycarbonyl)2-oxoethyl)-,
inner salt

CO 2 H

Benzoic acid, 4,4′-(λ4-sulfanediylidenedinitrilo)bisN Si(CH 3 ) 3

N + C − ( CO 2 E t) 2

+ −C ≡N− N Ph

2,4-Cyclohexadien-1-one, 4hydroxy-6-(triphenylphosphoranylidene)- (the alternative ionic
structure is named Phosphonium,(2,5-dihydroxyphenyl)triphenyl-, inner salt)
Hydrazinium, 1-[(4-methylphenyl)methylidyne]-2-phenyl-,
inner salt

Cationic “ium” compounds with internally compensating borate anions are
named where possible by coordination nomenclature (¶ 215); the term “borata”
is avoided.

¶ 201

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Example:

−

1

−

Cl

Cl
B
3+

N
N

−

N
N

3+
B

−

HN

−

Cl
−

Boron, tetrachlorobis[µ-(1Hpyrazolato-κN 1 :κN 2 )]di- (not4H,4H,8H,8H-7a,8a-Diaza-3a,4adiazonia-4,8-diborata-s-indacene,
4,4,8,8-tetrachloro-)

5

70

O

HN
N2

+
−

1
5

O

2

N

N+Me

N+Me

3

3

1,2,3-Oxadiazolium, 5-amino-3methyl-,
inner salt (formerly Sydnone
imine, 3-methyl-)Cl−

Meso-ionic compounds such as sydnone derivatives are named, if possible,
at an “-ium” parent by use of the term “inner salt” in the modification.
Examples:mesoionic form

5

O

HO

5

N2

+
−

3

+
−

10a
10b

O

2

N

O−

2

1

O

3

10a

N4

+
10b

N

2
3

N4

N
N + CHM e 2

N C H Me 2
HO2C

1

O

1

1

O

O

preferred structure

O

C

7

6

7

6

3

O−

1,2,3-Oxadiazolium, 4-carboxy-5hydroxy-3-(1-methylethyl)-,
inner salt (formerly Sydnone,
4-carboxy-3-(1-methylethyl)-[1,2,3]Oxadiazolo[4,3-a]isoquinolin4-ium, 5,6-dihydro-1-hydroxy-,
inner salt

71

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 203

E. STEREOCHEMISTRY AND STEREOPARENTS

¶ 202
203
204
205
206
207

Introduction
Stereochemistry
Alkaloids
Amino acids
PeptidesProteins

202. Introduction. A discussion of stereochemical descriptors for systematically named compounds, modified stereoparents, and coordination
compounds follows this introduction. The remainder of Section E is directed
to various classes of stereoparents. A stereoparent is an index heading parent
the name of which implies specific stereochemical information. Illustrative
structural diagrams for stereoparents that have received entries in current
indexing are provided in the Chemical Substance Index; these diagrams
indicate both the stereochemistry and the numbering systems from which
locants are derived. The bond lengths and angles shown in these diagrams havebeen drawn in a standard format and do not necessarily represent the actual
shape of the compounds.
It is convenient to divide natural products into four classes according to themethods by which they are indexed. The classification has been mostcompletely worked out for alkaloids, discussed more fully in ¶ 204, below.
Class A contains those substances, of little or no stereochemicalcomplexity, which are indexed systematically rather than at stereoparents.
Class B stereoparents represent groups of natural products which havecyclic molecular skeletons in common. The base structure is derived byremoval of all chemical functions but retention of hydrocarbon substituentsand the pattern of hydrogenation; the name is derived from the trivial names of
the related natural products, and author numbering is adopted if possible.
General substitutive nomenclature, as illustrated in previous sections of thisintroduction, is used to convert the stereoparents into complete index names byaddition of prefixes, suffixes and conjunctive terms. Examples of Class B
stereoparents are Prostane and Picrasane:

Example:L-Proline,

compd. with (8α,9R)-cinchonan-9-ol (1:1)
Acyclic acetals of functions expressed by “-one” suffixes or “oxo”
substituents of stereoparents are indexed as dialkoxy derivatives. Cyclic
acetals of stereoparent diols with formaldehyde are named as [methylenebis(oxy)] derivatives of the stereoparent; other cyclic acetals are named
similarly if subsidiary functions of the stereoparent are involved, but by
modification terms if a principal chemical function has been acetalized.
Lactones of principal functions are also named in the modification.
Examples:
21 CH2OH
18 Me 20
Me
CO

O

O
19

11

Me

H

9
1

O

10

4

14

8

H

17

13

9

H

11

Me
20

11

Me
H

Prostane ((1S,2S)-1-heptyl-2octylcyclopentane)

19 Me
1

O

4

11

Me

9

10
5

Me

H

20

Me

8
H
7
6

H

13
14

8

OH
17

Androst-5-en-3-one, 17-hydroxy-,cyclic 1,2-ethanediyl acetal,(17β)-

H

13

21
19

H

9

10

3

O

1

Pregnane- 3,11,20- trione, 21hydroxy -16,17- [(1- methylethylidene)bis(oxy)]-,(5α,16α)-

6

H

1

7

Me
O

18 Me

H

¶ 208
209
210
211
212

Carbohydrates
Cyclitols
Nucleosides and Nucleotides
Steroids
Terpenes

Me
13
14

H
O

Picrasane ((3S,3aS,6aR,7aS,8R,11aS,
11bR,11cS)-hexadecahydro3,8,11a,11c-tetramethylphenanthro[10,1-bc]pyran)

H 17

18

Class C stereoparents imply both stereochemistry and chemical functionality. Other functions (including higher functions) are expressed as substituents. Examples will be found in the discussion of alkaloids (¶ 204). Miscellaneous Class C stereoparents include Leucomycin V. Their derivatives are indexed like alkaloids.
Class D stereoparents possess incompletely elucidated structures. If sufficient information is available, they are named systematically and no
stereochemical descriptor is assigned. When no systematic name is possible,
the trivial name in the original document is used.
Because treatment of stereoparents by the general rules of substitutive
nomenclature can sometimes lead to loss of stereochemical information,
special rules for their derivatives are employed. Thus, esters and semicarbazones (and their chalcogen analogs) are named as derivatives of the stereoparents, not at “Class II” acid names or as Hydrazinecarboxamide derivatives.
Esters formed by an acidic and an alcoholic stereoparent are indexed at thestereoparent that contains the highest chemical function.
Examples:4

6

When two or more stereoparents are covalently attached to one another thecompound is normally indexed at the stereoparent that expresses (a) the largest
number of highest chemical functions, (b) the most preferred skeleton.
Citation of additional and modified stereochemistry at stereoparent andstereoparent derivative names is discussed in the following section.
203. Stereochemistry is expressed in CA index names1 by three methods:
The stereochemistry for the heading parent of systematically named
compounds, including some natural products with only one or two chiral centers, e.g., most carbohydrates with four or fewer carbon atoms, simple alkaloids and terpenes, and some steroid degradation products, is expressed in themodification, following all other structural information such as “ethyl ester,”and ahead of descriptive terms related to a specific abstract, such as “spectrumof.” Additional stereochemical expressions are included with the substituent
and modification terms to which they refer. The terms used in this “systematicstereochemistry” are the main subject of the present section.
Natural products, especially those with a multiplicity of chiral centers,
are conveniently indexed at fundamental trivial names (stereoparents) where
they and their derivatives can be found at headings familiar to users in thealkaloid, carbohydrate, steroid, and terpene fields. The concept ofstereoparents has been discussed above; the separate natural product classes towhich it is applied are the subjects of ¶¶ 204-212.
Coordination compounds require specialized descriptors to describe thearrangement of ligands around the central atom. These are discussed in the
final part of this paragraph.
I. Systematically named compounds. New rules have been adopted forsystematic stereochemistry in CAS index nomenclature. These conventions
have been applied since March 1997 to systematically named fragments ofstructures containing stereoparents. The new policy was expanded in June

Androstan-17-ol,
butanoate, (5α,17β)The preferred CA name is the one that employs the stereoparent in the index
heading parent. Addition compounds and salts containing more than one stereoparent derivative are assigned a preferred index name based on chemicalfunctionality of the stereoparents.

1For a more extensive discussion of the stereochemical descriptors foundin CA index names, see J. E. Blackwood and P. M. Giles, Jr., J. Chem. Inf.
Comput. Sci. 1975, 15, 67-72; M. F. Brown, B. R. Cook, and T. E. Sloan,
Inorg. Chem. 1975, 14, 1273-1278; ibid. 1978, 17, 1563-1568.

¶ 203Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

1998 (CA Volume 129) to all systematic organic compounds.
The methods described below are a simplification of previous CAS stereochemical practice. Rules that were in use since the beginning of the Ninth
Collective Index period (1972) have now been thoroughly revised. The needfor a single expression to describe the total stereochemistry of a molecule has
been eliminated. Stereochemical terms are now placed within the parts of achemical name to which the stereochemical information applies. Only the stereochemistry contained in the heading parent is expressed in the name modification following all other structural information.
In general, the new rules are consistent with IUPAC recommendations
and produce CAS index names containing stereochemical information which
can be readily interpreted.
The terms R and S are employed for chiral elements possessing either absolute or relative stereochemistry. The term rel is used in conjunction with R
and S for structures with only relative stereochemistry. E and Z are used primarily to describe geometrical isomerism about double bonds. The relative terms
cis, trans, endo, exo, syn, anti, α, and β are used as alternatives to R and S incertain limited situations.
Assignment of the absolute terms R and S depends on the priority ranking
of atoms or groups attached to the stereochemical element whose chirality(“handedness”) is to be determined by the Cahn-Ingold-Prelog Sequence
Rule.2,3 This ranking depends first on the descending order of atomic numberof the atoms directly attached to the chiral center; thus, for bromochlorofluoroiodomethane the order is I, Br, Cl, F. In the following diagrams these atoms
are represented by a, b, c, and d, respectively. The least preferred atom orgroup, d, is represented by a dotted line to indicate it is to be considered to be
below the plane of the paper, while a, b, and c are to be imagined to project
toward the viewer at an angle. (The analogy of an automobile steering wheelwith three radial bars is a useful one to visualize.) R is assigned to a clockwise(right-handed) sequence of a, b, c, while S denotes a counterclockwise(anticlockwise) sequence.

a

a
d

c

d
b

b
R

c
S

Alternative ways of drawing chiral diagrams are often more convenient:either (a) at most two bonds (as indicated by ordinary lines) are shown to be in
the plane while one projects forward and one backward (as indicated by awedge and a dotted line, respectively), or (b) two bonds are shown projecting
forward and two backward, as in the diagram below. In both instances it must
be remembered that the atom or group of lowest priority, d, must be oriented
away from the viewer so that the clockwise or counterclockwise arrangementof a, b, and c is correctly observed.
In organic compounds it is generally necessary to compare the ranking of
two or more carbon bonds. This is done by proceeding outward one step at atime until a decision is reached.

The following groups are arranged in descending order of Sequence Rulepriority: -SCH3, -SH, -OCOCH3, -OCH2CH3, -OCH3, -OH, -NO2,-N(CH3)2, -NH2, -COOH, -COCH3, -CHO, -CH2OH, -C≡N, -CH2NH2,-C(CH3)2CH2CH3,-C(CH3)=CH2,-CH(CH3)CH2CH3,-C6H5,-CH2CH2CH3, -CH2CH3, -CH3. It is essential to rank branched chains by arigorous procedure if assignment errors are to be avoided. In
CH3

HO
CH
H3C- CH
|
CH3

c

OCH3

≡

CH

C

anti

syn

Z

exo
Y

CH2 OH bd

In the structure above, H clearly has the lowest priority, but it is necessary
to establish the ranking of the three carbon groups. This is done by arranging
the atomic numbers of the most senior substituent on each carbon in descending order: Cl, O, H. This elicits the absolute stereochemical descriptor R.
Branching, especially branching close to the chiral center, raises the priority
ranking of alkyl groups. Multiple bonds of all kinds are handled by“duplicating” or “triplicating” both of the atoms connected by the bonds; thus:(D) α and β are employed for ring positions of certain meso cyclic compounds. In the diagram below, the senior groups at the three stereogenic centers(by the Sequence Rule) are a, c, e; the junior groups are b, d, f. The α-side of
the reference plane is that side on which the preferred substituent lies at thelowest-numbered stereogenic position; c lies on the same side as a, so both areassigned α descriptors; e lies on the opposite side of the reference plane and isassigned a β descriptor; hence: 1α, 2α, 4β. It should be noted that this usage
differs from that for cyclic stereoparents (¶ 203II, below), in which “α-” means“below the plane” and denotes absolute configuration.
α-side

a

f
C

4

H

(C)

H

(C)

endo

reference planeH≡ — C| — C—|a

it can be immediately perceived that H has the lowest rank (d) and that of thethree carbon bonds CH3 has rank c. Proceeding outward to the left and rightfrom the chiral enter we observe that each carbon is attached to one oxygen,one carbon, and one hydrogen. The rule to be observed here is that we should
now proceed just one step along the senior (highest-priority) branches (in thisinstance through the oxygens) to find H on the left, C (preferred) on the right.
The fact that, in the junior branch, the priorities are reversed, with C attached
to two C’s and an H on the left, to only one C and two H’s on the right, isdisregarded, because this stage in the process is never reached. Only when aone-step search of the senior branches results in a tie is the junior branch inspected to the same extent. (This would have been necessary, with a consequentassignment of S instead of R, if -OCH3 replaced -OH in the diagram, even if,
at the same time, -OCH2CH3 replaced -OCH3 on the right.)
In complicated cases it is sometimes necessary to construct an explorationtable or tree diagram in assigning R and S descriptors. A useful summary ofSequence Rule procedures is included in Section E of the IUPAC rules,2 but
consultation of the papers of Cahn, Ingold and Prelog, especially their 1966
paper,3 may be necessary for resolution of the most difficult cases.
Relative descriptors of various kinds are used as follows:(A) cis and trans are restricted to cyclic structures with two achiral stereogenic atoms (an atom is stereogenic when interchange of two of the atoms orgroups attached to it produces a nonidentical compound). An example is 1,3Cyclobutanediol. The cis isomer has the senior groups (as defined by the Sequence Rule) on the same side of the reference plane.
(B) endo and exo are used only for achiral ring positions on the X and Y
bridges of bicyclo[X.Y.Z]anes (¶ 155) in which X ≥ Y > Z > 0, and X + Y < 7.
The exo isomer has the configuration in which the senior substituent is on thesame side of the reference plane as the Z bridge (see diagram below).
(C) syn and anti are restricted to achiral ring positions on the Z bridge of abicyclo[X.Y.Z]ane in which X ≥ Y > Z > 0, and X + Y < 7. The syn isomer has
the senior substituent oriented towards the X bridge.

a— HC = CH —C
d

CH2 ClCb

CH2CH3HX

c H3 C72— CH = O

≡

H
—C—O
|
|
(O) (C)

Only the immediate atoms are replicated; the procedure is not carried further.
Aryl, e.g., phenyl, naphthalenyl, radicals are handled in a similar manner.

e

3

2

1

b

d

senior groups

β-side(E) E and Z (from German: “entgegen” (opposite) and “zusammen”(together)) are geometrical stereodescriptors for substances having achiralelements resulting from double bonds. In a compounda2International Union of Pure and Applied Chemistry.

Nomenclature ofOrganic Chemistry, Section, A, B, C, D, E, F and H, 1979 ed., Pergamon
Press, Oxford (England) 1979, Section E, Appendix 2, pp. 486-490.
3R. S. Cahn, C. K. Ingold, and V. Prelog, Angew. Chem., Int. Ed. Engl.
1966, 5, 385-415 (errata: 1966, 5, 511). For a modification in the treatmentof cyclic pathways, see V. Prelog and G. Helmchen, ibid. 1982, 21, 567-583.

c
X=Y

b

d

the double bond can be considered to be in a vertical plane, and a, b, c, and din a horizontal plane. When the senior atom or group at X (a) and the senior

73

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

atom or group at Y (c) are on the same side of the vertical reference plane, thedescriptor Z is cited; its isomer is assigned an E descriptor.4(G) The (±) descriptor is only used for indicating stereoparents are racemic
instead of absolute. The optical rotation descriptors (+) and (-) indicate the signof rotation of plane-polarized light in the visible range (400-700 nm). The original literature should be consulted for the specific conditions under which theoptical rotation was obtained.

C11H23NO3
Stereo: absolute (-)

Me
H OH
|
N

R

S

These descriptors, alone or in combination, are employed to express
the total stereochemical information for a chemical substance as follows:(1) Stereochemistry for the index heading parent is cited at the end of thepreferred (inverted) index name. Locants are used with all stereochemicalterms, except cis and trans, relating to the parent.
(2) Stereochemistry for substituents and modifications of the parent are expressed at the beginning of each individual nomenclature fragment to which
the stereochemical terms apply.
(3) The preferred stereo terms are R, S, E, and Z. Each is preceded by a locant, arranged in locant order, and separated by commas. The resulting stereochemical expression is enclosed in curves and followed by a hyphen, e.g.,(1R,2S,3R,5E)-.
(4) For substances with only partially known stereochemistry, stereogenic
elements of unknown configuration are ignored for nomenclature purposes.
The term [partial] is no longer used.
(5) The term rel is used as a global expression to denote that the entire stereochemistry of a structure is relative only. Thus, rel appears at the end of thename modification following any stereochemical terms describing the parent.
(6) The sign of optical rotation, (+) or (-), follows the term rel when thecomplete relative configuration of a substance is defined but the absolute stereochemistry is unknown.
(7) When the substance has only one chiral element, not defined by the author, the sign of rotation is cited alone at the end of the inverted name.
(8) In the uninverted name (+), (-), rel, rel-(+), or rel-(-) appear at the beginning of the name, before any other terms.
(9) When the absolute configuration of a substance is unknown, either of
two enantiomeric structures may be used to depict the relative configuration.
Both the inverted and uninverted names will express that enantiomer which results in the first occurring R term in the inverted CAS index name.
(10) Stereogenic centers which cannot be expressed as R or S may be described using endo, exo, syn, anti, cis, trans, α, or β.
(11) Bicyclo[X.Y.Z]ane compounds in which X≥Y>Ζ>Ø, and X+Y<7, andwhich contain achiral stereogenic elements are the only structures for which
endo, exo, syn, and anti are used. These terms are each preceded by a locant
which is followed by a hyphen with the resulting stereochemical expression enclosed in curves, e.g., (3-endo, 8-anti).
(12) The terms cis and trans are used for eight-membered or smaller rings
substituted in only two achiral stereogenic positions. No locants or enclosing
marks are used with single occurrences of these terms. Multiple terms for ringassemblies, e.g., bicyclohexyl, are cited in the order of unprimed, primed, double-primed, etc., rings and separated by commas and enclosed in curves.
(13) Use of α and β is restricted to cases not covered by the above rules.
These terms are not cited in the same stereochemical expression in combination with other relative terms.
Examples:C7H13NO2
Stereo: absolute

CO

S

OH

OH

2,3-Piperidinediol, 2-[(5R)-5-hydroxyhexyl]-, (2S,3S)C8H11C10
Stereo: relative

S

OH

S
H

R

S

Cl

Tricyclo[3.2.1.02,4]octan-2-ol, 5-chloro-, (1R,2S,4R,5R)-relC19H30O3
Stereo: absolute partial

E
H
X

R

R O
H

Me

E
OH
X

X
Me

S
OH

3-Pentene-1,2-diol, 1-[(2R,7aR)-3a-(2E,4E)-2,4-hexadinenyloctahydro-2benzofuranyl]-, (1S)C11H15Br
Stereo: relative

CH2 BrE
Z

Cyclohexene, 1-[(1Z, 3E)-5-bromo-1,3-pentadienyl]-

H
N

¶ 203

OMe

C9H14O4
Stereo: absolute

SOH

2-Piperidinecarboxylic acid, methyl ester, (2S)OC10H18O2
Stereo: relative

E

S

CO

OEt

R H

2-Pentenoic acid, 5-hydroxy-5-(2R)-2-oxiranyl-, (2E,5S)-

OH
S

O

C14H20I2O2
Stereo: relative (+)

R
O

Me

1-Oxaspiro[5.5]undecan-7-ol, (6R,7S)-rel-

R

R

E

CHI2

CO

Z
Me

4J. E. Blackwood, C. L. Gladys, A. E. Petrarca, W. H. Powell, and J. E.

Rush, “Unique and Unambiguous Specifications of Stereoisomerism about a
Double Bond in Nomenclature and Other Notation Systems”, J. Chem. Doc.
1968, 8, 30 -32.

2-Butenoic acid, 4,4-diiodo-, (1R,3R,5Z)-3-methyl-5propylidenecyclohexyl ester, (2E)-rel-(+)(The Z double bond is cited on the atom closer to the parent.)¶ 203Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

74

C12H14O4
Stereo: relative

C14H22O2
Stereo: absolute
O

CO2 H

Me

R

O

Me

S

O

S

S

O

H

R

H

Me

Spiro[5H-indene-5,2´-[2H]pyran]-1(4H)-one, decahydro-7a-methyl-,(2´R,3aS,7aS)-

Benzoic acid, 4-[(2α,4β,5β)-4,5-dimethyl-1,3-dioxolan-2-yl]-(The lower locant (2´ ) is used to cite the R center.)(The 2-position on the dioxolane ring is achiral stereogenic.)

C8H11BrO
Stereo: absolute

The stereochemistry of some compounds cannot be described completelyby the rules above. The presence of stereochemical information in an original
document is indicated in the index entries for such compounds by themodification term “stereoisomer.”
Examples:

Me

S
OH

[This achiral stereogenic system canonly be described by syn or anti,
but these descriptors are notallowed for this ring system.]

S
O
R
R
Br

stereoisomer

Bicyclo[2.2.1]heptan-2-one, 3-bromo-7-methyl-, (1S,3R,4R,7S)OHC16H20O3
Stereo: absoluteHO
stereoisomer[This achiral stereogenic system canonly be described by the α / βsystem, which is not allowed inrings of this size. Had the systembeen chiral, R and S could havebeen used.]S

Molecular addition compounds, mixtures and polymers of components withstereogenic elements have the stereochemical descriptors cited with therespective components; a descriptor for the entire addition compound, etc., iscited last, if known.

R

O

Ph

CO

Examples:S

Cyclohexanol, 4-aminotrans-, acetate (1:1)

OH

Benzeneacetic acid, α-hydroxy-, (3-endo)bicyclo[3.2.1]oct-3-yl ester, (αS)-

2-Furancarboxylic acid, tetrahydro-2-methoxy(2R)-, compd. with rel-methyl (1R,2S)2-aminocyclobutanecarboxylate

C21H36O4
Stereo: relative

1,2-Cyclobutanedicarbonyl dichloride(1R,2R)-rel-, polymer with rel-(2R,5S)-2,5-dimethylpiperazine

Et
OH
H

H
CO

O

OH

H

[1, 1´-Bicyclohexyl]-4-carboxylic acid, 4´-ethyl-1-hydroxy-,trans-4-hydroxycyclohexyl ester, (cis,trans)(The unprimed ring is cis and the primed ring is trans.)
C12H14O4
Stereo: absolute

CO2 H
O

Me
S

O

H

S
Me

Benzoic acid, 4-[(4S,5S)-4,5-dimethyl-1,3-dioxolan-2-yl](The 2-position on the dioxolane ring is non-stereogenic.)

Although the polymer in the final example above probably has cis-transstereochemistry, these terms are not repeated at the monomer headings; thestructural repeating unit entry (¶ 222), however, would cite the descriptors in
the order dictated by that heading.
II. Stereoparents have been discussed in ¶ 202.
A stereochemical descriptor is cited in an index modification at astereoparent heading to express differences between the stereoparent
illustrative diagram and the structure of the reported substance. In the diagrams
the configurations on ring-system substituents are indicated by dotted lines for
α and “wedges” for β. Variations for specific derivatives are indicated by citing
appropriate α and β terms with the locants of the modified centers. Variant stereochemistry for acyclic, bridge and spiro centers is indicated by E and Z or by
R and S as described for systematic stereochemistry, above. If a variation is notreported, the normal stereochemistry is considered to be retained. When themodified stereochemistry is unknown, e.g., indicated by a wavy line in a structural diagram, the descriptor x (xi) is assigned to that position. Descriptors arealso cited for added configurations (when the stereoparent diagram shows nostereochemistry at a center). When the added stereochemistry is in a stereoparent substituent or modification, the descriptor is cited as a prefix, e.g.,[(5α,16E)-androstan-16-ylidene]-. When the center is in a systematically
named substituent or modification term, the descriptor is placed with the systematic nomenclature term, e.g., Pregnane-3, 20-dione, 5-hydroxy-6[(1Z) -3-hydroxy-1-propenyl]-, (5α,6β)-.
Examples (the stereoparent diagram is compared with an author’s diagram
for a derivative in each case):

75

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
CH 3

O

=
CH3

are not required for 4-and 6-coordinate anionic coordination complexes containing nonmetallic central atoms and identical monodentate ligands: they canbe assumed to be tetrahedral and octahedral, respectively. The terms are omitted also when information is lacking.

21Me

C

20 CH
2
18 Me

H
H3C H

19
1

H
H

11

Me
9

H

H

4

A pregnane derivative

17

T-4
SP-4
TB-5
SP-5
OC-6
TP-6
PB-7
OCF-7
TPS-7
CU-8
SA-8
DD-8
HB-8
OCT-8
TPT-8
TPS-8
TPS-9
HB-9

8

10

O

H 13 14H

6Pregnane (stereoparent)(The configuration at positions 8, 9, 10, 13 and 14 correspond; position 5 has
added stereochemistry; position 17 has modified stereochemistry. The
stereochemical descriptor at Pregn-6-ene-3,20-dione is (5α,17α)-.)
H
CH3

CH2OH

18

Me

O

O

H3C H

HO2CCH2

H

1

OH
H
H

An androstane derivative

HO

17

19

OH

Me 11H 13
9

H
4

14

8

10

OH

¶ 203

H

tetrahedral
square planar
trigonal bipyramidalsquare pyramidaloctahedral
trigonal prismatic
pentagonal bipyramidaloctahedral faced monocapped
trigonal prismatic square faced monocappedcubicsquare antiprismatic
dodecahedral
hexagonal bipyramidaloctahedral trans-bicapped
trigonal prismatic triangular faced bicapped
trigonal prismatic square faced bicapped
trigonal prismatic square faced tricapped
heptagonal bipyramidal

6

Androstane (stereoparent)

Positions 8, 9, and 13 are normal; position 14 is substituted, but has normal
configuration. Position 10 has unknown modified stereochemistry;
positions 3, 5 and 16 have added stereochemistry and the substituent at 16
is a stereoparent (β-D-glucopyranosyl radical).
The stereochemical descriptor is (3β,5α,10ξ,16β)-. (The stereochemistry
within the stereoparent radical is expressed by the substituent radical
name.)
III. Coordination compounds. The stereochemistry of mononuclear
complexes is expressed by special descriptors. The term “stereoisomer” is used
for polynuclear coordination complexes when all the nuclear stereochemistry
is known. When no nuclear stereochemistry is known, ligand stereochemistry
is cited using the rules for systematic organic compounds. No ligand
stereochemistry is cited unless all ligand stereochemistry is described. When
more than one ligand is stereogenic, the stereochemistry for the complex iscited as if all ligand stereochemistry is in one organic ligand. The discussionthat follows is necessarily brief; for a more detailed explanation the review by
T. E. Sloan5 should be consulted.
For coordination numbers 1, 2, and 3, no nuclear stereochemistry is
possible. Ligands are assigned systematic descriptors according to the rules in
I above. If the chirality of a 3-coordinate tetrahedral complex is reported, it isdescribed as R or S by application of the Sequence Rule as described above.
The special coordination descriptors comprise:(a) a symmetry site term to describe the molecular geometry about thenuclear atom;(b) a configuration number to identify the atoms on each axis and plane of
the system;(c) a chirality symbol to differentiate members of enantiomeric pairs (whenthe structure has no reflection symmetry); and(d) a ligand segment (when ligands have stereochemistry of their own) citedas described in ¶ 203I, above.
Symmetry site terms are comprised of one- to three-letter abbreviations to
describe the geometry around the central atom combined with the coordination
number. They are generally based on information reported by an author, butsome assumptions are made in indexing: square planar for 4-coordinate
Pd2+, Pt2+, Rh+, Ir+, Au3+, Se2+, and Te2+; square pyramidal for 5-coordinate nitrido complexes of all metals and oxo complexes of technetium (thenitrido and oxo ligands are assumed to be axial); octahedral for all 6-coordinate complexes unless the ligand constraints prohibit this geometry; or if ananionic nonmetallic coordination center contains six identical monodentate
ligands; tetrahedral for 4-coordinate complexes of (a) all 4-coordinate metallic complexes except Mn, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, or Au; (b)any 4-coordinate complex of Fe2 -, Ru2 -, Os2 -, Co-, Rh-, Ir-, Ni0, Pd0, Pt0, Cu+,
Ag+, or Au+; (c) Ni2+, Fe2+, Fe3+, or Mn2+ with four halides or pseudohalides;(d) Co2+ with four monodentate ligands; (e) all 4-coordinate nonmetallic complexes except Se2+ and Te2+ (tetrahedral descriptors are not cited for anionicnonmetallic complexes containing four identical monodentate ligands); and (f)substances indexed at Antimony(1+), Arsenic(1+), Bismuth(1+), and Phosphorus(1+) (not Phosphonium, see ¶ 184). Americyl, neptunyl, plutonyl, anduranyl (Mo2n+) groups in 5, 6, 7, 8, and 9 coordinate complexes are assumed
to be trans. Molybdenyl and tungstyl are assumed to have cis oxo groups. The
ammines are assumed to be trans in the Reineckate anion.
Planar ring systems, α-dioximes, 2,2´:6´,2´´-terpyridine and 2,2´,2´´- nitrilotris[ethanol] as ligands impose their geometry on the central atom; thus, azinc-porphine complex is square planar, not tetrahedral. Symmetry site terms

Configuration numbers depend first upon application of the Sequence Ruleto determine order of seniority (priority) of atoms coordinated to the central
atom. When constitutionally equivalent atoms are present, the same priority
number is assigned to each; thus in Ma2b2c2, the order is 1,1,2,2,3,3. When achoice of configuration number is possible, preference is given to the atom oflower priority (higher numerical value). Tie-breaking is necessary withequivalent sets of polydentate ligand atoms. Chiral ligands, otherwise
identical, are ranked with the R-form above the S-form. The chirality symbols
C— for clockwise — and A— for anticlockwise (counterclockwise)—are used
to denote absolute stereochemistry in coordination compounds, except that R
and S are used for tetrahedral complexes, and ∆ (delta) and Λ (lambda) for
octahedral complexes containing cis-bis(monodentate)bis(bidentate) ligands
and tris(bidentate) ligands, respectively. Chirality symbols are placed after
configuration numbers, which are determined and cited as follows:(a) Tetrahedral complexes (T-4) are assigned no configuration number.
The chirality symbol R or S is assigned as for organic compounds with a single
chiral center.
(b) Square planar complexes (SP-4) have the ligating atoms at thecorners of a square. The rank number of the atom diagonally opposite thesenior atom (1) is cited as the configuration number. Three isomers are possible
when all four ligands are different.
Example:
1

3

2

=4

Stereochemical descriptor= (SP- 4- 4)-(No chirality symbol is required)

4(c) Trigonal bipyramidal complexes (TB-5). The configuration number
comprises the rank numbers for the atoms at the ends of the major axis cited
without punctuation in descending order of priority. If the complex has noreflection symmetry, the order of atoms in the plane perpendicular to the axis
is expressed by C (clockwise ascending sequence of numerals, equivalent todescending priority) or A (anticlockwise) as viewed from the highest priority
ligand on the major axis.
Example:Configuration number

1

= 13

Chirality symbol=A

Stereochemical descriptor= (TB-5-13-A)-

2
4

M
5

(When all five coordinating atoms are different, 10
configurations are possible. Each is chiral, affording
20 possible stereoisomers.)

3(d) Square pyramidal complexes (SP-5) have a lone coordinating atomon the principal axis and four atoms in a square planar configuration at rightangles to this axis. The first digit of the configuration number is the priority
number of the lone atom; the second digit is the priority number of the atom
situated diagonally opposite to the most senior coordinating atom in the plane.
The chirality symbol is derived by viewing the plane from the position of thelone axial atom and tracing a path around the square plane from the most senior
atom to the next most senior atom present. If this path is clockwise, C is theassigned chirality symbol; if anticlockwise, the symbol is A.
Example:Configuration number

2

3

5T. E. Sloan in Topics in Inorganic and Organometallic Stereochemistry, G.
Geoffroy, ed., John Wiley & Sons, Inc., New York, 1981, 1-36.

Configuration number

1

M
5

4

= 25

Chirality symbol=A

Stereochemical descriptor= (SP-5-25-A)-(When all coordinating sites are unlike, 15 configurations
are possible. Each is chiral, affording 30 possible
stereoisomers.)¶ 203Naming and Indexing of Chemical Substances for Chemical Abstracts 2007(e) Octahedral systems (OC-6) for which C and A can be used aschirality symbols (see above) have configuration numbers of which the first
digit is derived from the priority number of the atom opposite to atom 1 and thesecond digit from the priority number opposite to the senior atom in the plane
perpendicular to the axis containing atom 1. When no reflection symmetry ispresent, the chirality symbol is derived by viewing the plane from atom 1 andtracing a path clockwise (C) or anticlockwise (A) from the most senior atom tothe next most senior atom.
Examples:The helicity symbol replaces the chirality symbol in octahedral complexesof this type. In the complex named in abbreviated fashion as[Co(1,2-pn)3]3+ the ligands themselves have chirality (denoted by R or S), andtheir geometry around the cobalt atom is described by use of “1” (for bonding
to a secondary carbon) and “2” (for bonding to CH2). The helicity can be seen
to correspond to the diagram above and the symbol ∆ is therefore appropriate.
CH3
R

H2C
CH
1
2
H N H2N
1

Configuration number

3

M
4

5

H2N

= 24

HC

Chirality symbol=C

Stereochemical descriptor= (OC-6-24- C)-

R

CH 3

R

1

PMe2 Ph+PMe2 Ph
2

1

Cl-

2
2

= 21

Chirality symbol=∆

Stereochemical descriptor= (OC-6-21-∆-(R),(R),(R)]-

2

≡

Ru
O ≡C

1

M

R

Configuration number

2

-H

2

CH 2

CH 3

R
R

≡

CH

1
NH2 CH2
Co3 + 2
NH2
2
NH2

2

1
6

76

PMe2 Ph

2

4

M
3

2
1

(The priorities of the ligand atoms are determined by arranging their atomic
numbers (17,15,6 and 1) in descending order thus: Cl,P,C and H. There arethree identical ligands of order 2; one is on the main axis (opposite ligand 1),
the others are in the transverse plane opposite 3 and 4; the higher number iscited. The transverse pathway from the preferred 2 to the neighboring (lesspreferred) 2 is clockwise when viewed from atom 1.)

Octahedral complexes containing identical bis(tridentate) ligands are
assigned geometric and chirality symbols in the same manner as normal
octahedral complexes. However, in order to distinguish between enantiomers
it is necessary to add primes to the donor atoms of one ligand. The primes are
retained in the configuration number and this distinguishes between
enantiomers.

= 24

Stereochemical descriptor= (OC-6-24- C)-

C

H2C
H

Configuration number

O

O
--

--

O

O + C

CH2

--

N
CH2

2

Co

N
--

H2C

O

C

O

O

For octahedral complexes with two or three bidentate ligands oriented in a
skew configuration, the helicity symbols ∆ and Λ are employed instead ofchirality symbols, they are related to right-handed and left-handed spirals,
respectively, as follows:
A

A

B

B

N

N

≡

2

M
1

2´
1´

O

Configuration number= 1′1′

Stereochemical descriptors= (OC- 6- 1′1′)-(f) Trigonal prismatic complexes (TP-6). The configuration number isobtained by citing the priority numbers of the three atoms opposite to (eclipsedby) the preferred triangular face, i.e., the face containing the maximum numberof ligating atoms of highest priority (lowest numerals). These numbers arecited to correspond to the ascending numerical order of the respective eclipsing
atoms. A chirality symbol, C or A, denotes the direction of numericalprogression of the eclipsed atoms.
Example:3

4

Configuration number

N

N

C

H

1
1´

1
2

6

= 526

Chirality symbol=A

Stereochemical descriptor= (TP- 6- 526-A)

5

B

A

A

(a) ∆

(b) Λ

B

In diagram (a) above, BB is a tangent to the right-handed helix that has axis
AA and radius NN; (b) shows its mirror image, a left-handed helix. Turning
each diagram through 90 degrees in either direction results in the simplified
diagrams (c) and (d), respectively.

(g) Stereochemical descriptors were extended to 7-, 8-, and 9- coordinate complexes in CA indexes in 1977.6
In the following table, all 12 model polyhedra for 7-, 8-, and 9-coordinate
complexes are shown, with examples of priority numbers for ligands fromwhich configuration numbers are derived.
1. Pentagonal bipyramidal
3

B
A

A

2

B
A

A

≡

1

B

B

(c)

(d)

2

2

A

A

C

B
C

(e)

2

4
4

PB-7-34-12342

2. Octahedral faced monocapped
4

5

5

B

4
3

3

4

3

AA and BB have now lost their respective identities as axis and tangent andcan be considered either as two tangents or as two segments of a double helix.
BB is in front of AA in both diagrams; in (c), when AA is horizontal, BB
descends to the right, in (d) to the left.
In the octahedral complex, pictured as a regular octahedron in (e) below, thelines AA and BB represent two bidentate ligands oriented as in (c) above andrepresented by the helicity symbol ∆. (A third bidentate ligand, if it were
present at CC, would not affect the helicity.)

1

3

2

2

1
1

≡

2

1
4

3

2
1

6 M. F. Brown, B. R. Cook, and T. E. Sloan,
OCF-7-4-213251
Inorg.
Chem. 1978,

17, 1563 -1568.

77

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

3. Trigonal prismatic square faced monocapped

9. Trigonal prismatic triangular faced bicapped

4

3
4

4

¶ 203

3

≡

5

2

1

2
4

1

4

2

5

≡

1

6

5

4

1

4

3

3

TPS-7-4-214345

5

2
4

4

4. Cubic

4

4

4
6

3

5

1

TPT- 8- 36- 142454

1

≡

3
3
3

5

4

1

1

3

3

10. Trigonal prismatic square faced bicapped
4

2

2

1

1

1

CU-8-13153234
2

≡

2
6

3

4

3

4

5. Square antiprismatic

≡

1
2

3

TPS-8-13252416

3

2

11. Trigonal prismatic square faced tricapped

1

5

2

4

2

2

5

1

2

5

2

1
5

1

6

5

2

4
2

1

1

SA-8-12522413

52

6. Dodecahedral

3

2

≡

1

1

3

2

2

2

4

4

1

4

4

2
1

3

≡

1

4

5

2

1

5

4

TPS-9-241251341

22

12. Heptagonal bipyramidal
2
2

3
2

DD-8-24122532

7. Hexagonal bipyramidal

5
5
6

1

3

3

2

5

3

≡

1

2
1

3
5

3
4

3

1

1

1

≡

1

6
2

2

3

1
4

4

6

6

4

2

HB-9-22-1134165

3

HB-8-13-234653

8. Octahedral trans-bicapped
3

1
1

4

5

2
4

5

2
4

≡

3
4

3
4

4

3

OCT-8-33-124445

The configuration number is assigned by orienting the model structure withthe highest-order axis in the vertical plane. The model structure is then viewed
from the highest priority ligating atom on the highest-order axis or from a pointon the highest-order axis above the most preferred end or terminal plane perpendicular to the axis. The most preferred end or terminal plane is that end
plane which either contains the greatest number of atoms, contains the greatest
number of highest priority ligating atoms, or is adjacent to a plane containing
the greatest number of highest priority ligating atoms. (Note that the OCF-7(octahedral faced monocapped), TPS-7 (trigonal prismatic square faced
monocapped), and TPS-8 (trigonal prismatic square faced bicapped) model
structures are of low symmetry and have only one correct orientation.)
The configuration numbers for the model structures coded PB-7, OCF-7,
TPS-7, HB-8, OCT-8, TPT-8, and HB-9 begin with the priority numbers of theligating atom(s) on the highest-order axis and are given in lowest numericalorder sequence. These priority numbers are separated from the remainder ofthe configuration number by a hyphen. The remaining portion of the configuration number is derived by viewing the structure from the highest-priority ligating atom on the highest-order axis, or from the axial ligating atom located¶ 203Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

above the preferred plane, and by citing the priority number of the ligating
atom with the highest priority in the plane adjacent to that atom. The configuration number is then completed by continuing to cite the priority numbers of
the ligating atoms in sequence as they are encountered, either clockwise or anticlockwise around the projection of the model structure, alternating between
planes where necessary, when viewing from the highest priority atom. For
those model structures with eclipsed pairs of ligating atoms, the priority numbers are given in pairs with the priority number for the preferred atom in thefirst plane followed by that for the eclipsed atom. The remaining priority numbers are given as they are encountered, either clockwise or anticlockwisearound the projection of the model structure as viewed from the preferred endof the highest-order axis. For compounds in which clockwise and anticlockwise citations of the configuration number give two different configuration
numbers (generally chiral compounds), the correct one is the lower numericalsequence as determined at the first point of difference. The remaining fivemodel structures, CU-8, SA-8, DD-8, TPS-8, and TPS-9, do not have a ligating
atom on the highest-order axis and thus do not have a distinct portion of theconfiguration number set off by a hyphen. These model structures are viewed
from a point on the highest-order symmetry axis above the preferred terminal
plane as defined previously. The configuration number is derived by first citing
the priority number of the preferred ligating atom in the preferred end plane
and then citing the priority number of the ligating atom it eclipses, if one exists.
In the next step, one proceeds clockwise or anticlock-wise around the projection of the model structure, giving the priority numbers of the ligating atoms as
they are encountered, alternating between planes when necessary. Again, theclockwise or anticlockwise direction is chosen to give the lowest-order numerical sequence for the configuration number as determined at the first point ofdifference.
When there are two or more equivalent bidentate or tridentate ligands andthe same priority numbers thus occur in equivalent ligands, the ties are broken
by identically priming all the CIP priority numbers of the ligating atoms withina ligand to determine both the configuration number and the chirality symbol.
In those complexes with symmetrical polydentate ligands, tetradentate,hexadentate (including symmetrical macrocyclic) ligands, etc., ties between
equivalent ligating atoms are broken by priming the ligating atom priority
numbers in chelating groups or pairs, thereby reducing the polydentate ligand
to groupings of equivalent bidentate or tridentate ligands. When two or more
nonequivalent tie-breaking choices exist for the coordination polyhedra ofcoordination numbers 7, 8, and 9, the tie is resolved by (a) assigning the lowest
priming to the preferred symmetry axis or plane, and (b) assigning the lowest
priming to give the lowest numerical value to the configuration number at the
point of difference. Primes are restricted to the configuration number foroctahedral complexes containing two identical tridentate ligands and trigonalprismatic complexes containing two or more identical polydentate ligands andfor all 7, 8 and 9 coordinate complexes. The use of primes is exemplified by
the first example below, which is explained in some detail.
Examples:Trigonal prismatic square faced monocapped (TPS-7)
2

F-

H2C
H2C

3

C

2

1

- Cl

1Cl-

2´

N

N-

H

2

Fe 3+

4´

Cl
C

N

CH2

4

CH

H2

≡

Ta
2

2

F-

-F

≡

1

1

2

2

1

2

F-

Cl-

2

1

2

(TPS-7-2-122212-A)(The direction must be selected so as to cite the priority number of the atom in
the next lower plane.)

Cubic (CU-8)
2

4

Cl -

OH2

1

5

3

- Br

≡

F-

5+

5

2

- Cl P a

NH3

4
2

2

4

1
3

2

Cl -

H2O

4

2

(CU-8-13242542-A)(Each face must be tested to determine the preferred terminal plane. As drawn
in this example, the preferred face (terminal plane) is on the left side of the
cube. Consequently the cube must be re-oriented before assigning thedescriptor.)

Square antiprismatic (SA-8)
1

Br 3

F-

2

- Cl

1
4
4

5

OH2

3

2´

≡

5

4

H3N

OH2

- Br

Cl -

1

2

2

3

2

1
4

2

4´

CH2
H

N

1

F-

5+

5+
Ta

CH3

C

N

2

1

Pentagonal bipyramidal (PB-7)

CH3

78

4

(SA-8-14324125-C)-

2(PB-7-11-232´4´4)-(The preferred orientation must be determined before the descriptor
assigned.)

The ligands of highest atomic number (chlorine) are numbered 1. An
exploration table (not shown) may be needed to establish the order of priorities(2,3, and 4) of the nitrogen ligands.7 No chirality symbol (C or A) is needed.
Dodecahedral (DD-8)

Octahedral faced monocapped (OCF-7)
1

Br3

H 3C

F-

1

1´

C

3
5

6

O

NH3

4

≡

3+
Nb

1
1

5

C
6

2

O

H3C

2

O
1´

O C
O C CH3
- CH
- CH
CH3
Ho+
C
3
O C
O
1´´

H2O

HC-

1´´

1´´
1´´

CH3

≡

1

1´
1

1´

1

CH3
H2O

2
2

2

1

4

Br-

H2O

(DD-8-111´´1´´1´1´22)-

Cl2(OCF-7-1-316254-C)-

7R. S. Cahn, C. K. Ingold, and V. Prelog, Angew. Chem. Int. Ed. Engl.

1966, 5, 391-395.

(The preferred orientation must be determined before the descriptor is
assigned; also, the pathway is selected to pass through the atom of highest
priority (lowest numerical value) in the next lower plane.)

79

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Hexagonal bipyramidal (HB-8)

S

Cl 2

1

Cl -

Br -

Ta

S

1
1

2

3

Br -

4

5

Me

U

H2O

≡

OH2

6+

Me

4

1

1
5

3

F-

S

3

1

Br -

≡

Me

3

5+

Me
Me

2

Me

2

Cl -

Heptagonal bipyramidal (HB-9)

Me

3

2

¶ 204

5
5

2

4
3

S

4

F-

-F

Cl -

4

2

3

Me

4

2

4

F-

(HB-8-34-122343-A)-

4(HB-9-24-1153245-C)-

Octahedral trans-bicapped (OCT-8)
5

O

1

Br-

1

≡

5

5
4
3

2

1

Br -

- Cl

^

^^^

^^^

^^^

2

2

Br -

6

≡

Re 3 +

5
5
1

2

4 OH2
6

F-

H3N

3

3

6

O
5

(TPT-8-55-132664-C)-(The preferred orientation must be determined before the descriptor is
assigned.)

Trigonal prismatic square faced bicapped (TPS-8)
O5

4

N

4

OH2

OH2 2 + O
Sr
1

H

N

N

4

H

O
2

4

O

OH2

3

4

5

O

N
N

4

1

Cl-

O

6

OH2

(TPS-9-143352226-A)-

4

O

NH3

5

6

H3N O

H

4

^^

- Cl

1

^^^

5

2

^^^

^^

6

assigned.)

Trigonal prismatic triangular faced bicapped (TPT-8)

2

^^^

^^^

^^

^^

(The preferred orientation must be determined before the descriptor is

3

^^^

^^

(OCT-8-55-112346-A)-

≡

3

^^^

2

- Cl ^^^^^^^^^^^^^^^^^^^^^^ F
5+
Re
^^^^^
^^^^^
^^^ H -

2 ^^^^^^^^^^^^^^^^^^^^^^^^ 3

^^^

O
5

^^

F3

5

F-

3

^^^

NH3

^^^

6

Br

^^^

1-

^^^

2

^^^

4+
U

Trigonal prismatic square faced tricapped (TPS-9)

6

1

^^^

4

OH2

^^^

2

-Cl

N

O

≡

3

2

H
1

4
4

OH2
4

(TPS-8-13445244-A)-(The pathway is selected to pass through the atom of highest priority (lowest
numerical value) in the next lower plane.)Mononuclear coordination complexes containing ligands which require theuse of η do not follow the stereochemical rules for other mononuclear
coordination complexes. When the author indicates stereochemistry for the
total complex, the term “stereoisomer” is used. Ligand stereochemistry in πcomplexes is described using the rules for systematic organic stereochemistry(see ¶ 203 I). No ligand stereochemical descriptor is cited unless all ligand
stereochemistry can be described. However, ligand stereochemical descriptors
are cited even if the geometry about the metal is unknown. When more than
one ligand is stereogenic, the stereochemistry for the complex is cited as if allligand stereochemistry is in one organic ligand. An exception is made formetallocenes.
Metallocenes, when asymmetrically disubstituted, are not superimposable
on their mirror images; they can therefore exist as enantiomers. The absoluteconfiguration of the chiral center of highest priority is determined by the
Sequence Rule and cited as R or S when specific information is stated in theoriginal document. (The configuration of the other four centers is then fixed.)
Metallocenes which have stereochemistry only in the substituents have thatindicated as described by the rules in I above.
Partial stereochemistry is not cited for coordination compounds.
204. Alkaloids are divided into classes largely in accordance with theirstereochemical complexity. Class A alkaloids include substances containing
only one chiral center, or none at all, or whose stereochemistry, typically
restricted to a single ring system, is easily defined. Alkaloids of this class areindexed systematically; cross-references are found at the alkaloid names.
Example:TropineSee 8-Azabicyclo[3.2.1]octan-3-ol, 8-methyl-, (3-endo)Class B alkaloids possess more complex stereochemistry. They have beenorganized as derivatives of a single stereoparent of known absoluteconfiguration common to several alkaloids. (Class C alkaloids are those whichhave not yet been organized in this way, but whose absolute configuration is
known.) Class B stereoparents are illustrated in the Chemical Substance Index
when justified by current entries. The following is a partial list of thosecurrently employed for alkaloids:¶ 204

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Aconitane
AjmalanAspidospermidine
CevaneCinchonan
Curan
Eburnamenine
Ergoline
Ergotaman
Erythrinan
6,14-Ethenomorphinan

Hasubanan
Hetisan
Ibogamine
Morphinan
Oxayohimban
Sarpagan
Solanidane
Strychnidine
Veatchane
Yohimban

Deviations in stereochemistry for specific derivatives of Class B alkaloids
are indicated in the modification (¶ 203 II). The prefixes, suffixes, conjunctive
names, etc., of regular substitutive nomenclature are employed in naming
derivatives. Radicals, e.g., aconitanyl, are formed from the stereoparent namesin the usual way. Ring modifications as expressed by prefixes such as cyclo,
homo, nor, and seco, on the heading parent, are not permitted and systematic
nomenclature is used. Carboxylic acids are formed from Class B stereoparentsby oxidation of an existing carbon to form an “-oic acid” or by addition of acarboxyl group to form a “-carboxylic acid”; the latter type of name is preferred
if a choice is presented. Removal of hydrogen is indicated by “dehydro” terms
in the inverted part of the heading.
Class C alkaloids are indexed at stereoparent names supplied in theliterature, the numbering system is that most commonly adopted in original
documents, and the numbering is extended, if necessary, to include all
positions except acyclic hetero atoms. The latter are denoted by italic element
symbols, with superscripts, if necessary, derived from the lowest numbered
atom to which the hetero atom is attached, e.g., N 6, O2. Illustrative diagrams in
the Chemical Substance Index at Class C alkaloid names, currently
Cephalotaxine and Vincaleukoblastine, indicate the stereochemistry andnumbering systems. Derivatives of Class C alkaloids are named, when sufficient information is presented, by modifying the stereoparent name. Suffixes
are not used except for “-oic acid,” to denote oxidation of a methyl group or
removal of an ester group. “Hydro” terms are employed to indicate saturationof positions; “de” terms, e.g., “dehydro,” “deoxy,” “deepoxy,” “deoxo,” “demethyl,” “de(methoxycarbonyl),” denote removal of atoms or groups, which
may be replaced by other groups; e.g., Vincaleukoblastine, 3-de(methoxycarbonyl)-3-(hydroxymethyl)-. Higher functions attached to Class C stereoparents are indexed as substituents. When an alkaloid derivative can be named
at two or more Class C stereoparents, the decision depends in descending order of preference on (a) removal of the fewest different substituents; (b) removal of substituents of lowest molecular weight; (c) retention of thestereoparent of highest molecular weight; (d) addition of prefixes related to thelowest number of smallest substituents; (e) the least stereochemical change; (f)the lowest locants for substituents; (g) the earliest index positions of the index
name.
Derivatives of Class C alkaloids that meet the criteria for Class A alkaloids
are named systematically by substitutive nomenclature. When a Class C
stereoparent structure contains an oxo group, derivatives of the group, e.g.,
oximes or hydrazones, are expressed in the modification; otherwise they are
expressed as substituents, e.g., as (hydroxyimino) or hydrazinyldene radicals.
Esters are named analogously in the modification or by (acyloxy) or [(alkyloxy)carbonyl] substituents. Stereochemical deviations of Class C alkaloid derivatives are expressed as the final term in the modification in the usual way.
Quaternary alkaloids are either (a) alkaloids that contain a cationic nitrogenatom, or (b) alkaloids that have been quaternized, e.g., by methylation of atertiary nitrogen group. Names of (a) are completed by citing the anion (ifknown) in the modification, e.g., “chloride”; (b) are usually named by adding“ium” to the neutral alkaloid name, and indicating the quaternizing substituentsas in regular substitutive nomenclature; e.g., Morphinanium, 17,17-dimethyl-, iodide (1:1) by quaternization of Morphinan). When the location of thequaternary center is unknown, the “ium” ending is omitted and the quaternarycompound is named as alkaloid compd. with iodomethane (1:1). Nonquaternary derivatives of the alkaloids described in (a), above, are named by subtractive
prefixes, e.g., demethyl, or by “dihydro” terms.
Removal of a methyl group from the carbon skeleton of an alkaloid isindicated by “nor” with the locant of the carbon atom lost, but removal of amethyl group from a hetero atom is expressed by “demethyl.”
Ring contraction and enlargement in alkaloids is not permitted, and revert
to systematic nomenclature.
Ring closure may be effected by insertion of heteroatoms (other thannitrogen) as bridges while maintaining stereoparent nomenclature, e.g.,
Aspidospermidine, 19,21-epoxy-. Such a bridge may also include one carbon
atom, e.g., 6,14-Ethenomorphinan, 7,5-(methyleneoxy)-. Replacement of
one carbon atom by a heteroatom or insertion of additional nitrogen or replacement of existing nitrogen is not permitted.
Seco alkaloids are formed by ring cleavage and addition of hydrogen at theresulting terminal groups. Such compounds are given systematic names.
Ring-fused derivatives of alkaloid stereoparents are named systematically.
Degradation products of alkaloids in which ring cleavage and removal oflarge portions of the molecule still leave intact some rings and the original
stereochemical relationships are named, when possible, as derivatives of asmaller alkaloid stereoparent. When this is impossible and the structure is
known, degradation products of Class C alkaloids are named systematically,
but, for those of unknown structure, only the author’s names are employed.
For steroidal alkaloids, see ¶ 211.
205. Amino acids. The following biologically significant amino acids are

80

stereoparents:

Alanineβ-Alanine
Alloisoleucine
Allothreonine
Arginine
Asparagine
Aspartic acid
Cysteine
CystineGlutamic acid
Glutamine
GlycineHistidine
Homocysteine
Homoserine

Isoleucine
Isovaline
LeucineLysineMethionine
Norleucine
Norvaline
Ornithine
Phenylalanine
ProlineSerineThreonine
Tyrosine
Tryptophan
Valine

The following amino carboxylic, amino sulfonic, and amino arsonic acids,
indexed prior to 1972 at their trivial names, are now named either
systematically or as derivatives of an amino acid listed above:
Trivial name
Allocystathionine
Anthranilic acidArsanilic acid
(3 isomers)
Carnosine
Creatine
Cystathionine
Ethionine
Hippuric acid
Lanthionine
Metanilic acid
Panthothenic acid
Sarcosine
Sulfanilic acid
TaurineThyronine
Thyroxine

CA Index Name
Homocysteine, S-(2-amino-2-carboxyethyl)Benzoic acid, 2-aminoArsonic acid, As-(aminophenyl)Histidine, β-alanylGlycine, N-(aminoiminomethyl)-N-methylHomocysteine, S-(2-amino-2-carboxyethyl)Homocysteine, S-ethylGlycine, N-benzoylCysteine, S-(2-amino-2-carboxyethyl)Benzenesulfonic acid, 3-aminoβ-Alanine, N-(2,4-dihydroxy-3,3-dimethyl1-oxobutyl)- (see ¶ 224)
Glycine, N-methylBenzenesulfonic acid, 4-aminoEthanesulfonic acid, 2-aminoTyrosine, O-(4-hydroxyphenyl)Tyrosine, O-(4-hydroxy-3,5-diiodophenyl)-3,5-diiodo-

The configurational descriptors D- and L- are placed before the stereoparent
names; no descriptor is cited for the optically inactive mixture or racemic form;
thus, L-Leucine; D-Valine; Phenylalanine. In the absence of contrary evidence,the L-isomer is assumed for amino acid stereoparents, except Glycine and βAlanine, which possess no asymmetric center, and Alloisoleucine and Allothreonine (see below). When the original document clearly indicates that an
amino acid is synthetic, it is indexed as the racemic form. The same assumptions are made for their radicals, which are employed in peptide nomenclature,and for derivatives such as esters, salts, and N-, O-, and S-derivatives indexedat the stereoparent. No assumptions are made for carbon-substituted derivatives or for derivatives named systematically. Systematically named amino acids of known stereochemistry are assigned the absolute descriptors R and S in
the modification. Of the diastereoisomeric pairs, assumptions in favor of Isoleucine over Alloisoleucine and of Threonine over Allothreonine are made.
The absolute descriptors R and S (with locants) are cited in the modificationsof diastereoisomeric derivatives of amino acid stereoparents to define the second asymmetric center, e.g., L-Aspartic acid, 3-hydroxy-, (3R)- and L-Proline, 4-methyl-,(4S)-.
Phenylalanine is a stereoparent employed for Alanine, 3-phenyl-. It istreated in substitutive nomenclature as though it were the conjunctive nameBenzenealanine. The naturally occurring isomer is L-Phenylalanine, which
affords the radical L-phenylalanyl. Derivatives containing higher functions ormore preferred ring systems are named systematically according to the regularrules.
Example:PhCH 2 C(NH2) CO 2H

1-Naphthaleneacetic acid,
α-amino-α-(phenylmethyl)-

Radicals derived from the names of amino acid stereoparents, e.g., glycyl,
L-alanyl, L-phenylalanyl, are employed only in naming peptides (¶ 206). In

other situations, systematically named radicals are used; e.g., (2-aminoacetyl)
instead of glycyl. The phenylalanyl radical is considered to be a
specially named one -part radical; no parentheses are placed around it when it
is unsubstituted. Stereoparent radical names are derived by replacing the final“-ine” by “-yl” (an exception is Cysteine, which affords cysteinyl);
Tryptophan gives tryptophyl; Aspartic acid and Glutamic acid radicals are
as follows:

81

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

-COCH2CH(NH2)CO-

aspartoyl

Examples:HO2CCH2CH(NH2)CO-

α-aspartyl

EtO2C(CH2)2CH(NH2)CO2Me

L-Glutamic acid,-COCH2CH(NH2)CO2H

β-aspartyl-CO(CH2)2CH(NH2)CO-glutamoyl

HO2CNHCHMeCO2Et

L-Alanine, N-carboxy-,

HO2C(CH2)2CH(NH2)CO-

α-glutamyl-CO(CH2)2CH(NH2)CO2H

γ-glutamyl

Amino acids are given less preference for special treatment than otherstereoparents. They are ranked just above the unsubstituted parent acids; thus,
Alanine (2-aminopropanoic acid) is ranked above Propanoic acid but below
Butanoic acid. All carbon-substituted derivatives of Glycine and β-Alanine
are indexed at systematic names, but the carbon-substituted radicals are
permitted in peptide nomenclature.
Examples:Glycine, N-benzoyl-

BzNHCH2CO2H
N

2

1

L-Phenylalanine, 4-chloro-β-ethyl(βR)- (not L-Norvaline, 3(4-chlorophenyl)-,(3R)-)

CHEt CH(NH 2) CO 2 HβαClMe(CH2)5CMe(NH2)CO2H

Octanoic acid, 2-amino-2-methyl(not Alanine, α-hexyl-)

1-ethyl ester (the locant “l” is citedfor clarity, even though the N-ethyl
ester is indexed as L-Alanine,N-(ethoxycarbonyl)- (¶ 185))

H2
N

HS ( CH2 ) 2

+

H2
N

( CH2 )2 SH

O
-

O

2

Cu
O
-

Copper, bis (L-homocysteinatoκN, κO)-,(T-4)-

Benzenepropanoic acid, β-amino(βR)- (not β-Alanine, 3-phenyl-, (3R)-)

O-Substituted derivatives of the hydroxy amino acids (Allothreonine,
Homoserine, Serine, Threonine, and Tyrosine) and S-derivatives of themercapto amino acids (Cysteine and Homocysteine) are named at thosestereoparents, e.g., Serine, O-methyl- and L-Cysteine, S-acetyl-. The stereoparent Methionine, CH3SCH2CH2CH(NH2)COOH, is the S-methyl derivative of Homocysteine. Derivatives in which this methyl group is substituted
are indexed as Homocysteine derivatives. S-Oxide derivatives of Cysteine andHomocysteine are indexed as sulfinyl and sulfonyl derivatives of simpler parents; however, S-oxides of S-substituted derivatives (including Methionine) are
named as such.
Conjunctive names are not formed from amino acid stereoparents attached
to ring systems; instead, such a combination is usually indexed at a systematic
conjunctive name with an “α-amino” substituent. Derivatives of Arginine,
H2NC(:NH)NH(CH2)3CH(NH2)COOH, substituted in the guanidino group areindexed as derivatives of Ornithine, H2N(CH2)3CH(NH2)COOH.
Histidine (R = H) is capable of existing in the following tautomeric forms:
RN

5-ethyl 1-methyl ester

Amides of amino acids are indexed at systematic names, e.g., Acetamide,
2-amino- (not Glycinamide), but peptide amides (¶ 206) are indexed at
C-terminal amino acid names, e.g., Glycinamide, L-alanyl-.
Anhydrides of amino acids are indexed at the amino acid name with“anhydride” or “anhydride with” terms in the modification. Cyclic anhydrides
and lactones are indexed as heterocycles. Hydrazides are indexed at acidheadings with “hydrazide” terms in the modifications. Molecular addition
compounds of nonstereoparents with amino acids named as stereoparents
receive preferred index names at the latter, but Formula Index entries will befound also at the other component(s). The preferred name of an addition compound of two or more stereoparents is chosen on the basis of the maximum
number of highest functions in the stereoparent.
Beryllium, magnesium, aluminum, gallium, indium, thallium, andtransition-metal salts of amino acids are indexed as coordination compounds(¶ 215) if sufficient information is presented, and the special stereochemical
descriptors (¶ 203 III) for such compounds are then adopted. Other salts areindexed at such names as Glycine, sodium salt (1:1); L-Phenylalanine, methyl
ester, hydrochloride (1:1).
Example:O

PhCH(NH2)CH2CO2H¶ 206

206. Peptides are generally named by use of amino acid stereoparents(¶ 205) and stereoparent radicals; the L-isomers are assumed for indexing
purposes in the absence of contrary information. Trivial names of some
peptides and all proteins are employed, and special “Cyclo” names are used fortri- and higher cyclic peptides.
Linear peptides without trivial names are indexed at “amino acid sequencenames.” The heading parent is the C-terminal amino acid. Enclosing marks
and locants for points of attachment of the amino acid radicals are omitted;
however, Greek-letter locants are cited for aspartyl and glutamyl radicals, and“N 6- ” and “N 5- ” are used with Lysine and Ornithine, respectively, and theirradicals, when the attachment is not on the α-amino group (N 2-position). NDerivatives of the radicals are expressed as substituents. Esters of carboxy
groups of aspartic and glutamic acid residues are cited in the modification; Oand S-acyl derivatives of seryl, cysteinyl, etc., radicals are named as, e.g., Oacetyl-L-seryl, etc., radicals and even when a hydroxyl- or mercapto-groupcontaining amino acid is the heading parent, the O- or S-acyl group is treatedas a substituent.
Examples:N
CH2 CH (NH2) CO2 H

N(a)

CH2 CH (NH2) CO2 H
RN

H-L-Met-L-Asp(NH2)-L-Pro-D-Phe-L-Phe-OH
L-Phenylalanine, Lmethionyl-L-asparaginyl-Lprolyl-D-phenylalanyl-(b)

When the tautomers are stabilized by substitution on a nitrogen atom of thering, two isomers result. The side chain has been arbitrarily assigned to the 4position of the ring and, if R = ethyl, the structures shown above are indexed:(a) L-Histidine, 3-ethyl(b) L-Histidine, 1-ethylIt should be noted that while (b) conforms to the correct treatment for
1H-Imidazole, the numbering of (a) violates the rules (3H-Imidazole is not
used as a heading parent) and is adopted only for these special cases. A 1substituent is assumed in indexing indefinite 1- or 3-derivatives of Histidine.
Esters of amino acid stereoparents with nonstereoparents are indexed at theamino acid names; e.g., L-Alanine, 4-carboxyphenyl ester. Esters with otherstereoparents are indexed at the parent which represents the greatest number ofhighest functions. Usually only one index entry is made for an ester. Locants
are used with ester terms when necessary.

HO2CCH2CO 2H||
H2NCHCONHCHCONHCHCH2OAc|

MeSCH2
L-Tyrosine, L-α-aspartylS-methyl-L -cysteinyl-O-

acetyl-¶ 206

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

MeO2 C(CH2 )2(CH2 )2 CO2 Me||
PhCH2O2CNHCHCONHCHCONHCHCONHCHCO2Me||(CH2)2CO2Me
MeO2 C(CH2 )282

acids are assigned “Cyclo” names formed by citing the amino acid radicals(with substituents) as for an amino acid sequence name, placing them in
enclosing marks, and prefixing the term “Cyclo”. The order of citation is bylowest alphabetical order of parent amino acid residues (substituents are
disregarded) when the residue is standard, but when it is nonstandard (e.g., 2aminobutanoyl), substituents are included in determining the order of citation.

L -Glutamic acid, N-[(phenylmethoxy)carbonyl]-Lα-glutamyl-L-α-glutamyl-Lα-glutamyl- ,
1,2,3,41,45-pentamethyl ester

HN(CH2)2SMeCH 2Ph||CH2CHCONHCHCONHCHCONHCHCONHMe||
CH2CO2HNH2
L-Phenylalaninamide , L-tryptophyl-Lmethionyl-L-α-aspartyl-N-methyl-

To be named as such, a linear peptide must have at least two standard aminoacids. In peptide nomenclature, standard amino acids are defined as amino acidstereoparents (¶ 205), plus α-Asparagine, H2NCOCH(NH2)CH2COOH, and
α-Glutamine, H2NCOCH(NH2) (CH2)2COOH. Peptides that do not meet thisrequirement are named systematically; e.g., Butanoic acid, 4-amino-2-[(2aminoacetyl)amino]-, (2S)-.
When the above requirement is met, nonstandard α-amino acids areallowed as residues in terminal or nonterminal positions. Nonstandard aminoacids in which the amino group is not α to the carbonyl are allowed provided
they are nonterminal. All nonstandard amino acids are assigned systematicacid or acyl names. Absolute stereochemistry is described by the use of R/Sterms preceded by locants; e.g., L-Alanine, 5-oxo-L-prolyl-(αS)-αamino-4-chlorobenzenebutanoyl-; 1H-Indole-2-carboxylic acid, Lseryl-L-methionyloctahydro-, (2S,3aR,7aR)-; L-Proline, L-histidyl(3R)-3-(methylamino)hexanoylglycyl-L-α-aspartyl-.
Branched-chain peptides may comprise N 5- or N 6- isopeptide derivatives ofOrnithine or Lysine, respectively, or O- or S-derivatives of hydroxy or mercapto amino acids (heterodetic homomeric peptides). Both types are named as
substituted derivatives of the parent linear peptides.
Examples:H-L-Ala-D-Gln-L-Lys-D-Ala-OH
H-L-Ala-D-Gln-L-Lys-D-Ala-L-Ala-L-Ala
H-L-Ala-L-Ala
D -Alanine, L -alanyl-D -glutami nyl -N 6 -[ L - alanyl- D -glutaminyl - N 6- ( L- alanyl- L- alanyl )-Llysyl -D -alanyl-L -alanyl-L -ala nyl ]-L -lysyl -Cyclo[L-alanyl-N 5-acetyl-D-ornithylglycyl-L-alanyl-D-prolyl-O(1,1-dimethylethyl)-L-seryl] (noteNH - CH - CO - NH - CH2 - CO - NH - CH - CO that the substituent “acetyl” is disregarded in determining preferred ciN
CO - CH - NH - COCH - NH - COtation of the peptide sequence; thelowest alphabetical sequence of parCH2 OCMe3
Me
ent-radical initial letters is “a, o, g,a, p, s”)
Me( CH2 ) 3 NH Ac

When ring formation has taken place by way of a side-chain peptide linkage, the acyclic peptide is named and the linkage expressed in the modification
by a phrase of the type “(10→4)-lactam” in which the lactam linkage is denoted by amino acid residue locants (numbered from the N-terminus) with theacid end of the linkage cited first.
Peptide lactones not assigned depsipeptide names (see below) are expressedby modification terms such as “(3→1)-lactone.” Peptides containing disulfide
linkages are indexed at the reduced (cysteinyl-group-containing) form withterms such as “(2→2´)-disulfide,” “cyclic (1→6)-disulfide” and “(5→3´)-disulfide with ...” in the modification.
N-(Peptidyloxy) derivatives of nitrogenous heterocycles are indexed at the
peptide names, with the rings cited as ester terms.
Depsipeptides contain ester linkages with hydroxy acids as well as amide(peptide) linkages with amino acids. Those with three or more acid residues, ofwhich at least two are standard amino acid residues, are indexed by “depsipeptide nomenclature”; otherwise a systematic name is employed. A depsipeptide
name is based on the C-terminal amino acid and indexed by methods analogous
to those for amino acid sequence names. Trivially named hydroxyacyl radicals (lactoyl, glycoloyl, etc.) are given systematic acyl radical names whennonterminal, but treated as substituents or ester terms when terminal.
Example:
HOCHMeCONHCHMeCO2CHMeCONHCHMeCO2H
L-Alanine, N-[(2R)-2-hydroxy-1-oxopropyl]L-alanyl-(2R)-2-hydroxypropanoyl-

Cyclic didepsipeptides are indexed as heterocycles. Cyclic tri- and higher
depsipeptides are indexed at “Cyclo...” names analogous to those for cyclic
peptides. Cyclic depsipeptides with one hydroxy acid are named as such, notas lactones.
Example:

CH2OH

Me

Cyclo[(2S)-2-hydroxypropanoyl-L-seryl-L-phenylalanyl-L-leucyl] (the hydroxy acyl
radical is alphabetized at “h,”not “p”)

O - CH - CO - NH - CH - CO
CO - CH - NH - CO - CH -NH

H-L-Leu-L-Ala-L-Phe

CH2CHMe2CH2 PhH-L-Pro-L-Met-L-Ser-L-Asp-OH
L-Aspartic acid, L-prolyl-L-methionyl-O-(L-leucyl-L-alanyl-L-phenylalanyl)-L-seryl-Higher functions in peptides are expressed as substituents. When the C- terminal residue is not an amino acid or amino acid amide, but an acid-related
compound such as an alcohol, aldehyde, or nitrile, the adjacent amino acidamide residue is adopted as the heading parent, and the terminal group isexpressed as an N-(cyanomethyl), N-(2-oxoethyl), etc., substituent.
Cyclic dipeptides are indexed at systematic heterocycle names, with crossreferences at “Cyclo” names (see below).
Example:
O
8a
1

N

H2
N

Pyrrolo[1,2-a]pyrazine-1,4-dione,hexahydro-

The Greek letter ψ, shorthand for “pseudo,” is used to convey the fact that a
peptide bond has been replaced by a pseudopeptide bond. If the structure
contains the moiety ...-NH-CHR-X-X´-CHR´-CO-..., where R and R´ areamino acid side-chain groups and X and X´ are the groups that replace thepeptide bond, then the format of the ψ term is ...-A-ψ(X-X´)-B-..., where A isthe amino acid whose carbonyl group has been modified to X (or remains
unmodified) and B the amino acid whose α-amino group has been modified toX´ (or remains unmodified). X and X´ are shown as strings of element symbols, separated by a bond; e.g., L-Leucine, L-alanyl-L-valyl-ψ(CH2-CH2)-Lisoleucyl-L-alanyl-.
Naturally occurring biologically active peptides with five or fewer aminoacid residues are indexed as described above. The more common natural peptides with six to fifty residues are assigned the trivial names commonly used in
the literature. For cysteine-containing natural peptides, only the reduced form
is illustrated (Oxytocin and Vasopressin, below, are exceptions).
Examples:H-L-Arg-L-Pro-L-Pro-Gly-L-Phe-L-Ser-L-Pro-L-Phe-L-Arg-OH
1

5

2

3

4

5

6

7

O

Bradykinin
Tripeptides and longer peptides containing two or more standard amino

8

9

83

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

→ L-Leu-D-Phe-L-Pro-L-Val-L-Orn
1

2

3

4

5

 L-Orn←L-Val←L-Pro←D-Phe←L-Leu ←
10

9

8

7

6

Gramicidin S

sulin (cattle), 30B-L-methionine-. The reduced forms of the individual insulin
chains are also stereoparents; internal disulfide bonds are expressed in themodification.
Actinomycins are a class of natural products that contain peptide chainsattached to non-peptide moieties. Actinomycin D (sometimes called C1) is one
member of the actinomycin family.
Example:5

B

Me - L - Val - O

2

3

4

5

L-Arg-L-Cys-L-Gln-L-Gln-L-His-NH2
14
15
16
17
18

MeGly 4 A

L-Pro 3

L-Pro 3 A

D-Val 2B

D-Val 2 A

CO-L-Thr 1B

CO-L-Thr 1 A

10

9

N

6

O

10a

1

NH2

4

O

5

12 Me

Kallidin, N2-L-alanyl- (N-terminal extension)
Glucagon (swine), N-acetyl- (N-terminal extension)
Bradykinin, 9a-L-valine-9b-L-lysine- (C-terminal extension)
Fibrinopeptide A (human), 16a-D-serinamide- (C-terminal extension)
Bradykinin, 6a-endo-L-alanine- (insertion)
Caerulein, 4-desulfo- (removal of modifying group)
Caerulein, 4-de(O-sulfo-L-tyrosine)- (removal of unit)
Combinations of various types of structural modifiers are indicated by citing
them in numerical order. When the modifying operations total at least one-halfthe number of units in the original parent, a regular peptide name is employed.
The Greek letter ψ (see above) is used in derivative names to indicate a
modified peptide bond. The format of the ψ term is ...-A-nψn+1(X-X′)-B-...,
where n is the residue number of the amino acid A whose carbonyl group has
been modified to X (or remains unmodified) and n+1 the residue number of theamino acid B whose α-amino group has been modified to X′ (or remains unmodified). A and B are cited in the name only if they are otherwise modified;e.g., Bradykinin, 7ψ8(CH=CH,E)-8-L-tyrosine-. The formatting of the stereochemical data for X-X′ follows standard literature practice.
In Angiotensin I and Angiotensin II, the amino acid in the 5-position, if
known, is cited in the inverted part of the heading, e.g., Angiotensin I, 5- Lisoleucine-.
Oxytocin and Vasopressin derivatives in the disulfide form are named atthese headings with replacement, etc., terms as usual, but reduced analogs areindexed at amino acid sequence names, not at Oxytocin (reduced) and
Vasopressin (reduced). The amino acid at position 8 of Vasopressin is always
specified if known.
In α1-39-Corticotropin (swine) “α” indicates that this was the first principle isolated; the superscripts give the range of amino acid units. Fragments
containing more than twelve sequential units receive names such as α1-24-Corticotropin and α11-39-Corticotropin. An amino acid sequence name is employed for fragments of fewer than twelve units.
Insulin contains two peptide chains, an A-chain of 21 amino acid units anda B-chain of 30 units, connected at two points by disulfide bridges. Replacement names that retain the disulfide bridges and have fewer than 11 and 15 residue changes in the A- and B-chains, respectively, are formed in the usual way.
Locants have superscript letters to indicate to which chain they belong; e.g., In-

Actinomycin D

NApamin (reduced)

Species variations are dealt with by citing the name of the species as ahomograph definition after the heading. Each species variant is an independent
stereoparent; e.g., Calcitonin (salmon reduced); Calcitonin (human reduced).
Replacement of one amino acid residue by another is indicated at a triviallynamed peptide heading by citing the names of the new amino acids in numerical (not alphabetical) order as substituents; e.g., Glucagon (swine), 4-L serine-10-L-alanine-. In addition, the chain of the reference compound can beextended at either end, either by substitution of the N-terminal α-amino groupor by citing additional terms with locants derived from the highest present byaddition of “a,” “b,” etc. In a similar manner, insertion of amino acid units between existing ones is indicated by “endo” terms with “a” locants derived fromthe lower of the two neighboring units (e.g., “3a” indicates insertion between“3” and “4”). Removal of a unit is indicated by a “de” term such as “4-desulfo”
to indicate removal of only a modifying group in a unit, or “6-de-L-glutamic
acid” to express removal of an entire unit.
Examples:A

B

6

L-Glu-L-Thr-L-Ala-L-Leu-L-Cys-L-Ala-L-Arg7
8
9
10
11
12
13

5

Me - L - Val - O

MeGly 4B
H-L-Cys-L-Asn-L-Cys-L-Lys-L-Ala-L-Pro1

¶ 208

Me 11

The “Me-L-Val” symbol denotes N-methyl-L-valine and “Me-Gly” denotes
N-methylglycine (sarcosine). Substitution in the phenoxazine ring is expressed
before amino-acid replacement, etc., in the peptide moiety.
Examples:Actinomycin D, 8-bromo-7-chloroActinomycin D, 2-deamino-2-hydroxy-3Α-D-proline-4Α-DnorleucineHomopolymers of amino acids are indexed by polymer procedures (¶ 122);e.g., L-Alanine, homopolymer. The structural repeating unit is indexed at
Poly[imino[(1S)-1-methyl-2 -oxo-1,2 -ethanediyl]]. The stereochemical assumptions are the same as for the monomeric amino acids. Peptides of indefinite molecular weight with repeating peptide sequences are named as
homopolymers at the peptide monomer names and at structural repeating unit
names.
207. Proteins. Proteins are arbitrarily defined for indexing purposes as
peptides containing more than 50 amino acids. Proteins whose complete aminoacid sequences are known are indexed as chemical substances from all patents
and journals covered by CAS. The protein sequence is entered into the CAS
sequence database, and is searchable and displayable on STN. Partial protein
sequences are also indexed from selected journals.
Each protein sequence is given a unique name based on controlled vocabulary, as well as author terminology, the species of origin, and additional
information which may include strain/clone, gene, and subunit/isoform, etc., asapplicable.
Protein fragments may be prefixed with two numbers, relating to the rangeof amino acids represented; e.g., 1-124-Somatotropin (cattle). Replacement
names, as for peptides, are used for analogs. If the range of amino acids cannot
be based on a complete protein, fragment is included in the name.
208. Carbohydrates. Carbohydrate stereoparents are defined for indexing
purposes as polyhydroxy acids, aldehydes, ketones, alkanes, and theirderivatives, with a skeleton of five or more carbon atoms, more than half ofwhich must be attached to oxygen (or another chalcogen) or nitrogen, and at
least one of the chalcogen attachments must be by a single bond to anonterminal carbon atom. At least half of the nonterminal carbon atoms must
be asymmetric. Anomeric carbon atoms, whether terminal or non-terminal, arenot counted in determining the number of asymmetric carbon atoms. Except
for uronic and ulosuronic acids, the open chain is numbered to give the highest
function the lowest possible locant. Illustrative structural diagrams related tocurrent index entries will be found in the Chemical Substance Index for openchain forms and common cyclic forms of carbohydrate stereoparents. Stereoparents representing the following carbohydrates and their derivatives are employed as heading parents:
Pentoses:
Hexoses:2-Hexuloses:
Acids:

Arabinose, Lyxose, Ribose, Xylose.
Allose, Altrose, Galactose, Glucose,
Gulose, Idose, Mannose, Talose.
Fructose, Psicose, Sorbose, Tagatose.
Ascorbic acid (¶ 224), Muramic acid,
Neuraminic acid.

Monosaccharides that exist in the open form are indexed at thestereoparents. Higher functions are expressed as substituents or in themodification. Derivatives of the cyclic forms are indexed at the highest
function if a glycosyl radical can be used to express the sugar, which is ranked
as a polyhydric alcohol unless a higher function, e.g., a nonglycosidic ketone
or aldehyde, is expressed as a suffix.

¶ 208

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

When a second stereoparent is represented in a structure, the parent ofhigher functionality is chosen in indexing.
Configurational descriptors, D and L, are placed before stereoparent names,
including monosaccharide semisystematic names (see below). Examples are
D-Glucose and L-arabino-Hexose, 2-deoxy-. In the Fischer projections of theopen forms, the carbon skeleton is displayed vertically, with locant “l” at the
top. The D-series can then be recognized by the hydroxyl group to the right ofthe bottom nonterminal asymmetric carbon atom.
Examples:
CHO
CHO
H

C

OH

HO

C

H

HO

C

H

CH2

OH

H

C

OH

HO

C

H

HO

C

H

H

C

OH

are also named in the modification.
Examples:D-Xylosediethyl dithioacetal
D-Xylose

2,3-diacetate 4,5-dibenzoate
Cyclic hemiacetal forms of monosaccharides are indexed by inclusion in
the name of a term indicating the ring size, if known; five, six, and sevenmembered rings, are denoted by “-furanose,” “-pyranose,” and “-septanose”
suffixes. Two anomers, named “α” and “β,” result on ring formation, and these
Greek letters are employed as anomeric prefixes, which are placed ahead of theconfigurational descriptors (D or L) in the name.
Fischer
projection

CH2 OHD- Galactose

L- Arabinose

84

Configurational prefixes, derived from trivial aldose names, are used insemisystematic carbohydrate nomenclature; for one asymmetric carbon atom,e.g., >CHOH, >CHOCH3, >CHNH2, glycero is the prefix used (with D or L as
described above); with two, erythro and threo; with three, arabino, lyxo, ribo,and xylo; with four, allo, altro, galacto, gluco, gulo, ido, manno, and talo.
(The centers need not be on neighboring carbon atoms.) For more than four
consecutive centers, combinations of these terms are used.
Examples (“X” is the group with the lowest-numbered carbon atom):

H C

OH

H C

OH

C

HO

H

H C

OH

H C

O

Haworthprojection
HOCH2

≡

O
OH
HO

OH
OH

CH2OH

α-D-Glucopyranose

X
X
HO

X
X
H

C

OH

Y

HO

C

H

HO

C

H

Y

D- glycero-

C

HO
H

C

H

The following examples show the derivation of names for ketoaldoses
when the ring closure involves (a) the aldehyde, and (b) the keto function.

CH2

CH2
HO

C

CH2
H

Y

HO

C

HOCH2
H

Y

(a) α-D-xylo-Hexopyranos-4-ulose

O
O

OH
OH

L- erythro-OH

In choosing a monosaccharide stereoparent name (when such a choice isnecessary), (a) the oxo (or higher) function is numbered low (except the
carboxyl group in uronic and ulosuronic acids); (b) the name appearing earliest
alphabetically is chosen; (c) “D” is preferred to “L”; (d) the anomeric prefix“α” is preferred to “β”; (e) lowest locants for substituents are employed; (f) thelowest locant is used for the first-cited substituent.
Systematic carbohydrate names, employed for monosaccharides other thanthose with trivial names, are based on stem names which express the size andfunction; the stem names for open-chain aldoses of five or more carbon atoms
are Pentose, Hexose, Heptose, Octose, Nonose, etc.; corresponding ketose
stems are Pentulose, Hexulose, etc. (Additional terms are used to indicate ring
size if necessary; see below.) The stem names are preceded by stereochemical
descriptors. 2-Hexuloses have trivial names (see above); other ketoses are
named systematically, e.g., L-erythro-2-Pentulose. For meso-forms, the Dand L- configurational symbols are not needed; e.g., erythro-3-Pentulose.
Diketoses have names of the type D-threo-2,4-Hexodiulose; ketoaldoses have“-osulose” names such as D-ribo-Hexos-3-ulose; dialdoses have names such as
D-gluco-Hexodialdose; chalcogen analogs are indexed by use of thio, etc., prefixes, e.g., D-Glucose, 1-thio-; replacement of hydroxyl by hydrogen is denoted by “deoxy” terms.
Substitution on carbon with prior removal of a hydroxyl group requires
citation of “deoxy” and the substituent prefix in alphabetic order, e.g.,
D-Glucose, 2-(acetylamino)-2-deoxy-. When the existing hydrogen issubstituted on a carbon atom already carrying an oxygen (or other chalcogen)or nitrogen group in the open or cyclic forms, the italic capital letter C isemployed, e.g., D-Ribose, 3-C-(nitromethyl)-. When both the hydrogen andhydroxyl are replaced by nonchalcogen, nonnitrogen substituents, the stereochemistry is expressed by a Sequence Rule descriptor at the systematic saccharide name, e.g., D-ribo-Hexose, 3-bromo-3-chloro-3-deoxy-, (3S)-.
Substitution of hydrogen on a hydroxyl group of a carbohydrate is denotedby “O” locants (or by “S”, etc., if chalcogen replacement has also taken place).
Examples:D-Mannose, 2,3,4,5,6-penta-O-methylD-Glucose, 2-S-ethyl-2-thioD-Glucitol, 1-O-ethyl-1-C-(phenylamino)-

Cyclic acetals employ bivalent radicals with “O” terms, e.g., D-Ribose,
2,3:4,5-bis-O-(1-methylethylidene)-.
Oximes and hydrazones are expressed in the modification, osazones
similarly as dihydrazones of osuloses. Hydrates, acetals, hemiacetals and esters

O
HO

OH

(b) α- L -xylo-Hexos-2-ulo-2,5furanose

CHO
OH
HOCH 2More complicated cases, e.g., cyclic forms of dialdoses and higher ketoses,
are named in accordance with rules (lowest locants for the keto group,alphabetically preferred configurational prefixes, etc.) already described.
Locants, e.g., “-6,10-” are inserted before the ring-size descriptor in the name,and “α” or “β” is also cited if the anomeric carbon is numbered lower than thereference carbon atom in the ring being formed, otherwise R or S is used.
Nitrogen analogs of cyclic sugars are named systematically.
Intramolecular anhydrides are denoted by terms such as “1,5-anhydro” inwhich the locants define the pair of hydroxyl groups involved. The sulfur
analogs are named with “dideoxy-epithio” terms. Intermolecular anhydrides
are polysaccharides (below); intermolecular dianhydrides are named by citing
the word “dianhydride” after the name(s) of the parent monosaccharides (analdose precedes a ketose); two pairs of locants define the positions of theanhydride linkages.
Example:6

HOCH2 O
O
2
5
HO
CH
2
3
HO

1

1´

CH2

O
5´
HO

2´

3´

O
HO

4´

β-D-Fructofuranose β-D-threo-2pentulofuranose 1,2´:2,1´-dianhydride

Carbohydrate acids are named by characteristic suffixes, as follows:
The stems of aldaric, aldonic and uronic acid names are derived from trivial(common) aldose names whenever possible. Acids containing a keto function
are named from the systematic stem names. Acid halide, amide, and nitrile
names are derived as usual. Esters, hydrazides, salts, and lactones are
expressed in the modification. Lactams are named systematically (¶171).
Examples:D-Gluconoyl chloride

85

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
α-D-Glucopyranuronamide, 1,1´-iminobis[1-deoxy-

1 CO2H1 CO2H

2 C=0

1 CHO

( C HOH )( C HOH )( C HOH )x

Glycosides are mixed acetals derived by replacement of the hydrogen atomon the anomeric hydroxyl group of a saccharide by a group derived from analcohol or phenol. Glycoside heading parents, e.g., α-D-Ribofura-noside, areemployed. In the inverted part of the heading, the radical derived from thealcoholic or phenolic aglycon is cited, followed by a space. Then any substituents of the saccharide are expressed in the usual way. When functions higher
than the saccharide (which is normally a polyol) are present in the aglycon, aheading parent which expresses the greatest number of highest functions ischosen, provided that an appropriate glycosyl radical name can be employed toexpress the saccharide as a substituent. When the functionality is equal in thetwo portions of the molecule, the stereoparent is preferred. Glycoside parents
are also derived from uronic acids and ulosonic acids, e.g., α-D-Mannopyranosiduronic acid; α-D-arabino-2-Hexulofuranosidonic acid.
Examples:x

x

C H2OHC H2OHC O2H-onic acid-ulosonic acid-uronic acid

1 CHO

1 CO2H

2 C=O

1 CO2H( C HOH )( C HOH )2 C=O( C HOH )

x

x

¶ 208

x

C O2H

C O2H

C O2H

-ulosuronic acid-aric acid-ulosaric acid
HOCH2
OMe

O
OH Br

L-Ribonic acidγ-lactone

β-D-Mannopyranoside, methyl 2bromo-2-deoxy-

HO

The trivial names Muramic acid and Neuraminic acid are used for the
structures shown below; the acyl radicals muramoyl and neuraminoyl, and theglycosyl radicals muramosyl and neuraminosyl, are also employed in indexing.
(Isomuramic acid is treated similarly; it is the muramic acid (S)-epimer about
the carbon atom bearing the carboxyl group.)
Examples:

H2N

O

OH

AcOCH2OH
H C OH
OH

HO

OMe

AcO
O

HOCH2
O
OCHMeCO2 H

CO2H
HOCH2

H C OHNH2

α- D -erythro-Hexopyranosid-3ulose, methyl 2-deoxy4,6-diacetateO

O

α-D-Ribofuranoside, methyl 1-thio-

CH2 OHSMe

α-Muramic acid(the (R)-epimer)

β-Neuraminic acid

Glycosyl radicals derived from trivially and systematically named saccharides by removal of the anomeric (hemiacetal) hydroxyl group have the suffix“-osyl,” e.g., β-D-mannopyranosyl (if the ring size is known), D-mannosyl, αD-arabino-hexopyranos-2-ulos-1-yl. Uronic acid radicals are derived by replacing the “-ic acid” by “-osyl,” e.g., β-D-glucopyranuronosyl; acid derivatives, e.g., uronamides, yield “-uronamidosyl” radicals, etc.
The following stereochemical and ring size assumptions are made when an
author does not completely define a glycosyl radical:
FOR

ASSUMEgalactosyl

D-galactopyranosyl

glucosyl

D-glucopyranosyl

mannosyl

D-mannopyranosyl

xylosylD-xylopyranosyl

L-fucosyl

6-deoxy-L-galactopyranosyl

D-fucosyl

6-deoxy-D-galactopyranosyl

rhamnosyl

6-deoxy-L-mannopyranosyl

HO

OH

Glycosides of ring systems are indexed at the saccharide headings unlessthe aglycon contains a higher function or the glycosyl attachment is at a nitrogen atom. C-Glycosides (glycosyl derivatives with carbon-carbon bonds) of
ring systems are indexed at the higher function.
Examples:D-Glucitol, 1,5-anhydro-1-C-phenyl-(1R)4H-1-Benzopyran-4-one, 8-β-D-glucopyranosyl-2-phenylA naturally occurring glycoside is indexed at the systematic (or stereoparent) name if the structure, including the ring-size of the saccharide, is known,
whether or not all the stereochemistry has been elucidated. (A “glucoside” isassumed to be the β-D-glucopyranoside, a “rhamnoside” the 6-deoxy-α-Lmannopyranoside.)
N-Glycosyl derivatives of heterocycles are usually indexed at the heterocycle names (see also Nucleosides and Nucleotides, ¶ 210), but a saccharide containing an expressed aldehyde or higher functional suffix is preferred.
Examples:

NH 2
6

1

N

fructosyl
apiosylD-fructofuranosyl
D-apio-β-D-furanosyl

Note that no assumption is made for fucosyl when the absolute stereo is notindicated.
Glycosyl halides, isocyanates, etc., without functions higher than a polyol
in the unsubstituted saccharide have names containing the “-osyl” radical;
otherwise the heading parent expresses the higher function.
Examples:Glycosylamines are named by similar principles.
Examples:α-D-Glucopyranosylamine

N9

3

5´

4

N

HOCH2

3H-Purin-6-amine, 3-β-D-ribo
furanosyl-

O

4´

1´
2´

3´

HO OH
O
S

α-D-Mannopyranosyl bromide
β-D-Glucopyranuronic acid, 1-chloro-1-deoxy-

7

N

5

N
Me O2 C
HO

O
OH

OH

O

β-D-Galactopyranuronic acid, 1deoxy-1-(2,5-dioxo-3-thiazoli
dinyl)-,
methyl ester¶ 208

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Alditols are polyhydric alcohols derived mainly by reduction of aldehydes.
They are named by changing the suffix “-ose” to “-itol.” Since the end groups
are alike, they are more symmetrical than saccharides; the preferred heading
parent is the one in which the trivial name (or the configurational prefix(erythro, etc.) of a semisystematic name) and then the configurationaldescriptors (D and L) expresses the lowest alphabetic order. Hence Gulitol iscross-referred to Glucitol, and D-glycero-L-gulo is preferred over D-glyceroD-ido. Lowest locants for substituents are considered only after the heading
parent has been determined.
Example:
CH2OH

CH2OH

MeO

C

H

H

C

OH

H

C

OH

HO

C

H

≡

H

C

OH

HO

C

H

HO

C

H

H

C

OMe

CH2 OH

D-Galactitol, 5-O-methyl- (notL-Galactitol, 2-O-methyl-)

CH2 OHThe meso alditols (Ribitol, Xylitol, Allitol, and Galactitol) do not require D or
L unless they are substituted unsymmetrically, in which case the D-form ischosen. Higher chemical functions than the alditol are expressed as
substituents of the alditol parent.
Branched-chain monosaccharides are generally named as derivatives of thelinear saccharides, selecting first the highest function and then the longest
chain, but the trivial name Apiose is used.
Example:
1 CHO

H
5

HOCH 2

2
3

C
C

209. Cyclitols are cycloalkanes in which a hydroxyl group is attached toeach of three or more ring atoms. Cyclitols of the cyclohexane series constitutethe inositols; those that contain at least five asymmetric centers in the ring, of
which at least three are directly bonded to oxygen (or another chalcogen) or
nitrogen, are given Inositol stereoparent names; the others are named
systematically as cyclohexanepolyols. Relative stereochemistry is expressedby special italicized configurational prefixes. The eight Inositol stereoparents,
arranged according to the number and position of hydroxyl groups on the sameside of the cyclohexane ring (as indicated by the numerical locants, which are
not used in indexing) are:
(1,2,3,4,5,6)(1,2,3,4,5)(1,2,3,4)(1,2,3,5)(1,2,4,5)(1,2,3)(1,2,4)(1,3,5)cis-Inositol
epi-Inositol
allo-Inositol
myo-Inositol
muco-Inositol
neo-Inositol
chiro-Inositol
scyllo-Inositol

Choice of a preferred index name for an inositol derivative depends on (a)the alphabetically preferred configurational prefix in the order: allo, chiro, cis,
epi, muco, myo, neo, scyllo; (b) the preferred configurational descriptor (D overL); (c) the lowest set of locants for substituent prefixes (¶ 137). The configurational descriptor D or L may be determined by numbering the hydroxyl groups(or replacement groups) which lie on one side of the ring beginning at eachpossible “position 1.” If the groups, e.g., the 1,2,4-groups in chiro-Inositol, areup when numbering clockwise, or down when numbering counterclock-wise,
the descriptor is L; if the groups are up in numbering counterclockwise or downin numbering clockwise, the descriptor is D. The D-stereoparent is chosen regardless of high locants for substituent prefixes. The D and L descrip-tors areused only when optical activity is present and can be determined from the original document.
Example:D-ApioseOH
CH2 OH

4

HO

1

HO

OH

1

6 OH OH

6

HO

Olefinic monosaccharides are expressed by “en” in the stereoparent.
Destruction of the anomeric center leads to an anhydro unsaturated alditol withthe multiple bond assigned the lowest possible locant after the alphabetic
choice (D before L, α before β) has been made. Geometrical isomerism about adouble bond, when known, is indicated by E and Z descriptors.
Examples:D-threo-Hex-2-enose, 2-(acetyl-

amino)-2,3-dideoxy(2Z)9H-Purin-6-amine, 9-(2,3-dideoxyβ-D-erythro-hex-2-enopyranosyl)D-xylo-Hex-1-enofuranosylamine,

2-deoxy-N-phenylOligosaccharides of known structure are given carbohydrate names which
express the monosaccharide content. The open-chain form is used in naming
reducing oligosaccharides in the absence of anomeric prefixes or contrary
derivative information.
Trisaccharides and higher members are named by use of “arrow” nomenclature, in which arrows and locants indicate the direction and position of linkages from anomeric carbon atoms to hydroxylic carbon atoms. The reducing
monosaccharide unit is named as the stereoparent. Other substituents of theparent are named last.
Examples:Stachyose.

See D-Glucose, 4-O-β-D-galactopyranosylSee α-D-Glucopyranoside, β-D-fructofuranosyl
See D-Glucose, O-β-D-glucopyranosyl-(1→4)-O-β-D-glucopyranosyl-(1→4)See α-D-Glucopyranoside, β-D-fructofuranosyl
O-α-D-galactopyranosyl-(1→6)-O-α-Dgalactopyranosyl-(1→6)-

Polysaccharides are often indexed at common names, e.g., Agar,
Amylopectin, Cellulose, Starch. Homoglycans (polysaccharides derived
from one type of sugar residue) are named by converting the “-ose” suffix ofan aldose or ketose, or the “-ic acid” of a glycuronic acid, to “-an,” e.g., β-DMannan, (1→4)-; L-Arabinan; D-Glucuronan. Heteroglycans contain morethan one kind of saccharide; the name, e.g., Glucuronoarabinoxylan, expresses the saccharide with the higher chemical function first; if the functions arealike, longer chain and then alphabetic order decide. Esters and most otherderivatives are cited in the modification. Synthetic homopolymers andcopolymers are indexed by polymer nomenclature, e.g., L-Arabinose, homopolymer.

OH

OH

OH

Lactose.
Sucrose.
Cellotriose.

86

OH
D-chiro-Inositol

HO
OH

HO
L-chiro-Inositol

Ethers are named as O-derivatives; chalcogen analogs are expressed by“thio,” etc., in the inverted part of the heading. Esters are expressed by modification terms, e.g., “hexaacetate.” Glycosides areindexed at the Inositol
stereoparent with O-glycosyl substituent prefixes. 1,2,3,4,5-Cyclohexanepentols (quercitols) are indexed at the alphabetically preferred Inositol parent byuse of a “deoxy” prefix, and D or L determined as described above, e.g., D-chiro-Inositol, 2-deoxy- (not D-chiro-Inositol, 5-deoxy; not D-muco-Inositol, 2deoxy-; not L-muco-Inositol, 1-deoxy-). Replacement of one, two, or three hydroxyl groups, with retention of configu-ration, is expressed by “deoxy” terms
and appropriate radicals. The capital italic letter C is used to denote replacement of hydrogen on a carbon atom to which a hydroxyl group is also attached,e.g., scyllo-Inositol, 1-C-methyl-.
Inosamines and their N-acyl (including carboxy) derivatives are usually indexed at such names as neo-Inositol, 2-amino-2-deoxy-, but Streptamine is
the stereoparent for 1,3-diamino-1,3-dideoxy-scyllo- inositol and derivatives.
Example:H2NC( =NH)NHNHC ( =NH)NH 2
HO
OH

Streptamine, N,N´-bis(aminoiminomethyl)-

HO
OH

Inosose is the stereoparent for 2,3,4,5,6-pentahydroxycyclohexanone
stereoisomers.
Example:
HO

O
OH

HO

epi-3-Inosose (not muco-3-Inosose)
HO
6
1

HO

87

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

210. Nucleosides and Nucleotides are hydrolytic products of nucleic acids;
chemically, nucleosides are N-glycosyl derivatives of heterocyclic bases,
principally purine and pyrimidine, and nucleotides are esters of nucleosides
with phosphoric acid and polyphosphoric acids.
The bases are named systematically, with the tautomerism resolved forindexing purposes in favor of highest expressed function, etc. (¶ 122).
Trivial Name

Index Name

AdenineCytosine
GuanineHypoxanthine
ThymineUracilXanthine

9H-Purin-6-amine
2(1H)-Pyrimidinone, 4-amino6H-Purin-6-one, 2-amino-1,7-dihydro6H-Purin-6-one, 1,7-dihydro2,4(1H,3H)-Pyrimidinedione, 5-methyl2,4(1H,3H)-Pyrimidinedione
1H-Purine-2,6-dione, 3,7-dihydro-

Example:
O
7

H2N

N

5

HN

N9

4

N
3

Guanosine 3´-(trihydrogen
diphosphate), 2´-deoxy5´-acetate

5´

Trivial names for seven common nucleosides and the related nucleotides
are employed as stereoparents; these nucleosides are:Purine derivatives
Adenosine
Guanosine
InosineXanthosine

Pyrimidine derivatives
Cytidine
Thymidine
Uridine

The seven stereoparents (above) are heading parents for derivatives,
including N-acyl and N-carboxy derivatives, e.g., Adenosine, N-acetyl-; Cytidine, N-(ethoxycarbonyl)-. When a chemical function higher than carboxamide (¶ 106), except N-carboxy, is present, an index parent which expresses it
is chosen, unless lack of a suitable radical precludes expression of the nucleoside residue as a substituent prefix (this occurs when the higher function is attached to the saccharide at any position other than “1´”). Replacement ofoxygen in the saccharide moiety or on the heterocycle by sulfur is expressed bya “thio” prefix, and the regular methods of carbohydrate nomenclature (¶ 208)
are employed for other saccharide modifications, including ester formation
other than phosphates.
Examples:Me 2 N

N
6

1

N

7
5

N
N9

4

N

Adenosine, 3´-(acetylamino)-3´deoxy-N,N-dimethyl-

3
5´

¶ 211

AcOCH2
O

4´

1´
2´

3´

OP(O)(OH)OP(O)(OH)2
P´P

Coenzyme A is employed as a stereoparent for adenosine 5´-(trihydrogen
diphosphate) 3´-(dihydrogen phosphate) P´-[(3R)-hydroxy-4-[[3-[(2-mercaptoethyl)amino]-3-oxopropyl]amino]-2,2-dimethyl-4-oxobutyl ester; functional
derivatives, notably esters such as “S-acetate,” are also indexed at this stereoparent.
Esters and molecular addition compounds of nucleoside and nucleotide
stereoparents, including “-ylic acids,” with nonstereoparents are indexed at thestereoparents regardless of functionality.
Example:Inosine 5´-(trihydrogen diphosphate)2´-(dihydrogen phosphate), P´ → 5´-ester with 3-(aminocarbonyl)-1-β-D-ribofuranosylpyridinium, inner salt
Oligonucleotides contain not more than eight nucleotide units connected byphosphoric acid residues. Higher-molecular-weight compounds are indexed aspolynucleotides (see Polymers ¶ 222) or at the headings DNA or RNA. Phosphate links attached to the preferred stereoparent of an oligonucleotide form
parts of “-ylyl” radical substituents.
The heading parent is attached to the rest of the nucleotide chain at its 5´position. Arrows are employed with locants, as in oligosaccharide nomenclature (¶ 208), to indicate progression and points of attachment on saccharide residues beginning at the end of the chain furthest from the preferred stereoparent.
Esters and substituents of “-ylyl” radicals are named as substituents without regard to higher functions. Nonnucleotidylyl esters of the stereoparent are expressed in the modification. When a cyclic ester is part of the polynucleotide
linkage, the locants for the ester are separated by a hyphen, and the arrow to
the point of attachment follows in the usual way, e.g., Adenylic acid, adenylyl-(2´-3´→5´)-.
Example:

HOCH2
4´

O

NH 2

1´

3´ 2´

1

AcNH OH

7

6

N

5

N

N9

4

N
3

5´

HO(CH2)2OP(O)(OH)OCH2
NHMe
Cl CO( CH2 ) 2

N
6

3

1

N

O

5-Pyrimidinepropanoyl chloride,
1,2-dihydro-4-(methylamino)2-oxo-1-β-D -ribofuranosyl(not Cytidine, 5-(3-chloro-3-oxopropyl)-N-methyl-)

5´

O

1´

O
3´

2´

7

N

O OH
5´

4´

O

5

1
6

NH

9

MeOP(O)OCH2

HOCH2
4´

4´

O

N

4

N
3

NH2

1´

1´

3´

2´

HO

OH

Nucleotides are indexed at stereoparents descriptive of the type andposition of the phosphate residue on the sugar moiety. Esters with phosphoricacid, H3PO4, are “-ylic acid” stereoparents. Each isomer has its own heading,e.g., 5´-Adenylic acid for the 5´-(dihydrogen phosphate) of Adenosine. When
more than one such acid residue is present, the lowest locant is chosen for thestereoparent, e.g., 3´-Adenylic acid, 5´-(dihydrogen phosphate). Cyclic phosphates are expressed in the modification at the nucleoside name by such phrases as “cyclic 3´,5´-(hydrogen phosphate).”Nucleoside esters with unsubstituted linear polyphosphoric acids areindexed at stereoparents which express the complete ester name, e.g.,
Guanosine 3´-(trihydrogen diphosphate). An unspecified isomer is assumed
to be the 5´-isomer. Di- and triesters with the same acid are indexed at the lowest numbered isomer heading. Substituted derivatives and esters with nonphosphorus acids are named like those of the nucleotides.

3´

2´

HO

OH

Guanosine, 5´-0-[hydroxy(2-hydroxyethoxy)phosphinyl]-Pmethyladenylyl-(3´→5´)-Intermolecular cyclic nucleotides are named like the linear compounds, butwith the term “cyclic nucleotide” in the modification.
211. Steroids are cyclopenta[a]phenanthrene derivatives that are indexed
as stereoparents (¶ 202) at trivial names that imply stereochemistry. The
following steroid numbering system is employed:¶ 211

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Me

29

Me
28 CH

21

18

Me
19

11

Me

1

24

20
17

H

25

O

Me

Me

H
H

Br

H
H

8

H

H

O

Me

H

14

10

4

Me

27

Me

26

H 13

9

2

22

Me

88

HO

Spirostan-3-ol, 24-bromo(3β,5β,24R,25R)-(configurations foradded stereochemistry at C-3 andC-24 are indicated: there is no
modified stereochemistry)H

6

When two methyl groups are present at the 4-position, as well as one at the
14-position, along with a 1,5-dimethylhexyl substituent at position 17, thecompound is indexed as a terpene stereoparent (¶ 212); otherwise the steroid or
terpene stereoparent is employed that requires least modification.
The hydrogenated ring system without substituents is Gonane; Estrane hasa methyl group only at the 13-position; the compound with only a 10-methylgroup is named as 18-Norandrostane. The following stereoparents arederivatives of Androstane (hexadecahydro-10,13-dimethyl-1H-cyclopenta[a]phenanthrene) with various side chains at the 17-position:-CH2MePregnane-CHMePr

Cholane-CHMe(CH2)3CHMe2

Cholestane-CHMe(CH2)2CHMeCHMe2

Ergostane-CHMe(CH2)2CHEtCHMe2

Stigmastane

The implied configurations in all cases are 8β,9α,10β,13β,14α. The
configuration at the 5-position, when known, is cited as added stereochemistry
in the modification. Pregnane is 17β; Cholane and Cholestane are 17β,20R;
Ergostane is 17β,20R,24S; Stigmastane is 17β,20R,24R.
Unsaturation in steroids is expressed by “en” and “yn” infixes, e.g.,
Estra-1,3,5(10)-triene; Androst-1-en-16-ol, (5α)-. The first example requires two locants for the last cited double bond; this situation is avoided where
possible, with steroids containing benzenoid rings, by rearrangement of bonds;
e.g., Gona-5,7,9-triene (not Gona-5(10),6,8-triene).
Cyclosteroids contain an additional ring formed by a valence bond between
two existing ring positions or between a ring position and an angular methylgroup or side-chain atom. They are indexed at such stereoparents as 3,5Cyclopregnane and 9,19-Cycloandrostane.
Bufanolide and Cardanolide are stereoparents with a δ-lactone and a γ-lactone ring, respectively, attached to the 17-position of Androstane. The configurations are as for Cholane except for 14β instead of 14α. When a carboxylic
acid or higher function is present the lactone ring is opened and named in themodification.
Example:Elimination of an acyclic carbon atom (or methyl group) from a steroid isexpressed by the prefix “nor” with the locant for the carbon removed; (but21-Norpregnane is indexed at Androstane, 17-methyl-). Elimination of one or
two carbon atoms from the C-17 side chain of C27 and larger steroids may be
expressed by “nor” and “dinor,” unless a smaller stereoparent is thereby
obtained; e.g., 21,27-Dinorcholestan-26-oic acid; 26,27-Dinorcholestane;
but Cholane-24-carboxylic acid (not 26,27-Dinorcholestan-25-oic acid).
Removal of C-18 and C-19 by “nor” terms is independent of treatment of the
C-17 side chain; hence 18,19-Dinorpregnane (not Gonane, 17-ethyl-).
Ring modification expressed by “nor”, “homo” and “seco” are no longer
permitted. Such substances are named systematically.
Replacement (“a”) nomenclature (¶ 127) is no longer used for heterosteroids, e.g., 2-thiaandrostane, and 3-aza-A-homoandrostane, are now given
systematic names.
Steroidal alkaloids containing exocyclic nitrogen are indexed at steroid
stereoparents. Thus Irehine is cross-referred to Pregn-5-en-3-ol, 20-(dimethylamino)-, (3β,20S)-. Kurchi alkaloids are named as derivatives of the stereoparent Conanine; implied configurations are the same as for Pregnane, withthe addition of 20β.
Example:
Me
N

Me
H

H

Me
H

Con-5-enin-3-amine
(3β)-

H

H 2N

The solasodine-tomatidine and solanidine groups of Solanum alkaloids areindexed at Spirosolane and Solanidane stereoparents, respectively.
Example:

H
Me

O

Me

O

N
H

Me
Me
HO2C

H

H
HO

H

24-Norchol-20(22)-ene-19,23-dioic
acid, 3,5,14,21-tetrahydroxyγ-lactone, (3β,5β,14β)-

Furostan is a stereoparent which represents 16β,22-epoxycholestane; thishas a furan ring fused to the steroid system in the 16,17-position. Spirostan isa 16,22:22,26-diepoxycholestane derivative. Configurations at the 5-, 22-, and25-positions of furostan and at the 5- and 25-positions of spirostans are
expressed in the modifications if known.
Examples:CH2 OH
MeMe(CH2)2 C- - H
Me

H
O

H
H

H

H
H

H
HO

H
H

Me

Solanid-5-en-3-ol(3β)-(When C-5 is asymmetric, itsconfiguration, when known, iscited.)

OH

HO

Me

H

Furostan-26-ol(5α,20β,22α,25S)-(configuration at
C-20 is reversed from that shown inthe stereoparent diagram)

Veratrum alkaloids are indexed, according to type, at the stereoparents
Veratraman and Cevane. Buxus alkaloids are indexed at such headings as
9,19-Cyclopregnane.
Radicals derived from steroid stereoparents are employed when the highest
function is present in a nonsteroid part of the molecule (except the esters,
semicarbazones and additional compounds are always indexed at thestereoparents (¶ 202)). Radical names are formed in the usual way, and the freevalency can be at an acyclic atom; e.g., estra-1,3,5(10)-triene-17-yl, cholest-4en-26-yl. No radical names are formed from cardanolides or bufanolides. Configurations are cited ahead of the entire substituted radical; e.g., [(3β,5α)-3-hydroxyandrostan-5-yl]-. For acetals of steroids, see ¶ 202.
Steroids with -O- and -OO- bridges are indexed by use of “epoxy” and“epidioxy” substituents at the stereoparents. Steroid stereoparents may be
adopted as components of spiro systems (¶ 156), e.g., Spiro[androst-4-ene2,1´-cyclopropan]-3-one.
Fused steroid names are used on a restricted basis. The steroid component
is named first when fusion is to a heterocycle; the reverse order occurs with lesspreferred carbocycles. Each system retains its own numbering and thenonsteroid is given primed locants. When saturation is expressed at positions
common to both components, steroid locants are cited if possible.

89

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Examples:
Me
H

Me

H

H

H

3´H-Cyclopropa[2,3]androsta-2,4diene, 2,3-dihydro-, (2α,3α)-

H

¶ 212

Abnormal configurations are expressed by “α” or “β” at angular carbon
atoms in ring systems, and by “R” and “S” when there is inversion on a bridgeor side-chain. Additional stereochemistry produced by substitution is expressed similarly. All terms cited with a stereoparent are considered to be absolute, not relative. The geminate methyl groups of triterpenes have no
implied configuration associated with the locants; “α” or “β” is cited whensubstitution in the methyl groups makes this necessary.
Because lowest locants are assigned to principal groups, in accordance withgeneral systematic nomenclature, the author’s numbering may be changed inindexing, especially with a symmetrical stereoparent such as Gammacerane.
Example:

OH
Me

OH
1

H

Me

Me
H

N

18

N
H

13

H

2´H-Androst-2-eno[3,2-c]pyrazol17-ol,(5α,17β)-

H

Me

29

Me

11

H

H

27

9
Me
8 25

6

10

Me

14

4

Me

24

Me

23

Me

17 H

H

Gammacer-15-en-3-ol,(3β)- (not Gammacer-6-en21-ol, (21α)-)30212. Terpenes contain repeating isopentane units:C( — C - C - C - C— )n

Mono-, sesqui-, di-, sester-, tri-, and tetraterpenes contain two, three, four, five,six, and eight such units; tetraterpenes are usually called carotenes (see below).
Most mono-, sesqui-, and diterpenes are indexed by the principles of systematic substitutive nomenclature; stereoparents are employed for terpenes that
contain four or more rings, or possess three or more elements of stereochemistry, at least one of which is associated with a bridged or side-chain center, or acenter in a ring of twelve or more members.
Examples:“Friedo,” preceded by D, has been used to indicate D:A, D:B, or D:C as
prefixed to pentacyclic triterpene stereoparents that angular methyl groups
have shifted from their normal positions. These names are no longer used, andthese substances are named as derivatives of other triterpenes.
The prefix “neo-” preceded by an italicized capital A indicates that ring A
has undergone a rearrangement. These names are no longer used.
In the gammacerane skeleton, A´-Neo- is used.

H
13

Me

17

21
22

29

CH — Me
Me
28

Me

29

Me
30

30

Me

Cyclohexanol, 3-methyl-2-(1methylethyl)-,(1S,2R,3R)- (o-Neoisomenthol)OH

Me

Bicyclo[3.1.1]heptane, 2,6,6-trimethyl- (Pinane)

1
7

6

Me

27

27

CHMe2

5

Me
1

Me

28

H

Me

22

Me

Me

6

H

18

14

Me

H

19

O

7

Me

Bicyclo[2.2.1]heptan-2-one, 1,7,7trimethyl- (Camphor)

4MeA´ - Neo-

Normal arrangement

The prefix “cyclo” indicates a valence bond forming an extra ring, e.g., in
9,19-Cyclolanostane a “fused” cyclopropane ring is formed.
Principal groups are expressed as “-oic acid,” “-al,” “-one,” “-ol,” etc., by
the procedures of general substitutive nomenclature. Terpene radicals areformed in the usual way. Configurational terms are placed ahead of the complete radical (cf. Steroids, ¶ 211).
Lactones of triterpene acids are indexed at the acid names; cyclic acetals are
likewise expressed in the modification at stereoparent headings.
Carotenoids comprise carotenes (hydrocarbons) and xanthophylls (theiroxygenated derivatives) in which eight isoprene units are joined in such amanner that the arrangement is reversed at the center of the molecule, whereby
the two central substituent methyl groups are in 1,6-relationship and the remaining methyl groups in 1,5-relationship. The class also includes some rearranged and degraded compounds, but excludes Retinol and related C20compounds (see below).
General entries are found at Carotenoids in the General Subject Index.
Specific substances are indexed at Carotene:

H

Me
H

CHMe2

19

16

17

Naphthalene, decahydro-1,6-dimethyl-4-(1-methylethyl)-,(1S,4S,4aS,6S,8aS)- (Cadinane)

20

Me

Me Me

Me

1

15
10
5

Me
18
18´

Me

Me
Me 2CH

H

Me

5´

10´

Naphthalene, decahydro-1,4a-dimethyl-7-(1-methylethyl)-,(1R,4aR,7R,8aS) (Eudesmane)

The stereoparent Trichothecane, a sesquiterpene “epoxide,” is used inindexing, and other derivatives of sesquiterpenes and diterpenes may be usedas stereoparents when they meet the criteria. Gibbane is a partiallystereospecific stereoparent employed in naming gibberellic acid derivatives.
Two tetracyclic diterpene stereoparents are Kaurane and Atisane. Cyclic
triterpenes include Gammacerane, Lanostane, Lupane, Oleanane, andUrsane.

15´

Me
20´

Me
19´

1´

Me Me
16´

17´

Each dotted curved line represents two double bonds or their equivalent; thus,
individual compounds may have acyclic end groups with two double bonds, or
terminal cyclohexenyl groups, or one of each. By extension, Carotene is usedas the stereoparent representing dihydro and tetradehydro derivatives which
possess cyclopentyl and phenyl end-groups. Two Greek letter prefixes on the
Carotene stereoparent, cited in (Greek) alphabetical order, are employed toexpress the terminal structures of specific compounds:¶ 212

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

16

17

Me

Me

1

17

16

Me

Me

R

1

6

17

16

Me

Me

R

R

Me

Me

6

Me

18

18

18

ε

β

Ψ

16

17

Me CH2R
17

Me

5

1

16

Me

Me

6

16

1

Me

6

17

Me

R

Me

Me

Me

R

90

Carotenoids with diosphenol end-groups are indexed as the keto tautomers;e.g., β,β-Carotene-3,3´,4,4´-tetrone. For carotenoids with identical end
groups, lowest locants are assigned to the principal groups, if present, and thento prefixes; e.g., ε,ε-Carotene-2,3´-dione, 2´-methoxy- (not ε,ε-Carotene2´,3-dione, 2-methoxy-).
“Retro” carotenes have undergone a shift of the alternating single-doublebond system by one position. A prefix such as “4,7´-retro-” is applied to thestereoparent to express this situation; the first cited locant shows where a
proton has been gained, the second, where a proton has been lost.
“Apo” carotenes names are no longer used. Oxidative degradation productsof carotenes are named at retinol, retinoic acid, etc., or systematically.
Stereochemistry of carotenoids is of two types. The geometricalconfiguration around double bonds is implied by the stereoparent stem
Carotene to be all-trans. Abnormal configuration at one or more positions isindicated in the modification by terms such as “15-cis-.” Absolute configuration at chiral centers is expressed by “R” or “S.”Example:

18
18

18

ϕ

κ

α-Carotene is indexed at β,ε-Carotene, β-carotene is β,β-Carotene; γ-carotene is β,Ψ-Carotene; and lycopene is Ψ,Ψ-Carotene. The plain (unprimed)
locants are assigned to the end of the molecule related to the first-cited Greek
letter.
“Hydro” and “dehydro” express addition and subtraction of hydrogen;oxygen functions are expressed by “-oic acid,” “-al,” “-one,” “-ol,” etc., in theusual way. Oxygen bridges are indicated by “epoxy,” it being understood thatthe oxygen replaces one hydrogen atom at each bridgehead; thus, an “epoxide”
is an epoxy-dihydro derivative.
Example:

16

17

Me

Me

1
6

HO

7

19

20

Me

Me

Me

6
5

1

20

Me

Me
15

11

O
16
Me

χ

19

10

Me
18

17

OH
OH

17´

18´

Me

1´
6´

Me

Me
16´

O

15´

Me

Me

20´

19´

κ,κ-Carotene-6,6´-dione, 3,3´-dihydroxy-,(3S,3´S,5R,5´R)15

11

O

Retinol and its relatives are indexed at stereoparent headings.

5

Me
18

Me

OH

5´

O
7´

11´

15´

Me

Me

20´

19´

Me
18´

17

Me

16
1

6

1´

Me
17´

20

Me

CH=CHC=CHCH=CHC=CHCH2OH
7

6´

19

Me

Me
11

15

Me
18

Retinol (stereoparent)
β,β-Carotene-3,3´-diol, 5,6:5´,6´-diepoxy-5,5´,6,6´-tetrahydroAddition of water (H, OH) or methanol (H, OCH3) to a double bond isexpressed by “dihydro-hydroxy” and “dihydro-methoxy.” When the “-ol” suffix can be used only for some of the hydroxy groups, the “dihydro-hydroxy”
method is employed for all.

Illustrative diagrams for Retinol and Retinoic acid appear in the Chemical
Substance Index. Vitamin A1 is indexed at Retinol; Vitamin A2 at Retinol,
3,4-didehydro-. The hydrocarbon “Retin” is used as a stereoparent, as well.
The all-trans configuration is assumed; if abnormal stereochemistry is reported, it is expressed in the modification by terms such as “13-cis-”.

91

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 215

F. SPECIALIZED SUBSTANCES

Introduction
AlloysCoordination compounds
Dyes
Elementary particles
Enzymes

¶ 213
214
215
216
217
218

213. Introduction. The special classes of chemical substances discussed
in this section exclude those natural products and their derivatives, largely indexed at stereoparents, which were the subject of the previous section. The
topics covered here fall into three groups: inorganic (alloys, coordination compounds, elementary particles, and general inorganic compounds); biological(enzymes, porphyrins and bile pigments, and vitamins); and special subjects
not chemically related to any particular class (dyes, isotopes, mixtures, andpolymers). The arrangement is alphabetic.
214. Alloys, including those with nonmetallic and gaseous components, areindexed and registered by CAS as specific chemical substances. The percentage composition is expressed in the modification in descending order of abundance of metals, either as individual round numbers or as ranges. Components
present in amounts below 0.1% are generally ignored. The metal in greatest
amount is indexed at an “element alloy base” heading parent.
Example (an alloy of 69.93% copper, 17.45% nickel, 10.29% aluminum,
1.50% cobalt, 0.83% iron):
Copper alloy, baseCu 70,Ni 17,Al 10,Co 1.5,Fe 0.8
Binary alloys of 50-50% composition are indexed at the base heading forthe metal with the earliest alphabetical element symbol.
If ranges, rather than specific compositions, are supplied in the original document for all or some components, they are cited thus: Cu 68-73,Ni 16-18,Al
9-10,Co 1-2,Fe 0.7-1. Alloys of unknown percentage composition are enteredonly at nonbase headings, unless the base component is known.
Example (An alloy of iron and thulium, base component unknown):
Iron alloy, nonbase
Fe,Tm
The symbols are cited in alphabetical order, except that the base element isplaced first if known; e.g., Al,Co,Fe,Ni or (for a cobalt base alloy) Co,Al,Fe,Ni.
Alloys with trade names or code designations (other than standards) sometimes vary in reported composition; therefore, the numerical values are omitted
from the entries. The base metal symbol is placed first and the others in alphabetical order; finally, the trade name or code designation is cited in parentheses.
If only the base metal is known, the parenthetical expression alone is cited in
the modification.
Examples:Copper alloy, base
Cu,Fe,Ni (Cunife I)
Nickel alloy, base
(Permalloy)
Numerical values are included in entries for trade-named alloys of fixedcomposition and for those identified by the following U.S. standards: AA, AISI, AMS, ASTM, AWS, CDA, SAE, and UNS. The international standards of
ISO and the standards of most other countries are also recognized for the purpose of CA indexing of alloys.
Cermets are alloys containing nonmetals. They are indexed at metal alloy
headings or at nonmetal headings with “alloy” in the modification dependingon the composition.
Example (a cermet containing tungsten carbide (WC) 94%, cobalt 6%):Tungsten carbide (WC)alloy, WC 94,Co 6
Alloys containing gases (0.1% or more) are indexed similarly.
Example:Nickel alloy, baseNi 99,H 1
Steel is a heading parent for iron-carbon alloys so described and either containing a minimum of 97% iron or having no disclosed compositions. The steel
composition or a designation (such as AISI 1017) which implies the composition is cited in the modification.

Inorganic compounds
Isotopes
Mixtures
Polymers
Porphyrins and Bile pigments
Vitamins

¶ 219
220
221
222
223
224

Examples:Steel(AISI 1017)
Steel
Fe 98,Mn 1.5,Si 0.5,C 0.1
Isotopically labeled alloys are distinguished by the mass number on the element symbol.
Example:Aluminum alloy, baseAl 95,235U 5
215. Coordination compounds are molecules or ions in which a central
atom (in polynuclear compounds, more than one) has atoms or groups of atoms, called ligands, attached to it to the extent of its coordination valency. The
central atom may be of any element, but it is usually a metal atom. The metals
comprise all elements except the following: Ar, As, At, B, Br, C, Cl, F, He, H,
I, Kr, Ne, N, O, P, Rn, Se, Si, S, Te, Xe. (Prior to CA Volume 95 (see ¶ 101),
antimony was also indexed as a nonmetal.) Compounds of nonmetals are generally not indexed as coordination compounds, but there are several exceptions, e.g., tetra- and hexavalent sulfur compounds (¶ 200), and borates
containing ligands other than oxo and hydroxy. Hydride derivatives of antimony, bismuth, germanium, tin, and lead are not named as coordination compounds, but rather as covalent derivatives of the hydride heading parents, e.g.,
Stibine, Germane (¶¶ 181, 199).
A ligand is any atom or group of atoms, charged or neutral, that is attachedto the central atom of a coordination complex. The atoms of a ligand that are
attached to the central atom are called coordinating atoms regardless of the typeof bonding involved. A ligand with more than one coordinating site is
described as multidentate; when more than one such site is engaged with asingle central atom, it is a chelate ligand; when it is coordinated with two or
more central atoms it is a bridging ligand.
Neutral compounds with monoatomic ligands (except hydride) and mononuclear carbonyls and nitrosyls are given binary salt names. Common oligomeric salts are named in the monomeric form, e.g., Aluminum chloride(AlCl3), but studies of the dimers, etc., are indexed at the oligomeric names,e.g., Aluminum, di-µ-chlorotetrachlorodi-.
Coordination compounds may be anionic, neutral, or cationic, in accordance with the oxidation state of the central atom and the number and nature of
the ligands; when the latter are derived from the molecular skeletons of substitutive nomenclature, including nonmetal hydrides, by loss of hydrogen, they
are considered negative in computing the total charge of the complexes containing them. This charge is expressed by a Ewens-Bassett number, e.g., (3+)
or (2−), placed after the heading parent derived from the name of the central
element; thus, Copper(1+), Borate(2−). Absence of a Ewens-Bassett number
indicates that the complex expressed by the complete boldface heading is neutral. Ligands are cited in alphabetical order and their ligating atoms are identified by a modification of the Kappa system1. The periodic table symbol of theligated atom is stated as an italic capital-letter locant preceeded by the greek
letter kappa, e. g. κN, κO1, κS1. These letter locants are placed at the portionof the name corresponding to their attachment on the coordination center. Letter locants are not cited with (a) regular substituent prefixes, e.g., methoxy,
phenyl, 2-pyridinyl; (b) other sigma-bonded ligands in which hetero atoms areeither absent or uninvolved in the coordination; (c) monoatomic ligands, e.g.,hydro, iodo; (d) ligands with unspecified bonding; (e) neutral and monoanionicorganic ligands derived from cyclic or acyclic compounds containing only one
hetero atom capable of coordination, e.g., triethyl phosphine, pyridine, N,Ndimethylmethanamine, N-methylmethanaminato, provided that the hetero
atom is coordinated but no carbon atom is also bonded; (f) the following simple
polyatomic inorganic ligands: amido, ammine, aqua, selenyl, telluryl, hydroxy, imido, mercapto, phosphino, and (except sometimes when present as
bridges) azido, carbonyl, dinitrogen, dioxygen, nitrosyl, peroxy, and carbonothioyl.
1IUPAC, Nomenclature of Inorganic Chemistry, Recommendations 1990,
Blackwell Scientific Publications, Oxford (England), 1990.

¶ 215

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

The preferred Chemical Substance and Formula Index entries for coordination compounds are made at the central element names (or the derived “-ate”
names) as discussed above.

Examples (letter locants are added to many of these names in particular coordination names; e.g., (acetato-κO,κO′)):
−O

2C

−

(carboxylato) (this is an exception:
not [carboxylato(2−)])

Example:Cobalt(1+), (5,12-dimethyl-1,4,8,11-tetraazacyclotetradeca4,11-diene-κN1,κN4,κN8,κN11)-,(SP-4-1)-, [131154-44-4]
Me
H
N

N
Co+
N
H

N

AcO−

− CH

(acetato)

2 CO 2−[acetato(2−)]

Ph 2 ( O ) P−

(diphenylphosphinyl)

Ph 2 P( O ) O −(diphenylphosphinito)

O-

Me

Cationic complexes are highest in order of precedence (¶ 106) among coordination compounds. (A positive element heading, e.g., Phosphorus(1+), is
ranked just above the corresponding “-onium” heading, e.g., Phosphonium.)
Neutral complexes are lower in the order of precedence, followed by anioniccoordination compounds. For mixed polynuclear complexes, the preferred element (or derived “-ate”) heading is that appearing earliest in the following list:
Rn, Xe, Kr, Ar, Ne, He, Fr, Cs, Rb, K, Na, Li, H, Ra, Ba, Sr, Ca, Mg, Be, (Lrto Ac), (Lu to La), Y, Sc, Hf, Zr, Ti, Ta, Nb, V, W, Mo, Cr, Re, Tc, Mn, Os,
Ru, Fe, Ir, Rh, Co, Pt, Pd, Ni, Au, Ag, Cu, Hg, Cd, Zn, Tl, In, Ga, Al, B, Pb,
Sn, Ge, Si, C, Bi, Sb, As, P, N, Po, Te, Se, S, O, At, I, Br, Cl, F.
Many ligand names correspond to those of the substituent prefixes of general nomenclature. They include hydro, chloro (etc.), oxo, thioxo, hydroxy,
mercapto, peroxy, diazenyl, and sulfo. Among ligand names which differ are
the following: superoxido (O2−), amido (H2N−), imido (HN=), chloramido(ClHN−), nitrido (N≡), phosphido (P≡), arsenido (As≡).
“Ato” ligand names are employed to express loss of hydrogen from inorganic “oxo” acids named as “-ic acids” and their chalcogen analogs. Those
named as “-ous acids” correspondingly afford “-ito” ligands. Loss of one, two,etc., protons from polybasic acids is expressed by Ewens-Bassett numbers(loss of one hydrogen atom from most other classes of compounds is denoted
simply by omission of a Ewens-Bassett number). Letter locants (see above) aresometimes employed. “Ato” and “ito” ligand names are always placed in enclosing marks.
Examples:− O −PF (O )−O −[phosphorofluoridato(2−)]

O 3 C lO −(perchlorato)−

OSO2O−[sulfato(2−)]−

O S (O )O −[sulfito(2−)]

O 2 N−(nitrito-κN) (not nitro)− O =N O −(nitrito-κO) (not nitrito)− O −N =N −O −[hyponitrito(2−)]

O P(O − ) 3[phosphato(3−)]−

92[1,2-benzenediolato(2−)]
O−O

2 C( CH 2 ) 3 CO 2−[pentanedioato(2−)]

A c O ( CH 2 ) 2 O −(2-hydroxyethyl acetato) (an ester isnamed in its uninverted form)

M e O−S( O ) 2 −O −(monomethyl sulfato) (derived frommethyl hydrogen sulfate)(methyl glycinate) (derived fromglycine methyl ester)

H 2 N− CH 2 CO 2 M e

Metal radical names (¶ 194) such as aluminio, aurio, and sodio, are used in
the presence of higher compound classes or more preferred metals when themetal replaces a single hydrogen, but not to “place” a metal directly on anothermetal (see polynuclear complexes, below); e.g., Ethyl, 2-sodio- (a free-radical
name); Potassium, (5-lithio-1-naphthalenyl)-. Because metal radicals carryno implication of valency, hydrogen and other attached atoms and groups must
be expressed, e.g., dihydroaluminio for H2Al−.
π-bonded ligands, and ligands attached to metal atoms by both π and σbonds, are named by prefixing the Greek letter η (eta) or by using a combination of η and κ treatments. (Delocalized bonds are “fixed” for the purpose ofnaming the ligand so that lowest locants are given first to the point of attachment, then for unsaturation, etc.) Locants (if available) for atoms contributing
to the ligand-metal bonding are cited ahead of “η” and the entire descriptor soformed is enclosed in parentheses; alternatively, if all the skeletal atoms of an
unsubstituted conjugated acyclic or cyclic molecule or radical are involved, asuperscript denoting the number of such atoms is cited immediately after “η”
and the locants are omitted. Ligands with negative charges on adjacent hetero
atoms are named instead as the neutral unsaturated compounds. σ-bonded
ligands are named as regular radicals, e.g., 2,4-cyclopentadien-1-yl. (Thename cyclopentadienyl is used without locants in the absence of further information.)
Examples:The following cyanato radicals are employed:−OCN−(cyanato-κN) (not isocyanato)[(1,2,3-η)-2,4-cyclopentadien-1-yl]

−

−NCO−

(cyanato-κO) (not cyanato)
and similarly for thiocyanato, etc. Oxo acids which require synonym line formulas at their own heading parents are given more specific names when converted into ligands, e.g., [monothiosulfato(2−)], [trimetaborato(3−)].
Anionic carbon-attached ligands containing no anionic hetero atom attachments to the metal, and acyl ligands containing no anionic hetero atom attachments except for the acyl portion, are given names identical with those of
normal substituent prefixes, e.g., ethyl, 2-pyridinyl, 1H-imidazol-2-yl, (phenylsulfonyl). Phosphino, phosphinyl, and (2-phenyldiazenyl) radicals are also
used. Anionic ligands derived from heterocycles by loss of a proton only froma hetero atom in the ring, and containing no additional hetero atoms in the ringor substituents, are also named by substituent prefixes, e.g., 1-piperidinyl. Allother anionic heterocyclic ligands are given “ato” names; they include porphines, phthalocyanines, corrins, other heterocycles containing rings of morethan ten members, and heterocyclic ligands containing more than one hetero
atom (including substituents). Unsubstituted phenoxy and methoxy through(dodecyloxy) radicals are used to express these ligands, but the chalcogen analogs and the substituted oxy radicals are named (1-chloromethanolato), (2propanolato) (not (1-methylethoxy)), (ethanethiolato), etc. Organic “-ic acids”
and organophosphorus acids afford ligand names in which “-ic acid” or “-ousacid” is replaced by “-ato” or “-ito”, respectively. Ligands from esters are
named in uninverted form. The “ato” suffix denotes loss of one proton in allcases unless a Ewens-Bassett number, e.g., “(2−),” is cited.

(η5-2,4-cyclopentadien-1-yl)

−

CH 2

(η3-2-propen-1-yl)

HC − —
CH 2[(1,2,3,3a-η)-azulene]M93

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007[(1,2,3-η)-4-oxo-2-cyclohexen-1-yl]-

− —

−CN

NC −
−

O

Fe
− CN

(The choice is based on the preferred parent radical; the locants“α,1,2-” cannot be used because“α-” does not relate to the parent
radical.)

O

O

Me
CH

−

CN

(η

CH 2
-

Ο

− −
O +O
2

Cu

E t O2 C− N N−[(1,2,3-η)-4-ethoxy-1-methyl-4oxo-2-buten-1-yl]

HC − —

2+• 2 Ν Η 4 + • Cu

2+

NC

3-2-methylene-6-oxocyclohexyl)

−
CN

¶ 215

Ferrate(4−), hexakis(cyano-κC)-,
ammonium copper(2+) (1:2:1),(OC-6-11)- (Note that the ratio isexpressed in the same order as theindex name, i.e., first the heading,then the modification terms.)

Cuprate(2−), [[1,1′-diethyl 2,2′[1,2-ethanediylbis[(imino-κN)methylidyne]]bis[propanedioato3
CO 2 E t • 2 Κ+ κO ]](4-)]-, potassium (1:2) (Notethat ring systems formed entirely bycoordination are not recognizedas such in index names.)

HC—CO 2Et

In polynuclear compounds (see below) a colon partitions the locants into
sets to indicate bonding to different metal atoms.
Examples:
H 2C

CH 2

−
M′— C

−
C —M

H2C

CH 2

[µ-[(η3:η3)-2,3-bis(methylene)-1,4butanediyl]][µ-[(1,2-η:2,3-η)-1,2-propadiene]]

When more than one complex anion is present, the choice is determined
first by the preferred central element (see above); then by the highest numericalvalue, e.g., Antimonate(3−) is preferred over Antimonate(1−); finally, by theearliest index position of the entire entry.
Example:

CH 2

−
Br
Br −

Cationic molecules (¶ 184) are named in the unchanged (but uninverted)
form when present as ligands, except that a Ewens-Bassett number denotes the
charge when necessary; e.g., oxonium, [hydrazinium(1+)], [hydrazinium(2+)],(1-methyl-4-aza-1-azoniabicyclo[2.2.2]octane). When protons have been lostfrom hetero atoms of such ligands, “ato” names are used.
Example:−N H

Cobalt(3+), hexaammine-,(OC-6-11)-, lithium (OC-611)-hexakis(cyano-κC)ferrate(4−)(8:4:7)

L i 4 [ Co ( N H 3 ) 6 ] 8 [ Fe ( CN ) 6 ] 7

CH 2
M ′ — C− — M

Anionic mononuclear complexes which contain simple anions as well as
simple cations are named at the complex anion heading, as shown above. The
cations are named in the modification, followed by the simple anions. Thus
Borate(1−), tetrahydro-, europium(2+) bromide (1:1:1). When a complex
or organic cation is present, this receives the preferred entry.
Example:

Br

−

Br

Sb 3+
Br −

Br −

(C H 2 ) 2 O −Enclosing marks are used with all “ato” ligand names and with ligands, like(cyano-κC), that have letter locants; “bis,” etc., (rather than “di,” etc.) are used
to indicate two or more, e.g., bis(benzoato). When a Ewens-Bassett number isalso present, the “ato” name is bracketed, e.g., [tetrahydroborato(1−)]. Whensuch a ligand name includes a multiplicative radical (¶ 125), it is closed off andfollowed by the Ewens-Bassett number, which in this case may be (1−), and thetotal name bracketed.
Example:Br− −OH −
O
O

O

−

−O

O

Ge 4+

P
O

• Na + • 2 H +

P
−

O−

O

Germanate(3−), hydroxybis[phosphato(3−)-κO, κO′]-,sodium hydrogen (1:1:2)
SO3-[[2,2′-[1,3-propanediylbis(nitrilomethylidyne)]bis[phenolato]](1−)]
Ligands from dioximes, trihydrazones, etc., are expressed by enclosing thename and then citing the Ewens-Bassett number (which may be (1−) in thiscase also) to indicate the number of protons lost; e.g., [(2,3-butanedione dioximato)(1−)].
Neutral ligands are enclosed by parentheses or brackets (as required), except for ammine, aqua, carbonyl, and nitrosyl, e.g., (dinitrogen), (phosphine),(benzene); they are multiplied by “bis,” “tris,” etc.
Anionic mononuclear complexes are indexed at “-ate” headings derived
from the name of the central element, e.g., Borate, Cuprate. The total chargeof the complex anion is cited by a Ewens-Bassett number, and in the inverted
part of the name the ligands are cited in alphabetical order. All cations are
named in the modification in alphabetical order, except that hydrogen is placed
last. Ratios are employed for all univalent and multivalent cations. For metals
of variable valency, Ewens-Bassett numbers are cited after their names.
Examples:-F

FAl 3+-FFF-• Η +• 2Νa +• 4ΝΗ 4+−Complexes that contain ligands with uncoordinated acid functions, e.g.,
carboxylic acids or inorganic oxo acids, are named as though all acidic protons
were dissociated from the uncoordinated groups; the cations and acid hydrogens are then cited in the modification.
Examples:C H =N (CH 2 ) 3 N= CH

F-

Br

−

−

Antimonate(3−), hexabromo-,(OC-6-11)-, ammonium (OC-611)-hexabromoantimonate(1−)(1:4:1)

−O

OH

−

Br

Br −

[1-(2-hydroxyethyl)-1,1-dimethylhydraziniumato(2−)]

Me 2 N +

Br

Sb 5+

•

Br −

−

Aluminate(3−), hexafluoro-,
sodium hydrogen (1:2:1),(OC-6-11)(For the significance of the final
term, see ¶ 203III.)

1

O3S

27

N

25a
21a
21
20 N
19
18a

26

N

N

30

2+

Cu
- 31
N 32 N
14

N

O3S

4a
5
6

N

• 4

7
12

13

-

28a
28
- 29

Νa +

7a

SO3

Cuprate(4−), [29H,31H-phthalocyanine-2, 9,16,23-tetrasulfonato(6−)-κN29,κN30,κN31,κN32]-,
sodium (1:4), (SP-4-1)- (notCopper, [29H,31H-phthalocyanine2,9,16,23-tetrasulfonato(2−)κN29,κN30,κN31,κN32]-,
tetrasodium salt)

Cationic mononuclear complexes are indexed at the central element nameswith a Ewens-Bassett number to indicate the total charge on the cation. The
ligands are cited in the inverted part of the heading in alphabetical order, theassociated anions (if any) in the modification; ion terms, e.g., “ion(1+),” are notcited. Ratios are used with all anions (both univalent and multivalent) and with
mixtures of anions and cations, the first numeral relating to the heading cation,
the others to the modification terms in sequence. The Formula Index headings¶ 215

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

exclude the atoms expressed by modification terms.
Example:

C−
O−

N

N

Me
3

Co

•

N

−

O

−CN

NC −

Me

3+

N

Me

Fe

−
NC

HC

−
CN
3+

− CN

Me

Me 3+P

Cobalt(3+), hexaammine-,(OC-6-11)-, lithium hydrogen(OC-6-11)-hexakis(cyanoκC)ferrate(4−) (8:2:2:7)

When more than one complex cation is present in a compound, the choiceof preferred index entry is based on the nature of the central atom (see above
for precedence list of elements), e.g., the heading parent Platinum(2+) is preferred over Palladium(3+). If the elements are alike, the complex with thehigher positive charge is preferred.
Example:
H2
N
+

Pt 2

H2C

N
H2

N
H2

CH 2

H2 C

CH 2

H2C

H2
N

Cl −

H2
N

+

Pt 4
N
H2

Cl −

N
H2

CH 2
CH 2

• 4 ClO 4 −Platinum(2+), bis(1,2-ethanediamine-κN1,κN2)-, (SP-4-1)-, dichlorobis(1,2-ethanediamineκN1,κN2)platinum(2+)
perchlorate (1:1:4)

C≡O
C≡ O

N

• ClO 4−

+

B 3
− −
O

Metallocenes (dicyclopentadienyl metal complexes in which all carbon atoms of the cyclopentadiene rings contribute to the metal-ligand bondings) areindexed at the parents Ferrocene, Nickelocene, Cobaltocene, Osmocene,
Ruthenocene, etc.
Example:
Cl

Cl
−

Fe

2+

F
−

O

Copper, bis[4-fluoro-2-(hydroxyκO)benzaldehydato-κO]-

O
Cu 2

O

+

O

Ferrocene, 1,1′-dichloro-−

When additional ligands or ring systems more complex than cyclopentadiene are present, the compounds are indexed at the names of the central metals.
All positions of each cyclopentadiene ring are considered equivalent, and substituents are assigned lowest locants without regard to attachment of the metal.
In order of precedence, metallocenes are ranked with the neutral coordination
complexes (¶ 106), Ferrocene, for example, being placed just below Iron as
an index parent. Radical names, e.g., ferrocenyl, 1,1′-ferrocenediyl, can beformed.
Example:
CH 3

|

2+

−

Fe

Neutral mononuclear coordination complexes are indexed at the central element names without a Ewens-Bassett number.
Example:−Boron(1+), (2,2′-bipyridine-κN1,κN1′)(oxydi-2,1-phenylene)-, (T-4)-,
perchlorate (1:1)

N

−

F

CH

Η
C

Mn +

CH
Ph

Cationic complexes containing both complex mononuclear cations andsimple cations are indexed at the names of the former; associated complex anions are also indexed as usual.
Example:H2
N−

Cobalt(1+), bis[[(2,3-butanedione
di(oximato-κN)](1−)]bis(methanamine)-,(OC-6-11)-, (OC-6-11)-hexakis(cyano-κC)ferrate(3−) (3:1)

L i 2 H 2 [C o(N H 3 ) 6 ] 8 [ Fe ( CN) 6 ] 7

Η
C

−
CN

OH
MeN H 2

H2C

Manganese, dicarbonyl[(1,2,3,4,5-η)1-methyl-2,4-cyclopentadien-1-yl][phenyl(trimethylphosphonio)
methyl]-Me

MeN H 2
HO

94

C
O
HgCl

Mercury, [2-(acetyl-κO)ferrocenylκC]chloroSuffixes are not attached to metallocene heading parents, and conjunctive
names are not derived from them; thus, Ferrocene, carboxy- (not Ferrocenecarboyxlic acid); Ferrocene, 1,1′-bis(carboxymethyl)- (not 1,1′-Ferrocenediacetic acid). Bridged derivatives are named by use of bivalent substituent
prefixes.
Example:−Neutral complexes with internal charge compensation, e.g., with ligands
which are inner salts, etc., are named according to structures provided in theoriginal documents.
Example:2+

Fe

Ferrocene, 1,1′:3,3′-bis(1,3propanediyl)-

−

CH 3
N
H 2C

Iron, trichloro(1-methyl-4-aza-1azoniabicyclo[2.2.2]octane-κN4)-

+

CH 2

CH2

The cationic analog of Ferrocene is named Ferrocenium.
Example:−−CH 2 CH 2

H 2C

N
Fe
−C l

Cl −

H
C−
C
O

C
2+

O

Cu
H 2O O H 2

+

2+

+

Fe 3

Fe3

−

−

1,1′′:1′,1′′′-Biferrocenium(2+)

Cl−

SO 3

−

Copper, diaqua[4-[1,3-di(oxo-κO)3-phenylpropyl]benzenesulfonato(2−)]-Polynuclear coordination complexes may have (a) direct linkages between
the central metal atoms; (b) bridging ligands connecting them; (c) both kindsof linkages. A bridging ligand is designated by the Greek letter µ (mu); when
it binds more than two central atoms, a subscript is cited with it, e.g., µ3. Whenthe ligand name itself requires enclosing marks, an extra set is employed forthe µ-ligand, otherwise none are used; e.g., µ-chloro, [µ-(acetato-κO:κO′)]. Aµ-ligand is cited just ahead of the same ligand without the prefix, disregarding

95

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

in the ordering process any accompanying letter locants, e.g., [µ-(acetatoκO:κO′)] (acetato-κO). Colons within letter-locant sets indicate the distribution of bonds from a bridging ligand to individual metal atoms.
Bridging ligands are not treated as multiplying radicals; i.e., the total of
nonbridging ligands on all nuclear atoms is indicated directly. The number ofnuclear atoms is indicated, after citation of all ligands, by “di,” “tri,” etc. Letter-locant sets are partitioned by colons. The cyclic structure of an oligomericcomplex is indicated by “cyclo” as the first term in the modification. Direct
linkages between like or unlike metals are always indicated, if known, by suchterms as “(Fe-Fe)” or “(Co-Re),” whether or not bridging ligands are present.
(In more complicated cases the total number of various bondings is expressedin terms such as “(3Co-Co)(3Co-Fe).”) For “cluster” compounds, in which
three or more central atoms form a core, the geometrical descriptors triangulo,
tetrahedro, or octahedro are assigned if the information is available. The term
cluster is used for 13 or more direct metal linkages.
The entry is made at the name (or derived “-ate” term) of the preferred metal, e.g., Cobalt, Cobalt(2+), Cobaltate(1−); other metals with their associatedligands are named as complex ligands of the preferred atom(s). These complex
ligands are placed in a single alphabetical sequence with bridging and nonbridging ligands bonded to the preferred metal. (Metal radicals, e.g., cobaltio,
mercurio, are not used in naming polynuclear complexes.)
Examples:
Et
CO
S
− +
O C —Fe — Fe—C O
−
S
CO
OC
Et
OC

Iron, hexacarbonylbis[µ-(ethanethiolato)]di-,(Fe-Fe)

+

CO
o

OC
OC

CH = CHCO

o

Mn

CO
CO

Cr

OC

Chromium, tricarbonyl[µ-[(1,2,3,4,5η)-1-[1-oxo-3-(η6-phenyl)-2propen-1-yl]-2,4-cyclopentadien1-yl]](tricarbonylmanganese)-

A polynuclear coordination complex of known formula but unknown structure is indexed at the heading parent for the most preferred central element (orits “-ate” term). The ligands are cited in the inverted part of the heading in alphabetical order, followed by the less preferred metals (or their “-ate” terms)
in descending order of precedence.
Examples:Titanium, dichlorodiethyldihydroxy(aluminum)-

A lT iCl 2 E t 2 ( O H ) 2[ A g A u Cl 6 ] 2 −Aurate(2−), hexachloroargentate-[ N b 6 O 3 ( SO 4 ) 1 2 ] 8 −Niobate(8−), trioxododecakis[sulfato(2−)]hexa-[ Cu 4 ( O H ) 5 [ N [ ( CH 2 ) 2 O H ] 3 ] 4 ] 3 +SO 3 H

Me
• Na

N =N
(MeH g) 4 S

CO

CO

OC
Mn

CO
CO

CO

0

0

Ir

Ir
0

H 2N
Pd

CO
CO
CO

Iridium, dodecacarbonyltetra-,tetrahedro

0

OC Ir
OC
OC

H 2N

Chromate(1−), pentacarbonyl(pentacarbonylmanganate)-,(Cr-Mn)(Note: The “-ate” ending is used in
all central atoms names in anioniccomplexes)

CO

OC

OC
OC
OC

CO

−
Cr

0

OC

Ir
CO

CO
CO

NH 2
S − 2+ − S
NiPd• 2 Cl −S− −S
NH2Palladium(2+), tetrakis[µ-[2(amino-κN)ethanethiolato-κS:κS]](nickel)di, chloride (1:2)

Polynuclear complexes with extended structures caused by bridging
ligands are indexed at monomer headings, with a modification term such as“homopolymer.” Bridging ligands within the monomeric unit are named as
usual, but those which bind the units to one another are not named by use of the“µ” prefix.
Examples:
Cl−
2+

Cu
Cl

O−

Cl− • Cs+−

Cuprate(1−), trichloro-, cesium(1:1),
homopolymer

x

CH 2

O−

+

Cu 2

O CH

HC= O

Copper, [5-[(3-formyl-4-hydroxyphenyl)methyl]-2-(hydroxy-κO)x
benzaldehydato(2-)-κO]-,
homopolymer

Copper(3+), pentahydroxytetrakis[2,2′,2′′-nitrilotris[ethanol]]tetra-

216. Dyes of established structure are indexed at their systematic names by
the regular rules of substitutive nomenclature. The Colour Index2 is employed
as the chief reference source for the chemical constitution of trade-named dyes.
A dye of unknown structure is indexed at the C.I. name if this is available,
otherwise only at a trade name or other designation used in the original document. When the Colour Index shows an indefinite structure, the systematicname is still used if this can be done by omission of one or more locants or byuse of alternative locants, e.g., “5(or 6)-chloro-.”Example:Mercury(2+), tetramethyl-µ4-thioxotetra-

2+

¶ 216

HO

2-Naphthalenesulfonic acid, 6-hydroxy5-[2-(methylphenyl)diazenyl]sodium salt (1:1) (cross-reference
at C.I. Acid Orange 16)

Deliberate mixtures (¶ 221) of dyes with known structures are indexed ateach component with a “mixt. with” modification. Reaction products are notconsidered to be deliberate mixtures.
When an author supplies a structure for a trade-named dye which has been
assigned a C.I. name but no constitution in the Colour Index, an entry will befound at the systematic name for the author’s structures, and a separate entry,
in the Chemical Substance Index only, at the C.I. name. The cross-reference
continues to be based on Colour Index information; i.e., it runs from the tradename to the C.I. name as usual. If a trade name (or common name) is not listed
in the Colour Index, the author’s information (a C.I. number or name, or astructure) is used to make the index entry, cross-references and synonym.
Cyanine dyes (methines) are indexed systematically. Because the locationof the charge may be shown differently in different documents, the preferredring system (¶ 138) is selected as the site of the quaternized center in every caseand, if further criteria are needed, the structure named is chosen to conform to
the principles of maximum number of substituents, lowest locants, and earliest
index position.
Example (name in original document: 3′-ethyl-3-methyl-8-phenoxythiacarbocyanine iodide):

CHCH

S

Ph O
|
C

S

+N
Me

N
Et
I−

Benzothiazolium, 2-[3-(3-ethyl-2(3H)-benzothiazolylidene)-1phenoxy-1-propen-1-yl]-3-methyl-,
iodide (1:1)

2Colour Index, Society of Dyers and Colourists, Bradford, Yorkshire; andAmerican Society of Textile Chemists and Colorists, Research Triangle Park,
N.C., 3rd ed., 5 vols., 1971; vol. 6 (supplement to vols. 1-4), 1975; vol. 7 (supplement to vols. 1-4 and 6); 1982; vol. 5 (3rd revision) and vol. 8 (supplement
to vols. 1-4, 6, and 7), 1987.

¶ 216

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Fluoresceins, phthaleins, and sulfonephthaleins have tautomeric structuresin which a heterocyclic ring may be considered closed or opened, with generation of a carboxyl or sulfo group.
Example (fluorescein):OO

HOSpiro[isobenzofuran-1(3H),9′[9H]xanthen]-3-one, 3′,6′-dihydroxy-

O(a) Particle classes; e.g., Bosons, Fermions, Leptons, Hadrons, Baryons, Mesons, Hyperons, Nucleons, Tachyons, Quarks. These terms are employed as General Subject Index headings.
(b) Particles with symbols but no reported mass; e.g., Σ-Hyperon, π-Meson, Muon, Alpha particle, Beta particle, Neutron, Proton, Neutrino, Deuteron,Tau particle. The index headings have the form Meson, π, in which the particle
symbol appears in the heading after the name.
(c) Particles with unique symbols and masses; e.g., Hyperon Λ(2100),
Positive Muon, π+-Meson(140). The index entries are of the form Muon,+(106) and Meson, π+(140).
µ

OH

↑↓

(d) Particle resonances without reported masses; e.g., Meson resonance
K+ π, Nucleon resonance ∆, Nucleon resonance N*. The index entry corresponds to the information available, e.g., Nucleon, resonance; Nucleon, resonance ∆. For multiple resonances, more than one Chemical Substance Index
entry appears; e.g., Meson, K, resonance Kππ; Meson, π, resonance Kππ.

CO 2H

HO

96

O

O

Benzoic acid, 2-(6-hydroxy-3oxo-3H-xanthen-9-yl)-(e) Particle resonances with reported masses.
Examples of index entries:
Nucleonresonance N*(2040)

These compounds and their derivatives, including metal salts, are named in
the closed forms unless a covalently bound derivative of the acid group, e.g.,
an ester or amide, is present. The preferred (closed) forms are indexed asshown by the following cross-references:
Fluorescein.

See Spiro[isobenzofuran-1(3H),9′-[9H]xanthen]-3-one, 3′,6′-dihydroxy-

Phenolphthalein.

See 1(3H)-Isobenzofuranone,
3,3-bis(4-hydroxyphenyl)-Sulfonefluorescein.

See Spiro[3H-2,1-benzoxathiole-3, 9′-[9H]xanthene]-3′,6′-diol, 1,1-dioxide

Phenolsulfonephthalein.

See Phenol, 4,4′-(1,1-dioxido-3H-2,1-benzoxathiol-3-ylidene)bis-

Azo dyes from pyrazolines and from acetoacetanilide derivatives are indexed as the keto rather than the enol forms.
Cationic resonance-stabilized diamino derivatives of phenazine, phenoxazine, phenothiazine, xanthene, etc., are generally indexed as possessing thecation within the ring.
Lakes are pigments which comprise insoluble salts of soluble dyes. They
are indexed at the systematic names, e.g., as calcium or barium salts at the acidheading parent, if the constitution is known. The structure of a transition-metallake is usually not precisely defined; when it is, a coordination name (¶ 215) isused; otherwise it is indexed at a C.I. name (if such a name has been assigned
to the lake itself) or at trade names.
New dyes, as reported in patent specifications, are indexed at systematicnames, including coordination names (for metal complexes of precisely statedstructure).
Zinc chloride double salts cause an indexing problem, both because thesame dye can be used in the zinc-containing and zinc-free forms, and because
the toxicity of soluble zinc salts renders misindexing a serious matter. The
presence of zinc is never assumed; it is excluded from cross-references at C.I.
names and included in index entries for a specific trade-named dye only when
it is listed in the Colour Index as a zinc salt, or when its presence is indicatedby an original document. When a ratio is known, the appropriate entry is madeat the cationic heading, e.g., Benzenediazonium. Otherwise it is indexed as amolecular addition compound (¶ 192) of the “-ium” chloride and Zinc chloride(ZnCl2) with an indefinite ratio.
Sulfur dyes seldom have a known constitution. The preferred entry is a C.I.
name, if available; otherwise the trade name is indexed, or, as a last resource,
the starting material, e.g., Phenol, 4-amino-, sulfur dyes from.
217. Elementary particles and their atomic and molecular states are indexed as chemical substances. Elementary particle names follow a systematic
scheme.3 In this scheme, a given letter (Roman or Greek, upper or lower case)is used in the context of a given set of quantum numbers. This scheme replaces
the haphazard assignment of letters used previously. These particles may be
subdivided as follows:

3“Review of Particle Properties” published by the Particle Data Group isrecognized as an authority in this field. It appears in alternate years in Physics
Letters B and Review of Modern Physics (for example, see Physics Letters B,
1990, 239, I.6-I.11).

Meson, K
resonance K + K + (1280)
Meson, K
resonance KN (1780) (preferred entry)
Nucleonresonance KN (1780) (additional entry)(f ) Particles composed of nuclei of elements of less than 98% naturalabundance; e.g., lithium-6, boron-10, are indexed in the modification at the element headings. Specific particles from isotopes of hydrogen and helium-3
and -4 are indexed at Proton, Deuteron, Triton, Tau particle, and Alphaparticle, respectively. The zero-charge nucleon is indexed at Neutron.
Examplesof index entries (Notation in the original document: 115Inm(7Li,3n)119 Te):
Lithium, reactions
isotope of mass 7, indium-115 bombardment by
Indium, reactions
isotope of mass 115, bombardment of, by lithium-7
Tellurium, properties
isotope of mass 119, nuclear energy levels of, metastable, fromlithium-7 bombardment of indium-115
Neutronfrom lithium-7 bombardment, of indium-115
In particle-particle and particle-nuclei interactions, all new particles and nuclei are indexed, otherwise, interactions of known particles and nuclei are indexed according to the author’s emphasis.
(g) Particles of nuclei of elements of at least 98% natural abundance.
Such particles are not named at the beginning of the modification at the element name.
Examples of index entries (Notation in the original document:(12C,αp)):

63Cu-

Carbon, reactions
ions of carbon-12, copper-63 bombardment byCopper, reactions
isotope of mass 63, bombardment of, by carbon-12
Protonfrom carbon-12 bombardment, of copper 63
Alpha particle
from carbon-12 bombardment, of copper 63(h) Antielements and antiparticles are indexed at the element and particle
names with “Anti-” as a prefix; the symbol (the usual one with a vinculum added) is cited in the heading after a comma, and the isotope number of the antielement is given in the modification; e.g., Antihelium, He, isotope of mass 4;
Antiproton, p. The antielectron is indexed at Positron, and the negative muonand positive pion antiparticles are named as the particles of opposite charge,e.g., Meson, π+; Muon, µ−(106).

97

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007(i) Atomic and molecular states of elementary particles. General studies
are indexed at such headings as Mesonic atom, K-Mesonic atom, and Muonic
molecule. Specific atomic and molecular states are indexed at the element
name (“compounds” category) or particle name.
Examples of index entries:
1.

The original document describes the KBe mesonic atom:

Meson, K
mesonic atom with beryllium (KBe)¶ 219

Meitnerium (Mt); and 110 - Darmstadtium (Ds). For isotopically labeled inorganic compounds, see ¶ 220.
Elements of atomic number higher than 110, prior to 1982, were indexed atsuch headings as Element 114. They are now named by a combination of threesyllables derived from the atomic number, the numerals 0-9 corresponding to
the syllables nil, un, bi, tri, quad, pent, hex, sept, oct, and enn. The final “n” ofenn is elided before nil, and the “i” of bi and tri before ium, which is the invariant suffix.
Example:Ununquadium (formerly Element 114)

2. The original document describes the exotic combination of muonium
with chlorine:
Muon, µleptonic mol. with chlorine (µ+e−Cl0)
The atomic and molecular states of elementary particles are assigned thepreferred entry at the particle name, with an additional entry for the atom ormolecule.
( j)(e+e − ).

Muonium and positronium are used for the bound states (µ+e − ) and(k) Hypernuclei from hyperon interaction with atomic nuclei, and quark
nuclei from quark binding in atomic nuclei are indexed in the Chemical Substance Index at the element name.
Examples:Heliumhypernucleus of helium-5
Heliumquark nucleus

q((2

_1

3)

He) 1 /3+

218. Enzymes are indexed by CA at the names recommended by the Nomenclature Committee of the International Union of Biochemistry (IUB)4 andSupplements as far as is compatible with CA nomenclature and indexing practices. Each specific enzyme is assigned a CAS Registry Number which is cited
after the preferred index name in the Chemical Substance Index, where entries
are to be found.
Names for enzymes may comprise (a) a trivial substrate name combinedwith an action term, e.g., Lactate dehydrogenase, which is indexed at Dehydrogenase, lactate (this is E.C. 1.1.1.27, at which designation a cross-reference can be found); (b) a substrate name and the suffix “-ase,” e.g., Adenosine
triphosphatase, which is indexed at Phosphatase, adenosine tri-; (c) a name,similar to those in (b), but from which a heading parent expressing the enzyme
action cannot be readily separated, e.g., Asparaginase, which is indexed at this
name; and (d) other single terms which may describe the source, e.g., Papain,or the action, e.g., Lysozyme or Chymotrypsin; such enzymes (mainly proteinases) are indexed at these names.
Qualifying phrases, which form part of the total enzyme name, appear in parentheses in the boldface heading after the main part of the name and express
coenzyme specificity, secondary enzyme activity, secondary product formed,
etc. Sometimes more than one type of information is expressed in this way.
Examples:Dehydrogenase, malate (decarboxylating)
Synthetase, acyl coenzyme A (guanosine diphosphate-forming)
Dehydrogenase, glyceraldehyde phosphate (nicotinamide adenine
dinucleotide phosphate) (phosphorylating)General studies of enzymes, and new enzymes, will be found at Enzymes
in the General Subject Index. When complete primary structural information(amino acid sequence) is reported for an enzyme, an entry with as much source
specificity as possible is made, e.g., Pepsin A (human pancreas), and a separate CAS registration linked to the structural information is prepared.
219. Inorganic compounds are indexed at names based on United Statesusage and the recommendations of the International Union of Pure and Applied
Chemistry. For elements 104-110, CAS follows the recommendations of the
ACS Committee on Nomenclature: 104 - Rutherfordium (Rf); 105 - Dubnium(Db); 106 - Seaborgium (Sg); 107 - Bohrium (Bh); 108 - Hassium (Hs); 109 -4Enzyme Nomenclature, 1992. Academic Press, Orlando, Florida, 1992,
862 pp. Supplements 1-3, Eur. J. Biochem. 1994, 223, 1-5; 1995, 232, 1-6;
1996, 237, 1-5.

The initial letters of the first three syllables of the names provide the symbols from which synonym line formulas are derived for binary compounds ofthese superheavy elements.
Example:Ununquadium fluoride (UuqF4) (formerly Element 114 fluoride (1:4))
These index headings are not subdivided into categories as is done for elements with established names (i.e., 1 through 110).
Elements reported or discussed without specific reference to atomic number
are indexed at Elements in the General Subject Index. Class headings in thesame index, e.g., Group IVA elements, Alkaline earth metals, Halogens,
Helium-group gases, Platinum metals, Transition metals, are employed forgeneral studies of varying specificity.
Molecular forms of the elements are indicated in the modification, exceptthat hydrogen and its isotopes, and nitrogen, oxygen, and the halogens are assumed to be diatomic (unless the term “atomic” is cited). Examples: Sulfur,
mol. (S8); Oxygen; Hydrogen, atomic.
Uninverted salt-type heading parents are used to index binary compounds,
double salts, mixed salts, and certain other ionic and simple covalent compounds. The electropositive (cationic) constituents are named first in alphabetical order, followed by electronegative (anionic) constituents in alphabeticalorder. In the case of binary compounds between nonmetals, that constituent isplaced first which appears earlier in the following sequence: Rn, Xe, Kr, Ar,
Ne, He, B, Si, C, As, P, N, H, Te, Se, S, At, I, CN, SCN, Br, Cl, O, O22−, F,
N31−, OCN. (Elements not listed here are treated as metals; prior to the Tenth
Collective Index (1977-1981) antimony was included among the nonmetals.)
For monoatomic anions, the ending “-ide” is cited. When a binary compoundcontains only nonmetals, the same sequence determines the order of the total
name, e.g., Silicon carbide (SiC).
A synonym line formula follows the name of each uninverted salt-type
heading parent. (Prior to the Tenth Collective Index (1977-1981), line formulas did not appear with unambiguous names, e.g., Sodium chloride, Zinc sulfide.) Beginning with the Twelfth Collective Period (1987-1991), line
formulas may be expressed with decimals or numerical ranges as well as integers.
Example:Sodium tungsten oxide (Na0.37WO3)
Hydrides of the metals antimony, bismuth, germanium, tin, and lead are indexed at hydride names such as Germane (¶ 199). Halides are indexed as derivatives at these headings, e.g., Stannane, tetrachloro- (not Tin chloride (SnCl4)); Plumbane, diiodo-. Hydrides, halides, etc., of most other elements areindexed at headings such as Sodium hydride (NaH); Thorium hydride iodide (ThHI3). The hydrides of nitrogen have trivial names: Ammonia, forNH3; Amidogen, for NH2; Hydrazine, for N2H4; and Hydrazoic acid, for
HN3. Some derivatives of ammonia also have trivial names: Chloramine, for
NH2Cl; Fluorimide, for NHF2; Hydroxylamine, for HONH2; Sulfamide, for
SO2(NH2)2; Sulfimide, for SO2NH. The cyclic trimer of sulfimide is indexedat the heterocyclic name: 1,3,5,2,4,6-Trithiatriazine, 1,1,3,3,5,5-hexaoxide.
Chalcogen hydride names include Water, for H2O; Hydrogen peroxide(H2O2); Hydrogen trioxide, for H2O3; Hydroxyl, for HO; Hydroperoxo, for
HO2; Hydrotrioxo, for HO3; Selenyl, for HSe; and Hydrogen sulfide (H2S).
Salts of hydric cations such as Ammonium, Phosphonium, Nitric acidium, are indexed at uninverted salt names with the “-ium” term cited first, or at“oxo” acid headings with “-ium salt” terms in the modification.
Examples:Ammonium chloride ((NH4)Cl)
Phosphonium cyanide ((PH4)CN)Oxonium chloride ((OH3)Cl)Perchloric acid, compounds
ammonium salt (1:1) (named like a metal salt of the same acid, see below)
Salts of Hydrazine and Hydroxylamine are named as molecular addition
compounds (¶ 192), e.g., Hydrazine, sulfate (2:1).
Binary oxides are indexed at headings such as Sodium oxide (Na2O), Iron
oxide (with a synonym line formula, if known), Chlorine oxide (ClO2). Uninverted peroxide, superoxide, and ozonide headings are also employed, e.g.,¶ 219Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Sodium peroxide (Na2O2). The oxides CO, CO2, SO2, SO3, and SiO2 are indexed at Carbon monoxide, Carbon dioxide, Sulfur dioxide, Sulfur trioxide, and Silica, respectively.
Mixed-metal oxides containing only the oxide (O2−) anion are indexed atoxide headings, with the metals cited in alphabetic order, e.g., Iron zinc oxide(Fe2ZnO4). Hydroxides of one or more metals are indexed at metal hydroxide
headings, e.g., Chromium hydroxide (Cr(OH)3). Mixed-metal oxides, hydroxides, and oxide-hydroxides that also contain a Group IA and/or Group IIA
metal are named at oxy-anion headings with cation terms in the modification,e.g., Stannate (Sn(OH)62−), potassium (1:2), (OC-6-11)-; Tantalate(Ta6(OH)O187−), potassium (1:7); Molybdate(2−), tetra-µ-oxotetraoxoferratedi-, sodium (1:2). Hydroxide-oxides that contain no Group IA or IIA metals are indexed at such headings as Manganese hydroxide oxide (Mn(OH)O).
The index heading parents Chromic acid (H2CrO4), Chromic acid
(H2Cr2O7), Manganic acid (H2MnO4) and Permanganic acid (HMnO4) areretained. Hydroperoxides are indexed at peroxide headings with synonym line
formulas, e.g., Sodium peroxide (Na(HO2)), for Na(OOH). Mixed peroxide,hydroperoxide, ozonide, and superoxide headings are also employed. Sulfides,
selenides, and tellurides are named like the oxides. The compounds CS2 and
COS are indexed at Carbon disulfide and Carbon oxide sulfide (COS), respectively.
Uninverted salt-type headings are used for halides, amides, arsenides,
azides, borides, carbides, cyanides, hydrazides, hydroxylamides, imides, nitrides, phosphides, and silicides. Synonym line formulas are used to differentiate the hydrazides (H3N21−) and (H2N22−); for special cases such as iodide(I31−), chloride (HCl21−), and fluoride (HF21−); and for arsine, phosphine, andstibine which have lost one or two protons, e.g., Arsenide (HAs2−). Otherwise
it is understood the anions are monoatomic and have lost all protons, e.g., As3−
, P3−, Si4−. Examples: Sodium chloride (NaCl), Potassium iodide (KI), Potassium iodide (K(I3)), Calcium niobium fluoride [formula unknown], Sodium phosphide (Na(H2P)), Cyanogen chloride ((CN)Cl).
In these compounds, and the oxides, sulfides, etc., discussed earlier, all metals are considered to be cationic. Nonmetals are placed in cationic or anionicsequence to balance the charges. If this violates the electronegativity sequencedescribed earlier, all metals are named as cations and all nonmetals as “-ide”
anion terms.
Examples:98

Example:C • 1 /1 0 H N O 3

Nitric acid, compd. with graphite(1:10)

The following metal-oxide radical names are sometimes used: americyl(O2Am− and O2Am=), chromyl (O2Cr=), neptunyl (O2Np− and O2Np=), permanganyl (O3Mn−), perrhenyl (O3Re−), pertechnetyl (O3Tc−), plutonyl(O2Pu− and O2Pu=), titanyl (O2Ti=), uranyl (O2U− and O2U=), vanadyl,(OV−, OV=, and OV≡), and zirconyl (OZr=). These names, and those for thethio, seleno, and telluro analogs, are used for the ions, e.g., Vanadyl ion(2+),
and to complete the salt names at coordination anion headings (¶ 215). They
are not used for their compounds with simple inorganic salts, nonmetal oxo acids, or organic acids.
Examples:U O 2 Cl 2

Uranium, dichlorodioxo-

K 2 U O 2 ( SO 4 ) 2

Uranate(2−), dioxobis[sulfato(2−)-κO]-, potassium (1:2)

The following nonmetal oxide radicals and their chalcogen analogs are
employed: nitrosyl (ON-), nitryl (O2N-), sulfinyl (OS=) (thionyl is limited tohalides and halogenides), sulfonyl (O2S=) (sulfuryl is limited to halides andhalogenides), thiotrithiazyl (N3S4-), diphosphoryl (O3P2 ),disulfonyl (O5S2-),
chlorosyl (OCl-), chloryl (O2Cl-), perchloryl (O3Cl-) (and similarly for otherhalogen radicals). For other phosphorus and sulfur radicals see ¶¶ 197, 200,
276, and the Illustrative List of Substituent Prefixes (Section H, ¶ 294).
Examples:Cl- S( O 2 ) - S( O 2 ) - Cl

Disulfonyl chloride( SO ) Br 2

Thionyl bromide

NOH(S2O7)

Nitrosyl (disulfate) ((NO)H(S2O7))( Se O 2 ) Cl 2

Selenonyl chloride

Aluminum gallium arsenide ((Al,Ga)As)Cadmium silicon phosphide (CdSiP2) (not Cadmium phosphide silicide)
Thallium phosphide selenide (TIPSe) (not Thallium selenium
phosphide)
Mercury iodide phosphide (Hg3I4P2)
Solid solutions are normally indexed as mixed salts (oxides, etc.). Decimal
fractions, which can include ranges of composition, are used as subscripts inthe accompanying formulas to specify stoichiometric relationships when applicable. As a result of nonstoichiometry, decimal fractions may not add to whole
numbers. The omission of such numerical designations indicates incomplete
information on the proportions in the original document.
Examples:Aluminum gallium arsenide (Al0.5Ga0.5As)
Cadmium mercury telluride ((Cd,Hg)Te)
Copper platinum sulfide (Cu1.7-1.8Pt3-3.2S6)

Compounds of the nonmetal radicals with “organic” acids (i.e., thosenamed as principal groups on molecular skeletons, such as carboxylic and sulfonic acids, ¶ 165) are indexed as anhydrides (¶ 179). For carbonyl compounds,
e.g., Carbonic dihydrazide, Imidodicarbonic diamide, Urea, see ¶ 183.
Metal carbonyls and nitrosyls are indexed at binary headings when they are
either mononuclear or of unknown polynuclear structure, e.g., Chromium carbonyl (Cr(CO)6), (OC-6-11)-. Polynuclear carbonyls and nitrosyls of known
structures are named as coordination complexes. (Simple metal nitrosyl dimers
may be hyponitrites, e.g., Na2N2O2, Hyponitrous acid, sodium salt (1:2).)
Polynuclear carbonyls and nitrosyls of known composition are indexed as coordination compounds (¶ 215).
Helium-group compounds are indexed like the analogous metal compounds, except that salts with acids are named at their own headings.
Examples:KrF2

Krypton fluoride (KrF2)

XeO4

Xenon oxide (XeO4)

K2[XeF8]

Xenonate(2−), octafluoro-,potassium (1:2)

X e ( ClO 4 ) 2

Xenon perchlorate (Xe(ClO4)2)(not Perchloric acid, xenon(2+) salt)

Iron manganese zinc oxide (Fe2.3Mn0.5Zn0.2O3.9)
Solid solutions that involve classes of substances, or are otherwise incompletely defined as to elemental constituents, are identified in the index modification by a phrase such as “solid solns. with ...”
Example:Iron oxide (Fe3O4)
solid solns. with ferrites
Salts of interhalogen anions are indexed as coordination compounds (¶215), e.g., Iodate(1−), dichloro-, sodium, for Na[ICl2]. Acetylides are indexed at names such as Sodium acetylide (Na(C2H)). The common nameCalcium carbide (Ca(C2)) is the single exception. Metal derivatives of substituted Ethyne and of other alkynes are indexed by organometallic nomenclature(¶ 194).
Examples:B rC≡ C A g

Silver, (2-bromoethynyl)-

E tC ≡C N a

Sodium, 1-butyn-1-yl-

Graphite compounds are indexed as molecular addition compounds. Prior
to CA Volume 95 (see ¶ 101), binary headings such as Graphitic acid, Graphite nitrate, etc., were employed.

Oligomeric inorganic compounds, except clusters, are reduced to their empirical formulas when the structures are unknown. When the actual structure of
the oligomer is defined in the source document or known from references, anentry is made at the empirical formula. Clusters with unspecified oligomericbonding are not reduced to their empirical formulas.
Examples:Al2Cl6

Aluminum, di-µ-chlorotetrachlorodi-

Be3Cl6

Beryllium, hexa-µ-chlorotri-,
triangulo

Metal-containing inorganic clusters receive standard nomenclature for inorganic compounds, e.g., Sodium fluoride (Na7F7), Lithium potassium
chloride (Li6K4Cl10). Nonmetallic inorganic clusters receive oligomericnames when the monomeric form does not receive a line formula. All othernonmetallic inorganic clusters receive regular inorganic names with a line formula denoting the oligomeric formula.

99

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Examples:(H F ) 3

Hydrofluoric acid,trimer(SF 6 ) 7

Sulfur fluoride (S7F42)

Complex, mixed, and multiple salts are indexed at their own headings or (ifcomplex cations or anions are present) as coordination compounds (¶ 215).
Mixed salts of a single oxo acid are indexed at the acid heading.
Examples:
Cl−
−

2+

|

Cl — Co — Cl− • 3 Cs+ • Cl−|

Cobaltate(2−), tetrachloro-,cesium chloride (1:3:1), (T-4)-

UOCl2

Uranium chloride oxide (UCl2O)

C o 5 (N O 3 ) 2 (SO 4 ) 4

Cobalt nitrate sulfate(Co5(NO3)2(SO4)4)

H 2 O 3 S• 1/2Fe• N H 3 •3H 2 O

Sulfuric acid,ammonium iron(2+) salt,
hydrate (2:2:1:6)

2N aC l• N a 2 SO 4

Sodium chloride sulfate(Na4Cl2(SO4))

B2O3•P2O5

Boron phosphate (B(PO4))Cl −Cyclic inorganic substances composed of two or more elements and containing no metals of Groups 1-13 are named as ring systems.
Se

S
S

Se

1,2,4,5,3,6,7- Tetrathiatriselenepane

Se

S

S

now, acids of metals (including antimony) are generally indexed at metal oxideand hydroxide headings, e.g., Antimony hydroxide (Sb(OH)3); however, themetal acid names Chromic acid (H2CrO4), Chromic acid (H2Cr2O7), Manganic acid (H2MnO4), and Permanganic acid (HMnO4) are retained as index
heading parents. Chalcogen and peroxy analogs of these metal and nonmetal
acids are named by prefixing the “-ic” or “-ous” acid name by seleno-, thio-, telluro-, or peroxy-. The number of substituting atoms or groups is indicated in
the synonym line formula in the heading.
For Carbonic, Carbonothioic, and Carbonoperoxoic acids, see ¶ 183.
Other peroxy acid names include Peroxychromic acid (H2CrO2(O2)2), etc.
The two mononuclear Boric acid headings are differentiated by the synonymline formulas HBO2 and H3BO3. Cyclic metaborates of the general formula
HnBnO2n, in which n is equal to or greater than 3, are also indexed at this heading. Thio, etc., acids are named at such headings as Thioboric acid (H3BS3).
Isopoly acids can be considered to arise formally by condensation of a mononuclear acid, thus, 2H3BO3 → H4B2O5 + H2O. The names used in indexing
isopoly acids are the same as those of the mononuclear precursors, e.g., Boricacid (H4B2O5). The synonym line formulas are usually empirical, but molecular formulas are shown for cyclic “meta” acids. Thus, Boric acid (H3B3O3).
For the former Hypoboric acid ((HO)2BB(OH)2) and its derivatives, see ¶ 182.
Examples of peroxy and chalcogen analogs of isopoly acids are Peroxydicarbonic acid (see ¶ 183), Thioboric acid (H2B2S4), Thiosilicic acid (H4Si3O4S3), Selenotellurodiarsenous acid (H4As2Se3Te2).
The single name Telluric acid is used in association with the following synonym line formulas: H2TeO3, H2TeO4, H2Te2O5, H2Te2O7, H6TeO6,
H8Te2O10.
Selenious and Selenic acid analogs in which one hydroxyl has been replaced by a univalent group are indexed at acid headings with nondetachable
prefixes, e.g., Fluoroselenious acid (HSeFO2), Amidoselenic acid (Se(NH2)(OH)O2). Replacement of both groups leads to a nonacid heading, e.g., Selenic
diamide (Se(NH2)2O2), Amidoselenonyl fluoride ((SeO2)(NH2)F) (acid halides rank higher than amides (¶ 106)). An example of a polyselenic acid derivative is Imidodiselenic diamide (NH[Se(NH2)O2]2).
Sulfur oxo acids are functional parent compounds. Analogs in which sulfur
is directly attached to a molecular skeleton, e.g., Benzene, Hydrazine, or Germane, are named as sulfonic, sulfinic, and sulfenic acids (¶ 165). For thionicacids, see ¶ 200. For Hydroxylamine-O-sulfonic acid, see ¶ 193. (Selenium
oxo acids are named similarly, except that selenium analogs of Sulfoxylic acidand Hydroxylamine-O-sulfonic acid and those thionic acids in which the sulfur has been totally replaced are not recognized in indexing.) The mononuclear
sulfur acids are:(HO)2S

Sulfoxylic acid

( H O ) 2 SO

Sulfurous acid (the selenium
analog is Selenious acid.)( H O ) 2 SO 2

Sulfuric acid (the selenium analog
is Selenic acid.)O

Dioxathiirane
O

S

Organic derivatives of these substances may also be named as rings when
there is no coordinate bonding.
O
CH3

S

Dioxathiirane, 3,3-dihydro3-mercapto-3-methylO

SH

Ammoniates are expressed in the modification at salt names, unless the ammonia is coordinated, in which cases “ammine” coordination names (¶ 215) are
employed.
Hydrates of simple metal salts are named by modification phrases and as coordination compounds if water is the only coordinating ligand. When otherligands are present, “aqua” coordination names (¶ 215) are used. Uncoordinated water is expressed as “hydrate” in the modification.
Examples:[N i(O H 2 ) 6 ] 2+ .2C l −Nickel(2+), hexaaqua-,
chloride (1:2), (OC-6-11)-

N iC l 2 .6H 2 O

Nickel chloride (NiCl2),
hydrate (1:6)

C a 3 (PO 4 ) 2 .3/2H 2 O

Phosphoric acid,calcium salt, hydrate (4:6:3)

Binary and pseudobinary inorganic acids are restricted to Hydrofluoric,
Hydrochloric, Hydrobromic, Hydriodic, Hydrocyanic, Hydrazoic (HN3),
Fulminic (HONC), Cyanic, and Thiocyanic acid, together with Hydrogen triiodide (HI3) and oligomers such as Hydrochloric acid, dimer. (For isocyanic
and isothiocyanic acids, see ¶ 183.)
Inorganic oxo acids. Protonic acids of anions containing only oxo or hydroxy ligands are given names terminating in “-ic acid” or “-ous acid.” Acids
ending in “-ous acid” are limited to the lower valent compounds of the elements
F, Cl, Br, I, S, Se, N, P, and As. The prefix “per-” is used to designate one oxoacid of manganese (see below), peroxy acids of boron, and oxo acids of the
halogens in the 7+ oxidation state. Inorganic oxo “-ic” and “-ous” acid names
are in general limited to hydroxy and oxo-hydroxy compounds of the nonmetals
As, At, B, Br, Cl, F, I, N, P, S, Se, Si, and Te, in any oxidation state. Prior to
the Tenth Collective Index (1977-1981), metal acid headings were employed;¶ 219

Analogs and derivatives of these acids are named by use of nondetachable prefixes such as amido, imido, chloro, azido, thio, seleno, and peroxy, with replacement of the acid class name by the preferred suffix or class term if allhydroxyl groups have been removed. Compounds containing only sulfur (or selenium) and halogen are indexed at binary names, e.g., Sulfur chloride (SCl2).
Monohydrazides are indexed at hydrazine headings, e.g., Hydrazinesulfonyl
chloride for H2NNHSO2Cl. Some trivial names are employed. For Sulfur diimide, see ¶ 200.
Examples:H2N(HO)S

Amidosulfoxylic acidH 2 N SCl

Amidosulfenyl chloride

H O ( N C) SO

Cyanosulfurous acid

Cl( N C) SO

Thionyl chloride cyanide(HO) 2 S(S) (or HO(HS)S(O))

Thiosulfurous acid (H2S2O2)

Cl( H 2 N ) S=N H

Amidoimidosulfurous chloride

H O ( N 3 ) SO 2

Azidosulfuric acidCl( H O ) SO 2

Chlorosulfuric acid

H O ( H 2 N ) SO 2

Sulfamic acidCl 2 SO 2

Sulfuryl chloride

F( O N ) SO 2

Nitrososulfonyl fluoride

H O ( H 2 N ) S( O ) =N H

Imidosulfamic acidF 2 N ( H 2 N ) SO 2

Sulfamide, N,N-difluoro-

Cl( H O ) S( O ) =N H

Chloroimidosulfuric acidCl 2 S( O ) S

Thiosulfuryl chloride ((S2O)Cl2)( H 2 N ) 2 S( O ) =N H

Imidosulfamide¶ 219Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

H O O (H O )SO 2

Peroxymonosulfuric acid

Nitrogen oxo acids are indexed at the following headings:

H O (H S S )SO 2

Thioperoxymonosulfuric acid((HO)(HSS)SO2)

HONO

Nitrous acid

HONO2

Nitric acid

HON=NOH

Hyponitrous acid

HON=N(O)OH

Hyponitric acid

Polynuclear sulfur and selenium acids have such names as Disulfuric acid(for (HO)S(O2)O(O2)S(OH)), Diselenious acid (for (HO)Se(O)O(O)Se(OH),
Trisulfuric acid, etc. Analogs are named by use of nondetachable prefixes andreplacement of the acid term (if all hydroxyl groups are absent).
Examples:Halide and halogenoid derivatives are indexed at nitryl and nitrosyl names,e.g., Nitrosyl chloride ((NO)Cl). The amides of nitric and nitrous acid are
Nitramide and Nitrosamide, respectively; organic derivatives are named as
N-nitro and N-nitroso amines.
Halogen oxo acids include:
HOCl
Hypochlorous acid

(N 3 )S O 2 O SO 3 H

Azidodisulfuric acid

H O (SO 2 N H ) 2 SO 3 H

Diimidotrisulfuric acidH 2 N S O 2 N H SO 3 H

Amidoimidodisulfuric acidHOBrO
H O 3 SO O S O 3 H

Peroxydisulfuric acid([(HO)S(O)2]2(O)2)

Bromous acid

HOClO2Chloric acid

Trisulfuryl chloride

HOIO2

Iodic acid (HIO3)

H2NSO2OSO2NH2

Disulfamide(HO)2IO2

Iodic acid (H2IO4)(C lS O 2 ) 2 N N H 2

1,1-Hydrazinedisulfonyldichloride

HOClO3

Perchloric acid

HOIO3

Periodic acid (HIO4)(HO)5IO

Periodic acid (H5 IO6)

C lSO 2 O SO 2 O S O 2 Cl

Phosphorus and arsenic acids. For mononuclear phosphorus and arsenic
acids, both nonsubstitutive, e.g., Phosphoric acid, Arsenous acid, and substitutive, e.g., Phosphonic acid, see ¶ 197. There are no official rules for naming
polynuclear phosphorus and arsenic acids; they are indexed by CA at names
traditionally used in the literature. Pyrophosphoric acid and its analogs and derivatives are indexed at Diphosphoric acid names, and similarly for Pyrophosphorous acid. Specific esters of Metaphosphoric acid (H3P3O9) are indexedat the heterocyclic parent 1,3,5,2,4,6-Trioxatriphosphorinane (¶ 197), andother meta acids are treated similarly. Mixed polynuclear phosphoric-phosphorous acids are indexed at headings which include Stock numbers (parenthetical Roman numerals) to indicate the sequence of trivalent and pentavalent
phosphorus atoms. When all hydroxyl groups have been replaced, the acidterm gives way to acid halide, amide, etc., suffixes. Amides of polyphosphorous acids are indexed by replacing the word “acid” by “amide” preceded by amultiplicative prefix; amides of polyphosphoric acids have names in which “ic acid” is simply replaced by “-amide,” e.g., Diphosphorous tetraamide, for[(H2N)2P]2O, and Peroxydiphosphoramide, for [(H2N)2P(O)]2O2. P,P′, etc.,
locants are used to designate the position of replacement amido and imino,
bridging imido, etc., groups.
Arsenic analogs are named analogously to the phosphorus examples below,
except that “Hypo-” and “Isohypo-” names and headings in which mixed valencies are denoted by “III” and “V” terms are not employed.
Examples:(HO)2P(O)OP(O)(OH)2

Diphosphoric acid(HO)2P(O)OP(O)(OH)OP(O)(OH)2

Triphosphoric acid(HO)2P(O)P(O)(OH)2

Hypophosphoric acid(HO)HP(O)P(O)(OH)2

Isohypophosphoric acid(HO)2POP(OH)2

Diphosphorous acid(HO)2POP(O)(OH)2

Diphosphoric(III,V) acid(HO)2POP(O)(OH)OP(OH)OP(O)(OH)2

Tetraphosphoric(III,V,III,V) acid(HO)2P(O)NHP(O)(OH)2

Imidodiphosphoric acid100

Mixed halides are indexed at such names as Chloryl fluoride ((ClO2)F).
Silicon oxo acids in CA indexing are named as Silicic acid with one of thefollowing synonym line formulas: H2SiO3, H4SiO4, H2Si2O5, H6Si2O7. The
same index heading is employed for cyclic acids of the general formulas
H2nSinO3n and H2nSi2nO5n in which n is equal to or greater than 3. The compound (HO)3SiSi(OH)3 is named Disilanehexol. (See also ¶ 199.)
Anhydrides of inorganic oxo acids with carboxylic, sulfonic, etc., acids areindexed at the organic acid heading (¶ 179); mixed inorganic anhydrides whichcontain neither free nor esterified hydroxyl groups are given uninverted salt
names.
Examples:
ClONO2Chlorine nitrate (Cl(NO3))

B(OPO2)3

Boron metaphosphate (B(PO3)3)

When free (or esterified) hydroxyl groups are present, the index entry is madeat the preferred acid heading with an “anhydride with” phrase is the index modification.
Examples:EtOSO2OClO3

Perchloric acid,anhydride with ethylhydrogen sulfate

HOSO2OSi(OH)2OSO2OH

Sulfuric acid,anhydride with silicic acid
(H4SiO4) (2:1)

Mixed anhydrides of inorganic peroxy and thio (etc.) acids are indexed similarly, with use of “anhydrosulfide with” terms when appropriate, but anhydrides with a peroxy, dithio, etc., linkage are indexed at Peroxide, Disulfide,etc.
Example:HO3SSSP(O)(OH)2

Disulfide, phosphono sulfo

Metal (and helium-group element) salts of inorganic oxo acids and their analogs are indexed at the oxo heading if only one anion is present (otherwise thesalt is indexed at its own heading, e.g., Potassium phosphate sulfate (K2H3(PO4)(SO4)). A Ewens-Bassett number is cited with a metal of variable valence, and the stoichiometry of the salt is indicated by “mono,” multiplicative
prefixes, or ratios, when necessary.
Examples:[(HO)2P(O)OP(O)(OH)]2NH

P′-Imidotetraphosphoric acid

Cl2P(O)OP(O)(OH)Cl

Trichlorodiphosphoric acid

H2N(HO)P(O)OP(O)(OH)2

Amidodiphosphoric acid(HO)2POP(O)(OH)NH2P′-Amidodiphosphoric(III,V) acid

3 HClO3 • Al

HO(HS)P(O)SP(O)(OH)SH

Thiodiphophoric acid([(HO)(HS)P(O)]2S)

Chloric acid,aluminum salt (3:1)

3 HNO3 • Ag

Nitric acid,silver(1+) salt (3:1)(HO)2P(S)SSP(S)(OH)2

Thioperoxydiphosphoric acid([(HO)2P(S)]2S2)

H2SO4 • Ca

Sulfuric acid,calcium salt (1:1)

H2N(HO)POP(S)(OH)2

P-Amido-P′-thiodiphosphoric(III,V) acid

HOSO2OSO2OH • Na

Disulfuric acid,sodium salt (1:1)

Cl(H2N)P(O)OP(O)Cl2

Amidodiphosphoryl chloride

2 H2NSO2OH • Sn

Sulfamic acid,tin(2+) salt (2:1)

Cl2P(O)OP(O)(Cl)F

Diphosphoryl chloride fluoride(Cl2P(O)OP(O)ClF)

HN(SO2F)2 • Ag

Imidodisulfuryl fluoride,silver(1+) salt (1:1)

H3PO4 • NH3 • Mg

Phosphoric acid,ammonium magnesium
salt (1:1:1)

2 HClO4 • Xe

Xenon perchlorate (Xe(ClO4)2)[(HO)2P(O)]3N

Nitridotriphosphoric acid[(H2N)2P(O)NH]2P(=NH)NH2P′-Iminodiimidotriphosphoramide

For further examples, see ¶ 197.

101

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Alums, chrome alums, etc., are indexed (a) at oxo acid names, e.g., Sulfuric
acid, compounds, aluminum potassium salt, hydrate (2:1:1:12), (b) at“ium” headings, e.g., Methanaminium, N,N,N-trimethyl-, aluminum sulfate(1:1:2) or (c) (if they contain conjugate acids of nitrogen bases) at names of acids and bases, e.g., Sulfuric acid, aluminum salt, compd. with guanidine(1:1:1).
Anions are indexed at names usually identical with those employed in binary cation-anion headings (see above), e.g., Hydride, for H1−; Carbide, for4−; Carbide (C 2−); Hydrazide (H N 1−). Anions from inorganic oxo acids
C2
3 2
are indexed at “ate” and “ite” headings with the retained hydrogen atoms or derivatives expressed in the modification; an ion term is expressed for esters andsalts. Oxo anions of metals have synonym line formulas; other polyatomic anions are assigned coordination anion names.
Examples:H 2 PO 4 −Phosphate,hydrogen (1:2)

EtSO 4 −Sulfuric acid,monoethyl ester, ion(1−)

AlO 2 −

Aluminate (AlO21−)

NO 3 2−

Nitrate(2−), trioxo-

Anions of elements without “-ide” names are indexed at the element names,with “ion” modification terms followed by a symbol to show the charge andcomposition, e.g., ion (Re1−), ion (Hg22−), ion (S81−).
Cations. The cation of hydrogen in the gas phase is indexed at Proton (¶217). Examples of other cation names are Sulfonium, for SH31+; Chloronium, for ClH21+; Ammonium, for NH41+; Ammoniumyl, for NH31+; Hydrazinium(1+), for N2H51+; Diphosphinium(2+), for P2H62+; Thiosulfuric
acidium(1+) (H3S2O31+); Plutonyl ion(1+), for PuO21+; Nitryl ion, forNO21+; Magnesium(1+), diiodo-, for MgI21+; Helium(1+), hydro-, for
HeH1+. Cations of elements are indexed at element headings with the ion specified in the modification, e.g., Carbon, ion (C21+).
Minerals are indexed at traditional and new mineral names as correlated by
the Commission on New Minerals and Mineral Names of the International
Mineralogical Association and reported in The American Mineralogist. Other
references used to standardize the spelling and transliteration of mineral androck names, as well as to standardize mineral formulas in the CA indexes are:(a) American Geological Institute, Glossary of Geology, Washington,
D.C., 1972, 857 pp.
(b) E. S. Dana, A Textbook of Mineralogy, 4th ed., revised and enlarged
by W. E. Ford, John Wiley and Sons, New York, 1958, 851 pp.
(c) J. D. Dana and E. S. Dana, System of Mineralogy, 7th ed., entirely rewritten and enlarged by C. Palache, H. Berman, and C. Frondel, John
Wiley and Sons, New York, Vol. I, 1944; Vol. II, 1951; Vol. III, 1962.
(d) R. W. Fairbridge, The Encyclopedia of Geochemistry and Environmental Sciences (Volume IVA of The Encyclopedia of Earth Sciences
series), Van Nostrand Reinhold Co., New York, 1972, 1321 pp.
(e) M. Fleischer, Glossary of Mineral Species, Mineralogical Record,
Tucson, Arizona, 1980, 192 pp.
(f) M. H. Hey, An Index of Mineral Species and Varieties, 2nd rev. ed.,
Trustees of the British Museum (Natural History), London, 1955, 728
pp. Appendixes, 1963, 135 pp; 1974, 168 pp.
(g) C. Hintze, Handbuch der Mineralogie, Supplement 2, Neue Mineralien und Neue Mineralnamen, Walter de Gruyter, Berlin, 1960, 958
pp.
(h) C. M. Rice, Dictionary of Geological Terms, Edwards Brothers, Ann
Arbor, Mich., 1961, 465 pp.
(i) H. Strunz, Mineralogische Tabellen, 4th rev. ed., Akademische Verlagsgesellschaft Geest und Portig K.-G., Leipzig, 1966, 560 pp.
(j) P. W. Thrush, A Dictionary of Mining, Mineral, and Related Terms,
U.S. Department of the Interior, 1968, 1269 pp.
Minerals of definite composition have a synonym line formula cited after
the name, e.g., Chromatite (Ca(CrO4)). When no mineral formula is given in
the original document, the assumed formula is that given in reference (e),above. New minerals are indexed at names and formulas supplied in original
documents and collected in each issue of the General Subject Index at New
minerals.
When one or more elements have replaced the whole or part of the original
element in a mineral, and no new mineral name has been coined, the replacing
element is named in the modification at the original heading.
Examples:¶ 220

jectival terms all end in “-an,” and are derived from the English or Latin namesof the elements, e.g., aluminian, beryllian, hydrogenian, aurian (from gold), sodian, zincian. The forms “-oan” and “-ian” are used for the lower and higher
oxidation states of arsenic, copper (cuproan and cuprian), iron (ferroan and ferrian), lead (plumboan and plumbian), manganese, mercury, and uranium.
Example:Sanbornite,lithian(Ba,Li)Si2O5Intermetallic compounds are indexed like molecular addition compounds (¶192). Only one index entry is made at the name of metal that is alphabetically
preferred.
Example:Antimony,
compd. with iron (2:1)

Sb2Fe

220. Isotopes. The isotopes of hydrogen of atomic masses two and three
are indexed at Deuterium and Tritium, respectively. Isotopes of other elements with a natural abundance less than 98% are indexed at the usual element
names with a phrase in the modification: “isotope of mass...” When the isotope
is metastable, this word appears in the descriptive part of the modification, e.g.,“formation of metastable.” Anions of nonmetals are named in the index headings, metal anions and all cations in the modification.
Examples:
Chloride (38Cl1−)
Hydride-d (not Deuteride)Tin,isotope of mass 120 (120Sn1−)
Chlorine,isotope of mass 37 (37Cl1+)
Molecular forms of isotopic elements are named in the index heading or indexed with “mol.” or “ion” terms in the modification; “mol. with” phrases are
employed for mixed hydrogen isotopes.
Examples:Iodide (131I31−)
Nitrogenmol. (N15N) (a labeled atom is cited after an unlabeled atom of the sameelement)
Heliummol. (3He2)
Deuteriumion (D21+)
Tritium
mol. with hydrogen (HT)Isotopically labeled organic compounds are indexed by the Boughton system by placing the symbol for the isotope (with a subscript numeral to indicate
the number of isotopic atoms) after the name or after the relevant portion of thename. When the isotopic labeling is part of the heading parent, locants are citedunless the labeled atom is one of the following: (a) one or more labeled atoms
attached to-or replacing-the central atom of a mononuclear molecular skeleton;(b) one or more labeled atoms included in a single functional suffix; (c) a single
labeled atom included in a homogeneous parent with two skeletal atoms andno functional suffix; (d) a single labeled atom included in a homogeneous
monocyclic ring with no functional or conjunctive suffix; (e) a labeled heteroatom included in a ring that has only one heteroatom of that kind; or (f) a labeledatom whose locant duplicates the element symbol. The locants (except Greek
letters) and symbols are in italics, and hyphens are used to separate them fromone another and from the remainder of the names. (In the following examples“d” has been used, but the tritium-labeled compounds are named quite analogously by citation of “t.” When both “d” and “t” are cited, they are separated
by a hyphen, e.g., Ethane-1-d-2-t.)
In labeled heading parents with single-word names and no hydrogen-containing principal group, the d is placed after the parent.
Examples:
MeD

Methane-d

BaSi 2 O 5

Sanbornite (Ba(Si2O5))

CD4

Methane-d4

Li 2 Si 2 O 5

Sanbornite
lithium (Li2(Si2O5))

F3CCH2D

Ethane-d, 2,2,2-trifluoro(not Ethane-2-d, 1,1,1-trifluoro-)

LiNaSi 2 O 5

Sanbornite
lithium sodium (LiNa(Si2O5))

Zn 2 SiO 4

Willemite (Zn2(SiO4))

ZnMgSiO 4

Willemitemagnesium (ZnMg(SiO4))

When partial replacement has occurred but stoichiometric information islacking, or when unusual elements are present, adjectival terms for these elements are cited in the modification in the Chemical Substance Index. The ad-

D
Cl

CD 3

Benzene-d, 2-chloro-6-(methyld 3)- (not Benzene-2-d,1-chloro-3-(methyl-d3)-)

MePD2

Phosphine-d2, methyl-(D2N)2CO

Urea-N,N,N′,N′-d4

¶ 220Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Deuterated alcohols, amines, or imines are indexed similarly. The “d” symbol is placed after the appropriate part(s) of the name.
Examples:DOND2

Hydroxyl-d-amine-d2

D3CCD2OD

Ethan-2,2,3,3,3-ol-d(D3C)2NH

Methan-d3-amine, N-(methyl-d3)-

H3SiND2

Silanamine-d2

DNHOD

Hydroxyl-d-amine-dD(CH2)2NH2

Ethan-2-d-amine

MeOD

Methanol-d

MeSO3CH2D

Methan-d-ol,
1-methanesulfonate (isotopicallylabeled “Class I” alcohols (¶ 185)
belong to “Class II”)

D

CD2 SH

Benzene-4-d-methane-α,α-d2thiol

When locants are expressed in a heading parent or parent radical for unsaturation, hetero atoms, indicated hydrogen, spiro or ring-assembly junctions,bridges (in fused ring systems), suffixes, or points of attachment (in radicals),
locants are cited for the labeled positions, whether or not their use would otherwise be necessary.
Example:2-Propanone-1,1,1,3,3,3-d6(D 3 C) 2 CO

Exceptions are “d” and “t” terms placed after the word “acid” and after thesuffixes of amines, imines, alcohols, etc. (see above), for which locants are seldom employed.
The examples above have dealt with organic compounds labeled with deuterium (tritium-labeling is handled similarly). Isotopes of elements other thanhydrogen in organic compounds are expressed by the appropriate symbols.
Nomenclature is similar, except that the instances in which the isotopic symbol
appears within the name are restricted to (a) names comprising more than one
word, (b) acids and acid derivatives with “carboxylic”, “sulfonic,” etc., names,and (c) conjunctive names.
Examples (labeled atoms are indicated by asterisks):* *Acetic-17O2 acid

MeC(O)OH∗Ph C( O ) O M e

Benzoic-18O acid
16O-methyl ester

OMe

D
D

Phen-2,3,4,5-d4-ol, 6-methoxy(not Phen-3,4,5,6-d4-ol,
2-methoxy-)

OH
D

D

Alanine-N,N,1-d3

MeCH(ND2)CO2D
DN

1H-Imidazole-1-d-2-carboxylic
acid-d

C O2D

102

∗
∗
Ph CH 2 CO 2 H

Benzeneacetic-carboxy,α-14C2 acid∗
M e CO F

Acetyl-17O fluoride∗∗
O =C=O

Carbon dioxide-18O2∗ ∗H 3 G e CN

Germane-74Ge-carbonitrile-15N∗O

N

When a heading parent contains locants the labeling of each part is expressed separately and locants for the labeling are cited.
Example:∗CO 2 H

Cyclohexanecarboxylic-14C acid,2-(oxo-17O)-

1,2-Ethane-1,1,2,2-d4-diol-1,2-d2

DOCD2CD2OD

The “d” symbol is placed after the appropriate word in multiword headings
for classes not yet discussed, e.g., Acetic-2,2,2-d3 acid-d; Acetyl-2,2,2-d3chloride. In most other cases the “d” is cited after the complete heading parent,
and conventional locants or italicized words are often necessary to denote thelabeled position.
Examples:DCH2CDO

Acetaldehyde-1,2-d2

D(CH2)2CONHD

Propanamide-N,3-d2
C HD 2

D 2C H

CDO

Benzaldehyde-formyl-d, 2,4-di(methyl-d2)- (not “bis(methyld2)”; the labeled and unlabeled
compound names are kept assimilar as possible)

Enclosing marks are used with a labeled radical if it is preceded by a locant
which expresses its attachment to a heading parent or parent radical, but not ifsuch a locant belongs to the radical itself.
Examples:
D3 C

CH 2 CD 3

Benzene, 1-(ethyl-2,2,2-d3)-4(methyl-d3)-∗∗
SO 3 ( CH 2 ) 2 Cl

MeBenzene-2-14C-sulfonic-35S acid2-chloroethyl ester (labeled “ClassI” acids (¶ 185) belong to “ClassII”)

In general, for all other compounds isotopic labeling of a heading parent isexpressed after the name, although, as in the first example below, a combination of these policies with those for “d” (or “t”) is sometimes necessary. Symbols for different isotopic elements which fall together are cited in alphabeticalorder and separated by hyphens. Labeling of radicals is expressed after the individual simple radical names.
Examples:•D CH 2 CH 2 O H

Ethan-2-d-ol-1-14C* *M e CO N H 2

Acetamide-1-13C-15N*
M e CO N D CH 2 CH D M e∗
H2 C= CH CH 2 O

Acetamide-N-d-15N, N-(propyl2-d)-

C O2 H

Benzoic acid, 4-(2-propen-1-yl-314C-oxy)-DN
N H C O2 H

Carbamic acid, N-(2-piperidinyl-1-d)-

Addition of deuterium, alone or with hydrogen, to a ring system is indicatedby hydro “substituents” and the “d” symbol. Where there is a choice, deuteriumis expressed in the heading parent.
Example:Apart from isotopes of “hydro” (see above), a multiplicity of substituentsthat are identical except for labeling are named separately. Multiplicative nomenclature is not employed with unsymmetrically labeled parents; instead, thatheading parent is chosen which contains (a) the maximum number of isotopic
atoms, (b) the alphabetically earliest isotope symbol.
Examples:
∗

Me

OH
D

1-Naphthalen-2,4-d2-ol, 1,2,3,4tetrahydro-4-d-1-methylD

D

Labeled protonated species (¶ 184) are expressed in index modifications byterms such as “conjugate acid-d (1:1)” and “monoprotonated-d”.

( H 3 C) 2 SiM e 2

Silane, dimethyldi(methyl-13C)-∗
Cl 2 C :Methylene, chloro-35Cl-chloro-37Cl-∗M e 2 CH N H CD M e 2

2-Propanamine-2-14C, N-(1methylethyl-1-d)- (not 2Propan-2-d-amine, N-(1methylethyl-1-14C)-)

103

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

For derivatives named in modifications, labeling is expressed by such terms
as “oxime-15N,” “calcium-44Ca salt,” “hydrate-d2 (1:2).” Ammonium-d4 salts
are treated like the analogous metal salts.
A name containing isotopic symbols is always employed for a labeled compound, regardless of how little of the labeled species is present so long as its
nature is known. When the number of labeled atoms is unknown, the heading
for the unlabeled compound is indexed and the modification contains a phrase
such as “labeled with deuterium” or “labeled with chlorine-37.”
Examples:Acetamide, labeled with carbon-14¶ 221

formulas are cited in the modification instead of a ratio, e.g., Iron, compoundwith uranium (Fe2235U).
Labeled minerals are indexed at the systematic and mineral names, as well
as at the name of the unlabeled mineral if it is studied. Labeling is indicated at
the mineral name by synonym line formulas which contain isotope symbols or
by modification phrases such as “labeled with boron-10” or “deuterated hydrate.”
Coordination compounds (¶ 215) containing isotopic nuclear atoms are indexed at the labeled element or “ate” term, e.g., Copper-64Cu, Borate(1−)10B. Labeled ligands have the isotopic symbols appended; the ligand names
are enclosed in parentheses if multiplicative prefixes are needed.
Examples:1-Propene, 1,1,2,2,3,3,3-hexachloro-, labeled with chlorine-36
When only the positions of the isotopic atoms are unknown, the labeling is
indicated, if possible, in the appropriate part of the name without citation of locants. Otherwise a “labeled with...” modification is used.
Examples:

D2O
Al
OD 2

D2 O
D2 O

1-Propene-14C2, 2-methoxyBenzoic acid, 4-(ethyl-14C)-

ND3

H3N

3+

NH 3

Co

Benzoic acid, 4-ethyl-, labeled with carbon-14
Isotopically labeled inorganic compounds are named by procedures similar
to those above when the unlabeled compounds have unambiguous names.
Examples:DNHT

Ammonia-d-t

P(SiD3)3

Phosphine, tri(silyl-d3)-

DP(O)(O−)2

Phosphonic-d acidion(2−)

H332PO4

Phosphoric-32P acid

H3PO4 • 3 22Na

Phosphoric acid,sodium-22Na salt (1:3)

HDSO4

Sulfuric acid-d

35

Hydrochloric-35Cl acid-t

ClT

Aluminum(3+), hexa(aqua-d2)-,(OC-6-11)- (see also ¶ 203 III)

3+ OD 2

D2 O

18OSO

Sulfur dioxide-18O

D218O

Water-d2-18O

In other cases labeled inorganic compounds are differentiated by synonymline formulas which contain isotope symbols. Isotopic atoms are cited after unlabeled atoms of the same element.
Examples:Hydrogen sulfide (D2S)
Cobalt iron oxide (CoFe2O318O)
Molybdenum carbonyl (Mo(CO)4(13CO)2)
Nitrogen fluoride (N15NF2)

H 3N• 3 ClO4-

NH 3

Cobalt(3+), pentaammineammined3-, (OC-6-22)-, perchlorate (1:3)

NH3

Isotopes of hydro ligands, like those of hydro “substituent” prefixes for labeled organic compounds, are expressed by “d” or “t” terms placed after citation of the hydro set.
Example:
−H

Me
3+

−D

Al
−D

N

CH2 D

Aluminum, (N,N-dimethylmethand-amine) trihydro-d2-,(T-4)-

Me

221. Mixtures. Certain mixtures are indexed like individual chemical substances and are assigned CAS Registry Numbers. These are compositions thatinvolve components that are intentionally admixed prior to the intended uses,
and remain discrete within the medium of the identified mixtures. Included arecommercial products with trade or trivial names, as well as mixtures reported
by authors to have particular properties or uses.
Such mixtures are indexed at the name of the preferred component, with allother such components expressed in the modification of the main entry. Solvents, fillers, binders, antioxidants, stabilizers, emulsifiers, plasticizers, andflavoring and coloring agents are disregarded if not specified as “active” interms of the intended or implied uses of the formulations. Inactive trace materials are also omitted.
The percentage composition is not expressed in the index entry; thus, in themodification term “mixt. with copper(2+) sulfate (1:1),” the ratio refers to thecopper sulfate, not to the mixture. Cross-references appear at trade and trivialnames encountered in original documents.
The preferred index entry is made at a stereoparent (¶ 202) if possible, e.g.,
D-Glucose or Pregn-4-ene-3,20-dione. Choices among stereoparents and nonstereoparents depend on functionality, as for molecular addition compounds (¶192) and polymers (¶ 222). Components are cited in the modification in alphabetical order, esters and salts being expressed in their uninverted format. The“compounds” functional subdivision is used for components that have subdivided headings.
Example:Sodium chloride (24NaCl)
Sodium sulfide (Na235S)
Uranium chloride (213UCl3)
Salts of inorganic oxo acids with labeled cations are named in the modification by such terms as “strontium-90Sr salt (1:1)” and “ammonium-d4 salt
(1:2),” but synonym line formulas are needed to indicate unsymmetrical labeling of cations or anions.
Examples:Phosphoric acidcalcium salt (Ca244Ca(PO4)2)
Phosphoric-32P acidcalcium salt (Ca3(PO4)(32PO4))
Compounds with indefinite labeled structures are indexed at the unlabeled
headings with “labeled with” modification phrases.
Labeled alloys are indexed like the unlabeled counterparts but with isotope
symbols included in the elemental composition at each heading, e.g., Aluminum alloy, base, Al 95, 233U 5. For intermetallic compounds, synonym line

Glycine, compounds
mixt. with egg white and sodium chloride (NaCl)(Chemical Substance Index entry; cross-reference at Yumol)
Mixtures with ten or more indexable components are indexed and registered as the individual components only with the phrase “mixt. contg.” as derivative information in the index entry. Mixtures of ten or more indexable
components with trade or trivial names are indexed at the commercial nameonly.
A mixture of salts of a single parent is indexed only once.
Example:Carrageenan, hydrogen sulfate, calcium salt,
mixt. with potassium and sodium salts
Mixed reactants and impure reaction products are not indexed in this way,
nor are unresolved natural products, mixed stereoisomers (other than pure racemates), commercially available mixtures of structural isomers, column fractions from distillations or chromatography, catalyst systems, welding fluxes,
polymer blends, composites, or mixtures involved in physicochemical studies(as of phase systems) without emphasis on intended use. In these cases, separate entries are made at the headings for each significant component, with information on other components included in the index modifications (¶ 10A).

¶ 221

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Certain specific substances that are mixtures, but not regarded as sufficiently well defined to be classified as chemical substances of unique composition,
are identified by headings in the General Subject Index. Examples are Air,
Copper ores, Gasoline, Granite, Peanut oil, Petroleum.

Examples:—O

222. Polymers. Classes of polymers, natural and synthetic, are indexed in
the General Subject Index.
Specific polymers are named on the basis of the monomers from which they
are formed and/or on the basis of their structure, as represented by a structural
repeating unit (SRU). Since original documents do not always provide sufficient structural information to allow generation of the SRU name, the method
most frequently used for describing polymeric substances is by citation of thecomponent monomers. A few commercial polymers, each of which accounts
for a large number of index entries, are indexed only at the SRU-based systematic polymer name. Systematic nomenclature is discussed first in the following
paragraphs, followed by monomer-based polymer nomenclature.
Systematic (SRU) nomenclature for polymers has been adapted from thesystem developed by the Committee on Nomenclature of the Division of Polymer Chemistry of the American Chemical Society5. Names derived by thissystem, in addition to monomer-based entries, are cited for polymers whose
structural repeating units are well-documented or can confidently be assumed.
“Expected,” “idealized,” or “drawn-for-convenience” SRUs are not given systematic polymer names. Occasionally, when there is no information on thecomponent monomers in the original document, an entry derived from the SRU
name is the only index entry available.
The SRU is named by citation of one or more multivalent radicals of regularsubstitutive nomenclature. Many of these radical names will be found in the
Illustrative List of Substituent Prefixes (Section H, ¶ 294); others are suppliedin the various sections dealing with classes of compounds from which the radicals are derived. The SRU name is enclosed in parentheses or brackets, andprefixed by the term “Poly”. Each multivalent radical retains its own numbering and is oriented, if possible, so that the point of attachment written at the left
end of the repeating unit is assigned the lowest possible number. This permits
the naming of the SRU in a directional manner, reading from left to right. The
largest possible multivalent radicals are chosen as all or part of the name, andnaming proceeds from left to right, starting with the most preferred multivalentradical. (See the following sections for the choice of most preferred radical.)Unsaturation and substituents are indicated by appropriate locants. Functional
derivatives, such as esters and hydrazones and oxides of hetero atoms which
are an integral part of the repeating unit are expressed by prefixes rather thanby modification terms, and are numbered as low as possible while preserving
the preferred names of the parent radicals. Salts of acids and anions of quaternary “-onium” compounds, and oxides of hetero atoms which are an integral
part of the repeating unit are cited following the name of the SRU. The numberof free valencies between units is minimized; i.e., unsaturated radicals are preferred.
Polymers of unspecified length and chains of reported “average” length, arenamed by the methods described above. The prefix “oligo-” is not used to differentiate polymers of relatively low molecular weight from high polymers.
When, however, the number of structural repeating units is exactly specified,
the oligomer is usually named according to the principles of substitutive nomenclature.
Examples:(−CH 2 −) n

Poly(methylene)(−CHMeCH 2 −) n

Poly(1-methyl-1,2-ethanediyl)(−CH=CH−) n(not (=CHCH=) n )Poly(1,2-ethenediyl) (not Poly(1,2ethanediylidene))[−(CO) 2 (CH 2 ) 2 −] nPoly(1,2-dioxo-1,4-butanediyl) (notPoly(1,4-dioxo-1,4-butanediyl))(−CH=CHCHMeCH 2 −) n

Poly(3-methyl-1-butene-1,4-diyl)

For more complex examples, further criteria for arranging the components
of an SRU are required. The descending order of priority of citation (and of
structuring of the SRU) is (a) heterocyclic rings, (b) acyclic hetero atoms in theorder: O, S, Se, Te, N, P, As, Sb, Bi, Si, Ge, Sn, Pb, B, Hg, (c) carbocyclic
rings, (d) acyclic carbon chains. If substituents are present, otherwise identicalparent radicals in the SRU are chosen by the principles, in turn, of maximum
number, lowest locants, and earliest alphabetical order of substituents. The
shortest path (smallest number of atoms) is taken from the most preferred multivalent radical to another occurrence of the same radical (if present) within the
SRU, then to the next most preferred radical, and so on.

5“A Structure-based Nomenclature for Linear Polymers”, Macromolecules

1968, 1(3), 193-198. The IUPAC recommendations (Pure Appl. Chem. 1976,
48, 373-385; 1993, 65 (7), 1561-1580) are in full agreement with CAS practice.
The IUPAC term “constitutional repeating unit” (CRU) corresponds to CA’s
SRU.

104

Poly(oxy-1,4-phenylene-1propene-1,3-diyl)

CH =CH CH 2 —n[−NHCO(CH 2 ) 2 −] nPoly[imino(1-oxo-1,3-propanediyl)][−(SO 2 ) 2 (CH 2 ) 2 −] nPoly(disulfonyl-1,2-ethanediyl)
Poly[oxycarbonyloxy(methyl-1,2ethanediyl)] (The position of themethyl group is not assumed in thispolyester from carbonic acid and1,2-propanediol.)( — O CO 2 CH 2 CH 2 — ) n

{

+ Me
−H

—O

SO2

O

CM e 2nPoly[oxy-1,4-phenylenesulfonyl1,4-phenyleneoxy-1,4-phenylene(1-methylethylidene)-1,4phenylene] (With equal numbersof atoms between the oxygen atoms in two possible arrangements,
the preferred path includes the other hetero atom, sulfur, as early as
possible.)[ −O CH 2 SN H ( CH 2 ) 2 O CH 2 SCH 2 N H CH 2 −] nPoly(oxymethylenethioimino-1,2ethanediyloxymethylenethiomethyleneiminomethylene)(With equal distances between thetwo oxygen atoms and between theoxygen and sulfur atoms, the direction is determined by the shortest
distance between the oxygen atomand the hetero atom of third preference (nitrogen).)— NHCONHCOCO N H ( C H 2 ) 6—

CONH

n

Poly(iminocarbonyl-1,4-phenyleneiminocarbonyl-1,3-phenylenecarbonylimino-1,4-phenylenecarbonylimino-1,6-hexanediyl)(The citation proceeds in the increasing order of distances between the nitrogen atoms: 5,5,5,
and 6 intervening carbon atoms.)
5

1

1′

S

S

5′

N=N
N

N

3

3′

n

Poly([2,2′-bithiazole]-4,4′-diyl-1,4phenylene-1,2-diazenediyl-1,4phenylene)
Poly[imino[1-oxo-2-(propoxycarbonyl)-1,2-ethanediyl]] (not Poly[imino(1-carboxy-2-oxo-1,2ethanediyl)], propyl ester)[−NHCOCH(CO 2 Pr)−] n— N + M e 2 ( CH 2 ) 2 —• Br −nPoly[(dimethyliminio)-1,2ethanediyl bromide (1:1)](the ionic derivative term is
included in the SRU)

105

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

When SRUs are bridged only by metals, systematic polymer nomenclature
is not used; instead, the substance is indexed either at the monomeric salt nameor by coordination nomenclature (¶ 215), with a modification phrase, in either
case, such as “homopolymer” or “polymer with” (see below).
End groups, when known, are specified by means of appropriate radical
names, together with Greek letters “α-” and “ω-” expressed as substituents.
The α-end group is the group attached to the left end of the SRU when the
structure is ordered by the specified rules; it is cited first, regardless of alphabetical order.
Examples:Cl−(CH2)n−CCl3

Poly(methylene)
α-chloro-ω-(trichloromethyl)-

Cl3C−(CF2−CH2−)nCl

Poly(1,1-difluoro-1,2-ethanediyl)
α-(trichloromethyl)-ω-chloro-

Linear double-strand (“ladder” and “spiro”) polymers may sometimes be
named as a chain of quadrivalent radicals. Two pairs of locants, separated by acolon, indicate the distribution of bonds.
Example:—CH 2
CH—

Poly(1,4:2,3-butanetetrayl)

CH—
—CH 2

n

When a ladder polymer must be named as an SRU of one or more quadrivalentradicals linked through one or more bivalent radicals (here, these terms are extended to mean radicals attached to four or two different atoms, not only to radicals with four or two free valence bonds) the direction of citation is from themost favored quadrivalent radical by the shortest path to the next most favoredquadrivalent radical, and so on; then toward the most favored bivalent radical.
Rings are broken (a) to minimize the number of free valencies of the total“mer,” (b) to maximize the number of most preferred hetero atoms in the ringsystem, (c) to maintain intact the most preferred ring system (¶ 138). End
groups, when known, are identified by α and α′ (at the left terminus as the
structure is drawn) and by ω and ω′ (at the right terminus) as locants for substituent prefixes, e.g., α,α′-dihydroxy-ω,ω′-dihydro-.
Examples:4

1

are not assigned systematic names; they are indexed at the monomer names
only.
The previous paragraphs described a systematic nomenclature for polymers
of well characterized structure, and for polymers whose structural repeating
unit (SRU) can be confidently assumed. The latter are restricted to (a) polyamides from a dibasic acid (or derivative) and a diamine, or from an amino acidor lactam; (b) polyesters from a dibasic acid (or derivative) and a dihydric alcohol, or from a hydroxy acid or lactone; (c) polyurethanes from a diisocyanate
and a dihydric alcohol; and (d) polycarbonates from carbonic acid (or an esteror halide) and a dihydric alcohol.
Polymers manufactured from known monomers are generally indexed at
the monomer names whether or not systematic (SRU) entries are also made.
An exception is the treatment of a few very common industrial polymers, e.g.,nylon 6, nylon 66, terephthalic acid polymer with ethylene glycol, which, topreclude inordinate repetition of a large number of index entries at various
names assigned SRU names.
Example:Terephthalic acidSee 1,4-Benzenedicarboxylic acid
1,4-Benzenedicarboxylic acid, polymers
polymer with 1,2-ethanediol—see Poly(oxy-1,2-ethanediyloxycarbonyl-1,4-phenylenecarbonyl)
A cross-reference appears also at 1,4-Benzenedicarboxylic acid, esters, 1,4dimethyl ester, polymer with 1,2-ethanediol; and two corresponding crossreferences at 1,2-Ethanediol, polymers.
Polymers from a single monomer are indexed at the monomer name withthe term “homopolymer” cited in the modification. (The terms “peptides,”“polyamides,” and “polyesters” are not used for specific homopolymers at
monomer headings.)
Examples:(BuCH=CH 2 ) n

1-Hexene,
homopolymer (only index entry)[H 2 C=CMeCO 2 (CH 2 ) 12 Me] n

2-Propenoic acid, 2-methyl-,tridecyl ester, homopolymer(only index entry)[H 2 N(CH 2 ) 10 CO 2 H] n

Undecanoic acid, 11-amino-,
homopolymer (the Formula Index
entry appears at C11H23NO2 ; asystematic entry is also made at theassumed SRU name: Poly[imino(1-oxo-1,11-undecanediyl)],(C11H21NO)n)58aPoly(2,3:6,7-naphthalenetetrayl6-methylene)

n

O
4

5

7

8

O

N

N

O

O 14a N

N

O

1

12

11

14

n
O

Poly([1,4]dioxino[2,3-b]-1,4-dioxino[2′,3′:5,6]pyrazino[2,3-g]quinoxaline-2,3:9,10-tetrayl9,10-dicarbonyl) (The same
number of free valences canbe expressed by breaking theoxygen ring or the partiallysaturated hydrocarbon ring;
the latter course keeps intact
the maximum number ofheterocyclic rings.)

6

1

O

O
2 Si

O
3

O

n

Poly[1,3-dioxa-2-silacyclohexane5,2-diylidene-2,2-bis(oxymethylene)] (not Poly[1,3-dioxa-2silacyclohexane-2,5-diylidene5,5-bis(methyleneoxy)] (Thedirection is determined by theshortest path from the hetero
atom in the ring to the acyclic
hetero atom.)Linear polymers composed of SRUs within SRUs, e.g.,[-[O(CH2)2]m-O2C(CH2)4CO2-]n¶ 222

Polymers formed from two or more monomers are indexed at the preferredmonomer name with the modification term “polymer with” followed by theother monomer names in alphabetical order. No attempt is made to indicate thepercentage composition of copolymers. Ratios typically refer to specificmonomer salts. The preferred index name is determined by the usual rules forselection of a heading parent (¶ 138) but a stereoparent is preferred over a nonstereoparent, e.g., D-Glucose, polymer with butanedioic acid. For identicalheading parents, the choice is determined by (a) maximum number of substituents, (b) lowest locants of substituents, (c) maximum number of occurrencesof the index heading parent (in a multiplicative name), (d) earliest index position of the index heading. When the choice is dependent on modification
terms, it is determined as follows: (a) underivatized heading preferred over derivatives cited in the modification; thus, a free acid is preferred over an ester;(changes in format caused by elevation of modification terms into the headingfor purposes of subdivision are ignored in applying this rule; thus Acetic acidis preferred over Acetic acid ethenyl ester); (b) class of derivative in the descending order: anhydride, ester, hydrazide, hydrazone, oxime; (c) largest
number of (most preferred) derivative; thus, monoester preferred over dioxime
preferred over monooxime; (d) lowest expressed locants of derivative terms;
thus, for 1,2,4-Benzenetricarboxylic acid, a 1,2-diester is preferred over a
1,4-diester; (e) the earliest alphabetical order; thus, “ethyl ester” preferred over“propyl ester.”
Examples:1(a)1-Heptene,
polymer with 1-hexene2(a)2-Propenoic acid,butyl ester, polymer with 1-ethenyl-4-methylbenzene and2,5-furandione

Peptides of established structure are indexed at systematic peptide names
such as Glycine, glycylglycyl- (see ¶ 206). Peptides of unknown structure areindexed as polymers.
Example:[HO 2 CCH(NH 2 )(CH 2 ) 2 CO 2 CH 2 Ph] n

L-Glutamic acid,5-(phenylmethyl) ester, homopolymer¶ 222

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

and the assumed structural repeating unit:—N H C O C H|(C H 2 ) 2 CO 2 CH 2 Ph

Poly[imino[(2S)-1-oxo-2-[3-oxo-3(phenylmethoxy)propyl]-1,2ethanediyl]]nWhen more than one amino acid is present and the sequence is unknown, acopolymer is indexed, and named at the preferred amino acid monomer.
Alternating, block, and graft polymers are distinguished from random polymers by indexing as copolymers at the monomer names. The term “alternating”, “block”, or “graft” (or a combination thereof) is cited in a special
modification after all other structural information but before descriptive phrases relating to properties, uses, etc. The more specific block terms, diblock, triblock, tetrablock, and pentablock are also used. Differentiation between thepolymeric substrate and the applied monomer is not made; e.g., whether 1-hexene is grafted on 1-heptene homopolymer or vice versa, the index entry is at 1Heptene, polymer with 1-hexene, graft. The term “random” is not employed
by CA in indexing specific polymers.
Siloxanes prepared by hydrolytic polymerization of chlorosilanes are indexed at the monomer names with the term “hydrolytic” cited in the modification to indicate the essential role of water in forming a polymer chain of -Si-Ounits. The term “hydrolytic” is used in addition to the term “homopolymer” or“polymer with”.
Example:Benzene, 1,1′-(dichlorosilylene)bis-,
polymer with dichlorodimethylsilane, hydrolytic
Polymers of specific compounds with classes of compounds are indexed at
the specific monomers in the Chemical Substance Index and at the class name,e.g., Aldehydes or Nitriles, in the General Subject Index.
Example:1-Hexene, 5-methylpolymer with unsatd. nitriles
Nitrilesunsatd.; polymers with 5-methyl-1-hexene
Formaldehyde homopolymers containing only oxymethylene repeating
units are indexed only at the heading Poly(oxymethylene) in the Chemical
Substance Index. Commercial and impure polyformaldehydes are indexed at
Polyoxymethylenes (a plural class heading in the General Subject Index) unless author emphasis is centered on Paraformaldehyde. Formaldehyde copolymers are indexed as polymers formed from two or more monomers (except
Formaldehyde copolymers with Phenol, Urea, or 1,3,5-Triazine-2,4,6-triamine.
Oligomers of definite structure are indexed as specific compounds by theregular principles of index nomenclature. When the precise structure is notknown but the number of units is specific, “dimer,” “trimer,” etc., is expressedin the modification at the name of the monomer. The term “oligomeric” may
be cited after “homopolymer” or “polymer with . . .” if this aspect is stressedin the original document.
Telomers with a definite structure are named systematically.
Examples:Cl-(CH2)6-CCl3

Heptane, 1,1,1,7-tetrachloro-

Cl-(CF2-CH2)n-CHCl2

Poly(1,1-difluoro-1,2-ethanediyl),
α-chloro-ω-(dichloromethyl)-

2-Propenoic acid, 2-methyl-,
homopolymer, 9-anthracenylmethyl ester
2-Propenoic acid, 2-methyl-,decyl ester, homopolymer, hydrolyzed
Poly[1-(4-sulfophenyl)-1,2-ethanediyl],
propyl ester
Ethenol (vinyl alcohol) polymers that are indexed at that heading are exceptions (they are prepared by hydrolysis of ethenol ester polymers). Acetals of
ethenol homopolymer and ethenol polymers with ethenyl acetate are indexedat the homopolymer or copolymer with the term “cyclic acetal” followed by the
specific aldehyde name in the modification. Additional entries appear in the
General Subject Index at the trivially named class terms, Polyvinyl acetals andPolyvinyl butyrals. Acetals of other ethenol polymers and acetals with unspecified aldehydes are indexed at the underivatized polymer and at the classterm with a modification term, e.g., chlorinated benzals, to indicate the type ofacetal when appropriate.
Molecular addition compounds of polymers are indexed in the usual way (¶192), e.g., Ethenesulfonic acid, homopolymer, compd. with 4-ethenylpyridine
homopolymer. The preferred name is cited at each molecular formula in the
Formula Index. (See ¶ 198)
Polyethylene and polypropylene glycols are indexed as specific compounds
when the precise structure is reported and not more than ten repeating units arepresent, e.g., 3,6,9,12,15-Pentaoxaheptadecane-1,17-diol, hexamethyl-.
The position of methyl substituents is not assumed; if it is reported, locants arecited. Glycol polymers of eleven units or more are indexed at Poly(oxy-1,2ethanediyl), α-hydro-ω-hydroxy-, and Poly[oxy(methyl-1,2-ethanediyl)],α-hydro-ω-hydroxy-. The class term Polyoxyalkylenes in the General Subject Index is used as an additional entry for all specific polyalkylene glycols except when the alkanediyl group is ethanediyl or propanediyl and for cases
where the nature of the alkanediyl group is unknown. When it is known, theSRU can be named specifically; thus, Poly[oxy(2-phenyl-1,3-propanediyl)],α-hydro-ω-hydroxy-. Polyethylene-polypropylene glycols are named as copolymers: Oxirane, 2-methyl-, polymer with oxirane.
Esters and ethers of polyalkylene glycols containing not more than ten repeating units are indexed by the regular principles of substitutive nomenclature. For larger polymers, the ester or ether is expressed as a substituent at the
SRU-based heading. Mono derivatives are cited in the α-position, with ω-hydroxy at the other terminus. Dissimilar diesters or diethers are expressed in alphabetical order. Ester-ethers have the acyl group or the inorganic-type ester,
including borono, phospho, sulfo, substituted sulfonyl groups, etc., assigned
to the α-position, and the ether at the ω-end. When appropriate information islacking, an ester or ether term is cited without locant. When multiplying radicals must be employed, they are given α-locants.
Examples:

Me(CH2)16CO

Ac

Poly(oxy-1,2-ethanediyl),α-(1-oxooctadecyl)-ω-hydroxy-

O2 CCMe = CH2nPoly[oxy-1,2-ethanediyl],
α-acetyl-ω-[(2-methyl-1-oxo2-propen-1-yl)oxy]O(CH2)2n

O(CH2)11Me

Poly(oxy-1,2-ethanediyl),α-(1-oxo-2-propen-1-yl)-ω(dodecyloxy)Me(CH 2 ) 16 CO 2

1-Hexene,telomer with tetrachloromethane(CH2)2OnO(CH2 )2O2 C(CH2 )16 Mem

Poly(oxy-1,2-ethanediyl),
α,α′-1,4-phenylenebis[ω-[(1oxooctadecyl)oxy]-

Post-treated polymers are described by modification terms after the polymer has been described.
Examples:2-Propenoic acid,homopolymer, sodium salt
(No ratios are used for polymer salts unless specificstoichiometry is possible and is specified.)nOH

O(CH2)2

O(CH2)2

H2C = CHCO

Telomers of unknown structure are indexed as copolymers with the term “telomer with . . .” cited in the modification.
Example:106

Polynucleotides (cf. Nucleotides, ¶ 210) are indexed as “homopolymer” or“polymer with . . .” at the “-ylic acid” monomers (5′-isomers).
Examples:Benzenamine, 4-ethenyl-,
polymer with ethenylbenzene, hydrochloride(No ratios are used for polymer salts unless specificstoichiometry is possible and is specified.)

5′-Adenylic acid,homopolymer

1,4-Dioxane-2,5-dione, 3,6-dimethyl-,
homopolymer, copper(2+) salt (2:1)(The polymer chain has only one carboxy group and one hydroxygroup a specific salt ratio is possible.)5′-Guanylic acid,polymer with 5′-adenylic acid and 5′-cytidylic acid

Cytidine, 5′-O-phosphonoadenylyl-(3′→5′)-,homopolymer

107

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Polynucleotides in which different primary chains are associated intermolecularly by hydrogen bonds are indexed as molecular addition compounds (themodification term “complex” is used in this special case); e.g., 5′-Adenylic acid, homopolymer, complex with 5′-uridylic acid homopolymer (1:1).
In more complicated cases, a combination of policies is applied.
Examples:zine is employed instead of 21H,23H-5,10,15,20-Tetraazaporphine, and its
fused tetrabenzo derivative is 29H,31H-Phthalocyanine. Radicals are formedin the regular way; e.g., 21H,23H-porphin-2-yl, 29H,31H-phthalocyanine2,9,17,24-tetrayl.
The metal complexes, including the biologically important porphyrin ironand magnesium complexes (hemes and chlorophylls) are indexed as coordination compounds (¶ 215) with italic letter locants to indicate coordinating atoms.
Example:−p−A−p−G−p−U−p−A−p−G−p−C−p−U−p−A−p−G−p−U−

Me−Guanosine, 5′-O-phosphonoadenylyl-,(3′→5′)- polymer with 5′-cytidylicacid and 5′-uridylic acid−p−U −p − U−p−C −p−U −Synthetic rubber
styrene-vinyl bromide(General Subject Index entry)
Benzene, ethenyl-,
polymer with bromoethene, rubber(preferred Chemical Substance Index entry)

2 C( CH 2 ) 2

16

Hexanedioic acid,polymer with 1,4-butanediol, fiber (an additional Chemical Substance Index entry is made at the SRU name.)
Stereochemistry of polymers is expressed by special modification terms
when the necessary information is reported; such terms include isotactic, syndiotactic, threo-diisotactic, erythro-diisotactic, and disyndiotactic. The term
“atactic” (for a random configuration) is not employed by CA in indexing specific polymers.
In addition to the special terms above, polymer stereochemistry is defined,
when appropriate, by the regular descriptors E, Z, R, and S (¶ 203 I). For commercial elastomeric polymers, which cannot generally be assumed to be stereochemically homogeneous, terms such as “1,2-configuration,” and “cis-1,4configuration” are included in the descriptive portions of index modifications,but are not made part of the unique preferred CA index names.
223. Porphyrins and Bile pigments. The porphyrins embrace all cyclic
tetrapyrroles in which single methene groups link pairs of pyrrole rings. The
parent 21H,23H-Porphine is used, with a suffix to express principal groups if
present, for all derivatives, including hydrogenated derivatives, unless an author emphasizes the absence of hydrogen at the 21- and 23-positions.
Example:
20

18

20

1

N

24
23

4

16

NH

N

23
24

26
25

N

HN
8

13

9

11

Indicated hydrogen is not expressed with Phorbine, which contains six saturated centers. Removal of hydrogen is indicated by dehydro terms, e.g.,
Phorbine, 3,4-didehydro-. Metal complexes, radicals, etc., are named as forthe analogous porphine derivatives.
Example:Magnesate(1-), [(3S,4S,21R)-9-ethenyl14-ethyl-21-(methoxycarbonyl)4,8,13,18-tetramethyl-20-oxo-3Et−
phorbinepropanoato(3-)-κN23,κN24,
15
N
N
24
25
κN25,κN26]-, hydrogen (1:1), (SP-4-2)• H+
Mg 2+
26
23
(cross-reference from Chlorophyl−N
17Nlide a)18 Me
Me

H C=CH
Me
7

5

Me

NH

5

2

N

20

O

Bile pigments are indexed at 21H-Biline, the numbering system of which
derives from that of porphyrin (the carbon atom involved in ring closure, C-20,
is omitted from the numbering system).
18
19

1

17

HN

N

N

24
23

15

3

N

21
22

5

21H-Biline

7

13
10

12

8

All derivatives, including hydrogenated derivatives, are indexed at 21HBiline unless hydrogen is absent at the 21-position, in which case the 22H-parent is preferred over lower positions. The (all-Z) stereochemistry shown in the
diagram above is assumed. The 1,19-dihydroxy derivatives are tautomericwith the dioxo compounds, which are preferred in indexing.
Example:CH =CH 2

Me
19

O O
1

CH 2 =CH
N

24
23

14

Me

Me

HN

21 4
22

N

N

11

8

Porphyrin analogs containing additional hetero atoms are indexed by organic replacement nomenclature (¶ 127) at such names as 21H-5-Thiaporphineand 21H,23H-5,15-Diazaporphine. The trivial name 21H,23H-Porphyra-

5

6

Me
10

7
10

22

1

O 2 C( CH 2 ) 2 21
M e O2 C

9

13
12

12

15

21H,23H-Porphine21
22

Phorbine
6

14

16

HN

Ferrate(2−), [7,12-diethenyl3,8,13,17-tetramethyl-21H,23Hporphine-2,18-dipropanoato(4−)κN21,κN22,κN23,κN24]hydroxy-,hydrogen (1:2), (SP-5-13)(cross-reference from Hematin)

2

22

18

3

15

CH =CH 2
Me

21

1

17

• 2H+
11

Phorbine is a cyclopentaporphine derivative:−

Synthetic polymeric fibers
adipic acid-butanediol (General Subject Index entry)

9

14

Me

10

For studies indexed at Rayon, Acetate fibers, etc., no additional index entries will be found, but for studies of fibers of specific chemical composition
entered at Polyamide fibers, Synthetic polymeric fibers, etc., additional information is entered at the appropriate chemical substance name, except wherea cross-reference to the fiber class appears.
Example:Me−−

5′-Guanylic acid,polymer with 5′-adenylic acid,complex with 5′-uridylic acid,polymer with 5′-cytidylic acid (1:1)

Trade names are frequently used for polymers and are cross-referred to specific polymers if the components can be structurally defined. If the polymer
components are unknown, or only partially known, or cannot structurally be
defined, an index citation is made at the trade name and at the appropriate polymer class name.
Natural rubber is indexed at the General Subject Index heading Natural
rubber and chlorine-treated rubber at Chlorinated natural rubber. When asynthetic rubber is indexed at Butadiene rubber, Isoprene rubber, etc., noadditional entry will be found in the printed Chemical Substance Index, but forstudies indexed at Synthetic rubber, Urethane rubber, or at Polysulfide
rubber, information will also be found, when available, at the appropriate
printed chemical compound or polymer heading, with “rubber” cited in the index modification.
Examples:6

N 21 22N+
20 HO — Fe 3−
19
N24 23 N
1−O

CH =CH 2

4

O 2C( CH 2) 2

−p −A −p − G−p−A −p−A −¶ 223

21H-Biline-8,12-dipropanoic acid,
2,17-diethenyl-1,10,19,22,23,24hexahydro-3,7,13,18-tetramethyl-1,19-dioxo(cross-reference from Bilirubin)( CH 2 ) 2 CO 2 H( CH 2 ) 2 CO 2 H

For derivatives of Corrin, see Vitamin B12 (¶ 224).

¶ 224

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

224. Vitamins, being structurally diverse, are indexed by more than one
method. The headings Vitamin B, Vitamin K, etc., are used to index groupsof compounds having similar physiological activities, especially for biologicalstudies. Such headings as Vitamin B4, Vitamin B6, Vitamin F, may each refer to one or more specific compounds or to nothing more than an ill-defined
vitamin activity. They are used in indexing when employed in original documents, and CAS Registry Numbers are assigned to them.
Vitamin A is a heading parent employed for the group of A vitamins andfor vitamin A activity in general. Vitamin A1 is indexed at the carotenoid heading Retinol (¶ 212); Vitamin A2 is indexed at Retinol, 3,4-didehydro-. Related trivially named heading parents are Retinoic acid and Retinal. In all thesecases, an all-trans-configuration about the double bonds is implied by thenames. Abnormal stereochemistry is specifically cited in the modification.
Vitamin B is a heading parent employed for the B-complex and vitamin B
activity in general. Vitamin B1 and related compounds are indexed at the systematic names. (The trivial name Thiamine, not used as a CA index heading,
implies presence of a chloride anion.)
Example:108

Examples:
1
6

Me

N

H O CH 2

4-Pyridinecarboxaldehyde, 3hydroxy-5-(hydroxymethyl)-2methyl-

OH
CHO

1

N

Me

6

H O CH 2

3-Pyridinemethanol, 4-(aminomethyl)-5-hydroxy-6-methyl-OH
CH 2 N H 2

NH 2
N

+
CH2 — N

Me

S

N

•

Cl

−

( CH2 ) 2 OH

1

Me

6

Thiazolium, 3-[(4-amino-2methyl-5-pyrimidinyl)methyl]5-(2-hydroxyethyl)-4-methylchloride (1:1)

The diphosphoric (pyrophosphoric) acid ester of Vitamin B1 (cocarboxylase) is indexed by expressing the ester as an “a”-named substituent; i.e., the 5(2-hydroxyethyl) group becomes 5-(4,6,6-trihydroxy-4,6-dioxido-3,5-dioxa4,6-diphosphahex-1-yl)-. Vitamin B2 contains a ribitol residue and is indexedat the stereoparent
Riboflavin:MeN

H O CH 2

3,4-Pyridinedimethanol, 5hydroxy-6-methyl-OH
CH 2 O H

Vitamin B12 is an index heading used for the vitamin itself:

H 2NCO(CH 2 ) 2Me Me
H 2NCOCH 2

CH 2 CO N H 2

−

Me
Me

( CH 2 ) 2 CO N H 2

CN
N | N
Co 3+

−

5 ′C H 2 OH

H

N

4′

H2NCOCH 2

3′

CH 2 NHCO(CH 2 ) 2

H O —C —H
H O —C —H

N

Me Me

Riboflavin

MeMe( CH 2 ) 2 CO N H 2

2′

H O —C —H
Me

91′ CH2
1
N 10a NN

CHMeOP(O) (O −) O OH

O

Me

N
Me

N
6

4

3

Me

NH
HOCH 25OO

Plain locants are employed for ring substituents, primed locants for the ribitol moiety. Binary headings analogous to those for nucleotides (¶ 210) areused for phosphates, diphosphates (pyrophosphates), etc., e.g., Riboflavin 5′(dihydrogen phosphate). Functional derivatives of Riboflavin are expressedin the modification, e.g., 2′,3′,4′-triacetate, other derivatives as substituents.
Analogs in which ribitol is replaced by other alditols are indexed at the alditol
stereoparent names, e.g., D-Galactitol, 1-deoxy-1-(3,4-dihydro-7,8-dimethyl-2,4-dioxobenzo[g]pteridin-10(2H)-yl)-.
Vitamin B3 is indexed at 3-Pyridinecarboxamide; Vitamin B5 is a littleused term for Pantothenic acid, which is indexed at β-Alanine:
H O C H 2 C Me 2 C H (OH) CONH( CH 2 ) 2 CO 2 H

β-Alanine, N-[(2R)-2,4-dihydroxy-3,3dimethyl-1-oxobutyl)-]Vitamin B12

The terms Cyanocobalamin and Cobalamin are not used in index names.
Derivatives, other than functional derivatives, of Vitamin B12 are indexedlargely in accordance with rules of the International Union of Pure and Applied
Chemistry,6 which should be consulted for details.
The fundamental ring system is Corrin, which is numbered like Porphyrin,
the locant “20” being omitted to facilitate analogous treatment of derivatives;
the methene bridges which remain are numbered “5,” “10,” and “15.” The index heading (in the General Subject Index) for this class of compounds is Corrinoids, and specific compounds are generally indexed at the largest
appropriate heading parent chosen from the following: Cobyrinic acid, Cobinic acid, Cobamic acid, or the corresponding amides.

Vitamin B6 is a heading parent employed for studies in which the precise
compound is not further specified. The individual compounds and their derivatives are indexed systematically at pyridine headings.

6IUPAC, “Nomenclature of Corrinoids (Rules approved 1975)”, Pure Appl.
Chem. 1976, 48, 495-502; Biochemistry 1974, 13, 1555-60.

109

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007(b)

RCOCH2 )2 MeMeCH 2 COR( a) R C O CH 2

( CH2 )2 COR

Me
Me

N
−
N

H

(d)

N
Co 3

+

N

( g) R C O C H2MeMeR1 C O (C H2 ) 2

( f)

(c )

Me

( CH2 )2 COR ( e)Me

R= R1 = OH

Derivatives are named in accordance with the rules for carbohydrates (¶208), e.g., L-Ascorbic acid, 5,6-O-(1-methylethylidene)-; L-threo-2,3-Hexodiulosonic acid, γ-lactone (cross-reference from L-Dehydroascorbic acid).Vitamin D is an index heading used for vitamin D activity in general.
Vitamin D1 is a molecular addition compound of Vitamin D2 and (3β,9β,10α)ergosta-5,7,22-trien-3-ol (lumisterol). Vitamins D2 and D3 are given systematic names.
Vitamin E is used as a heading for Vitamin E activity in general. Individual compounds, notably α-tocopherol, exhibiting this activity are indexed systematically.
Example:Me

Cobyrinic acid

R= R1 = NH2

Cobyrinamide acid

R= OH; R1= NHCH2CHMeOH

Cobinic acid (in Cabinamide, R= NH2)

R= OH; R1= NHCH2 CHMe

Cobamic acid (in Cobamide, R= NH2)|
OP (O) (O ) O − OH

¶ 224

O

Me

(CH2)3(CH2)3(CH2)3
Me

CHMe2

Me

Me
HO
Me

2H-1-Benzopyran-6-ol, 3,4-dihydro2,5,7,8-tetramethyl-[(4R,8R)-4,8,12-trimethyltridecyl]-, (2R-)

OH
O
HOCH 2

In Cobamic acid and Cobamide, the structures (above) have been shownas inner salts; the cobalt(3+) nucleus is also coordinated with the nitrogen atoms with loss of one proton overall. The compound therefore still possesses a
1+ charge. Similarly, Cobyrinic and Cobinic acids (and their amides), whichlack the phosphate group, have a 2+ charge, and can form dihydroxides, cyanide hydroxides, etc. Partial amides of Cobyrinic acid are designated by useof the small italic locants shown in the diagram above; e.g., Cobyrinic acidabcdeg-hexamide, dicyanide. Substitution on amide groups is indicated by N
with a superscript, e.g., Nf-(carboxymethyl)-. In modifications at corrinoid
headings, the various types of derivatives are cited in the following order: (a)groups linked to the cobalt atom, e.g., Co-ammine, Co-methyl deriv., Co-(pyridine); followed by anions, e.g., cyanide, acetate (salt); and then “hydrate” if
present; (b) lactones and lactams formed between acetic or propanoic residues
and existing or added hydroxyl and amino groups; (c) esters of the corrin moiety, e.g., dihydrogen phosphate (ester); (d) “inner salt” (for zwitterionic structures); (e) further ester terms for a polybasic acid residue such as phosphoricacid, e.g., “3-ester with. . . .”When the cobalt is in a 2+ rather than a 3+ oxidation state, Ewens-Bassett
numbers (¶ 215) or Stock numbers are cited in the heading; e.g., CobinamideCo(1+), Co-ethyl deriv., hydrate (1:1) (the “1+” designation belongs to theentire cobinamide parent, and results from coordination of the Co(2+) atomwith loss of a proton from corrin; the modification term renders the total compound neutral); Cobamide-Co(II) (the Stock number is employed because no
charge remains; a proton has been lost from corrin and another from the phosphoric acid group by inner salt formation).
Analogs of Cobyrinic acid, etc., in which cobalt is replaced by anothermetal are named by substituting a suitable term for “Co-” in the original name.
Thus, the iron(2+) and nickel(3+) analogs of cobyrinic acid are named Ferrobyrinic acid and Nickelibyrinic acid, respectively. The hydrogen analog isHydrogenobyrinic acid.
Vitamin C is indexed at L-Ascorbic acid:O =C
H O —CO
H O —CH —C
H O —C —H
C H 2O H

L-Ascorbic acid

Vitamin K is used as a group heading; the specific compounds are named
systematically.
Examples:
Me

Me

Me

O

CHMe2
( C H2 ) 3(CH2) 3

( C H2 )3Me

1,4-Naphthalenedione, 2-methyl-,
3-[(2E,7R,11R)-3,7,11,15-tetramethyl-2-hexadecen-1-yl]-

O

O
Me
CH 2

H

H

C=C
CH 2

Me

6

O

1,4-Naphthalenedione, 2-[(2E,6E,10E,
14E,18E)-3,7,11,15,19,23-hexamethyl-2,6,10,14,18,22-tetracosahexaen-1-yl]-3-methyl-¶ 225

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

110

G. CHEMICAL SUBSTANCE NAMES FOR RETROSPECTIVE SEARCHESIntroduction
Acetals
Acid halides
Acids
Additive Nomenclature
Alcohols and Phenols
Aldehydes
Alkaloids
AlloysAmidesAmidines
AminesAmino acids
Anhydrides
Azo and azoxy compounds
Boron compounds
Carbohydrates
Carbonic acid and relatives
Coordination compounds
Diazo compounds
Dyes
Elementary particles
Enzymes
EstersEthersFormazan
Functional derivatives
Guanidine and relatives
Hydrazine
Hydroxylamine
IminesIndex name selection
Indicated hydrogen
Inorganic compounds
Inositols
Iodine compounds
Isocyanides

¶ 225
226
227
228
228A
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260

225. Introduction. The current name-selection policies for chemical substances described in Sections A through F above were introduced in 1972.
These policies, which are now well-established, enable the index user to derive
preferred CA names for substances of specific molecular structure and thereby
to find information about them in current and recent indexes. However, incarrying searches back beyond 1972, difficulties can arise. The current CA
name of our compound has been determined; but where will we find this same
substance in older CA indexes? Cross-references in these indexes are helpful,but of course none exist that lead from current names to those in Eighth (andearlier) Collective Indexes. As a last resource, the Formula Indexes can be consulted. But a simpler method, especially in searching for groups of compounds,
is to read the appropriate paragraphs of this section. Although published originally (in the Volume 76 Index Guide under the title “Ninth Collective Index
Changes”) to alert index users to prospective changes, it will now be foundmost serviceable to remind retrospective searchers of the main nomenclaturechanges occurring in 1972. For example, ¶ 228 (below) indicates that peroxoic
acids, in Volume 75 and earlier indexes, will be found at Peroxy headings, thataldehydic, anilic, and hydroxamic acid headings were also employed, and thatmany acids were indexed at trivial names; ¶ 270 explains that cationic compounds currently indexed at aminium headings were formerly entered at Ammonium; and ¶ 281 gives examples of current and former names for cyclic
epoxides.
The changes in name selection policies described in this section are 1972changes unless otherwise specified. The very few revisions found necessary in
the Tenth (1977-1981) and Eleventh (1982-1986) Collective Index periods
mainly affect inorganic compounds and are described in ¶¶ 239, 257, and 273.
Changes in name-selection policies for the Twelfth (1987-1991) and Thirteenth (1992-1996) Collective Index periods affect alloys, carbohydrates (lactams), coordination compounds, formazans, index name-selection (multiplicative names), inorganic compounds (line formulas of clusters, intermetallic
compounds), molecular addition compounds (common components; hydrates),
nitrilimines, onium compounds (free radicals), peptides, phosphonium ylides,
phosphoryl-halides and halogenoids, polymers (block, graft, and hydrolytic),
ring systems (list of common systems), salts (list of common anions), stereochemistry (sign of optical rotation), and zwitterions (inner salts, sydnones).
These are described in this section at their respective paragraphs listed above.
The changes for the Fourteenth (1997-2001) Collective Index periods affectcoordination nomenclature, stereochemical practices, and stereoparents andare described in ¶ ¶ 242, 284, and 285.
The arrangement of subjects is alphabetic, and references are supplied ineach case to the paragraphs in Sections A through F where a complete accountof current policies will be found. The index (Section M) may also be consulted.
Headings found in current indexes are shown in boldface within the following paragraphs.
226. Acetals are indexed like ethers (¶ 196); thus, Acetone, diethyl acetal
became Propane, 2,2-diethoxy-. Cyclic acetals, except those of stereoparents

KeteneKetones
Locants
Metallocenes
Mixtures
Molecular addition compounds
Multiplicative prefixes
NitrilesNitroneNucleosides and Nucleotides
Onium compounds
Order of precedence of compound classes
Organometallic compounds“Oxo” acids
PeptidesPeroxides
Phosphorus compounds
Polymers
Porphyrins and Bile pigments
Replacement (“a”) nomenclature
Replacement nomenclature for functions
Ring systems
Salts
Silicon compounds
Spelling
Stereochemistry
Stereoparents
Steroids
Substituent prefixes (radicals)
Sulfur compounds
Sulfones and Sulfoxides
Tautomers
Terpenes
Thiols
Urea
Vitamins
Zwitterionic compounds

¶ 261
262
263
264
265
265A
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
281A
282
283
284
285
286
287
288
289
289A
290
291
292
293
293A

(¶ 202), are indexed at the ring names. Epoxides are likewise indexed at thenames of the appropriate ring systems, e.g., Oxirane.
227. Acid halide names (¶ 170) were affected by the discontinuance ofmost trivial acid names. Isocyanates, isothiocyanates, and isocyanides are now
named like the halides. In the following examples, names prior to 1972 areshown in parentheses.
Benzenepropanoyl chloride
Butanethioyl fluoride
Benzenesulfonyl isocyanate(Hydrocinnamoyl chloride)(Butyryl fluoride, thio-)(Benzenesulfonic acid, anhydridewith isocyanic acid)228. Acids. Carbonic acid and related compounds including Formic acid(¶ 183) are now relegated to a position below “organic” acids and above inorganic “oxo” acids (¶ 106).
Among carboxylic acids, the only trivial names retained were Acetic acidand Benzoic acid. (When oxygen in the functional group of these two acids is
replaced, systematic functional replacement names, e.g., Ethanimidic acid,
Benzenecarbothioic acid, are employed.) All other organic acids (carboxylic,sulfonic, sulfinic, etc.) are named systematically (¶ 165); e.g., Propanoic acid(formerly Propionic acid); Benzoic acid, 2-hydroxy- (Salicylic acid); 2Butenedioic acid (2E)- (Fumaric acid); Benzenesulfonic acid, 4-amino- (Sulfanilic acid).
Use of replacement affixes (¶ 129) for modified carboxylic, sulfonic, etc.,groups was extended for Volume 76. In the following examples, the names
formerly used are shown in parentheses:
Ethanimidothioic acid
3-Pyridinecarbohydrazonicacid,
methyl ester
Butanediperoxoic acid
2-Propanesulfeno(thioperoxoic) acid

(Acetimidic acid, thio-)(Nicotinic acid, methyl ester,
hydrazone)(Peroxysuccinic acid)(Peroxy-2-propanesulfenic acid,thio-)

Aldehydic, amic, anilic, hydroxamic, hydroximic, nitrolic, and nitrosolic
acids are now named as derivatives of carboxylic acids, amides, etc.
Examples:1-Naphthalenecarboxylicacid, 8-formylPropanoic acid,
3-amino-3-oxoButanoic acid,4-oxo-4-(phenylamino)Acetamide, N-hydroxyEthanone, 1-nitro-, oxime
See also Oxo acids (¶ 273).

(Naphthalaldehydic acid)(Malonamic acid)(Succinanilic acid)(Acetohydroxamic acid)(Acetonitrolic acid)

111

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

228A. Additive Nomenclature. The terms oxide, sulfide, selenide, andtelluride are used as part of the modification to describe the presence of a chalcogen atom attached to trivalent antimony, arsenic, bismuth, nitrogen or phosphorus, or to divalent sulfur, selenium, or tellurium (¶ 123). However,acceptable unambiguous locants are often lacking to describe the exact
location when multiple possibilities are present and the result is a name whichis less specific than the structure.
Effective with Volume 124, oxides, etc. attached to the parent portion of thename continue to be cited as oxide, sulfide, etc., with an appropriate locant in
the modification portion of the name, however, if the attachment is not to theparent, terms such as oxido, sulfido, selenido, or tellurido will be cited withlocants, in the substituent or modification, as appropriate.
229. Alcohols and Phenols (¶ 175) are treated as of equal seniority in theorder of chemical functions; previously, alcohols (in which the hydroxyl groupis formally attached to a saturated carbon atom) were placed just ahead ofphenols. Now, the preference of cyclic over acyclic hydrocarbons (¶ 138) oftencauses a change of nomenclature unless a conjunctive name can be used.
Examples:OH

Phenol, 3-[(hydroxymethyl)thio](formerly Methanol, [(m-hydroxyphenyl)thio]SC H 2 O H
CH2OH

OH

Benzenemethanol, 2-hydroxy(formerly Benzyl alcohol,
o-hydroxy-) (the preferredheading parent is larger than
Phenol)Radicofunctional names previously used for unsubstituted Ethyl throughDodecyl alcohol were replaced by Ethanol, 1-Propanol, etc. Iso-, sec- andtert-names are no longer used, except to index “isooctanol,” etc., when no
further information is provided. Isopropyl alcohol is now indexed at 2-Propanol; sec-Butyl alcohol at 2-Butanol; and tert-Butyl alcohol at 2-Propanol,
2-methyl-. Phenol was retained as a heading parent, but all other triviallynamed phenols, including polyhydric benzene derivatives, are named systematically at such names as Phenol, 2-methyl- (formerly o-Cresol) and 1,3,5Benzenetriol. Naphthalenol (formerly Naphthol) and Anthracenol (formerly
Anthrol) are now spelled out.
230. Aldehydes (¶ 173) are named systematically by use of the suffixes“-al” and “-carboxaldehyde,” except for the three trivial names Acetaldehyde,
Formaldehyde, and Benzaldehyde. Chalcogen analogs are all named systematically. Examples (previous index names are on the right):
Propanal
Benzaldehyde,
2-hydroxy-3-methylBenzenecarbothioaldehyde
Butanedithial(Propionaldehyde)(2,3-Cresotaldehyde)(Benzaldehyde, thio-)(Succinaldehyde, dithio-)231. Alkaloids (¶ 204). Many alkaloids indexed prior to 1972 at trivialnames are now indexed systematically. The remaining trivial headings (stereoparents) are limited to alkaloids exhibiting stereochemical complexity. Class A
alkaloids (named systematically) therefore comprise a much larger group thanpreviously, when it was restricted to compounds containing no asymmetriccenter. Classes B and C are largely unchanged, except that the number of Class
B alkaloid stereoparents (“systematic” alkaloid names) has been greatly increased with a consequent reduction in the number of Class C alkaloid stereoparents (trivial names for alkaloids of known constitution, including allstereochemistry). Class D alkaloids (those not fully elucidated) are indexed at
systematic names without stereodescriptors if sufficient information is available, otherwise at author names or as Class B stereoparents with partial stereochemical information.
232. Alloys (¶ 214) are now indexed and registered as specific chemical
substances. The components, if known, are cited as symbols in the modification with their percentage compositions (when present to the extent of 0.1% ormore). Cross-references from trade names and some code designations havebeen provided (without percentage compositions); e.g., Alnico V. See Iron
alloy, base, Fe,Al,Co,Cu,Ni,Si,Ti (Alnico V). Beginning in 1992 “nonbase”
headings, e.g., Cobalt alloy, nonbase, for the other component elements are
no longer made. For alloys of unknown percentage composition, only the “nonbase” headings for the components are employed.
233. Amides (¶ 171) are named systematically by use of the suffixes“-amide” and “-carboxamide.” The three remaining exceptions are Formamide, Acetamide, and Benzamide, but their chalcogen and imidic analogs are
now named systematically; for example, Acetamide, thio- is named as Ethanethioamide. Anilides are now indexed as N-phenyl amides. Secondary andtertiary amides are named at the preferred primary amide name. Thio analogs
of sulfonamides are named as sulfonothioamides and sulfonodithioamides. See
also Urea (¶ 292).
234. Amidines (¶ 171) are indexed systematically as imidamides, i.e., asamides of imidic acids; thus, Formamidine in Volume 76 became Methanimidamide. Amidoximes are named as N-hydroxy imidamides.
235. Amines (¶ 176) are all named systematically; Aniline is indexed atBenzenamine; Methylamine became Methanamine. Derivation of aminenames for amino derivatives of nitrogen heterocycles is now permitted; Pyridine, 2-amino- (pre-1972 name), is now 2-Pyridinamine; and Piperidine, 4-(2aminopropyl)-, became 4-Piperidineethanamine, α-methyl-. Secondary andtertiary amines are named as derivatives of the preferred primary amines, e.g.,¶ 241

Ethanamine, N-ethyl- (formerly Diethylamine). Amino derivatives of thehydrides Borane, Phosphorane, and Stannane are now indexed at Boranamine, Stannanediamine, etc.
236. Amino acids (¶ 205) which are biologically significant are usuallyindexed at the trivial (or “common”) names which are now classed as stereoparents. A few trivial names of α-amino carboxylic acids (Allocystathionine,
Carnosine, Creatine, Cystathionine, Ethionine, Hippuric acid, Lanthionine,
Pantothenic acid, Sarcosine, Thyronine, Thyroxine) and all trivial names ofamino sulfonic acids were discontinued. The configurational descriptor is now
placed in the heading as a prefix, thus: L-Leucine. The new stereoparent Phenylalanine is now employed, instead of Alanine, phenyl-, for C6H5CH2CH(NH2)COOH. Amino acid radicals are now employed only in naming peptides.
O- and S-Derivatives of hydroxyl- and mercapto-group-containing aminoacids, e.g., Serine and Cysteine, are now indexed at those heading parents.
Esters of stereoparent amino acids with systematically named hydroxy compounds are indexed at the stereoparents. An ester with another stereoparent is
indexed at the component possessing the higher function. Normally, only one
entry is now made for each ester (¶ 247).
Beginning in 1992, primed locants are assigned to the side-chain methylgroup of isoleucine, alloisoleucine, leucine, valine, and isovaline. Such
branched-chained derivatives of these acids are no longer named as derivativesof the linear acid (Butanoic acid or Norvaline).
237. Anhydrides (¶ 179) of unsubstituted monobasic organic acids prior
to Volume 76 (1972) were named in the heading, e.g., Acetic anhydride; now
they are cited in the modification at the acid heading. Anhydrides of organic
acids with inorganic monobasic oxo acids are named at the organic acidheading with an “anhydride with...” phrase in the modification, not at suchformer headings as Acetyl nitrate, but anhydrides of organic acids with isocyanic and isothiocyanic acids are treated like the corresponding acid halides. The
term “bimol. monoanhydride” is employed when appropriate, with locants
before the second word if necessary, at polybasic organic acid headings.
Cyclic anhydrides are now indexed as diones at the oxygen heterocycle
names. Heading parents such as Dicarbonic, Dicarbonimidic, and Tricarbonic acid are used for carbonic acid anhydrides and their analogs (¶ 183).
Anhydrides of phosphonic, phosphorous, arsonic, and arsonous acids are now
treated like phosphoric acid anhydrides, e.g., Diphosphonic acid. “A” names
are used for anhydrides when the requirements (¶ 127) are met.
238. Azo and azoxy compounds (¶ 193) in the absence of higher functions(e.g., nitrogen heterocycles, or functions expressible by a suffix) are indexed at
Diazene, HN=NH (formerly Diimide). Azobenzene thus became Diazene,
diphenyl-, and Naphthalene-2-NNO-azoxymethane became Diazene, methyl2-naphthalenyl-, 1-oxide. Prior to 1992, formazans were of higher functionality than azo and azoxy compounds, but now have no special rank (¶ 249).
239. Boron compounds (¶¶ 159, 182). Cyclic compounds in which ligands
bridge two boron atoms are named as coordination compounds; for example,
Diazoniadiboratacyclobutane
H2
N
H2B

BH 2
N
H2

is now indexed at Diborane(6), di-µ-amino-. Derivatives of polyboranes are
given low numbers for substituents regardless of the direction of numbering.
Boronic acid is treated as an independent index heading parent; thus, Benzeneboronic acid was renamed Boronic acid, phenyl- in 1972.
Since the Tenth Collective Index period (1977-81), most molecular
addition compounds of boron have been indexed as coordination compounds.
From the same date, Hypoboric acid, ((HO)2BB(OH)2), has been indexed at
Diborane(4), tetrahydroxy-.
240. Carbohydrates (¶ 208). Glycosides of known constitution are now
indexed at the systematic names; they are ranked as polyhydric alcohols, not as
aldehydes or ketones, and when attached to a carbon atom of an aglycone containing a higher chemical function are indexed at a name which expresses thatfunction. N-Glycosyl derivatives of heterocycles have continued to be indexedat the heterocyclic parents.
Radical (substituent prefix) names are no longer formed from alditols.
Oligosaccharides indexed prior to Volume 76 at common names, e.g.,
Sucrose, are now named by systematic carbohydrate nomenclature.
The names Erythrose and Threose were discontinued except in the namingof polysaccharides. “Arrow” nomenclature was extended to all tri- and higher
oligosaccharides, including those indexed at “-oside” heading parents.
Configurational descriptors (D-, L-, and DL-) are now always placed aheadof the heading parent; e.g., D-Glucopyranoside.
The index parent Cellulose acetate was discontinued; entries since 1972
have been made instead at Cellulose, esters, with modifications such as“monoacetate,” “diacetate,” and (for the indefinite ester) “acetate.”
The naming of intramolecular amides of carbohydrate acids as lactams was
discontinued for the Twelfth Collective Index. Such amides are named systematically as heterocyclic derivatives (¶ 171).
241. Carbonic acid and relatives (¶ 183) underwent name changes inseveral respects. Carbonic acid itself was retained but is now classed below
all “organic” acids, including carboxylic and sulfonic acids, and above inorganic oxo acids (¶ 106). It is the parent of numerous acids, amides, acid halides,
etc., derived from it by the use of affixes and suffixes. Thus, Carbonic acid,thio-, became Carbonothioic acid; Imidocarbonic acid, HN=C(OH)2, became
Carbonimidic acid; Formic acid, chlorothio-, hydrazone, H2NN:C(Cl)SH,
became Carbonochloridohydrazonothioic acid. Cyanic acid, Thiocyanic¶ 241

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

acid, etc., were retained. Carbamic acid was kept as an acceptable abbreviatedversion of Carbonamidic acid; the abbreviation is also employed when otheraffixes are present, as indicated in the following list of revised names.
Carbamic acidH2NCO2H

Carbamohydrazonic acid

H2NC(=NNH2)OH

Carbamimidic acid

H2NC(=NH)OH

Carbamothioic acid,S-ethyl ester

H2NC(O)SEt

Carbamo(dithioperox)imidicacid

H2NC(=NH)SSH

Carbonic acids with a single hydrazide residue replacing an acid group areindexed, not as Carbonohydrazidic acid derivatives, but at Hydrazine index
heading parents such as Hydrazinecarboxylic acid. The dihydrazide is named
Carbonic dihydrazide. Phosgene, C(:O)Cl2, is indexed at Carbonic dichloride.
Carbonic acid is now a “Class I” acid in the naming of esters (¶¶ 185, 247)
as are Formic acid, Carbamic acid, Carbamic acid, methyl-, and Carbamic
acid, phenyl-.
242. Coordination compounds (¶ 215). Beginning in Volume 76 (1972),
the stereochemistry (when known) of mononuclear coordination complexes
has been described in the index name modification by capital italic letter
symbols (¶ 203 III).
The ligating atoms of ligands, with certain limitations, are denoted bycapital italic element-symbol locants for mononuclear complexes and for nonbridging ligands of polynuclear complexes. Use of these locants has resulted ina change in some simple inorganic ligand names; thus nitrito became (nitritoκO) and nitro became (nitrito-κN).
Delocalized ligands are now denoted by the “hapto” convention, in which
the Greek letter eta (η) is employed, along with locants to indicate the particular ligand atoms involved, or else a superscript indicating the total number ofsuch atoms (when all are involved).
Compounds containing more than one complex anion are indexed at thepreferred anion while other anions are cited with (simple) cations in the modification.
Ligands containing ester groups now normally include the esters in theligand names. The rules for choice of a radical name for a ligand, rather than aname ending in “-ato,” underwent some modification. Enclosing marks are
employed around all “-ato” ligand names, and additional enclosing marks areadded for bridging ligands when the ligand name itself requires enclosing
marks; e.g., [µ-(acetato-κO:κO′)].
Beginning in Volume 106 (1987) salts of dithio(seleno, telluro) organic
acids and polythio(seleno, telluro) arsenic and phosphorus acids with coordination metals are structured and named at the chelated forms.
Metal “radical” names, e.g., “aluminio,” are no longer employed for attachment of one metal to another in a binuclear complex, or as multiplicative
radicals (¶ 194).
Numerical prefixes gave way to numerical ratios when mixed cations andanions (or at least one multivalent ion) are expressed in the modification. The
terms “ion(1+),” “ion(2+),” etc., are not cited in modifications.
Beginning in Volume 126 (1997), the Kappa system replaces the donor
atom system for describing the position of ligand attachment to a coordination
center. In the Kappa system, when it is necessary to indicate the attachment of
a ligand to a coordination center, the ligating atom(s) are indicated by the italic
element symbol of the atom(s) preceded by a Greek Kappa (κ). This combination of italic element symbol and Greek Kappa is placed after that portion of
the index name to which it directly applies; e.g., (2-aminoethanolato-κO).
Beginning with Volume 129, some substances which have had coordination
names will receive ring names.
Old Name
Sulfur, mercaptomethylperoxy-, (T-4)New Name Dioxathiirane, 3,3-dihydro-3-mercapto-3-methyl243. Diazo compounds, including diazohydroxides, etc., are now often
named at Diazene headings (¶ 193).
Example:Cl

N= NCN

Diazenecarbonitrile, 2-(4-chlorophenyl)- (formerly Benzenediazocyanide, p-chloro-)

112

Examples:LeptonMeson, π− (140)
Muon, µ+ (106)
Nucleonresonance N*(2040)
Positron
leptonic mol. with chlorine (e+e-Cl0)
Proton246. Enzymes (¶ 218) are now indexed as chemical substances to which
CAS Registry Numbers are assigned. These are inverted if they consist of morethan one word.
Examples:Dehydrogenase, lactate
Phosphatase, adenosine triAsparaginase
PapainThe heading may contain further information regarding secondary activities, etc.; thus: Dehydrogenase, malate (decarboxylating).
247. Esters (¶ 185). Some changes were made in the list of “Class I” (i.e.,common) acids. The following acids were added:
Benzoic acid, amino- (all isomers)
Carbamic acid, N-methylCarbonic acid
Phosphorodithioic acid
Phosphorothioic acid
Inorganic oxo acids other than Boric acid (H3BO3), Nitric, Phosphoric,
Phosphorous, Sulfuric, and Sulfurous acids were removed from the Class I
list and therefore are now preferred as the heading parents for esters with ClassI and Class II alcohols. (Additional entries for esters were discontinued.)
Cyclic esters are named as heterocycles. Esters of stereoparents with systematically named acids are indexed at the stereoparents (¶ 202).
The use of a radical term ending in “-yl ester” is now preferred to “ester
with...,” even when the alcoholic component contains a chemical function
higher than alcohol (see ¶ 250), unless the latter phrase is followed by a stereoparent, as in “5′-ester with adenosine,” or by an acid requiring a synonym line
formula, as in “triester with boric acid (H3BO3).” When the “-ate” form of a
polybasic acid name is cited in the modification at an alcohol heading, all freeacid groups are denoted by the word “hydrogen,” e.g., Cyclohexanol, 4bromo-, dihydrogen phosphate.
Esters of substituents of index heading parents are expressed as substituents. Thus, the acetate of Benzenesulfonic acid, 4-hydroxy- is named Benzenesulfonic acid, 4-(acetyloxy)-, and the methyl ester of Pyridinium, 3carboxy-1-methyl-, chloride, is indexed at Pyridinium, 3-(methoxycarbonyl)-1-methyl-, chloride (1:1).
Ortho esters are named as ethers, i.e., as alkyloxy and aryloxy substituents.
Organic replacement “a” names are used for esters where appropriate (¶ 127).
248. Ethers (¶ 196) are named as substituents of hydrocarbons and otherindex heading parents; Ether as a heading parent was discontinued. Thus, Ethyl
ether became Ethane, 1,1′-oxybis-. Polyethers may often be named by organic
replacement nomenclature (“a” names) (¶ 127). Methylenedioxy derivativesof benzene and its hydrogenated derivatives are named at 1,3-Benzodioxole.
249. Formazan (¶ 193) was retained in 1972, but was ranked just below
imines as the highest of the nitrogen compound classes lacking functional suffixes. Formazan radicals were also retained. However, beginning with theThirteenth Collective period formazan, in all its aspects, is named systematically (¶ 193).
250. Functional derivatives (¶ 112) (now restricted to acyclic anhydrides,
esters, hydrazides, hydrazones, and oximes) of principal chemical functions
have continued to be expressed in the index modifications at boldface index
headings, but derivatives of subsidiary functions are usually included in thesubstituent prefixes which follow the comma of inversion in an inverted
heading. Hence Benzoic acid, p-hydroxy-, ethyl ester, acetate, is now named
Benzoic acid, 4-(acetyloxy)-, ethyl ester (¶ 185). Esters are always expressedby use of an “-yl ester” phrase when possible, not by an “ester with” phrase,
unless a stereoparent or an acid which requires a synonym line formula is being
cited in a modification. Prior to Volume 76, “ester with” was used when the alcoholic component contained a higher functon; now, “ester with glycolic acid”
becomes “carboxymethyl ester.”
251. Guanidine and relatives. Guanidine (¶ 183) was retained as anindex heading parent for Carbonimidic diamide with the locants shown (numerical locants were formerly employed):
H 2 N C( =N H ) N H 2

The unsubstituted radical HN=N− is now named diazenyl (formerly diazeno).
244. Dyes (¶ 216) of known constitution are now always indexed at theirsystematic names. Previously, azo dyes and a few other classes were given C.I.
(Colour Index) names for indexing purposes. Mixed dyes are indexed (likeother mixtures, ¶ 221) at the names of their components when these are known.
C.I. names are employed, when available, for dyes of unknown composition.
245. Elementary particles (¶ 217) are now indexed and registered as
chemical substances.

N

N ′′

N′

It is ranked below Urea (carbonic diamide).
Biguanidine is now named 1,2-Hydrazinedicarboximidamide with thelocants shown:H 2 N C( =N H ) N H N H C( =N H ) N H 2
N

N′

1

2

N′′′ N′′It ranks as the amide of a diimidic acid of a nitrogen acyclic parent, e.g., above

113

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Benzenedicarboximidamide but below Benzamide.
Biguanide and Triguanide are now named systematically as Imidodicarbonimidic diamide and Diimidotricarbonimidic diamide, respectively.
252. Hydrazine (¶ 193) was retained as a trivial name for Diazane, andfunctional suffixes may be appended to it; thus, Hydrazinecarboxylic acid,H2NNHCO2H (formerly Carbazic acid), ranks above monocarboxylic acids
derived from carbon skeletons.
Hydrazides (¶ 189) and hydrazones (¶ 190) of principal chemical functions
expressed in the heading parent are cited in the modification as before, butthese derivatives of functions expressed as substituents are now “named
through” as in the case of esters (¶¶ 247, 250), by use of hydrazinyl and hydrazinylidene radicals.
Diacyl hydrazines are now indexed not at Hydrazine but as acyl hydrazidesof the preferred acid (¶ 189). Semicarbazones of nonstereoparents are no longer
indexed as such but as derivatives of Hydrazinecarboxamide, either as anindex heading parent or as an appropriate substituent. Semioxamazones aretreated as alkylidene hydrazides of Acetic acid, 2-amino-2-oxo-, RCH:NNHC(:O)C(:O)NH2. The heading parent Carbonic dihydrazide (¶ 183) was introducedfor H2NNHC(O)NHNH2 (formerly Carbohydrazide) and its derivatives, including compounds previously indexed as carbohydrazones of oxo parents.
253. Hydroxylamine (¶ 193) was retained as a heading parent; it ranks low
among nonfunctional nitrogen parents between Hydrazine, H2NNH2, andThiohydroxylamine, H2NSH (formerly Hydrosulfamine). N-Acyl derivativesof Hydroxylamine are now indexed at amide headings; N-alkyl derivatives atamine names. In the absence of N-substituents, O-derivatives are usuallyindexed at Hydroxylamine. Alkylidene derivatives are indexed as oximes of
the corresponding carbonyl compounds unless higher functions are present, inwhich case a (hydroxyimino) substituent prefix is employed (see ¶ 195).
254. Imines (¶ 177) are indexed by means of the suffix “-imine” appended
to the molecular skeleton, which may now be a nitrogen heterocycle; e.g.,4(1H)-Pyridinimine (formerly Pyridine, 1,4-dihydro-4-imino-). Cyclic imines
are indexed at the ring names; e.g., Aziridine (formerly Ethylenimine). Imines
rank below amines and all other compounds expressed by functional suffixes.
1-Iminoalkyl radicals are so named, not as imidoyl radicals; hence, formimidoyl has become (iminomethyl), and propionimidoyl is indexed as (1-iminopropyl).
255. Index name selection policies for chemical substances (¶ 138) wererevised for Volume 76 and subsequent volumes as follows:(a) “Like treatment of like things” was abandoned.
(b) The principle of “complexity” (a measure of the number of parentheses and brackets in a name) is no longer employed.
(c) The principle of “lowest locants” of substituents on an index heading
parent (¶¶ 137, 138) was introduced on a regular basis.
(d) The principle of “centrality” is now applied when a compoundcontains a sequence of three or more occurrences of the same heading parent.
(e) Conjunctive nomenclature (¶ 124) was extended for the first time tobenzene with a single acyclic functional substituent, as in Benzenemethanol(names such as Benzenediacetic acid were used previously). It was discontinued for compounds in which ring attachment is by a double bond, and for
Carbamic and Sulfamic acids, unsaturated acyclic functional compounds,
and acyclic difunctional compounds.
(f) Multiplicative nomenclature (¶ 125) based on hydrocarbons is now
permitted, as in Ethane, 1,1′-oxybis-, and Benzene, 1,1′-[1,2-ethanediylbis(thio)]bis-. The terms “bis,” “tris,” etc., not “di-,” “tri-,” etc., are always
employed in multiplying a parent. The use of two-part unsymmetrical multiplying radicals prior to 1972 meant that names such as (ethylidenesilylene)
could be misconstrued to be either CH3CH=Si= or −CH(CH3)−SiH2−. Thus, in1972 the use of “ylidene” radicals in combination with other bivalent radicals
in forming names of multiplying radicals was forbidden. Now, stringent
symmetry is required of compounds for which multiplicative names may be
used, and thus, beginning in 1994 such combinations in forming multiplying
radicals are no longer prohibited (¶ 125). (Ethylidenesilylene) can only represent CH3CH=Si= in a multiplicative CA index name.
Beginning with Volume 119, the principle of selection of a parent based on
preferred atomic content (¶ 138(b)) is also applied to a choice between two
acyclic skeletons named by organic replacement nomenclature (“a” names).
256. Indicated hydrogen (¶ 135) is always cited, never implied; thus,
Indene became 1H-Indene, and Fluorene is now named 9H-Fluorene.
Hydrogen not required for formation of a ring system, but “added” at the sametime as a functional (or radical) suffix is now described as “added hydrogen”(¶ 136). In tautomeric systems (¶ 122), lowest locants for indicated hydrogenare normally preferred; thus 1H-Purine, not 7H-Purine, is indexed in theabsence of information to the contrary.
257. Inorganic compounds (¶ 219) are largely indexed at names previously used. Binary names for derivatives of elements possessing hydride names
were changed to derivatives of the hydrides; e.g., Silane, tetrachloro- (formerly Silicon chloride (SiCl4)); Borane, trifluoro- (formerly Boron trifluoride).
When the compound is the halide of a recognized acid, it is so named; e.g.,
Phosphorous trichloride (formerly Phosphorus chloride (PCl3)). Pyrophosphoric acid, (HO)2P(O)OP(O)(OH)2, was renamed Diphosphoric acid, andanalogous compounds are named similarly; for example, Diphosphoryl chloride, Cl2P(O)OP(O)Cl2; P,P′-Diamidodiphosphoryl fluoride, (H2N)FP(O)OP(O)F(NH2); P′-Amidodiphosphoric(III,V) acid, (HO)2POP(O)(OH)(NH2).
Since the Tenth Collective Index period (1977-81), antimony has beenclassed as a metal, and synonym line formulas have been cited in index
headings with all binary salt-type names, e.g., Sodium chloride (NaCl). See
also ¶¶ 239, 273. Graphite derivatives have been indexed as molecular addition
compounds instead of at the pre-1977 headings Graphitic acid, Graphite¶ 265Anitrate, etc.
Beginning in 1982, elements of atomic number 104 and above have been
indexed at names derived from these numbers, e.g., Unnilquadium (formerly
Element 104).
Starting with Volume 122, for elements 104-109, CAS follows the recommendations of the ACS Committee on Nomenclature: 104 - Rutherfordium(Rf); 105 - Dubnium (Db); 106 - Seaborgium (Sg); 107 - Bohrium (Bh); 108 Hassium (Hs); and 109 - Meitnerium (Mt). Likewise, starting with Volume139, element 110 is called Darmstadtium (Ds).
Starting in 1987 inorganic line formulas may be expressed with decimals or
numerical ranges as well as integers, e.g. Aluminum gallium arsenide(Al0.15Ga0.85As).
For intermetallic compounds, beginning in 1992, additional entries for the
metals with the less alphabetically preferred names are discontinued.
258. Inositols (¶ 209) are now indexed at the separate stereoparents derived
by combining individual configurational prefixes with the name Inositol, e.g.,
myo-Inositol; scyllo-Inositol. These names in turn are preceded by the configurational descriptors D- and L-. When a choice must be made for derivatives,
the earliest alphabetic prefix is preferred; then the prefix D- is selected, rather
than L-; finally, lowest locants are assigned to substituent prefixes. Inosose
and Streptamine are retained as stereoparents.
259. Iodine compounds (¶ 188) with abnormal valencies are indexed bycoordination nomenclature (¶ 215); e.g., Iodine, dichlorophenyl- (formerly
Benzene, (dichloroiodo)-.
260. Isocyanides (¶ 188). Alkyl isocyanides, RNC, are now indexed substitutively; acid isocyanides are treated like acid halides. For example, Isopropyl isocyanide became Propane, 2-isocyano-; 2-Naphthalenecarbonyl
isocyanide was formerly indexed at 2-Naphthoic acid, anhydride with hydroisocyanic acid.
261. Ketene (¶ 174) is now indexed systematically at Ethenone; Ketene,
thio- at Ethenethione. Cyclic ketenes are named as cycloalkylidene (etc.) derivatives of the new heading parent Methanone, H2CO. Unsubstituted H2CO
is still indexed at Formaldehyde, but unsubstituted CH2S is named Methanethial. In the presence of chemical functions higher than ketone, the =CO
radical is named carbonyl (if the carbon atom does not form part of an acyclic
chain) or as (oxoalkyl). The isolated =CS radical is named carbonothioyl if
both free valencies are attached to a single atom, or if it is used in a multiplying prefix; otherwise as (thioxomethyl).
262. Ketones (¶ 174). All trivial names (including Acetone, Chalcone,
Benzil, Benzoin, and all flavone, quinone, phenone and naphthone headings)
were abandoned. The heading parent Ketone was discontinued. Methanone,
H2C:O, is used to index ketones having two ring systems directly attached.
The analogous headings Methanethione, H2C=S, etc., were introduced.
Acetone was changed to 2-Propanone, Acetophenone to Ethanone, 1phenyl-, Acetophenone, thio- to Ethanethione, 1-phenyl-, Anthraquinone to9,10-Anthracenedione, Benzil to Ethanedione, diphenyl-, Flavone to 4H-1Benzopyran-4-one, 2-phenyl-, and Uracil to 2,4(1H,3H)-Pyrimidinedione.
For a discussion of this last name, see ¶ 289A.
The ketone function is no longer overstepped; hence Ethanone, 1,1′-(1,5naphthalenediyl)bis- (formerly Naphthalene, 1,5-diacetyl-).
263. Locants (¶¶ 114, 137). The locants o-, m-, and p- were replaced by
Arabic numerals in all cases; as-, s-, and ν- were likewise replaced, except in
as- and s-Indacenes and their fused derivatives. Locants for unsaturation are
now always cited for molecular skeletons of three or more atoms except formonocyclic hydrocarbons containing one multiple bond. Polyvalent radicals
with free valencies located at two or more positions now have all locants cited;
thus, ethylene became 1,2-ethanediyl. In ring assemblies, locants for positionsof attachment are always cited except for two-component assemblies of cycloalkenes, cycloalkadienes, etc. Thus, 4-Biphenylamine became [1,1′-Biphenyl]-4-amine.
In multiplicative names, locants are always cited to indicate the position of
attachment of the multiplying radical to the heading parent.
Special rules whereby locants for fully halogenated compounds and radicals
were sometimes omitted are now discontinued.
Urea is now assigned the locants N- and N′- in place of 1- and 3- (¶ 183).
When locants are required for derivatives, e.g., esters, cited in modifications, all such locants are used (¶ 119).
Letter locants are now employed with ligand names in coordination nomenclature to define the ligating atoms (¶ 215).
264. Metallocenes (¶ 215), including Ferrocene and its derivatives, arenow considered to be neutral coordination complexes. Suffix-type names andconjuctive names are no longer used; hence Ferrocenecarboxylic acid is now
indexed at Ferrocene, carboxy-; and 1,1′-Ferrocenediacetic acid at Ferrocene, 1,1′-bis(carboxymethyl)-.
265. Mixtures (¶ 221) are now indexed and registered as individual
chemical substances if they are considered significant in their own right, e.g.,
pharmaceutical and pesticide mixtures which possess trade names, or mixtures
which are emphasized in an original document as possessing special properties.
Ingredients which are considered to be inactive within the intended use of a
mixture are disregarded, e.g., solvents, fillers, and inactive trace components.
Ratios of components are not cited. Cross-references from trade names, etc.,
are provided; e.g., Terracoat. See 1,2,4-Thiadiazole, 5-ethoxy-3-(trichloromethyl)-, mixt. with pentachloronitrobenzene.
265A. Molecular addition compounds (¶ 192). Ten additions were madeto the list of common components for the Twelfth Collective Index. The newadditions are Acetic acid, trifluoro-; Acetonitrile; Benzene; Benzene, methyl-;
Benzenesulfonic acid; Benzoic acid; Borate(1-), tetrafluoro-, hydrogen; Ethanamine, N,N-diethyl-; Methane, dichloro-; and Pyridine.

¶ 265A

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

The prefixes hemi- and sesqui- were replaced by the ratios (2:1) and (2:3),
respectively in names of hydrates and ammoniates for the Twelfth Collective
Index.
Beginning with the Thirteenth Collective Index period, restriction of the expression of the number of molecules of solvation to fifteen (pentadeca) is abandoned. Fractional coefficients are limited to two digits in both the numerator
and the denominator.
Beginning with the Fifteenth Collective period, molecular addition compounds are indexed at the preferred name only. The preferred name appears in
the Formula Index at the formula of each of the components. See ¶ 192 for thecomponents for which no name is printed in the Formula Index.
Beginning with the Sixteenth Collective period, ratios are used for all molecular addition compounds for which stoichiometry is expressed. Because
polymers are nonstoichiometric compounds, ratios are rarely used for molecular addition compounds of polymers.
266. Multiplicative prefixes (¶ 110). Bis-, tris-, etc., are used in multiplicative names instead of di-, tri-, etc., even when the heading parent is not otherwise substituted. Bis-, tris-, etc., are used with methylene in every
circumstance in general index nomenclature (but “di-O-methylene” is usedwith sugar names), and with oxy and thio, etc., to denote a multiplicity of single
chalcogen atoms; thus, [methylenebis(oxy)] denotes −O−CH2−O−, while (methyldioxy)- denotes CH3−O−O−. Bi-, etc., names for ring assemblies were discontinued for assemblies of rings joined by double bonds. All ring-assembly
names are enclosed in brackets when followed by a suffix; derived radicals aretreated similarly. Binaphthyl and Bianthryl become Binaphthalene and Bianthracene (see ¶ 281). Bi-, etc., names derived from acyclic compounds, e.g.,
Bicarbamic acid, Triguanide, are discontinued.
267. Nitriles (¶ 172). Only the trivial names Acetonitrile and Benzonitrile
are retained; otherwise, changes in nitrile names are almost entirely parallel tothose for the carboxylic acids (¶ 165) from which they and their names arederived. Thus, Hydrocinnamonitrile became Benzenepropanenitrile. Cyanamide was retained for H2NCN, but conjunctive “-carbamonitrile” names
were discontinued.
+ −The zwitterionic nitrilimines (RC≡N−N−R′) are named as substituted hydrazinium hydroxide inner salts (¶ 201) beginning in the Twelfth Collective
period.
268. Nitrone, H2C=NH=O, was renamed Methanimine, N-oxide (¶ 177);
N-alkyl nitrones are indexed as oxides at amine index heading parents; N-acylnitrones at amide headings.
269. Nucleosides and Nucleotides (¶ 210) have continued to be indexed attrivial names, e.g., Adenosine, Cytidine, although the purine and pyrimidine
bases from which they are derived are now named systematically; e.g.,
Cytosine is indexed at 2(1H)-Pyrimidinone, 4-amino- (¶ 122). N-Acyl derivatives of nucleosides are indexed at the nucleoside parents instead of at amide
names, but higher functions have continued to be indexed at the parents which
express them.
Substituents are now expressed at nucleotide headings, e.g., 5′-Uridylicacid, 2′-amino-2′-deoxy-3′-thio-. Mixed phosphate esters are indexed at thepreferred phosphate heading rather than at the plain nucleoside name; e.g.,
Inosine 5′-(trihydrogen diphosphate), 2′-(dihydrogen phosphate). Nucleosides and nucleotides are considered to be stereoparents (¶ 203), and theiresters with systematically named substances are therefore indexed at nucleoside or nucleotide index heading parents.
270. Onium compounds (¶ 184). Ammonium compounds are named fromthe corresponding preferred amines by use of “-aminium” as a suffix and expression of the remaining groups as N-substituents; e.g., Ethanaminium, Nethyl-N,N-dimethyl-, iodide (1:1) (formerly Ammonium, diethyldimethyl-,
iodide). Naming of cyclic quaternary nitrogen compounds and other cationicspecies, e.g., sulfonium compounds, is largely unchanged.
Localized cationic free radicals centered on hetero atoms (¶ 184) werenamed as derivatives of the index heading parents Ammoniumyl, Oxoniumyl,
Sulfoniumyl, etc. prior to the Thirteenth Collective period.
271. Order of precedence of compound classes (¶ 106) has continued toplay an important role in the selection of a preferred index name. Changes
include the following:(a) The heading parent Silane now ranks below cyclic carbon parents andabove acyclic carbon parents. This change does not apply to any other silicon
parents.
(b) More emphasis is placed on the presence of a principal chemical functional group (expressed as a suffix attached to a molecular skeleton). Thus
Ethanamine (a functional compound) is ranked above Quinoline (a nonfunctional molecular skeleton).
(c) Ferrocene and other metallocenes are ranked with neutral coordination complexes.
(d) Peroxy acids expressed as principal groups are ranked, as a class,higher than all other acids. Previously, each such acid was placed just above
the corresponding parent acid. Carbonic acid and related compounds are placed
below those acids, e.g., carboxylic and sulfonic, expressed as functional suffixes, and above inorganic “oxo” acids. Derivatives of Arsonic and Boronic
acids are named like those of other inorganic “oxo” acids with replaceable
nuclear hydrogen atoms; thus, Benzenearsonic acid has become Arsonic acid,phenyl-. Derivatives of isocyanic acid and its chalcogen analogs are named
substitutively by use of the prefixes isocyanato, isothiocyanato, etc.
(e) Alcohols and phenols now rank as equal in precedence.
(f) Ether, Sulfide, Selenide, and Telluride are no longer employed asheading parents and are therefore not listed in the Order of Precedence. Single
chalcogen atoms are named substitutively (by use of oxy, thio, etc., radicals) or

114

at organic replacement (“a”) names.
(g) Phosphorus compounds without functional suffixes are ranked
together (following nitrogen compounds). Formerly, phosphine oxide wasplaced above amines with phosphine and phosphorane following them. The
same policy is adopted in descending order for nonfunctional heading parents
derived from arsenic, antimony, bismuth, boron, silicon, germanium, tin, andlead. Then follow nonfunctional oxygen parents in the order: oxygen heterocycles, acyclic polyoxides (Trioxide, Peroxide), acyclic “oxa” names. Other
chalcogens are ranked below oxygen in the order: sulfur, selenium, tellurium.
Lowest in order of precedence are nonfunctional carbon skeletons.
(h) In each class of nonfunctional compounds, ranked in the order of themost preferred heteroatom it contains, cyclic compounds are preferred overacyclic, and acyclic parents named by “a” nomenclature are less preferred thanother acyclic parents of that hetero atom class. Among carbon compounds,
similarly, carbocycles are preferred to acyclic carbon chains, regardless oflength. Unsaturated skeletons are preferred to saturated skeletons with thesame number and type of skeletal atoms; thus, Benzene is preferred to Cyclohexane (no policy change), and Pyridine is preferred to Piperidine (reversalof policy).
272. Organometallic compounds (¶ 194). Binary compounds of element
hydrides, e.g., Arsorane, AsH5, Plumbane, PbH4, Germane, GeH4, areindexed at those headings. Thus, Lead chloride (PbCl4) became Plumbane,
tetrachloro-. (In the carbon series, Carbon tetrachloride became Methane,tetrachloro-.) Amino derivatives of hydrides are now assigned “-amine”
names, e.g., Germanediamine, and other functional suffixes are also employed, e.g., Bismuthinecarboxylic acid, but “-ol” to express a hetero-atomattached hydroxyl is used only with carbon and silicon. “A” names must (asusual) be employed when appropriate.
273. Oxo acids (¶ 219). Some changes (¶ 185) were made in 1972 to thecontent of the “Class I” list for esters of inorganic “oxo” acids. Pyrophosphoricacid, (HO)2P(O)OP(O)(OH)2, was renamed Diphosphoric acid. The newheading parent Diphosphonic acid was previously indexed at Phosphonicacid, anhydride. Since 1972, arsenic mononuclear acids have been treatedanalogously to phosphorus acids.
Examples:Arsenic acid (H3AsO4)(HO)3AsO

Arsonic acid(HO)2HAsO

Arsinic acid(HO)H2AsO

Arsenenic acid

HOAsO2Cyclic esters of arsenic and phosphorus acids are indexed at the ring names.
Since the Tenth Collective Index period (1977-81), metal oxo acids (including oxo acids of antimony) and their salts have been indexed as coordination
compounds or as mixed salts. The only exceptions are Chromic acid
(H2CrO4), Chromic acid (H2Cr2O7), Manganic acid (H2MnO4) and Permanganic acid (HMnO4), which were retained as index heading parents. A
few little-used nonmetallic oxo acid names, e.g., Mesosulfuric acid, were also
discontinued.
274. Peptides (¶ 206), other than biologically active peptides with trivialnames, containing two through twelve amino-acid residues are now indexed at
the name of the C-terminal unit in every case; peptide amides are treated analogously. No change was made in the treatment of larger peptides. Some trivial
acyl names were changed starting in the Twelfth Collective period (19871991). Thus α-aminobutyryl became 2-aminobutanoyl and lactoyl became 2hydroxypropanoyl. Cyclic peptides of two or three units are indexed at systematic ring-system names, larger compounds at “Cyclo” names such as Cyclo[Lalanyl-N5-acetyl-D-ornithylglycyl-L-alanyl-D-propyl-O-(1,1-dimethylethyl)-L-seryl] in which the units are cited in the order of occurrence, with preference given to the lowest alphabetic arrangement of parent amino-acid radicals.
Prior to 1987 the term “Cyclic” was used instead of “Cyclo”. Additional entries
are made at ring-system names. Peptides with fewer than four units and whichcontain disulfide linkages are now indexed, like larger peptides, at cysteine
rather than cystine names.
Linear depsipeptides are now usually indexed at the C-terminal amino-acidnames; terminal hydroxy acids are expressed as carboxyalkyl esters. Cyclic
depsipeptides are indexed at ring names or “Cyclo” names in analogy with peptides.
Effective with Volume 129, the rules for naming peptites have been revised
as follows: (1) In depsipeptide nomenclature, the chalcogen in a nonterminalhydroxy, mercapto, selenyl, or telluryl acid residue need no longer be α to thecarbonyl. Any position is acceptable. (2) In ψ nomenclature (adopted inVolume 126 for certain pseudopeptides), glycine may now serve as one of theψ residuesthe amino acids cited before and after the ψ term−−provided theother ψ residue is a standard chiral amino acid. In addition, a ψ residue may
now be N-terminal, provided its CO is not replaced, or C-terminal, provided its
NH is not replaced.
Naturally-occurring biologically active peptides and depsipeptides of six to
fifty units are indexed at the trivial names; those of five or fewer units are
named like other peptides at the C-terminal amino acid or “Cyclo” name; trivially named stereoparents such as Bradykinin and Gramicidin S have continued to be employed for substances containing six through fifty units. Small
species variations in trivially-named peptides are now interrelated by using one
form as the reference compound; e.g., Fibrinopeptide B (orang-utan). See

115

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Fibrinopeptide B (human), 10-L-leucine-12-glycine-; similar cross-references
are now made between trivial names of closely-related peptides and corticotropin sequences; e.g., Kallidin. See Bradykinin, N2-L-lysyl-; α1,39-Corticotropin (human). See α1,39-Corticotropin (pig), 31-L-serine-.
Esters of hydroxy and mercapto groups in amino-acid radicals of peptides
are now expressed as substituents; e.g., O-acetyl-L-seryl. Functional derivatives of carboxy substituents are expressed by radicals which include thecarboxyl group; e.g., N-[(phenylmethoxy)carbonyl].
Such former headings as Angiotensins were made singular in Volume 76.
The indexing of Oxytocins and Vasopressins was further refined. Bovine
insulin is now the reference compound for insulins, with the name Insulin (ox).
Actinomycin D is the reference stereoparent to which other actinomycins are
related for indexing purposes.
Proteins (¶ 207) are indexed at trivial names, with accompanying species information.
Synthetic peptides are indexed like polymers; the term “polymer with” isused instead of “peptide with” at amino-acid monomer names.
275. Peroxides (¶ 196). Binary headings were discontinued; Isopropyl
peroxide became Peroxide, bis(1-methylethyl). The heading Peroxide is a
nonfunctional oxygen compound; in the presence of more preferred compoundclasses, such radicals as (ethyldioxy) are employed. Hydroperoxide is a functional oxygen compound ranking just above amines; such names as Peroxyacetyl hypochlorite are replaced by Peroxide, acetyl chloro, etc.
276. Phosphorus compounds (¶¶ 197, 219). Functional suffixes are now
employed with phosphorus hydride names; e.g., Phosphinecarboxylic acid(formerly Formic acid, phosphino-) and Phosphoranamine (formerly Phosphorane, amino-). The phosphoro radical, −P=P−, was renamed 1,2-diphosphenediyl; phosphino was retained, but diphosphino, H2P−PH−, was renamed
diphosphinyl, and diphosphinetetrayl became 1,2-diphosphinediylidene. Phosphorothioic and Phosphorodithioic acids were added to Phosphoric andPhosphorous acids in “Class I” (¶ 185) for the indexing of esters. Pyrophosphoric acid was renamed Diphosphoric acid. Diphosphonic acid became the
new name for Phosphonic acid, anhydride.
Phosphonium ylides are indexed only as ylidene derivatives of Phosphorane (¶ 201). Prior to the Twelfth Collective period an additional Chemical
Substance and Formula Index entry appeared for the phosphonium ylide name.
The phosphoryl radical was eliminated for non-acid mononuclear analogsof phosphoric acid in Volume 120; thus phosphoryl chloride (POCl3) is now
phosphoric trichloride.
277. Polymers (¶ 222). Prior to the Fifteenth Collective period, polymers
with known component monomers were indexed at the name of each monomer
as actually reported in the original document. Polymers are now indexed at thepreferred name only. The preferred name appears in the Formula Index at themolecular formula of each monomer used in the polymer. Names based on
structural repeating units (SRUs) have continued to be used as additional index
names for polymers of well characterized or assumed structure. In the cases ofvery common trade-named industrial polymers of known composition forwhich cross-references are used, the SRU name is preferred. Thus, 1,4-Benzenedicarboxylic acid, polymers, polymer with 1,2-ethanediol. See Poly(oxy1,2-ethanediyloxycarbonyl-1,4-phenylenecarbonyl); Nylon 6. See Poly[imino(1-oxo-1,6-hexane-diyl)]. At monomer names, the terms “polymers,”“polyamides,” “polyesters,” etc., were replaced by “homopolymer” except for
general studies; “polymer with” was retained for copolymers named atmonomer headings and replaced such terms as “polyamide with”, “polyester
with”, etc.; “copolymers” is an acceptable general term. Block, graft, and alternating copolymers are registered and indexed with their own specific Registry
numbers starting in the Twelfth Collective period (1987-1991). The terms“block”, “graft” and “alternating” are part of the index name for these kinds ofpolymers. Starting with Volume 145 (June 2006), diblock, triblock, tetrablock
and pentablock polymers are indexed with their own specific Registry
numbers. The terms diblock, triblock, tetrablock and pentablock are part of theindex names for these polymers.
Siloxanes prepared by hydrolytic polymerization of chlorosilanes are now,
starting in 1994, registered and indexed at the monomer names with the term
“hydrolytic” cited in the modification, along with the term “homopolymer” or“polymer with”.
Cyclic acetals of ethenol homopolymer and ethenyl acetate-ethenol copolymer are indexed with their own specific Registry number starting with the
Sixteenth Collective period. (December 2006). The names include the phrase“cyclic acetal with” followed by a specific aldehyde name in the modification.
Phenol condensation products are now indexed at Phenol polymers, with
“polymer with formaldehyde” or other appropriate term cited in the modification. Urea condensation products are named analogously at Urea polymers.
278. Porphyrins and Bile pigments (¶ 223) were affected by the new rulethat indicated hydrogen of ring systems is always cited. 21H,23H-Porphine and21H,23H-Porphyrazine are the forms preferred for these and related substances
unless an original document emphasizes the absence of hydrogen at these positions. The 29H,31H-form of Phthalocyanine is preferred; the heading 21HBiline is employed unless hydrogen is absent from that position, in which case
22H-Biline is indexed. (An (all-Z) form is now assumed for Biline.)
Radicals. See Substituent prefixes (¶ 287).
279. Replacement (“a”) nomenclature (¶ 127), in which replacement ofcarbon by heteroatoms is indicated by terms such as “aza,” “oxa,” and “thia,”
was unchanged for cyclic skeletons, but was amended for acyclic compounds,
primarily to eliminate exceptions for certain classes, including silicon compounds. Now, “a” names are used whenever four or more “hetero units” (isolated hetero atoms, homogeneous hetero chains, or groups for which simple
radical names are employed, such as disiloxanediyl) are present, so long as the¶ 283

resulting name, including functional suffixes, does not express a lower functionality than the alternative conventional name. The hetero atoms must not bein an abnormal valency state (unless this valency can be readily expressed), andthe “a”-named chain must not be terminated by a nitrogen or chalcogen atom.
(“A” names are not used for peptides, polymers or purely inorganic chains.)
280. Replacement nomenclature for functions (¶ 129) was extended tovarious classes of acids and acid derivatives, as outlined by the following
examples (former names are in parentheses):
Ethanethioic acid
Ethane(dithioic) acid
Ethaneperoxoic acid
Butanebis(thioic) acid
Carbonothioic acid
Carbamodithioic acid
Methanimidamide
Imidodicarbonic acid
Diimidotricarbonimidic
diamide1,3-Benzenedisulfonothioic
acid(Acetic acid, thio-)(Acetic acid, dithio-)(Peroxyacetic acid)(Succinic acid, 1,4-dithio-)(Carbonic acid, thio-)(Carbamic acid, dithio-)(Formamidine)(Imidodicarboxylic acid)(Triguanide)(m-Benzenedisulfonic acid,
1,3-dithio-)

281. Ring systems (¶¶ 145-157). Fused oxireno and thiireno derivatives ofhydrocarbon rings are now indexed according to the general rule that the basecomponent should be a heterocycle; thus, Naphthalene, 2,3-epoxy- has become
Naphth[2,3-b]oxirene. Adamantane and its replacement derivatives areindexed at Tricyclo[3.3.1.13,7]decane, 2-Thiatricyclo[3.3.1.13,7] decane, etc.
(¶ 155). The locants o-, m-, p-, and ν- in ring names were replaced by numerals;
as- and s- are used only with Indacene and its fused derivatives; thus, mDioxane became 1,3-Dioxane; p-Terphenyl became 1,1′:4′,1′′-Terphenyl; sTriazine became 1,3,5-Triazine; and Benz[e]-as-indacene is unchanged.
Some trivial names were replaced; thus, Quinuclidine was renamed 1-Azabicyclo[2.2.2]octane. Radical names from these ring systems were changed correspondingly.
Special names for partially hydrogenated ring systems, e.g., Acridan, Indan,
Indoline, Phthalan, Pyrroline, were abandoned; thus Indan became 1H-Indene,
2,3-dihydro-. Norbornane, Norcarane, and Norpinane are now indexed at thesystematic “Bicyclo-” names.
Ring systems containing metals other than antimony, tin, lead, germanium,
or bismuth are now indexed by coordination nomenclature.
In ring-assembly names, points of attachment are now cited, except for twocomponent assemblies of cycloalkenes. Thus, 1,1′-Biphenyl, 1,2′-Binaphthalene (formerly 1,2′-Binaphthyl), Bi-2-cyclohexen-1-yl. Ring assemblies inwhich component rings are joined by double bonds are now indexed at a component name, e.g., Cyclopentane, cyclopentylidene- (formerly Bicyclopentylidene).
The Hantzsch-Widman system (¶ 146) was extended, beginning in 1987, topartially or fully saturated rings, formerly named by organic replacement nomenclature, e.g. Stannolane (formerly Stannacyclopentane). Prior to Volume
121 the rings 1,2,5-Oxadiazole and 2,1,3-Benzoxadiazole were named
Furazan and Benzofurazan, respectively.
Non-standard valence states (¶ 158) of certain ring heteroatoms were
denoted by the greek letter lambda (λ) starting in 1987, e.g. 1λ4,3λ4,5λ4,7λ41,3,5,7,2,4,6,8-Tetrathiatetrazocine (formerly 1H,3H,5H,7H-1,3,5,7,2,4,6,8Tetrathiatetrazocine).
Names for cyclic systems containing ring heteroatoms in non-standard
valence states described by the “hydro” prefix (¶ 158) were changed beginningin 1987 to allow the expression of principal suffixes and radicals, e.g. 2H-1,4Selenazin-2-one, 1,1-dihydro-1,1-dimethyl-(formerly 2H-1,4-Selenazine,
1,1-dihydro-1,1-dimethyl-2-oxo-).
281A. Salts (¶ 198). Beginning with the Twelfth Collective Index, salts ofsubstitutive cations no longer have additional index entries at the following
common anions: Acetic acid, 2,2,2-trifluoro-, ion(1-); Borate(1-), tetrafluoro-; Borate(1-), tetraphenyl-; Methanesulfonic acid, 1,1,1-trifluoro-,ion(1-); Phenol, 2,4,6-trinitro-, ion(1-); Phosphate(1-), hexafluoro-;
Sulfuric acid, monoethyl ester, ion(1-).
282. Silicon compounds (¶ 199). Former binary names for silicon halides
are now indexed at Silane; for example, Silicon chloride (SiCl4), is now
indexed at Silane, tetrachloro-. Functional suffixes are now appended to
Silane, Disilane, Disiloxane, etc., but conjunctive names are not formed fromthem. Silanol and Silanediol now rank above all carbon-skeleton monohydricand dihydric alcohols, respectively, by reason of their hetero atom content (¶106). Similarly, Silanamine ranks above Benzenamine, etc.
Silthianes are now spelled out as silathianes; 1,3-disiloxanediyl, 1,5-trisilathianediyl, 1,7-tetrasilazanediyl, etc., all rank as single hetero units (¶ 127) in
the formation of “a” names. A total of four such units (of any kind) are now
necessary for a compound to be named by replacement nomenclature.
Silicic acids now all belong to “Class II” in the naming of esters (¶ 185).
Since the Tenth Collective Index period, the Silicic acid heading has been generally restricted to mono- and dinuclear oxo acids of silicon.
283. Spelling (¶ 107). Elided forms of radicals were largely discontinued.
Nitramino became (nitroamino); acetoxy became (acetyloxy); naphthyl
became naphthalenyl. Ethoxy, methoxy, propoxy, butoxy, phenoxy, andthienyl were retained, but branched-chain radicals are now named as derivatives of the straight-chain alkoxy parents; thus, isopropoxy became (1-methylethoxy). Elided forms of heading parents (Pyridol; Pyridone) are now spelledout (Pyridinol; Pyridinone). Punctuation in compound names is unchanged.

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Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

284. Stereochemistry (¶ 203). Major revisions were made in this area for
the Ninth Collective Index Period (1972-76). The concept of stereoparents (¶285) was introduced for those substances, mainly natural products, containing
complex stereochemistry and not readily indexed at systematic names. For
other substances, the stereochemistry is expressed in the name by use of
relative and absolute descriptors, including cis- and trans-; endo- and exo-; αand β-; E- and Z-; R- and S-; and R*- and S*-. The Sequence Rule of Cahn,
Ingold, and Prelog is applied in the assignment of these descriptors. A special
system was developed for coordination compounds (¶ 203 III).
Beginning with Volume 120, the sign of optical rotation (+), (-), or (±)- is
assigned to substances with visual wavelengths other than the sodium-D line.
Beginning with Volume 126 (1997), in order to provide more accurate descriptions of and improved access to substances whose stereochemistry has notbeen completely defined, CAS now registers and names substances with partially defined stereochemistry. Previously, partial stereochemistry was generally ignored. The presence of unknown chiral centers is indicated by theaddition of ther term “[partial]-” to the end of the normal stereochemical descriptor. When the reference ring or chain has incompletely defined chiralatoms/bonds, the format cites the stereo using R and S terms with their nomenclature locants for all known centers. If this method is used to describe a substance for which only relative stereochemistry is known, “rel” is added to thestereochemical descriptor. Racemic mixtures of substances with single chiral
centers are now indexed, registered, and named as non-stereospecific substances. Racemates having more than one chiral center are indexed, registered, andnamed as having only relative stereochemistry.
Stereochemical descriptors were simplified beginning with Volume 129.
The need for a single expression to describe the total stereochemistry of amolecule has been eliminated. Stereochemical terms are now placed within theparts of a chemical name to which the stereochemical information applies.
Only the stereochemistry contained in the heading parent is expressed in thename modification following all other structural information. The use of theterm “[partial]” has been discontinued.
The terms R and S are employed for chiral elements possessing either
absolute or relative stereochemistry. The term rel is used in conjunction with
R and S for structures with only relative stereochemistry. E and Z are used primarily to describe geometrical isomerism about double bonds. The relative
terms cis, trans, endo, exo, syn, anti, α, and β are used as alternatives to R and
S in certain limited situations.
285. Stereoparents (¶ 202) are heading parents whose names imply stereochemistry, as indicated by structural diagrams shown at these names in theChemical Substance Index. Synonyms and cross-references for the systematicnames are always provided. The stereochemistry implied by the stereoparent,
and shown in the diagram, may be augmented or selectively reversed in thename. Stereoparents include biologically significant amino acids, carbohydrates, and cyclic natural products (alkaloids, steroids, terpenes) within certain
limitations. Stereoparents are preferred to systematically named substances ofhigher functionality in the naming of esters, mixtures, molecular addition compounds, and polymers. Derivatives of stereoparents are kept at the stereoparent
names as much as practicable, but substituents (¶ 287) are named systematically in accordance with the changes in general index nomenclature.
Beginning with Volume 126 (1997), infrequently used terpene, steroid, alkaloid, and antibiotic stereoparent terms have been replaced by systematicnames. For example, Nemuarine and 15-Thialanostane are no longer used inindex names. Frequently occurring stereoparents, such as Pregnane, Cholane,
Cholestane, 9, 10-Secocholestane, Morphinan, Retinoic acid, and Erythromycin are maintained. Cross-references from the previously used stereoparent
names will guide users to the corresponding systematic index names. Aminoacid sequence names are now assigned to most systematically named linear
peptides. In an amino acid sequence name, the C-terminal residue is the index
heading parent, and the other residues are cited in the substituent, beginningwith N-terminal residue and continuing from left to right in the sequence; e.g.,
L-Lysine, D-alanylglycyl-L-leucyl-. Psi (ψ) nomenclature is now used todescribe certain modifications of the peptide bond. The Greek letter ψ conveys
the fact that a peptide bond has been replaced by a pseudopeptide bond. In an
amino acid sequence name, the format of the ψ term is ...-A-ψ(X-X’)-B-...,
where A is the amino acyl radical whose carbonyl group has been modified to
X and B the amino acyl radical whose α-amino group has been modified to X’.
X and X’ are shown as strings of element symbols, separated by a bond; e. g.,...-L-valyl-ψ(CH2-NH)-L-tyrosyl-.
286. Steroids (¶ 211). Stereochemical descriptors, e.g., “5α-,” which
formerly appeared as a prefix at steroid names, were combined in Volume 76
with descriptors required for suffixes and substituent prefixes and are now
cited in parentheses in their own field.
Cyclogonanes were discontinued as the names of ring systems. Cyclogonane stereoparents are retained, with stereochemistry defined by illustrative
diagrams in the Chemical Substance Index.
Trivial names for steroids, including Cholesterol, Ergocalciferol, and Testosterone, were discontinued as heading parents.
Use of “homo” (to denote ring enlargement), “nor” (to denote ring contraction), and “seco” (to denote ring fission), are now further restricted.
Functional derivatives of steroids are indexed at the steroid names, either inthe substituents (for derivatives of subsidiary functions) or in the modifications(for derivatives of the principal functions). Acyclic acetals are expressed byalkyloxy or aryloxy substituents (¶ 196); cyclic acetals with formaldehyde bymethylenebis(oxy) radicals; other cyclic acetals by a modification phrase suchas “cyclic 1,2-ethanediyl acetal” (if a principal group has been acetalized) orby an alkanediylbis(oxy) or alkylidenebis(oxy) substituent. Steroidal lactones

116

are “opened” to permit the steroid stereoparent to be used; the lactone is thencited in the modification.
287. Substituent prefixes (radicals) (¶¶ 132, 161). Groups always expressed as substituents now include isocyano, isocyanato, isothiocyanato, etc.,
and groups terminating in oxy, thio, sulfinyl, sulfonyl, and their analogs, suchas seleno and telluronyl.
Changes in radical names include iodosyl (instead of iodoso) for −IO; andiodyl (instead of iodoxy) for −IO2. Morpholino was changed in Volume 76 to
4-morpholinyl; piperidino to 1-piperidinyl; the unsubstituted diazeno radical,
HN=N−, to diazenyl; p-phenylene, etc., to 1,4-phenylene, etc.; ν-phenenyl to
1,2,3-benzenetriyl; benzyl to (phenylmethyl); styryl to (2-phenylethenyl); ptolyl to (4-methylphenyl); 2,4-xylyl to (2,4-dimethylphenyl); and similarly forother radicals containing a benzene ring and one or more acyclic chains.
Thenyl became (thienylmethyl) and furfuryl became (2-furanylmethyl).
Ring-assembly radicals are now based on the ring assembly names, as,[1,2′-binaphthalen]-8′-yl and [1,1′-biphenyl]-4,4′-diyl (¶ 161).
Acyl radicals in substitutive names were replaced by substituted radicals(exceptions are acetyl, benzoyl, carbonyl, and, when unsubstituted, formyl).
Hence propionyl became (1-oxopropyl); acetimidoyl became (1-iminoethyl);succinoyl became (1,4-dioxo-1,4-butanediyl). The three radicals carbonimidoyl, −C(:NH)−; carbonohydrazonoyl, −C(:NNH2)−, and carbonothioyl, −C(:S)− were introduced for use in multiplicative nomenclature and for cases inwhich both free valencies are attached to the same atom. In other cases, (iminomethyl) (formerly formimidoyl), (thioxomethyl), etc., are employed.
Replacement (“a”) names for acyclic radicals (¶ 128) were introduced
under the same restrictions as for heading parents. The free valencies, not thehetero atoms, are preferred for lowest locants, which are always cited; e.g.,4,12-dioxa-7,9-dithiatetradec-1-yl.
Compound and complex radicals are now constructed in accordance withrevised rules which reflect the new policies for compounds. The most important changes were emphasis on hetero-atom content of the parent radical, abandonment of “like treatment of like things” and the “complexity” principle,
elimination of preference for unsaturated acyclic radicals regardless of size,
consistent application of the principle of “lowest locants” for substituents on
the parent radical, and adoption of more systematic radical names.
A list of substituent prefixes (radicals) as revised for the Ninth Collective
Index Period (1972-1976) constitutes Section H (¶ 294).
288. Sulfur compounds (¶ 200). Sulfide was discontinued as a heading
parent in Volume 76, as were such binary headings as Phenyl sulfide. Compounds containing one or more single sulfur atoms are now indexed substitutively by use of thio radicals or at “thia”-named index parents (¶ 127). Thus,
Sulfide, ethyl phenyl, became Benzene, (ethylthio)-, and Propyl sulfide is now
indexed at Propane, 1,1′-thiobis-. The retained headings Disulfide, Trisulfide, etc., rank as nonfunctional acyclic sulfur parents, below oxygen compounds and above selenium compounds. Within the class, a partial descendingorder is: heterocyclic sulfur compounds, e.g., Thiophene; “a”-named acyclic
hetero systems, e.g., 2,6,9,12,13-Pentathiapentadecane; acyclic trisulfide,disulfone, disulfoxide, disulfide.
1,2-Episulfides are named as Thiirane or Thiirene derivatives; 1,3-episulfides as Thietane or Thiete derivatives. Acyclic mercaptals and mercaptoles
are now named like sulfides by use of thio radicals.
Selenium and tellurium compounds are treated in strict analogy with sulfur
compounds.
289. Sulfones and Sulfoxides (¶ 200). Sulfone was discontinued as aheading parent, as were binary sulfone headings like Isopropyl sulfone, now
indexed at Propane, 2,2′-sulfonylbis-. Sulfonyl radicals are used for all compounds containing single SO2 groups, e.g., Butane, 1-chloro-3-(methylsulfonyl)- (formerly Sulfone, 3-chloro-1-methylpropyl methyl). Disulfone,
Trisulfone, etc., are retained. Sulfoxides are indexed in an analogous mannerby use of sulfinyl radicals. Acyclic skeletons containing four or more sulfur
units may be indexed at “thia”- names with oxide terms in the index modification. Cyclic sulfones and sulfoxides are indexed at ring names; e.g., Thiirane,
1,1-dioxide (formerly Ethylene sulfone).
289A. Tautomers (¶ 122). To avoid scattering of information in the index,
CA, aided by new machine programs, now indexes certain common tautomericsystems at single preferred index names, regardless of the particular structures
presented in original documents. The most common tautomers handled in thisway include compounds containing the nitrogenous skeletons N-N-N, N-C-N,
N-C-O, and N-C-S, as well as certain phosphorus and sulfur acids and amides.
In general, the preferred index name expresses the tautomeric form in which a
double bond extends to an oxygen atom, rather than to a sulfur or nitrogen;after this condition has been satisfied, the preferred name usually expresses the
maximum number of highest functions.
290. Terpenes (¶ 212) are now named at stereoparent names (¶ 285) only
when they contain four or more rings or possess complex stereochemistry.
Hence, many trivial names formerly employed as index headings are now
cross-referred to systematic names; e.g., Eudesmane. See Naphthalene,
decahydro-1,4a-dimethyl-7-(1-methylethyl)-, (1R,4aR,7R,8aS)-.
Illustrative diagrams for terpene stereoparents, e.g., Gammacerane,
Lanostane, showing the stereochemistry for each, are provided in theChemical Substance Index. New stereoparents, formed by ring enlargement,
contraction, scission, or addition, are adopted as they are needed. When ringscission results in a structure which does not qualify for a terpene stereoparent
name, systematic nomenclature is used.
Cyclic acetals of terpenes are expressed at stereoparent names, either in themodification or by use of appropriate substituents, in analogy with steroids(¶ 286). Lactones are expressed in the modification at terpene acid headings.

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Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

291. Thiols (¶ 175) have been affected only by the general changes inindexing policy (¶ 255), including those for conjunctive names, abandonment oftrivial names, and discontinuance of like treatment of like things. Thus, α-Toluenethiol became Benzenemethanethiol; p-Cymene-2-thiol became Benzenethiol, 2-methyl-5-(1-methylethyl)-; and Ethanethiol, 1,2-diphenyl-, became
Benzeneethanethiol, α-phenyl-.
292. Urea (¶ 183) was retained as a heading parent; Urea, thio-, and its derivatives are now indexed at Thiourea. In both cases, the locants 1- and 3- were
replaced by N- and N′-. Urea ranks as an amide of Carbonic acid, which is now
placed below the “organic” acids, including carboxylic and sulfonic acids.
Acyclic acyl ureas are therefore indexed at “organic” amide names. Pseudourea
was renamed Carbamimidic acid. In the following list, former names are shownin parentheses:
Urea, N ′-ethyl-N,N-dimethylAcetamide, N-(amino
carbonyl)Ethanethioamide, N-(aminocarbonyl)Urea, N-(aminoiminomethyl)1,2-Hydrazinedicarboxamide
Imidodicarbonic diamide
Urea, N,N ′-diphenylDiimidotricarbonic diamide
Carbamimidothioic acid,N-methyl-, ethyl ester(Urea, 3-ethyl-1,1-dimethyl-)(Urea, acetyl-)(Urea, (thioacetyl)-)(Urea, amidino-)(Biurea)(Biuret)(Carbanilide)(Triuret)(Pseudourea, 2-ethyl-3-methyl-2thio-)¶ 293A

293. Vitamins (¶ 224). Index headings such as Vitamin B, Vitamin F, areused for general discussions of vitamin activity and for ill-defined substances
named by authors. Otherwise, many specific vitamin names have been crossreferred to more systematic names. The stereoparent Retinol is used for
Vitamin A1 (Vitamin A2 is indexed at Retinol, 3,4-didehydro-); Riboflavine(Riboflavin beginning in Volume 86) for Vitamin B2; and L-Ascorbic acid for
Vitamin C. Vitamin B12 is the only specific vitamin name retained as aheading parent; related compounds have continued to be indexed at names suchas Cobinamide and Cobyrinic acid.
293A. Zwitterionic compounds (¶¶ 201, 224). Prior to Volume 119 theexpression “hydroxide, inner salt” was used in the modification of names ofzwitterionic compounds at “-ium” headings. “Hydroxide” was used as the saltphrase in the modification. Conceptually, a molecule of water (comprised of
the hydroxide anion and a hydrogen atom attached to a hetero atom) was “removed” by the use of the phrase “inner salt”. The term “inner salt” now indicates an unspecified compensating anion located in the same molecule as thecation. The assumed “hydroxide” anion is no longer expressed.
Beginning with Volume 121 meso-ionic Sydnone and Sydnone imine derivatives (¶ 201) are structured and named systematically as inner salts of 5Hydroxy-3-substituted-1,2,3-oxadiazolium and 5-Amino-3-substituted1,2,3-oxadiazolium, respectively. Hydrohalide salts of sydnone imines are
structured and named as onium halides.

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Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

118

H. ILLUSTRATIVE LIST OF SUBSTITUENT PREFIXES
294.
(The equals (=) directs the user from the boldface name to the current CA name; absence of the sign indicates that the boldface name is correct.)
abietamido = [[[1,2,3,4,4a,4b,5,6,10,10a-decahydro-1,4a-dimethyl-7-(1-methylethyl)-1-phenathrenyl]carbonyl]amino]
C19H29CONH−
acenaphthenyl = (1,2-dihydroacenaphthylenyl)(C12H9)−1,2-acenaphthenylene = (1,2-dihydro-1,2acenaphthylenediyl) −(C12H8)−
1-acenaphthenylidene = 1(2H)-acenaphthylenylidene (C12H8)=
acetamido = (acetylamino) AcNH−
acetenyl = ethynyl HC≡C−
acetimido = (acetylimino) or (1-iminoethyl) AcN=
or MeC(=NH)−
acetimidoyl = (1-iminoethyl) MeC(=NH)−acetoacetamido = [(1,3-dioxobutyl)amino]
MeCOCH2CONH−
acetoacetyl = (1,3-dioxobutyl) MeCOCH2CO−
acetohydroximoyl = [1-(hydroxyimino)ethyl]
MeC(=NOH)−
acetonyl = (2-oxopropyl) MeCOCH2−
acetonylidene = (2-oxopropylidene) MeCOCH=
acetoxy = (acetyloxy) AcO−
acetyl Ac (MeCO−)acetylene = 1,2-ethanediylidene =CHCH=
acridanyl = (9,10-dihydroacridinyl) (C13H10N)−
acryloyl = (1-oxo-2-propen-1-yl) H2C=CHCO−
acrylyl = (1-oxo-2-propen-1-yl) H2C=CHCO−
adamantyl = tricyclo[3.3.1.13,7]decyl (C10H15)−adamantylene = tricyclo[3.3.1.13,7]decanediyl−(C10H14)−
adipaldehydoyl = (1,6-dioxohexyl)
HCO(CH2)4CO−
adipamoyl = (6-amino-1,6-dioxohexyl)
H2NCO(CH2)4CO−
adipaniloyl = [1,6-dioxo-6-(phenylamino)hexyl]
PhNHCO(CH2)4CO−
adipoyl = (1,6-dioxo-1,6-hexanediyl)−CO(CH2)4CO−
adipyl = (1,6-dioxo-1,6-hexanediyl)−CO(CH2)4CO−
alaninamido = [(2-amino-1-oxopropyl)amino]
MeCH(NH2)CONH−
alanyl1 = (2-amino-1-oxopropyl)
MeCH(NH2)CO−
β-alanyl1 = (3-amino-1-oxopropyl)
H2N(CH2)2CO−
aldo2 = oxo O=
alloisoleucyl1 = (2-amino-3-methyl-1-oxopentyl)
EtCHMeCH(NH2)CO−
allophanamido = [[[(aminocarbonyl)amino]carbonyl]amino] H2N(CONH)2−
allophanoyl = [[(aminocarbonyl)amino]carbonyl]
H2NCONHCO−
allothreonyl1 = (2-amino-3-hydroxy-1-oxobutyl)
MeCH(OH)CH(NH2)CO−allyl = 2-propen-1-yl H2C=CHCH2−β-allyl = (1-methylethenyl) H2C=CMe−
π-allyl = (η3-2-propen-1-yl)[ C H 2 - - - C H - - - CH 2 ] −allylidene = 2-propen-1-ylidene H2C=CHCH=
ambrosan-6-yl = [decahydro-3a,8-dimethyl-5-(1methylethyl)-4-azulenyl] (C15H27)−
amidino = (aminoiminomethyl) H2NC(=NH)−amidoxalyl = (2-amino-2-oxoacetyl) H2NCOCO−
amino H2N−
(aminoamidino) = (hydrazinyliminomethyl)
H2NNHC(=NH)−(aminoiminophosphoranyl) = (P-aminophosphinimyl) H2NPH(=NH)−
ammonio H3N+−
amoxy = (pentyloxy) Me(CH2)4O−
amyl = pentyl Me(CH2)4−
tert-amyl = (1,1-dimethylpropyl) EtCMe2−
amylidene = pentylidene BuCH=
anilino = (phenylamino) PhNH−
anisal = [(methoxypheny])methylene]
MeOC6H4CH=
anisidino = [(methoxyphenyl)amino]
MeOC6H4NH−
anisoyl = (methoxybenzoyl) MeOC6H4CO−

anisyl = (methoxyphenyl) or [(methoxyphenyl)methyl] MeOC6H4− or MeOC6H4CH2−
anisylidene = [(methoxyphenyl)methylene]
MeOC6H4CH=
anthranilamido = [(2-aminobenzoyl)amino]
2−H2NC6H4CONH−
anthraniloyl = (2-aminobenzoyl)
2−H2NC6H4CO−
anthranoyl = (2-aminobenzoyl) 2−H2NC6H4CO−
anthraquinonyl = (9,10-dihydro-9,10-dioxoanthracenyl) (C14H7O2)−
anthraquinonylene = (9,10-dihydro-9,10dioxoanthracenediyl) −(C14H6O2)−
anthroyl = (anthracenylcarbonyl) (C14H9)CO−
anthryl = anthracenyl (C14H9)−anthrylene = anthracenediyl −(C14H8)−
antimono = 1,2-distibenediyl −Sb=Sb−
antipyrinyl (antipyryl) = (2,3-dihydro-1,5-dimethyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)
O
2

Ph N
MeN

1
5

Me

antipyroyl = [(2,3-dihydro-1,5-dimethyl-3-oxo-2phenyl-1H-pyrazol-4-yl)carbonyl]
O
2

Ph N
MeN

CO —

1
5

Me

apocamphanyl = (7,7-dimethylbicyclo[2.2.1]heptyl) (C9H15)−
apotrichothecanyl = (decahydro-3a,6,8a,8b-tetramethyl-1H-cyclopenta[b]benzofuranyl)(C15H25O)−
arginyl1=[2-amino-5-[(aminoiminomethyl)amino]-1-oxopentyl]
H2NC(=NH)NH(CH2)3CH(NH2)CO−arseno = 1,2-diarsenediyl −As=As−
arsenoso OAs−
arsinico3,4 HOAs(O)=arsinidenio H2As+=
arsinimyl AsH2(=NH)−
arsino AsH2−
arsinothioyl AsH2(S)−arsinyl AsH2(O)−arsinylidene AsH(O)=arso O2As−
arsonio H3As+−
arsono4 (HO)2As(O)−arsononitridyl AsH(≡N)−
arsoranyl AsH4−
arsoranylidene H3As=
arsoranylidyne AsH2≡arsylene = arsinidene AsH=
arsylidyne = arsinidyne As≡
asaryl = (2,4,5-trimethoxyphenyl)
2,4,5−(MeO)3C6H2−
asparaginyl1 = (2,4-diamino-1,4-dioxobutyl)
H2NCOCH2CH(NH2)CO−
α-asparaginyl1 = (3,4-diamino-1,4-dioxobutyl)
H2NCOCH(NH2)CH2CO−
asparagyl = asparaginyl
aspartoyl1 = (2-amino-1,4-dioxo-1,4-butanediyl)−COCH2CH(NH2)CO−
aspartyl = aspartoyl or unspecified aspartyl (seebelow)
α-aspartyl1 = (2-amino-3-carboxy-1-oxopropyl)
HO2CCH2CH(NH2)CO−
β-aspartyl1 = (3-amino-3-carboxy-1-oxopropyl)
HO2CCH(NH2)CH2CO−
astato At−
astatoxy = astatyl O2At−
atisanyl (from atisane) (C20H33)−
atropoyl = (1-oxo-2-phenyl-2-propen-1-yl)
H2C=CPhCO−
azelaoyl = (1,9-dioxo-1,9-nonanediyl)−CO(CH2)7CO−
azelaaldehydoyl = (1,9-dioxononyl)
HCO(CH2)7CO−
azi5 (see also azo) −N=N = 3H-diazirine (component ring in a spiro name)azido N3−
(azidoformyl) = (azidocarbonyl) N3CO−
azino =NN= = 1,2-hydrazinediylideneazo (see also azi) −N=N− = diazenyl or 1,2-diazenediyl
azoxy −N(O)=N− = (2-oxidodiazenyl)- or(1-oxido-1,2-diazenediyl)benzal = (phenylmethylene) PhCH=
benzamido = (benzoylamino) BzNH−
benzenesulfenamido = [(phenylthio)amino]
PhSNH−
benzenesulfonamido = [(phenylsulfonyl)amino]
PhSO2NH−
benzenetriyl C6H3 ≡benzenyl = (phenylmethylidyne) PhC≡
benzhydryl = (diphenylmethyl) Ph2CH−
benzhydrylidene = (diphenylmethylene) Ph2C=
benzidino = [(4′-amino[1,1′-biphenyl]-4-yl)amino]
4−(4−H2NC6H4)C6H4NH−
benziloyl = (2-hydroxy-2,2-diphenylacetyl)
Ph2C(OH)CO−
benzimidazolinyl = (2,3-dihydro-1H-benzimidazolyl) (C7H7N2)−
2-benzimidazolyl = 1H-benzimidazol-2-yl(C7H5N2)−
benzimido = (benzoylimino) or (iminophenylmethyl) BzN= or PhC(=NH)−
benzimidoyl = (iminophenylmethyl) PhC(=NH)−
benzofuryl = benzofuranyl (C8H5O)−
benzohydroximoyl = [(hydroxyimino)phenylmethyl] PhC(=NOH)−
o-benzoquinon-3-yl = (5,6-dioxo-1,3-cyclohexadien-1-yl) (C6H3O2)−
p-benzoquinon-2,5-ylene = (3,6-dioxo-1,4-cyclohexadiene-1,4-diyl) −(C6H2O2)−
benzoselenophene-yl C8H5Se−
benzoxy = (benzoyloxy) BzO−
benzoyl Bz (PhCO−)(benzoylacetyl) = (1,3-dioxo-3-phenylpropyl)
PhCOCH2CO−(benzoylformyl) = (2-oxo-2-phenylacetyl)
PhCOCO−
benzyl = (phenylmethyl) PhCH2−
benzylidene = (phenylmethylene) PhCH=
benzylidyne = (phenylmethylidyne) PhC≡
(benzyloxy) = (phenylmethoxy) PhCH2O−(benzylselenyl) = [(phenylmethyl)seleno]
PhCH2Se−bicarbamoyl = (1,2-hydrazinediyldicarbonyl)−CONHNHCO−
bicyclo[1.1.0]butylene = bicyclo[1.1.0]butanediyl−(C4H4)−biphenylyl = [1,1′-biphenyl]yl PhC6H4−
biphenylene = [1,1′-biphenyl]diyl −(C12H8)−
biphenylylene = [1,1′-biphenyl]diyl −(C12H8)−
bismuthino BiH2−
bismuthylene BiH=
bismuthylidyne Bi≡[2,2′-bithiophen]-5-yl C8H5S2−
2-bornyl = (1,7,7-trimethylbicyclo[2.2.1]hept-2yl) (C10H17)−3-bornylidene=(4,7,7-trimethylbicyclo[2.2.1]hept-2-ylidene) (C10H16)=
4 (HO) B−
borono2boryl BH2−
borylene BH=
borylidyne B≡
bromo Br−
1,3-butadienediylidene = 1,3-butadiene-1,4diylidene =C=CHCH=C=
butadiynylene = 1,3-butadiyne-1,4-diyl−C≡CC≡C−
2-butenylene = 2-butene-1,4-diyl−CH2CH=CHCH2−
butoxy BuO−
sec-butoxy = (1-methylpropoxy) EtCHMeO−
tert-butoxy = (1,1-dimethylethoxy) Me3CO

119

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

butyl Bu (Me(CH2)3−)butylβ = (2-methylpropyl) Me2CHCH2−
butylγ = (1,1-dimethylethyl) Me3C−
sec-butyl = (1-methylpropyl) EtCHMe−
tert-butyl = (1,1-dimethylethyl) Me3C−
1,4-butylene = 1,4-butanediyl −(CH2)4−
sec-butylidene = (1-methylpropylidene) EtCMe=(butyloxy) = butoxy BuO−
butynedioyl = (1,4-dioxo-2-butyne-1,4-diyl)−COC≡CCO−
butyryl = (1-oxobutyl) PrCO−

carvacryl = [2-methyl-5-(1-methylethyl)phenyl]
Me2CH

6
1

3

N
HN

CH2CH NHCO(CH 2) 2NH 2 CO —1 5caronaldehydoyl = [(3-formyl-2,2-dimethylcyclopropyl)carbonyl]
HCO
Me

3

Me

1

CO

cyanamido = (cyanoamino) NCNH−
cyanato NCO−
cyano NC−
cyclodisiloxan-2-yl
1Me[2-methyl-5-(1-methyl-

carvomenthyl=
ethyl)cyclohexyl]
Me2CH

6
1

cacodyl = (dimethylarsino) Me2As−
cadinan-1-yl = [octahydro-4,7-dimethyl-1-(1methylethyl)-4a(2H)-naphthalenyl] (C15H29)−
2-camphanyl = (4,7,7-trimethylbicyclo[2.2.1]hept2-yl) (C10H17)−
camphoroyl (from camphoric acid) = [(1,2,2-trimethyl-1,3-cyclopentanediyl)dicarbonyl]−CO(C8H14)CO−
5-camphoryl (from camphor) = (4,7,7-trimethyl-5oxobicyclo[2.2.1]hept-2-yl) (C10H15O)−
canavanyl = [O-[(aminoiminomethyl)amino]homoseryl]1 or [2-amino-4-[[(aminoiminomethyl)amino]oxy]-1-oxobutyl]
H2NC(=NH)NHO(CH2)2CH(NH2)CO−
caprinoyl = (1-oxodecyl) Me(CH2)8CO−
caproyl (from caproic acid) = (1-oxohexyl)
Me(CH2)4CO−
capryl (from capric acid) = (1-oxodecyl)
Me(CH2)8CO−
capryloyl (from caprylic acid) = (1-oxooctyl)
Me(CH2)6CO−
caprylyl (from caprylic acid) = (1-oxooctyl)
Me(CH2)6CO−
carbamido = [(aminocarbonyl)amino]
H2NCONH−
carbamoyl = (aminocarbonyl) H2NCO−
carbamyl = (aminocarbonyl) H2NCO−
carbanilino = [(phenylamino)carbonyl]
PhNHCO−
carbaniloyl = [(phenylamino)carbonyl] PhNHCO−
carbazimidoyl = (hydrazinyliminomethyl)
H2NNHC(=NH)−
carbazol-9-yl = 9H-carbazol-9-yl (C12H8N)−
carbazoyl = (hydrazinylcarbonyl) H2NNHCO−
carbethoxy = (ethoxycarbonyl) EtO2C−
carbobenzoxy = [(phenylmethoxy)carbonyl]
PhCH2O2C−
carbonimidoyl7 (see also (iminomethyl))−C(=NH)−
carbonothioyl7 (see also (thioxomethyl)) −CS−
carbonyl −CO−(carbonyldioxy) = [carbonylbis(oxy)] −OCO2−(1-carbonylethyl) = (1-methyl-2-oxoethenyl)
O=C=CMe−(carbonylmethyl) = (2-oxoethenyl) O=C=CH−(carbonylmethylene) = (1-oxo-1,2-ethanediyl)−COCH2− or (2-oxoethenylidene) O=C=C=
carboxy4 HO2C−(carboxyformyl) = (carboxycarbonyl) HO2CCO−(5-carboxyvaleryl) = (5-carboxy-1-oxopentyl)
HO2C(CH2)4CO−
carnosyl = (N-β-alanylhistidyl)1 or [2-[(3-amino1-oxopropyl)amino]-3-(1H-imidazol-4-yl)-1oxopropyl]

¶ 294

Me
10-caryl = [(7,7-dimethylbicyclo[4.1.0]hept-3yl)methyl] (C9H15)CH2−
cathyl = [(ethoxycarbonyl)oxy] EtOCO2−
cedranyl = (octahydro-3a,6,8,8-tetramethyl-1H3a,7-methanoazulenyl) (C15H25)−
cetyl = hexadecyl Me(CH2)15−
chaulmoogroyl (from chaulmoogric acid) = [13(2-cyclopenten-1-yl)-1-oxotridecyl]
C5H7(CH2)12CO−
chaulmoogryl (from chaulmoogryl alcohol) = [13(2-cyclopenten-1-yl)tridecyl] C5H7(CH2)13−
chloro Cl−(chloroformyl) = (chlorocarbonyl) ClCO−(chloroglyoxyloyl) = (2-chloro-2-oxoacetyl)
ClCOCO−(chlorooxalyl) = (2-chloro-2-oxoacetyl) ClCOCO−
chlorosyl OCl−chloryl O2Cl−
cholesteryl (from cholesterol) = cholest-5-en-3-yl(from cholestene) (C27H45)−
choloyl (from cholic acid) = (3,7,12-trihydroxy-24oxocholan-24-yl) (HO)3(C23H36)CO−
chromanyl = (3,4-dihydro-2H-1-benzopyranyl)(C9H9O)−
cinchoninoyl (from cinchoninic acid) = (4-quinolinylcarbonyl) (4−C9H6N)CO−
cinnamal = (3-phenyl-2-propen-1-ylidene)
PhCH=CHCH=
cinnamenyl = (2-phenylethenyl) PhCH=CH−
cinnamoyl = (1-oxo-3-phenyl-2-propen-1-yl)
PhCH=CHCO−
cinnamyl = (3-phenyl-2-propen-1-yl)
PhCH=CHCH2−
cinnamylidene = (3-phenyl-2-propen-1-ylidene)
PhCH=CHCH=
citraconimido = (2,5-dihydro-3-methyl-2,5-dioxo1H-pyrrol-1-yl)
O
5
1

N
Me
O
citraconoyl = (2-methyl-1,4-dioxo-2-butene-1,4diyl) −COCMe=CHCO−
conaninyl (from conanine) (C22H36N)−
cresotoyl (from cresotic acid) = (hydroxymethylbenzoyl) HO(Me)C6H3CO−
cresoxy = (methylphenoxy) MeC6H4O−
cresyl = (hydroxymethylphenyl) HO(Me)C6H3− or(methylphenyl) MeC6H4−
cresylene = (methylphenylene) −(MeC6H3)−
crotonoyl = (1-oxo-2-buten-1-yl) MeCH=CHCO−
crotonyl = (1-oxo-2-buten-1-yl) MeCH=CHCO−
crotyl = 2-buten-1-yl MeCH=CHCH2−
cumal = [[4-(1-methylethyl)phenyl]methylene]4−(Me2CH)C6H4CH=
cumenyl = [(1-methylethyl)phenyl] Me2CHC6H4−
cumidino = [[4-(1-methylethyl)phenyl]amino]
4-(Me2CH)C6H4NH−
cuminal = [[4-(1-methylethyl)phenyl]methylene]4−(Me2CH)C6H4CH=
cuminyl = [[4-(1-methylethyl)phenyl]methyl]4−(Me2CH)C6H4CH2−
cuminylidene = [[4-(1-methylethyl)phenyl]methylene] 4−(Me2CH)C6H4CH=
cumoyl = [4-(1-methylethyl)benzoyl]
4−(Me2CH)C6H4CO−
cumyl8 = [(1-methylethyl)phenyl] (Me2CH)C6H4−
α-cumyl = (1-methyl-1-phenylethyl) −PhCMe2−

4

H2Si

O

2

SiH
O
3

cyclohexadienylene = cyclohexadienediyl −C6H6−
cyclohexanecarboxamido = [(cyclohexylcarbonyl)amino] C6H11CONH−
1,2-cyclohexanedicarboximido = (octahydro-1,3dioxo-2H-isoindol-2-yl)ONOcymyl = [methyl(1-methylethyl)phenyl]
Me(Me2CH)C6H3−
cysteinyl1 = (2-amino-3-mercapto-1-oxopropyl)
HSCH2CH(NH2)CO−
cysteyl = (3-sulfoalanyl)1 or (2-amino-1-oxo-3-sulfopropyl) HO3SCH2CH(NH2)CO−
dansyl = [[5-(dimethylamino)-1-naphthalenyl]sulfonyl]
SO 2
Me2 N

decanedioyl = (1,10-dioxo-1,10-decanediyl)−CO(CH2)8CO−
decanoyl = (1-oxodecyl) CH3(CH2)8CO−
decasiloxanylene = 1,19-decasiloxanediyl−SiH2(OSiH2)8OSiH2−desyl = (2-oxo-1,2-diphenylethyl) PhCOCHPh−
diarsenyl HAs=As−
diarsinetetrayl = 1,2-diarsinediylidene =AsAs=
diarsinyl H2AsAsH−
1,2-diazenediyl = −N=N−
diazeno = diazenyl HN=N− or −N=N−
diazo5 (see also isodiazenylidene) N2=
diazoamino = 1-triazene-1,3-diyl −NHN=N−
diazonio N2+−
dibenzothiophene-yl = dibenzothienyl (C12H7S)−
diborane(4)tetrayl = 1,2-diborane(4)diylidene=BB=
1,2-dicarbadodecaboran(12)-1-yl (C2H11B10)−
digermanylene = 1,2-digermanediyl−GeH2GeH2−
digermthianyl = 1-digermathianyl H3GeSGeH2−
diglycoloyl = [oxybis(1-oxo-2,1-ethanediyl)]−COCH2OCH2CO−(dimethyliminio) Me2N+=
dioxy9 (see also epidioxy) −OO−
1,2-diphosphinediyl −PHPH−
diphosphinetetrayl = 1,2-diphosphinediylidene=PP=
diphosphino = diphosphinyl H2PPH−
diphosphinylidene H2P−P=
diseleno9 (see also epidiseleno and seleninoselenoyl) −SeSe−
disilanoxy = (disilanyloxy) H3SiSiH2O−
disilanyl H3SiSiH2−
disilanylene = 1,2-disilanediyl −SiH2SiH2−
disilazanoxy = (1-disilazanyloxy) H3SiNHSiH2O−
1-disilazanyl H3SiNHSiH2−
2-disilazanyl = (disilylamino) (H3Si)2N−
disiloxanediylidene = 1,3-disiloxanediylidene=SiHOSiH=
disiloxanoxy = (1-disiloxanyloxy) H3SiOSiH2O−
disiloxanylene = 1,3-disiloxanediyl −SiH2OSiH2−
disilthianoxy = (1-disilathianyloxy) H3SiSSiH2O−
distannanylene = 1,2-distannanediyl −SnH2SnH2−
distannthianediylidene=
1,3-distannathianediylidene =SnHSSnH=
6 −S(O)S(O)−disulfinyl
disulfonyl6 −SO2SO2−
dithio9 (see also epidithio and sulfinothioyl) −SS−¶ 294

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

(dithiobicarbamoyl) = (1,2-hydrazinediyldicarbonothioyl) −CSNHNHCS−(dithiocarboxy) HS2C−(dithiohydroperoxy) = (thiosulfeno)4 HSS−
dodecanoyl = (1-oxododecyl) Me(CH2)10CO−
duryl = (2,3,5,6-tetramethylphenyl) 2,3,5,6Me4C6H−
durylene = (2,3,5,6-tetramethyl-1,4-phenylene)−(2,3,5,6−Me4C6)−
enanthoyl = (1-oxoheptyl) Me(CH2)5CO−
enanthyl = (1-oxoheptyl) Me(CH2)5CO−
epidioxy10 (see also dioxy) −OO−
epidiseleno10 (See also diseleno and seleninoselenoyl) −SeSe−
epidithio10 (see also dithio and sulfinothioyl) −SS−
epioxy = epoxy (see also oxy and oxo) −O−
episeleno10 (see also seleno and selenoxo) −Se−epithio10 (see also thio and thioxo) −S−
epoxy10 (See also oxy and oxo) −O−(epoxyethyl) = 2-oxiranyl(formimidoylmethyl) = (2-iminoethyl)
HC(=NH)CH2−
formyl4 HCO−
fucosyl = (6-deoxygalactosyl) (C6H11O4)−
fumaraniloyl = [1,4-dioxo-4-(phenylamino)-2buten-1-yl] PhNHCOCH=CHCO−
fumaroyl = (1,4-dioxo-2-butene-1,4-diyl)−COCH=CHCO−
furfural = (2-furanylmethylene)
1

O

5

CH

furfuryl = (2-furanylmethyl)
1
5

O
CH2

furfurylidene = (2-furanylmethylene)
1

1O

5

O
CH

3

(2,3-epoxypropyl) = (2-oxiranylmethyl)
1O
3

furoyl = (furanylcarbonyl) (C4H3O)CO−
furyl = furanyl (C4H3O)−CH 2

eremophilan-1-yl = [decahydro-4,4a-dimethyl-5(1-methylethyl)-1-naphthalenyl] (C15H27)−
ethanediylidene = 1,2-ethanediylidene =CHCH=
1,2-ethenediyl −CH=CH−
ethinyl = ethynyl HC≡C−
ethoxalyl = (2-ethoxy-2-oxoacetyl) EtO2CCO−
ethoxy EtO−
(ethoxycarbonyl) EtO2C−(1-ethoxyformimidoyl) = (ethoxyiminomethyl)
EtOCH(=NH)−(ethoxyphosphinyl) EtOPH(O)−ethyl Et (MeCH2−)
ethylene = 1,2-ethanediyl −CH2CH2−[ethylenebis(nitrilodimethylene)] = [1,2ethanediylbis[nitrilobis(methylene)](−CH2)2N(CH2)2N(CH2−)2(ethylenedioxy) = [1,2-ethanediylbis(oxy)]−O(CH2)2O−
ethylidene CH3CH=
ethylidyne CH3C≡
1-ethylium-1-ylidene CH3C+=(ethyloxy) = ethoxy EtO−
(ethylselenyl) = (ethylseleno) EtSe−(ethylthio) EtS−
eudesman-8-yl = [decahydro-5,8a-dimethyl-2-(1methylethyl)-2-naphthalenyl] (C15H27)−
farnesyl (from farnesol) = (3,7,11-trimethyl2,6,10-dodecatrien-1-yl)
Me2C=CH(CH2)2CMe=CH(CH2)2CMe=CHCH2−
fenchyl = (1,3,3-trimethylbicyclo[2.2.1]hept-2-yl)(C10H17)−
1,1′-ferrocenediyl −(C5H4)Fe(C5H4)−
fluoranyl = (3-oxospiro[isobenzofuran-1(3H),9′[9H]xanthen]yl) (C20H11O3)−
fluoren-9-ylidene = 9H-fluoren-9-ylidene(C13H8)=fluoro F−
formamido = (formylamino) HCONH−
1-formazano = [2-(hydrazinylidenemethyl)diazenyl] H2NN=CHN=N−
5-formazano = [2-(diazenylmethylene)hydrazinyl] HN=NCH=NNH−
formazanyl = (diazenylhydrazinylidenemethyl)
HN=N−C(=NNH2)−
formazyl = [(2-phenyldiazenyl)(2-phenylhydrazinylidene)methyl] PhN=NC(=NNHPh)−formimidoyl = (iminomethyl) CH(=NH)−(1-formimidoylformimidoyl) = (1,2-diiminoethyl)
HC(=NH)C(=NH)−(formimidoylformyl) = (2-iminoacetyl)
CH(=NH)CO−

galloyl = (3,4,5-trihydroxybenzoyl)
3,4,5−(HO)3C6H2CO−
gentisoyl = (2,5-dihydroxybenzoyl)
2,5-(HO)2C6H3CO−
geranyl (from geraniol) = (3,7-dimethyl-2,6-octadien-1-yl) Me2C=CH(CH2)2CMe=CHCH2−
germacran-6-yl = [5,9-dimethyl-2-(1-methylethyl)cyclodecyl] (C15H25)−
germanetetrayl =Ge=
germyl H3Ge−
germylene H2Ge=
germylidyne HGe≡
gibbanyl (from gibbane) (C15H23)−(glucosyloxy) (C6H11O5)O−
glutaminyl1 = (2,5-diamino-1,5-dioxopentyl)
H2NCO(CH2)2CH(NH2)CO−
α-glutaminyl1 = (4,5-diamino-1,5-dioxopentyl)
H2NCOCH(NH2)CH2CH2CO−
glutamoyl1 = (2-amino-1,5-dioxo-1,5-pentanediyl) −CO(CH2)2CH(NH2)CO−glutamyl = glutamoyl or unspecified glutamyl (seebelow)
α-glutamyl1 = (2-amino-4-carboxy-1-oxobutyl)
HO2C(CH2)2CH(NH2)CO−
γ-glutamyl1 = (4-amino-4-carboxy-1-oxobutyl)
HO2CCH(NH2)(CH2)2CO−
glutaryl = (1,5-dioxo-1,5-pentanediyl)−CO(CH2)3CO−
glyceroyl = (2,3-dihydroxy-1-oxopropyl)
HOCH2CH(OH)CO−
glyceryl = 1,2,3-propanetriyl −CH(CH2−)2
glycidyl = (2-oxiranylmethyl)
1O
3

CH 2

glycinamido = [(2-aminoacetyl)amino]
H2NCH2CONH−
glycinimidoyl = (2-amino-1-iminoethyl)
H2NCH2C(=NH)−glycoloyl = (2-hydroxyacetyl) HOCH2CO−
glycolyl = (2-hydroxyacetyl) HOCH2CO−
glycyl1 = (2-aminoacetyl) H2NCH2CO−
glyoxalinyl = imidazolyl (C3H3N2)−
glyoxylimidoyl = (1-imino-2-oxoethyl)
HCOC(=NH)−glyoxyloyl = (2-oxoacetyl) HCOCO−(glyoxyloylmethyl) = (2,3-dioxopropyl)
HCOCOCH2−glyoxylyl = (2-oxoacetyl) HCOCO−
guaiacyl = (4-hydroxy-3-methoxyphenyl)
4−OH−3−(CH3O)C6H3− or (2-methoxyphenyl) 2−(MeO)C6H4−
guaian-8-yl = [decahydro-1,4-dimethyl-7-(1-meth-120

ylethyl)-6-azulenyl] (C15H27)−
guanidino = [(aminoiminomethyl)amino]
H2NC(=NH)NH−(guanidinoazo) = [3-(aminoiminomethyl)-1-triazen-1-yl] H2NC(=NH)NHN=N−
guanyl = (aminoiminomethyl) H2NC(=NH)−
heptadecanoyl = (1-oxoheptadecyl)
Me(CH2)15CO−
heptanamido = [(1-oxoheptyl)amino]
Me(CH2)5CONH−
heptanedioyl = (1,7-dioxo-1,7-heptanediyl)−CO(CH2)5CO−
heptanoyl = (1-oxoheptyl) Me(CH2)5CO−
hexadecanoyl = (1-oxohexadecyl) Me(CH2)14CO−
2,4-hexadiynylene = 2,4-hexadiyne-1,6-diyl−CH2C≡CC≡CCH2−
hexamethylene = 1,6-hexanediyl −(CH2)6−
hexanedioyl = (1,6-dioxo-1,6-hexanediyl)−CO(CH2)4CO−
hexanethioyl = (1-thioxohexyl) Me(CH2)4CS−
hippuroyl = (N-benzoylglycyl)1 or [2-(benzoylamino)acetyl] BzNHCH2CO−
hippuryl = (N-benzoylglycyl)1 or [2-(benzoylamino)acetyl] BzNHCH2CO−
histidyl1 = [2-amino-3-(1H-imidazol-4-yl)-1-oxopropyl]
3N
HN

CH2CH(NH2)CO1
5

homocysteinyl1 = (2-amino-4-mercapto-1-oxobutyl) HS(CH2)2CH(NH2)CO−homomyrtenyl = [2-(6,6-dimethylbicyclo[3.1.1]hept-2-en-2-yl)ethyl](C9H13)CH2CH2−
homopiperonyl = [2-(1,3-benzodioxol-5-yl)ethyl](C7H5O2)CH2CH2−
homoseryl1 = (2-amino-4-hydroxy-1-oxobutyl)
HO(CH2)2CH(NH2)CO−homoveratroyl = [2-(3,4-dimethoxyphenyl)acetyl] 3,4−(MeO)2C6H3CH2CO−
homoveratryl [2-(3,4-dimethoxyphenyl)ethyl]
3,4−(MeO)2C6H3CH2CH2−
hydantoyl = [N-(aminocarbonyl)glycyl]1 or [2[(aminocarbonyl)amino]acetyl]
H2NCONHCH2CO−
hydnocarpoyl (from hydnocarpic acid) = [11-(2cyclopenten-1-yl)-1-oxoundecyl](C5H7)(CH2)10CO−
hydnocarpyl (from hydnocarpyl alcohol) = [11-(2cyclopenten-1-yl)undecyl](C5H7)(CH2)10CH2−
hydracryloyl = (3-hydroxy-1-oxopropyl)
HO(CH2)2CO−
hydratropoyl = (1-oxo-2-phenylpropyl)
PhCHMeCO−hydrazi = diaziridine (component ring in a spiro
name) −NHNH−
1,2-hydrazinediyl −NHNH−
1,2-hydrazinediylidene =NN=
hydrazinyl H2NNH−
hydrazinylidene H2NN=
1-hydrazinyl-2-ylidene −NHN=
hydrazo = 1,2-hydrazinediyl
hydrazono = hydrazinylidenehydrocinnamoyl = (1-oxo-3-phenylpropyl)
Ph(CH2)2CO−
hydrocinnamyl = (3-phenylpropyl) Ph(CH2)3−hydroperoxy4 HOO−
(hydroperoxyformyl) = (hydroperoxycarbonyl)
HOOCO−hydroxamino = (hydroxyamino) HONH−
hydroximino = (hydroxyimino) HON=
hydroxy4 HO−(hydroxyarsinylidene) = arsinico3,4 HOAs(O)=hydroxyl = hydroxy4 HO−(hydroxyphosphinyl) HOPH(O)−(hydroxyphosphinylidene) = phosphinico3,4
HOP(O)=

121

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

hygroyl = (1-methylprolyl)1 or [(1-methyl-2-pyrrolidinyl)carbonyl]
Me
N

5

1

CO

imidazolidyl = imidazolidinyl (C3H7N2)−
imidazolinyl = (dihydro-1H-imidazolyl)(C3H5N2)−
imidocarbonyl = carbonimidoyl7 −C(=NH)−(imidocarbonylamino) = (carbonimidoylamino)
HN=C=N−
imino HN=
iminio H2N+=(3-iminoacetonyl) = (3-imino-2-oxopropyl)
HN=CHCOCH2−(iminodisulfonyl) = [iminobis(sulfonyl)]−SO2NHSO2−(iminomethyl) (see also carbonimidoyl) HN=CH−(iminonitrilo) = 1-hydrazinyl-2-ylidene −NHN=(iminophosphoranyl) = phosphinimyl
H2P(=NH)−
indanyl = (2,3-dihydro-1H-indenyl) (C9H9)−indenyl = 1H-indenyl (C9H7)−
1-indolinyl = (2,3-dihydro-1H-indol-1-yl)(C8H8N)−
2-indolinylidene = (1,3-dihydro-2H-indol-2ylidene) (C8H7N)=
indyl = 1H-indolyl (C8H6N)−
iodo I−
iodoso = iodosyl OI−
iodoxy = iodyl O2I−
isoallyl = 1-propen-1-yl MeCH=CH−
isoamoxy = (3-methylbutoxy) Me2CH(CH2)2O−
isoamyl = (3-methylbutyl) Me2CH(CH2)2−
sec-isoamyl = (1,2-dimethylpropyl)
Me2CHCHMe−
isoamylidene = (3-methylbutylidene)
Me2CHCH2CH=
isobornyl (from isoborneol) = (1,7,7-trimethylbicyclo[2.2.1]hept-2-yl) (C10H17)−
isobutenyl = (2-methyl-1-propen-1-yl)
Me2C=CH−isobutoxy = (2-methylpropoxy) Me2CHCH2O−
isobutyl = (2-methylpropyl) Me2CHCH2−
isobutylidene = (2-methylpropylidene)
Me2CHCH=isobutyryl = (2-methyl-1-oxopropyl) Me2CHCO−
isocrotyl = (2-methyl-1-propen-1-yl) Me2C=CH−
isocyanato OCN−
isocyano CN−− +isodiazenyl N=NH−
isodiazenylidene6 (see also diazo) N−=N+=isohexyl = (4-methylpentyl) Me2CH(CH2)3−
isohexylidene = (4-methylpentylidene)
Me2CH(CH2)2CH=
2-isoindolinyl = (1,3-dihydro-2H-isoindol-2-yl)(C8H8N)−
isoleucyl1 = (2-amino-3-methyl-1-oxopentyl)
EtCHMeCH(NH2)CO−isonicotinoyl = (4-pyridinylcarbonyl)

isophthaloyl = (1,3-phenylenedicarbonyl)
1,3−C6H4(CO−)2
isophthalylidene = (1,3-phenylenedimethylidyne)
1,3−C6H4(CH=)2
isopropenyl = (1-methylethenyl) H2C=CMe−isopropoxy = (1-methylethoxy) Me2CHO−
isopropyl = (1-methylethyl) Me2CH−
isopropylidene = (1-methylethylidene) Me2C=(isopropylidenedioxy) = [(1-methylethylidene)bis(oxy)] −OCMe2O−
isosemicarbazido = [2-(aminohydroxymethylene)hydrazinyl] H2NC(OH)=NNH−
isothiocyanato SCN−
isothiocyano = isothiocyanato SCN−
isovaleryl = (3-methyl-1-oxobutyl)
Me2CHCH2CO−
isovalyl1 = (2-amino-2-methyl-1-oxobutyl)
EtCMe(NH2)CO−isoviolanthrenylene = (9,18-dihydrodinaphtho[1,2,3-cd:1′,2′,3′-lm]perylenediyl)−(C34H18)−
kauranyl (from kaurane) (C20H33)−
kauranylene = kauranediyl (from kaurane)−(C20H32)−
kaurenyl (from kaurene) (C20H31)−
keto11 = oxo O=
labdan-15-yl = [5-(decahydro-2,5,5,8a-tetramethyl-1-naphthalenyl)-3-methylpentyl](C20H37)−
lactosyl = (4-O-β-galactapyranosyl-β-D-glucopyranosyl) (C6H11O5)O(C6H10O5)−
lactoyl = (2-hydroxypropanoyl)1 or (2-hydroxy-1oxopropyl) MeCH(OH)CO−
lanostenylene = lanostenediyl (from lanostane)−(C30H50)−
lauroyl = (1-oxododecyl) Me(CH2)10CO−
leucyl1 = (2-amino-4-methyl-1-oxopentyl)
Me2CHCH2CH(NH2)CO−
levulinoyl = (1,4-dioxopentyl) MeCO(CH2)2CO−
linalyl (from linalool) = (1-ethenyl-1,5-dimethyl-4hexen-1-yl) Me2C=CH(CH2)2CMe(CH=CH2)−
linolelaidoyl = (1-oxo-9,12-octadecadien-1-yl)
Me(CH2)4CH=CHCH2CH=CH(CH2)7CO−
linolenoyl = (1-oxo-9,12,15-octadecatrien-1-yl)
EtCH=CHCH2CH=CHCH2CH=CH(CH2)7CO−
γ-linolenoyl = (1-oxo-6,9,12-octadecatrien-1-yl)
Me(CH2)4CH=CHCH2CH=CHCH2CH=CH(CH2)4CO−
linoleoyl = (1-oxo-9,12-octadecadien-1-yl)
Me(CH2)4CH=CHCH2CH=CH(CH2)7CO−
lupanyl (from lupane) (C30H51)−
lysyl1 = (2,6-diamino-1-oxohexyl)
H2N(CH2)4CH(NH2)CO−
maleoyl = (1,4-dioxo-2-butene-1,4-diyl)−COCH=CHCO−
malonaldehydoyl = (1,3-dioxopropyl)
HCOCH2CO−
malonamoyl = (3-amino-1,3-dioxopropyl)
H2NCOCH2CO−
malonaniloyl = [1,3-dioxo-3-(phenylamino)propyl] PhNHCOCH2CO−
malonimido = (2,4-dioxo-1-azetidinyl)¶ 294

1,3-cyclohexanediyl]

6

CHMe2

1

Me
mercapto4 HS−
mesaconoyl = (2-methyl-1,4-dioxo-2-butene-1,4diyl) −COCMe=CHCO−
mesidino = [(2,4,6-trimethylphenyl)amino]
2,4,6−Me3C6H2NH−
mesityl = (2,4,6-trimethylphenyl)
2,4,6−Me3C6H2−
α-mesityl = [(3,5-dimethylphenyl)methyl]
3,5−Me2C6H3CH2−
mesoxalyl = (1,2,3-trioxo-1,3-propanediyl)−COCOCO−mesyl = (methylsulfonyl) MeSO2−
metanilamido = [[(3-aminophenyl)sulfonyl]amino] 3−H2NC6H4SO2NH−
metanilyl = [(3-aminophenyl)sulfonyl]
3−H2NC6H4SO2−
methacryloyl = (2-methyl-1-oxo-2-propen-1-yl)
H2C=CMeCO−
methallyl = (2-methyl-2-propen-1-yl)
H2C=CMeCH2−
methanetetrayl =C=
methene = methylene H2C=
methenyl = methylidyne HC≡
methionyl (from methionic acid) = [methylenebis(sulfonyl)] −SO2CH2SO2−
methionyl1 (from methionine) = [2-amino-4(methylthio)-1-oxobutyl]
MeS(CH2)2CH(NH2)CO−
methoxalyl = (2-methoxy-2-oxoacetyl)
MeO2CCO−methoxy MeO−
(methoxycarbonyl) MeO2C−
methyl Me (H3C)−[(methyldithio)sulfonyl] MeSSSO2−
methylene H2C=
(methylenedioxy) = [methylenebis(oxy)]−OCH2O−[(methylenedioxy)phenyl] = 1,3-benzodioxol-aryl (CH2O2)C6H3−(methylenedisulfonyl) = [methylenebis(sulfonyl)]−SO2CH2SO2−
methylidyne HC≡
methyliumylidene C+H=
methylol = (hydroxymethyl) HOCH2−(methyloxy) = methoxy MeO−
(1-methyl-2H-pyranium-2-yl)
Me
O+

6

1

(1-methylpyridinium-2-yl)
Me
N+

CO

1N

O
6

4

1

isonipecotoyl = (4-piperidinylcarbonyl)

HN 1

CO

6

isonitro = aci-nitro HON(O)=isonitroso = (hydroxyimino) HON=
1-isopentenyl = (3-methyl-1-buten-1-yl)
Me2CHCH=CH−
isopentyl = (3-methylbutyl) Me2CH(CH2)2−
isopentylidene = (3-methylbutylidene)
Me2CHCH2CH=
isophthalal = (1,3-phenylenedimethylidyne)
1,3−C6H4(CH=)2
isophthalaldehydoyl = (3-formylbenzoyl)
3−(HCO)C6H4CO−

N
O
malonyl = (1,3-dioxo-1,3-propanediyl)−COCH2CO−
maloyl = (2-hydroxy-1,4-dioxo-1,4-butanediyl)−COCH(OH)CH2CO−
maltosyl = (4-O-α-D-glucopyranosyl-β-D-glucopyranosyl) (C6H11O5)O(C6H10O5)−
mandeloyl = (2-hydroxy-2-phenylacetyl)
PhCH(OH)CO−
p-menth-2-yl = [2-methyl-5-(1-methylethyl)cyclohexyl] 2,5−Me(Me2CH)C6H9−
p-menth-3,5-ylene = [5-methyl-2-(1-methylethyl)-(methylselenyl) = (methylseleno) MeSe−(methylthio) MeS−
(methyltelluro) MeTe−(methyltrioxy) MeOOO−
morpholino = 4-morpholinyl
4
1O

N
6

myristoyl = (1-oxotetradecyl) Me(CH2)12CO−
naphthal = (naphthalenylmethylene) (C10H7)CH=
naphthalimido = (1,3-dioxo-1H-benz[de]isoquinolin-2(3H)-yl) (C12H6NO2)−
naphthenyl = (naphthalenylmethylidyne)(C10H7)C≡¶ 294

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

naphthionyl = [(4-amino-1-naphthalenyl)sulfonyl] 4,1−H2NC10H6SO2−
naphthobenzyl = (naphthalenylmethyl)(C10H7)CH2−
naphthothiophene-yl = naphthothienyl (C12H7S)−
naphthoxy = (naphthalenyloxy) (C10H7)O−
naphthoyl = (naphthalenylcarbonyl) (C10H7)CO−
naphthyl = naphthalenyl (C10H7)−
naphthylene = naphthalenediyl −(C10H6)−
1(2H)-naphthylidene = 1(2H)-naphthalenylidene

CH2(naphthylnaphthyl) = [binaphthalen]yl
C10H7C10H6−nazyl = (naphthalenylmethyl) (C10H7)CH2−
neopentyl = (2,2-dimethylpropyl) Me3CCH2−
neophyl = (2-methyl-2-phenylpropyl)
PhCMe2CH2−
neryl (from nerol) = (3,7-dimethyl-2,6-octadien-1yl) −Me2C=CH(CH2)2CMe=CHCH2−
nicotinimidoyl = (imino-3-pyridinylmethyl)(C5H4N)C(=NH)−
nicotinoyl = (3-pyridinylcarbonyl)
1

N
CO

6

nipecotoyl = (3-piperidinylcarbonyl)
1

HN
6

CO

nitramino = (nitroamino) O2NNH−
aci-nitramino = (aci-nitroamino) HON(O)=N−
nitrilio HN+≡
nitrilo N≡(nitrilophosphoranyl) = phosphononitridyl
HP(≡N)−
nitro O2N−
aci-nitro HON(O)=nitrosamino = (nitrosoamino) ONNH−
nitrosimino = (nitrosoimino) ONN=
nitroso ON−(nitrothio) O2NS−
nonanedioyl = (1,9-dioxo-1,9-nonanediyl)−CO(CH2)7CO−
nonanoyl = (1-oxononyl) Me(CH2)7CO−
norbornyl = bicyclo[2.2.1]heptyl (C7H11)−
norbornylene = bicyclo[2.2.1]heptanediyl−(C7H10)−
norcamphanyl = bicyclo[2.2.1]heptyl (C7H11)−
norcaryl (from norcarane) = bicyclo[4.1.0]heptyl(C7H11)−
norpinyl (from norpinane) = bicyclo[3.1.1]heptyl(C7H11)−
norleucyl1 = (2-amino-1-oxohexyl)
Me(CH2)3CH(NH2)CO−norvalyl1 = (2-amino-1-oxopentyl)
Me(CH2)2CH(NH2)CO−nosyl = [(4-nitrophenyl)sulfonyl]
4−O2NC6H4SO2−
octadecanoyl = (1-oxooctadecyl) Me(CH2)16CO−
octanedioyl = (1,8-dioxo-1,8-octanediyl)−CO(CH2)6CO−
octanoyl = (1-oxooctyl) Me(CH2)6CO−
tert-octyl = (1,1,3,3-tetramethylbutyl)
Me3CCH2CMe2−
oenanthyl = (1-oxoheptyl) Me(CH2)5CO−
oleananyl (from oleanane) (C30H51)−
oleoyl = (1-oxo-9-octadecen-1-yl)
Me(CH2)7CH=CH(CH2)7CO−
ornithyl1 = (2,5-diamino-1-oxopentyl)
H2N(CH2)3CH(NH2)CO−oxalaldehydoyl = (2-oxoacetyl) HCOCO−
oxalyl = (1,2-dioxo-1,2-ethanediyl) −COCO−
oxamido = [(2-amino-2-oxoacetyl)amino]
H2NCOCONH−

oxamoyl = (2-amino-2-oxoacetyl) H2NCOCO−
oxamyl = (2-amino-2-oxoacetyl) H2NCOCO−
oxaniloyl = [2-oxo-2-(phenylamino)acetyl]
PhNHCOCO−
oxazolinyl = (dihydrooxazolyl) (C3H4NO)−
oximido = (hydroxyimino) HON=
oxo5 (See also epoxy and oxy) O=(oxoarsino) = arsenoso OAs−
(oxobornyl) = (trimethyloxobicyclo[2.2.1]heptyl)(C10H15O)−(oxoboryl) OB−(1-oxoethyl) = acetyl Ac (MeCO−)(oxoethylene) = (1-oxo-1,2-ethanediyl) −COCH2−(2-oxo-2-phenylhydrazinyl) = (nitrosophenylamino) PhN(NO)−(oxophenylmethyl) = benzoyl Bz (PhCO−)(oxophosphino) = phosphoroso OP−(oxopyridinylmethyl) = (pyridinylcarbonyl)(C5H4N)CO−(2-oxotrimethylene) = (2-oxo-1,3-propanediyl)−CH2COCH2−(2-oxovinyl) = (2-oxoethenyl) OC=CH−
oxy9 (see also epoxy and oxo) −O−[oxybis(methylenecarbonylimino)] = [oxybis[(1oxo-2,1-ethanediyl)imino]]−NHCOCH2OCH2CONH−
palmitoyl = (1-oxohexadecyl) Me(CH2)14CO−
pantothenoyl = N-(2,4-dihydroxy-3,3-dimethyl-1oxobutyl)-β-alanyl1 or [3-[(2,4-dihydroxy-3,3dimethyl-1-oxobutyl)amino]-1-oxopropyl]
HOCH2CMe2CH(OH)CONH(CH2)2CO−
pelargonoyl = (1-oxononyl) Me(CH2)7CO−
pelargonyl = (1-oxononyl) Me(CH2)7CO−
pentadecanoyl = (1-oxopentadecyl)
Me(CH2)13CO−
pentamethylene = 1,5-pentanediyl −(CH2)5−3-pentanesulfonamido = [[(1-ethylpropyl)sulfonyl]amino] Et2CHSO2NH−
1,3-pentazadieno = 1,3-pentazadien-1-yl
H2NN=NN=N−
2-pentenediylidyne = 2-pentene-1,5-diylidyne≡CCH=CHCH2C≡
tert-pentyl = (1,1-dimethylpropyl) EtCMe2−
pentyl Me(CH2)4−
pentylidyne BuC≡
perchloryl O3Cl−
perseleno = seleninoselenoyl Se=Se=
perthio = sulfinothioyl S=S=
phenacyl = (2-oxo-2-phenylethyl) PhCOCH2−
phenacylidene = (2-oxo-2-phenylethylidene)
PhCOCH=phenanthrothiophene-yl = phenanthrothienyl(C16H9S)−
phenanthryl = phenanthrenyl (C14H9)−
phenanthrylene = phenanthrenediyl −(C14H8)−
phenenyl = benzenetriyl C6H3≡
phenethyl = (2-phenylethyl) PhCH2CH2−
phenethylidene = (2-phenylethylidene)
PhCH2CH=
phenetidino = [(ethoxyphenyl)amino](EtO)C6H4NH−
phenetyl = (ethoxyphenyl) (EtO)C6H4−
phenoxy PhO−
phenyl Ph (C6H5)−
phenylalanyl1 (from phenylalanine) = (2-amino-1oxo-3-phenylpropyl) PhCH2CH(NH2)CO−(phenylarsinico) = (hydroxyphenylarsinyl)
PhAs(O)(OH)−(phenylazo) = (2-phenyldiazenyl) PhN=N−[(phenylazo)imino] = (3-phenyl-2-triazen-1ylidene) PhN=NN=(phenylbenzoyl) = ([1,1′-biphenyl]ylcarbonyl)
PhC6H4CO
phenylene −(C6H4)−[phenylenebis(azo)] = [phenylenebis(2,1-diazenediyl)] −N=NC6H4N=N−[phenylenebis[2,1-diazenediyl(methylimino)]] =[phenylenebis(1-methyl-2-triazene-3,1-diyl)]−NMeN=NC6H4N=NNMe−[phenylenebis(1-oxo-1-ethanyl-2-ylidene)] =[phenylenebis(2-oxo-2-ethanyl-1-ylidene)]=CHCOC6H4COCH=(phenylenedimethylene) = [phenylenebis(methyl-122ene)] −CH2C6H4CH2−(phenylenedimethylidyne) =CHC6H4CH=(phenylenedioxy) = [phenylenebis(oxy)]−OC6H4O−(phenylglyoxyloyl) = (2-oxo-2-phenylacetyl)
PhCOCO−phenylidene = cyclohexadienylidene (C6H6)=(phenylimidocarbonyl) = (phenylcarbonimidoyl)7 PhN=C=(phenyloxalyl) = (2-oxo-2-phenylacetyl)
PhCOCO−(phenyloxy) = phenoxy PhO−
(phenylphenoxy) = ([1,1′-biphenyl]yloxy)
PhC6H4O−(phenylsulfenyl) = (phenylthio) PhS−
(phenylsulfinyl) PhS(O)−(S-phenylsulfonimidoyl) PhS(O)(=NH)−
phorbinyl (from phorbine) (C22H17N4)−
phosphinico3,4 HOP(O)=phosphinidene HP=
phosphinidenio H2P+=
phosphinidyne P≡
phosphinimyl H2P(=NH)−
phosphino H2P−
phosphinothioyl H2P(S)−phosphinothioylidene HP(S)=phosphinyl H2P(O)−phosphinylidene HP(O)=phosphinylidyne P(O)≡phospho O2P−
phosphonio H3P+−
phosphono4 (HO)2P(O)−(phosphonoformyl) = (phosphonocarbonyl)(HO)2P(O)CO−
phosphononitridyl HP(≡N)−
phosphoranyl H4P−
phosphoranylidene H3P=
phosphoranylidyne H2P≡
phosphoro = 1,2-diphosphenediyl −P=P−
phosphoroso OP−
phthalal = (1,2-phenylenedimethylidyne)
1,2−C6H4(CH=)2
phthalaldehydoyl = (2-formylbenzoyl)2−(HCO)C6H4CO−
phthalamoyl = [2-(aminocarbonyl)benzoyl]
2−(H2NCO)C6H4CO−
phthalanyl = (1,3-dihydroisobenzofuranyl)(C8H7O)−phthalidyl = (1,3-dihydro-3-oxo-1-isobenzofuranyl) (C8H5O2)−
phthalidylidene = (3-oxo-1(3H)-isobenzofuranylidene) (C8H402)−
phthalimido = (1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl) (C8H4NO2)−
phthalocyaninyl1 (from phthalocyanine)(C32H17N8)−
phthaloyl = (1,2-phenylenedicarbonyl)
1,2−C6H4(CO−)2
phthalylidene = (1,2-phenylenedimethylidyne)
1,2−C6H4(CH=)2
phyllocladanyl = kauranyl (from kaurane)(C29H33)−
phytyl = (3,7,11,15-tetramethyl-2-hexadecen-1-yl)
Me[CHMe(CH2)3]3CMe=CHCH2−
picolinoyl = (2-pyridinylcarbonyl)
1

6

N
CO

picryl = (2,4,6-trinitrophenyl) 2,4,6−(O2N)3C6H2−
pimeloyl = (1,7-dioxo-1,7-heptanediyl)−CO(CH2)5CO−
4-pinanyl (from pinane) = (4,6,6-trimethylbicyclo[3.1.1]hept-2-yl) (C10H17)−pinanylene = (trimethylbicyclo[3.1.1]heptanediyl)−(C10H16)−
pipecoloyl = (2-piperidinylcarbonyl)
6

H
N
1

CO

123

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007
pyridinio

piperidino = 1-piperidinyl
6

6
1

N
piperidyl = piperidinyl (C5H10N)−
piperidylidene = piperidinylidene (C5H9N)=
piperonyl = (1,3-benzodioxol-5-ylmethyl)
3,4−(CH2O2)C6H3CH2−
piperonylidene = (1,3-benzodioxol-5-ylmethylene) 3,4−(CH2O2)C6H3CH=
piperonyloyl = (1,3-benzodioxol-5-ylcarbonyl)
3,4−(CH2O2)C6H3CO−
pivaloyl = (2,2-dimethyl-1-oxopropyl) Me3CCO−
pivalyl = (2,2-dimethyl-1-oxopropyl) Me3CCO−
plumbanetetrayl =Pb=
plumbyl H3Pb−
plumbylene H2Pb=
plumbylidyne HPb≡
podocarpan-13-yl = (tetradecahydro-4b,8,8-trimethyl-2-phenanthrenyl) (C17H29)−
porphinyl (from porphine) (C20H13N4)−
pregna-5,16-dien-21-yl (from pregnadiene)(C21H31)−prenyl = (3-methyl-2-buten-1-yl) Me2C=CHCH2−
prolyl1 = (2-pyrrolidinylcarbonyl)
H
N

5

1

CO

2-propanesulfonamido = [[(1-methylethyl)sulfonyl]amino] Me2CHSO2NH−
propargyl = 2-propyn-1-yl HC≡CCH2 −propenyl = 1-propen-1-yl MeCH=CH−
2-propen-1-yl CH2=CH−CH2−propenylene = 1-propene-1,3-diyl −CH=CHCH2−
propenylidene = 1-propen-1-ylidene MeCH=C=
propioloyl = (1-oxo-2-propyn-1-yl) HC≡CCO−
propiolyl = (1-oxo-2-propyn-1-yl) HC≡CCO−
propionamido = [(1-oxopropyl)amino] EtCONH−
propionyl = (1-oxopropyl) EtCO−(propionyldioxy) = [(1-oxopropyl)dioxy]
EtC(O)OO−
propionyloxy = (1-oxopropoxy) EtCO2−
propoxy PrO−
propyl Pr (CH3CH2CH2−)
sec-propyl = (1-methylethyl) Me2CH−
propylene = (1-methyl-1,2-ethanediyl)−CHMeCH2−
propylidene EtCH=
propylidyne EtC≡
(propyloxy) = propoxy PrO−
protocatechuoyl = (3,4-dihydroxybenzoyl)
3,4−(HO)2C6H3CO−
pseudoallyl = (1-methylethenyl) H2C=CMe−
pseudocumidino = [(2,4,5-trimethylphenyl)amino]
2,4,5−Me3C6H2NH−
as-pseudocumyl = (2,3,5-trimethylphenyl)
2,3,5−Me3C6H2−
s-pseudocumyl = (2,4,5-trimethylphenyl)
2,4,5−Me3C6H2−
v-pseudocumyl = (2,3,6-trimethylphenyl)
2,3,6−Me3C6H2−
pseudoindolyl = 1H-indolyl (C8H6N)−
pteroyl = [4-[[(2-amino-3,4-dihydro-4-oxo-6-pteridinyl)methyl]amino]benzoyl] (C14H11N6O2)−
2H-pyranio
6
1 O+

2H-pyran-2-ylium-2-yl
6

1

O

+

pyrazolidyl = pyrazolidinyl (C3H7N2)−
pyrazolinyl = (dihydropyrazolyl) (C3H5N2)−

1N+

pyridyl = pyridinyl (C5H4N)−
pyroglutamoyl = (5-oxoprolyl)1 or [(5-oxo-2-pyrrolidinyl)carbonyl]
O

5

H
N
1

CO

pyromucyl = (2-furanylcarbonyl)
1
5

O
CO

pyrrolidyl = pyrrolidinyl (C4H8N)−
pyrrolinyl = (dihydropyrrolyl) (C4H6N)−
pyrrol-1-yl = 1H-pyrrol-1-yl (C4H4N)−
pyrroyl = (pyrrolylcarbonyl) (C4H3N)CO−
pyrryl = pyrrolyl (C4H4N)−
pyruvoyl = (1,2-dioxopropyl) MeCOCO−
p-quaterphenylyl = [1,1′:4′,1′′:4′′,1′′′-quaterphenyl]yl (C24H17)−quinaldoyl = (2-quinolinylcarbonyl)(2−C9H6N)CO−
quinolyl = quinolinyl (C9H6N)−
quinonyl = (dioxocyclohexadienyl) (C6H3O2)−
quinuclidinyl = 1-azabicyclo[2.2.2]octyl(C7H12N)−
α-resorcyloyl = (3,5-dihydroxybenzoyl)
3,5−(HO)2C6H3CO−
β-resorcyloyl = (2,4-dihydroxybenzoyl)
2,4−(HO)2C6H3CO−
γ-resorcyloyl = (2,6-dihydroxybenzoyl)
2,6−(HO)2C6H3CO−
rhamnosyl = (6-deoxymannopyranosyl)
HO

O
Me

HO

OH

ricinelaidoyl = (12-hydroxy-1-oxo-9-octadecen-1yl) Me(CH2)5CH(OH)CH2CH=CH(CH2)7CO−
ricinoleoyl = (12-hydroxy-1-oxo-9-octadecen-1yl) Me(CH2)5CH(OH)CH2CH=CH(CH2)7CO−
rosan-6-yl = (2-ethyltetradecahydro-2,4a,8,8-tetramethyl-9-phenanthrenyl) (C20H35)−
salicyl = [(2-hydroxyphenyl)methyl]
2−HOC6H4CH2−
salicylidene = [(2-hydroxyphenyl)methylene]
2−HOC6H4CH=
salicyloyl = (2-hydroxybenzoyl) 2−HOC6H4CO−
sarcosyl = (N-methylglycyl)1 or [2-(methylamino)acetyl] MeNHCH2CO−
sebacoyl = (1,10-dioxo-1,10-decanediyl)−CO(CH2)8CO−
λ4-selanylidene H2Se=
λ6-selanylidene H4Se=
seleneno4 HOSe−
selenino4 HOSe(O)−seleninoselenoyl Se=Se=
seleninyl OSe=seleno9 (see also episeleno and selenoxo) −Se−selenocyanato NCSe−
selenono4 (HO)SeO2−
selenonyl O2Se=
selenophenyl = selenophene-yl (C4H3Se)−
selenoxo5 (see also episeleno and seleno) Se=
selenyl4 HSe−semicarbazido = [2-(aminocarbonyl)hydrazinyl]
H2NCONHNH−
semicarbazono = [2-(aminocarbonyl)hydrazinylidene] H2NCONHN=¶ 294

senecioyl = (3-methyl-1-oxo-2-buten-1-yl)
Me2C=CHCO−
seryl1 = (2-amino-3-hydroxy-1-oxopropyl)
HOCH2CH(NH2)CO−
siamyl = (1,2-dimethylpropyl) Me2CHCHMe−
silanetetrayl =Si=
siloxy = (silyloxy) H3SiO−
silyl H3Si−
silylene H2Si=
silylidyne HSi≡sorboyl = (1-oxo-2,4-hexadien-1-yl)
MeCH=CHCH=CHCO−
spirohex-1-yl (C6H9)−
spirostanyl (from spirostane) (C27H43O2)−
stannanetetrayl =Sn=
stannyl H3Sn−
stannylene H2Sn=
stannylidyne HSn≡stearoyl = (1-oxooctadecyl) Me(CH2)16CO−
stibino H2Sb−
stiboso = (oxostibino) OSb−
stibyl = stibino H2Sb−
stibylene HSb=
stibylidyne Sb≡styrene = (1-phenyl-1,2-ethanediyl) −CHPhCH2−
styrolene = (1-phenyl-1,2-ethanediyl)−CHPhCH2−
styryl = (2-phenylethenyl) PhCH=CH−
suberoyl = (1,8-dioxo-1,8-octanediyl)−CO(CH2)6CO−
succinaldehydoyl = (1,4-dioxobutyl)
HCO(CH2)2CO−
succinamoyl = (4-amino-1,4-dioxobutyl)
H2NCO(CH2)2CO−
succinamyl = (4-amino-1,4-dioxobutyl)
H2NCO(CH2)2CO−
succinaniloyl = [1,4-dioxo-4-(phenylamino)butyl]
PhNHCO(CH2)2CO−
succinimido = (2,5-dioxo-1-pyrrolidinyl)
O
5
1

N
O
succinyl = (1,4-dioxo-1,4-butanediyl)−CO(CH2)2CO−
sulfamino = (sulfoamino) HOSO2NH−
sulfamoyl = (aminosulfonyl) H2NSO2−
sulfamyl = (aminosulfonyl) H2NSO2−
sulfanilamido = [[(4-aminophenyl)sulfonyl]amino] 4−H2NC6H4SO2NH−
sulfanilyl = [(4-aminophenyl)sulfonyl]
4−H2NC6H4SO2−
λ4-sulfanyl H2S=
λ6-sulfanyl H4S=
sulfeno4 HOS−
sulfhydryl = mercapto4 HS−
sulfinimidoyl HN=S=
sulfino4 HOS(O)−sulfinothioyl S=S=
sulfinyl OS=
sulfinylhydrazono = (2-sulfinylhydrazinylidene)
O=S=N−N=sulfo4 HO3S−
sulfonimidoyl HN=S(O)=sulfonodiimidoyl (HN=)2S=
sulfonyl −SO2−
sulfurtetrayl =λ4-sulfanetetrayl =S=
sulfurtriyl =λ4-sulfanylidyne HS≡
sulfuryl = sulfonyl −SO2−
tartaroyl = (2,3-dihydroxy-1,4-dioxo-1,4-butanediyl) −COCH(OH)CH(OH)CO−
tartronoyl = (2-hydroxy-1,3-dioxo-1,3-propanediyl) −COCH(OH)CO−
tauryl = [(2-aminoethyl)sulfonyl]
H2N(CH2)2SO2−
λ4-tellanylidene H2Te=
λ6-tellanylidene H4Te=
telluro6 (see also telluroxo) −Te−telluroxo5 (see also telluro) Te=¶ 294

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

telluryl4 HTe−terephthalal = (1,4-phenylenedimethylidyne)
1,4−C6H4(CH=)2
terephthalaldehydoyl = (4-formylbenzoyl)
4−HCOC6H4CO−
terephthalamoyl = [4-(aminocarbonyl)benzoyl]
4−(H2NCO)C6H4CO−
terephthalaniloyl = [4-[(phenylamino)carbonyl]benzoyl] 4−(PhNHCO)C6H4CO−
terephthaloyl = (1,4-phenylenedicarbonyl)
1,4−C6H4(CO−)2
terephthalylidene = (1,4-phenylenedimethylidyne) 1,4−C6H4(CH=)2
m-terphenylyl = [1,1′:3′,1′′-terphenyl]yl(C18H13)−terphenylylene = [terphenyl]diyl −(C18H12)−
tetradecanoyl = (1-oxotetradecyl) Me(CH2)12CO−
tetramethylene = 1,4-butanediyl −(CH2)4−
1,4-tetraphosphinediyl −(PH)4−
tetrasiloxanylene = 1,7-tetrasiloxanediyl−SiH2(OSiH2)2OSiH2−
tetrathio13 −SSSS−
tetrazanediylidene = 1,4-tetrazanediylidene=N(NH)2N=
tetrazanylene = 1,4-tetrazanediyl −(NH)4−
1-tetrazeno = 1-tetrazen-1-yl H2NNHN=N−
thenoyl = (thienylcarbonyl) (C4H3S)CO−thenyl = (thienylmethyl) (C4H3S)CH2−
thenylidene = (thienylmethylene) (C4H3S)CH=(thenyloxy) = (thienylmethoxy) (C4H3S)CH2O−
thexyl = 1,1,2-trimethylpropyl Me2CHCMe2−
thianaphthenyl = benzo[b]thienyl (C8H5S)−
thiazolidyl = thiazolidinyl (C3H6NS)−
thiazolinyl = (dihydrothiazolyl) (C3H4NS)−[(5-thiazolylcarbonyl)methyl] = [2-oxo-2-(5-thiazolyl)ethyl]
3

N
S

COCH2

1

thienyl (C4H3S)−(thienylthienyl) = [bithiophen]yl(C4H3S)(C4H2S)−
thio9 (see also epithio and thioxo) −S−(thioacetonylidene) = (2-thioxopropylidene)
MeCSCH=
thioacetyl = (1-thioxoethyl) MeCS−(thioarsenoso) = (thioxoarsino) S=As−(thiobenzoyl) = (phenylthioxomethyl) PhCS−(thiocarbamoyl) = (aminothioxomethyl) H2NCS−
thiocarbamyl = (aminothioxomethyl) H2NCS−(thiocarbonyl) = carbonothioyl7 −CS−(thiocarboxy)14 HOSC−
thiocyanato NCS−
thiocyano = thiocyanato NCS−
(thioformyl) = (thioxomethyl) HCS−
(thiohexanoyl) = (1-thioxohexyl) Me(CH2)4CS−
thiohydroperoxy = sulfeno4 HOS− or (mercaptooxy)4 HSO−
(thiohydroxy) = mercapto4 HS−

thiomorpholino = 4-thiomorpholinyl
41SN(thionitroso) SN−
thionyl = sulfinyl −SO−
(thiophenacyl) = (2-phenyl-2-thioxoethyl)
PhCSCH2−
thiophene-yl = thienyl (C4H3S)−(thiophosphono) = (hydroxymercaptophosphinyl)(HO)(HS)P(O)−(thioseleneno)4 HSSe−(thiosulfeno)4 HSS−
(thiosulfo)14 (HO2S2)−
thioxo5 (see also epithio) S=(thioxoarsino) SAs−
(thioxomethyl) (see also carbonothioyl) S=CH−
thiuram = (aminothioxomethyl) H2NCS−
threonyl1 (2-amino-3-hydroxy-1-oxobutyl)
MeCH(OH)CH(NH2)CO−
4-thujyl = [2-methyl-5-(1-methylethyl)bicyclo[3.1.0]hex-2-yl] (C10H17)−
thymyl (from thymol) = [5-methyl-2-(1-methylethyl)phenyl]Me61

CHMe 2thyronyl = [O-(4-hydroxyphenyl)tyrosyl]1 or [2amino-3-[4-(4-hydroxyphenoxy)phenyl]-1-oxopropyl] [4−(4−HOC6H4O)C6H4]CH2CH(NH2)CO−
toloxy = (methylphenoxy) MeC6H4O−
p-toluenesulfonamido = [[(4-methylphenyl)sulfonyl]amino] 4−MeC6H4SO2NH−
toluidino = [(methylphenyl)amino] MeC6H4NH−
toluoyl = (methylbenzoyl) MeC6H4CO−
toluyl = (methylbenzoyl) MeC6H4CO−
tolyl = (methylphenyl) MeC6H4−
α-tolyl = (phenylmethyl) PhCH2−
tolylene = (methylphenylene) −(MeC6H3)−
α-tolylene = (phenylmethylene) PhCH=
tosyl = [(4-methylphenyl)sulfonyl]
4−MeC6H4SO2−
triazano = triazanyl H2NNHNH−
1-triazeno = 1-triazen-1-yl H2NN=N−s-triazin-2-yl = 1,3,5-triazin-2-yl
NNN
trichothecanyl (from trichothecane) (C15H25O)−
tridecanoyl = (1-oxotridecyl) Me(CH2)11CO−(trimethylammonio) Me3N+−(trimethylarsonio) Me3As+−
trimethylene = 1,3-propanediyl −(CH2)3−(1,3,3-trimethyl-2-norbornyl) = (1,3,3-trimethylbicyclo[2.2.1]hept-2-yl) (C10H17)−(trimethylphosphonio) Me3P+−
triseleno13 −SeSeSe−
trisilanylene = 1,3-trisilanediyl −(SiH2)3−

NOTE: In addition to the following comments it must be understood thatstereochemical information is not provided for systematically named natural-product radicals in the list above. For example, the phytyl radical isnamed as 3,7,11,15-tetramethyl-2-hexadecenyl. Because the total stereochemistry of a phytyl compound may be influenced by the presence ofother chiral centers, it would be misleading to supply it with the radical
name.

124

trisiloxane-1,3,5-triyl = 1,3,5-trisiloxanetriyl−SiH(OSiH2−)2trithio13 −SSS−
trityl = (triphenylmethyl) Ph3C−
tropanyl = (8-methyl-8-azabicyclo[3.2.1]octyl)(C8H14N)−
tropoyl = (3-hydroxy-1-oxo-2-phenylpropyl)
HOCH2CHPhCO−
tryptophyl1 = [2-amino-3-(1H-indol-3-yl)-1-oxopropyl] (C8H6N)CH2CH(NH2)CO−tyrosyl1 = [2-amino-3-(4-hydroxyphenyl)-1-oxopropyl] 4−HOC6H4CH2CH(NH2)CO−
undecanoyl = (1-oxoundecyl) Me(CH2)9CO−
uramino = [(aminocarbonyl)amino] H2NCONH−
ureido = [(aminocarbonyl)amino] H2NCONH−
ureylene = (carbonyldiimino) −NHCONH−(ureylenediureylene) = [carbonylbis(2,1-hydrazinediylcarbonylimino)]−NHCONHNHCONHNHCONH−
ursanyl (from ursane) (C30H51)−
valeryl = (1-oxopentyl) BuCO−
valyl1 = (2-amino-3-methyl-1-oxobutyl)
Me2CHCH(NH2)CO−vanillal = [(4-hydroxy-3-methoxyphenyl)methylene] 4,3−HO(MeO)C6H3CH=
vanilloyl = (4-hydroxy-3-methoxybenzoyl)
4,3−HO(MeO)C6H3CO−
vanillyl = [(4-hydroxy-3-methoxyphenyl)methyl]
4,3−HO(MeO)C6H3CH2−
vanillylidene = [(4-hydroxy-3-methoxyphenyl)methylene] 4,3−HO(MeO)C6H3CH=
vanilmandeloyl = [2-hydroxy-2-(4-hydroxy-3methoxyphenyl)acetyl]
4,3−HO(MeO)C6H3CH(OH)CO−
veratral = [(3,4-dimethoxyphenyl)methylene]
3,4−(MeO)2C6H3CH=
veratroyl = (3,4-dimethoxybenzoyl)
3,4−(MeO)2C6H3CO−o-veratroyl = (2,3-dimethoxybenzoyl)
2,3−(MeO)2C6H3CO−
veratryl = [(3,4-dimethoxyphenyl)methyl]
3,4−(MeO)2C6H3CH2−o-veratryl = [(2,3-dimethoxyphenyl)methyl]
2,3−(MeO)2C6H3CH2−
veratrylidene = [(3,4-dimethoxyphenyl)methylene] 3,4−(MeO)2C6H3CH=
vinyl = ethenyl H2C=CH−
vinylene = 1,2-ethenediyl −CH=CH−
vinylidene = ethenylidene H2C=C=
xanthen-9-yl = 9H-xanthen-9-yl (C13H9O)−
xanth-9-yl = 9H-xanthen-9-yl (C13H9O)−
xenyl = [1,1′-biphenyl]-4-yl 4−PhC6H4−
xylidino = [(dimethylphenyl)amino]
Me2C6H3NH−
xyloyl = (dimethylbenzoyl) Me2C6H3CO−
xylyl = (dimethylphenyl) Me2C6H3−xylylene = [phenylenebis(methylene)]−CH2C6H4CH2−

6 This prefix is used when the free valencies are attached to different

atoms which are usually not otherwise connected.
7 This prefix is used as a multiplying radical or when both free valencies

are attached to the same atom.

8 The prefix “cumyl” has been used in the recent literature to mean α-

cumyl.
9 This prefix is used when the free valencies are attached to different

atoms which are not otherwise connected.
1 This prefix is used in peptide nomenclature.
2 This prefix may be used in a generic sense, e.g., aldoxime.
3 This prefix is only used as a multiplying radical and in structural repeat-

ing units of polymers.
4 This prefix is used only when unsubstituted.
5 This prefix is used when both free valencies are attached to the sameatom.

10 This prefix is used when the free valencies are attached to different

atoms which are otherwise connected.
11 This prefix may be used in a generic sense, e.g., ketoxime.
12 This prefix is used only in structural repeating units of polymers.
13 This prefix is used to denote a series of chalcogen atoms in a chain or

an indefinite structure.
14 This prefix is not used when the hydrogen atom has been substituted byanother atom or group if a definite structure can be determined.

125

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 296

J. SELECTED BIBLIOGRAPHY OF NOMENCLATURE OF CHEMICAL SUBSTANCES

Introduction
IUPAC, IUB, and IUBMB Nomenclature Rules andRecommendations
Organic chemistry
Biochemistry
Inorganic chemistry
Macromolecular chemistry
Miscellaneous
American Chemical Society Nomenclature
Chemical Abstracts Service Index Nomenclature

¶ 295
296
297
298
299
300

American Chemical Society Committee
History and Development of Chemical Nomenclature
GeneralOrganic chemistry
Biochemistry
Inorganic chemistry
Macromolecular chemistry
Stereochemistry

¶ 302
303
304
305
306
307
308

301

295. Introduction. The development of systematic chemical nomenclature
is shared by a number of organizations. In the United States the American
Chemical Society (ACS) established a Committee on Nomenclature andNotation as early as 1886, followed in 1911 by the ACS Committee on Nomenclature, Spelling, and Pronunciation, now known as the ACS Committee on
Nomenclature, Terminology and Symbols. In addition, subject nomenclaturecommittees and subcommittees exist in several ACS divisions.
Internationally, nomenclature commissions of the International Union ofPure and Applied Chemistry (IUPAC) and the International Union of Biochemistry and Molecular Biology (IUBMB)1 approve and publish detailed recommendations.2,3
Before becoming officially recommended nomenclature policy, a typical
path for a proposal originating in the United States has been as follows: an idea
(suggested by an author, editor, committee member, etc.) is submitted to a subcommittee of subject specialists, then to an ACS divisional committee, the
ACS Committee on Nomenclature, and finally to the appropriate nomenclaturecommission of the International Union of Pure and Applied Chemistry.
References to current nomenclature rules of IUPAC, IUB, IUBMB, andACS are listed below. A selection of references to older, superseded rules andto significant proposals of individual authors is also included because of the occasional use of such nomenclature in current chemical literature, and the needin retrospective searching. These older references also provide a historical perspective illustrating the precedents on which modern chemical nomenclatureare based.
Additional nomenclature information may be obtained from Chemical Abstracts Service.
IUPAC, IUB, and IUBMB Nomenclature Rules andRecommendations
296. Organic chemistry
1. International Union of Pure and Applied Chemistry. Organic Chemistry Division. Commission on Nomenclature of Organic Chemistry, A Guide to
IUPAC Nomenclature of Organic Compounds, Recommendations 1993, R.
Panico, W. H. Powell, Jean-Claude Richer, eds., Blackwell Scientific Publications, Oxford, UK, 1993, 190 pp. (Includes revisions, both published andhitherto unpublished, to the 1979 edition of Nomenclature of Organic Chemistry (see item 2, below). “Corrections to A Guide to IUPAC Nomenclature ofOrganic Compounds (IUPAC Recommendations 1993)”, Pure Appl. Chem.
1999, 71, 1327-1330.
2. ——, Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F,
and H, 1979 edition, J. Rigaudy and S. P. Klesney, eds., Pergamon Press,
Oxford, UK, 1979, 559 pp. (Section A, Hydrocarbons; Section B, Fundamental
Heterocyclic Systems; Section C, Characteristic Groups Containing C, H, O,
N, Halogen, S, Se, and/or Te; Section D, Organic Compounds Containing
Elements Which Are Not Exclusively C, H, O, N, Halogen, S, Se, and Te (Provisional Recommendations 1978); Section E, Stereochemistry (Recommendations 1974); Section F, General Principles for the Naming of Natural Products
and Related Compounds (Provisional Recommendations 1975); Section H,
Isotopically Modified Compounds (Approved Recommendations 1978). This
edition contains changes from previous editions of various sections. The firstedition of Sections A and B, known as the 1957 IUPAC Rules, was publishedin “Nomenclature of Organic Chemistry, 1957”, Butterworths Scientific Pub-

1Known as the International Union of Biochemistry (IUB) prior to 1992.
2K L. Loening, “International Cooperation on Scientific Nomenclature”, J.

Chem. Doc. 1970, 10, 231-236; “Terminology Guidelines and Their Application in the International Union of Pure and Applied Chemistry” in International Co-operation in Terminology Work, M. Krommer-Benz and K. G. Saur, eds.
Munich, 1986, pp. 92-116 (Infoterm Series 8).
3International Union of Pure and Applied Chemistry, “Guidelines for
Drafting IUPAC Technical Reports and Recommendations (2002)” in IUPAC
Handbook, 2002-2003, IUPAC, 2002, pp. 344-353; “Procedure for Publicationof IUPAC Technical Reports and Recommendations”, ibid., pp. 341-343.

lications, London, 1958, pp 3-70; this edition also appeared with comments in
J. Am. Chem. Soc. 1960, 82, 5545-5574. (These sections first appeared as“Tentative Rules for Organic Nomenclature”, C. R. de la Conf. Union Int.
Chim., Zurich, July 20-28, 1955, pp. 160-184.) A second edition of Sections A
and B appeared in “Nomenclature of Organic Chemistry”, Butterworths,
London, 1966, pp. 3-70. The first edition of Section C was published as “Nomenclature of Organic Chemistry, Section C”, Butterworths, London, 1965,
260 pp. and also appeared in Pure Appl. Chem. 1965, 11, 1-260. (Section C first
appeared as a paperback edition only as “Tentative Rules for Nomenclature ofOrganic Chemistry, Section C”, Butterworths, London, 1962, 238 pp.). A third
edition of Sections A and B and a second edition of Section C were publishedtogether as “Nomenclature of Organic Chemistry, Sections A, B, and C”, Butterworths, London, 1971, 337 pp. A summary of the changes that were madein Sections A, B, and C for the combined 1971 edition of these sections appears
in J. Chem. Doc. 1972, 12, 132-138. An early version of Section D was published in IUPAC Inf. Bull. Append. No. 31, August, 1973. The contents of thefirst edition of Section E appeared in Pure Appl. Chem. 1976, 45, 11-30, previously published as tentative rules in IUPAC Inf. Bull. No. 35, June, 1969, pp.
36-80, and in J. Org. Chem. 1970, 35, 2849-2867. Section F appeared earlier
in IUPAC Inf. Bull. Append. No. 53, December, 1976 and in Eur. J. Biochem.
1978, 86, 1-8. The contents of the first edition of Section H appeared in Pure
Appl. Chem. 1979, 51, 353-380, published previously as provisional recommendations in IUPAC Inf. Bull. Append. No. 62, July, 1977, and in Eur. J.
Biochem. 1978, 86, 9-25.
3. ——, “Revision of the Extended Hantzsch-Widman System of Nomenclature for Heteromonocycles (Recommendations 1982)”, Pure Appl.
Chem. 1983, 55, 409-416. Published previously as provisional recommendations in Pure Appl. Chem. 1979, 51, 1995-2003. For WWW version by G. P.
Moss see http://www.chem.qmw.ac.uk/iupac/iupac.html
4. ——, “Treatment of Variable Valence in Organic Nomenclature(Lambda Convention) (Recommendations 1983)”, Pure Appl. Chem. 1984, 56,
769-778. Published previously as provisional recommendations entitled “TheDesignation of Non-Standard Classical Valence Bonding in Organic Nomenclature” in Pure Appl. Chem. 1982, 54, 217-227. For WWW version by G. P.
Moss see http://www.chem.qmw.ac.uk/iupac/iupac.html
5. ——, “Extension of Rules A-1.1 and A-2.5 Concerning NumericalTerms Used in Organic Chemical Nomenclature (Recommendations 1986)”,
Pure Appl. Chem. 1986, 58, 1693-1696. Published previously as provisional
recommendations in Pure Appl. Chem. 1983, 55, 1463-1466.
6. ——, “Nomenclature for Cyclic Organic Compounds with Contiguous
Formal Double Bonds (The δ-Convention) (Recommendations 1988)”, Pure
Appl. Chem. 1988, 60, 1395-1401. For WWW version by G. P. Moss see http://www.chem.qmw.ac.uk/iupac/iupac.html
7. ——, “Revised Nomenclature for Radicals, Ions, Radical Ions, andRelated Species (Recommendations 1993)”, Pure Appl. Chem. 1993, 65, 13571455. A revision of Subsection C-0.8 of the 1979 edition of Nomenclature ofOrganic Chemistry (See item 2, above).
8. International Union of Pure and Applied Chemistry. Organic Chemistry Division. Commission on Nomenclature of Organic Chemistry. International Union of Pure and Applied Chemistry and International Union of
Biochemistry. Commission on Biochemical Nomenclature, “Nomenclature of
Carotenoids (Rules Approved 1974)”, Pure Appl. Chem. 1975, 41, 405-431(amendments: Biochemistry 1975, 14, 1803-1804). Published previously as
tentative rules in Biochemistry 1971, 10, 4827-4837. (These publications supersede rules in J. Am. Chem. Soc. 1960, 82, 5583-5584.)
9. ——, “Rules for Cyclitol Nomenclature (Recommendations 1973)”.
Biochem. J. 1976, 153, 25-31. Published previously as tentative rules in J. Biol.
Chem. 1968, 243, 5809-5819.
10. International Union of Pure and Applied Chemistry. Organic Chemistry
Division. Commission on Nomenclature of Organic Chemistry. Commission on
Physical Organic Chemistry, “Glossary of Class Names of Organic Compounds
and Reactive Intermediates Based on Structure (Recommendations 1995)”, Pure
Appl. Chem. 1995, 67, 1307-1375. For WWW version by G. P. Moss see http://www.chem.qmw.ac.uk/iupac/iupac.html
11. ——, “Basic Terminology of Stereochemistry (Recommendations
1996)”, Pure Appl. Chem. 1996, 68, 2193-2222. For WWW version by G. P.
Moss see http://www.chem.qmw.ac.uk/iupac/iupac.html

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12. International Union of Pure and Applied Chemistry. Organic Chemistry Division. Commission on Physical Organic Chemistry, “Glossary of Terms
Used in Physical Organic Chemistry (Recommendations 1994)”, Pure Appl.
Chem. 1994, 66, 1077-1184. Published previously as Recommendations 1982
in Pure Appl. Chem. 1983, 55, 1281-1371 and as provisional recommendationsin Pure Appl. Chem. 1979, 51, 1725-1801. For WWW version by G. P. Mosssee http://www.chem.qmw.ac.uk/iupac/iupac.html
13. ——, “Names for Hydrogen Atoms, Ions, and Groups, and for Reactions Involving Them (Recommendations 1988)”, Pure Appl. Chem. 1988, 60,
1115-1116.
14. ——, “Nomenclature for Organic Chemical Transformations (Recommendations 1988)”, Pure Appl. Chem. 1989, 61, 725-768 (includes provisional
recommendations previously published as “Nomenclature for Straightfor-ward
Transformations” in Pure Appl. Chem. 1981, 53, 305-321).
15. International Union of Pure and Applied Chemistry. “Nomenclature
and Terminology of Fullerenes: A Preliminary Survey”, Pure Appl. Chem.
1997, 69, 1411-1434.
16. International Union of Pure and Applied Chemistry. Organic Chemistry Division. Commission on Nomenclature of Organic Chemistry, “Nomenclature of Fused and Bridged Fused Ring Systems (IUPAC Recommendations
1998)”, Pure Appl. Chem. 1998, 70, 143-216.
17. ——, “Phane Nomenclature. Part I: Parent Phane Names (IUPAC
Recommendations 1998)”, Pure Appl. Chem. 1998, 70, 1513-1545.
18. ——, “Extension and Revision of the von Baeyer System for Naming
Polycyclic Compounds (Including Bicyclic Compounds) (IUPAC Recommendations 1999)”, Pure Appl. Chem. 1999, 71, 513-529.
19. ——, “Extension and Revision of the Nomenclature for Spiro Compounds (IUPAC Recommendations 1999)”, Pure Appl. Chem. 1999, 71, 531-558.
20. ——, “Revised Section F: Natural Products and Related Compounds(IUPAC Recommendations 1999)”, Pure Appl. Chem. 1999, 71, 587-643. Superseded Section F published first in 1976, and then in 1978 (see item 2,
above).
21. International Union of Pure and Applied Chemistry. Organic Chemistry Division. Commission on Physical Organic Chemistry, “Glossary of Terms
Used in Theoretical Organic Chemistry (IUPAC Recommendations 1999)”,
Pure Appl. Chem. 1999, 71, 1919-1981.
22. International Union of Pure and Applied Chemistry. Organic and Biomolecular Chemistry Division. Commission on Nomenclature of Organic
Chemistry, “Nomenclature for the C60−Ih and C70−D5h(6) Fullerenes (IUPAC
Recommendations 2002)”, Pure Appl. Chem. 2002, 74, 629-695.
23. ——, “Phane Nomenclature. Part II: Modification of the Degree ofHydrogenation and Substitution Derivatives of Phane Parent Hydrides(IUPAC Recommendations 2002)”, Pure Appl. Chem. 2002, 74, 809-834.
297. Biochemistry
1. International Union of Biochemistry and Molecular Biology, Biochemical Nomenclature and Related Documents 1992, 2nd. ed., Portland Press, Ltd.,
London, 1993. A compendium of recommendations of IUPAC and IUB
produced by the Commission on Biochemical Nomenclature (CBN), the Nomenclature Committee of IUB (NC-IUB), and the IUPAC-IUB Joint Commission on Biochemical Nomenclature (JCBN), prepared by C. Liebecq for theCommittee of Editors of Biochemical Journals (CEBJ). The compendium
includes Sections E and F of the IUPAC Organic Rules (see ¶ 296, item 2); nomenclature recommendations given in items 8-9, ¶ 296 and items listed below,
except for items 20, 22, 23, 24, 29, 38, 39 and 40. It includes only the tentative
rules of item 5. Section H of the IUPAC Organic Rules and item 29 appear in
the 1979 edition of the compendium published in 1978 by The Biochemical
Society, London. Also included in the 1992 compendium are “Isotopically
Labeled Compounds: Common Biochemical Practice”; “Isotopically Substituted Compounds”; “Names for Hydrogen Species” (see ¶ 296, item 13); and“Excerpts from Newsletters of the Nomenclature Committees of IUB”.
2. International Union of Pure and Applied Chemistry and International
Union of Biochemistry. Commission on Biochemical Nomenclature, “Nomenclature of Phosphorus-Containing Compounds of Biochemical Importance(Recommendations 1976)”, Eur. J. Biochem. 1977, 79, 1-9.
3. International Union of Pure and Applied Chemistry and International
Union of Biochemistry. Joint Commission on Biochemical Nomenclature,“Nomenclature of Tetrapyrroles (Recommendations 1986)”, Pure Appl. Chem.
1987, 59, 779-832. Replaces “Recommendations 1978”, Pure Appl. Chem.
1979, 51, 2251-2304 of which an amended version appears in Eur. J. Biochem.
1980, 108, 1-30 and an abbreviated version by P. Karlson in Hoppe-Seyler’s Z.
Physiol. Chem. 1981, 362, vii-xii.
4. ——, “Nomenclature of Steroids (Recommendations 1989)”, Pure
Appl. Chem. 1989, 61, 1783-1822. (corrections: Eur. J. Biochem. 1993, 213, 2).
For WWW version by G. P. Moss see http://www.chem.qmw.ac.uk/iupac/iupac.html. [Supersedes “Definitive Rules for Nomenclature of Steroids”, Pure
Appl. Chem. 1972, 31, 283-322 (book form: Butterworths, London, 1972), previously published as tentative rules in Biochemistry 1969, 8, 2227-2242(amendments. ibid. 1971, 10, 4994), both of which superceded the definitiverules in “Nomenclature of Organic Chemistry, 1957” Butterworths Scientific
Publications, London, 1958, pp. 71-82 and J. Am. Chem. Soc. 1960, 82, 55775581, and in “Nomenclature of Organic Chemistry” Butterworths, London,
1966, pp. 71-81 (tentative rules for which appeared in C. R. de la Conf. Union
Int. Chim., Zurich, July 20-8, 1955, pp. 190-207)].
5. ——, “Nomenclature of Lignans and Neolignans (IUPAC Recommendations 2000)”, Pure Appl. Chem. 2000, 72, 1493-1523.

126

Carbohydrates
6. International Union of Pure and Applied Chemistry and International
Union of Biochemistry and Molecular Biology. Joint Commission on Biochemical Nomenclature. “Nomenclature of Carbohydrates (Recommendations
1996)”, Pure Appl. Chem. 1996, 68(10), 1919-2008. For WWW version by G.
P. Moss see http://www.chem.qmw.ac.uk/iupac/iupac.html [Supercedes “Tentative Rules for Carbohydrate Nomenclature, Pt. 1”, Biochemistry 1971, 10,3983-4004 (errarta: ibid. 1971, 10, 4995)] (see also ¶ 302, item 14).
7. International Union of Pure and Applied Chemistry and International
Union of Biochemistry. Joint Commission on Biochemical Nomenclature,“Conformational Nomenclature for Five and Six-Membered Ring Forms of
Monosaccharides and their Derivatives (Provisional Recommendations)”,
Pure Appl. Chem. 1981, 53, 1901-1906. Published as “Recommendations
1980” in Eur. J. Biochem. 1980, 111, 295-298 (A preliminary version was publishedin J.Chem. Soc.,Chem.Commun.1973, 505-508.See ¶ 302, item18).
8. ——, “Nomenclature of Branched-Chain Monosaccharides (Provisional Recommendations)”, Pure Appl. Chem. 1982, 54, 211-215. Published as“Recommendations 1980” in Eur. J. Biochem. 1981, 119, 5-8 (corrections:ibid. 1982, 125, 1).
9. ——, “Nomenclature of Unsaturated Monosaccharides (Provisional
Recommendations)”, Pure Appl. Chem. 1982, 54, 207-210. Published as “Recommendations 1980” in Eur. J. Biochem. 1981, 119, 1-3 (corrections: ibid.
1982, 125, 1).
10. ——, “Abbreviated Terminology of Oligosaccharide Chains, Provisional”, Pure Appl. Chem. 1982, 54, 1517-1522. Published as “Recommendations 1980” in J. Biol. Chem. 1982, 257, 3347-3351.
11. ——, “Polysaccharide Nomenclature (Provisional)”, Pure Appl.
Chem. 1982, 54, 1523-1526. Published as “Recommendations 1980” in J. Biol.
Chem. 1982, 257, 3352-3354.
12. ——, “Symbols for Specifying the Conformation of Polysaccharide
Chains (Provisional)”, Pure Appl. Chem. 1983, 55, 1269-1272 and as “Recommendations 1981,” in Eur. J. Biochem. 1983, 131, 5-7.
13. International Union of Biochemistry. Nomenclature Committee,“Numbering of Atoms in myo-Inositol (Recommendations 1988)”, Biochem. J.
1989, 258, 1-2.
Amino Acids, Peptides, Proteins, and Nucleic Acids
14. International Union of Pure and Applied Chemistry and International
Union of Biochemistry. Commission on Biochemical Nomenclature, “Abbreviated Nomenclature of Synthetic Polypeptides (Polymerized Amino Acids)(Revised Rules)”, Pure Appl. Chem. 1973, 33, 437-444. Published previously
as revised recommendations in Biochemistry 1972, 11, 942-944.
15. ——, “Abbreviations and Symbols for Nucleic Acids, Polynucleotides
and their Constituents (Rules Approved 1974)”, Pure Appl. Chem. 1974, 40,
277-290. Published previously as revised rules in Biochemistry 1970, 9, 40224027.
16. ——, “Abbreviations and Symbols for Description of Conformation of
Polypeptide Chains (Rules Approved 1974)”, Pure Appl. Chem. 1974, 40, 291308. Published previously as tentative rules in IUPAC Inf. Bull. Append. No.
10, February, 1971 and as “Tentative Rules (1969)” in Eur. J. Biochem. 1970,
17, 193-201.
17. ——, “Nomenclature of Peptide Hormones (Recommendations
1974)”, Biochemistry 1975, 14, 2559-2560.
18. International Union of Pure and Applied Chemistry and International
Union of Biochemistry. Joint Commission on Biochemical Nomenclature.
“Nomenclature and Symbolism for Amino Acids and Peptides (Recommendations 1983),” Pure Appl. Chem. 1984, 56, 595-624 (corrections: Eur. J.
Biochem. 1993, 213, 2). A combination and revision of four previously published recommendations: (a) “Nomenclature of α-Amino Acids (Recommendations 1974)”, Biochemistry 1975, 14, 449-462; published previously as
provisional recommendations in IUPAC Inf. Bull. Append. No. 46, September
1975 (these publications supersede rules published in J. Am. Chem. Soc. 1960,
82, 5575-5577); (b) “Symbols for Amino Acid Derivatives and Peptides (Rules
Approved 1974)”, Pure Appl. Chem. 1974, 40, 315-331; published previously
as recommendations in Biochemistry 1972, 11, 1726-1732; (c) “Naming Synthetic Modifications of Natural Peptides (Definitive Rules)”, Pure Appl. Chem.
1972, 31, 647-653; published previously as tentative rules in Biochemistry
1967, 6, 362-364; (d) “A One-Letter Notation for Amino Acid Sequences (Definitive Rules)”, Pure Appl. Chem. 1972, 31, 639-645; published previously as
tentative rules in Biochemistry 1968, 7, 2703-2715. For WWW version by G.
P. Moss see http://www.chem.qmw.ac.uk/iupac/iupac.html
19. ——, “Abbreviations and Symbols for the Description of Conformations of Polynucleotide Chains (Provisional)”, Pure Appl. Chem. 1983, 55,
1273-1280; appeared also as “Recommendations 1982” in Eur. J. Biochem.
1983, 131, 9-15.
20. ——, “Nomenclature of Glycoproteins, Glycopeptides, and Peptidoglycans (Recommendations 1985)”, Pure Appl. Chem. 1988, 60, 1389-1394(corrections: Eur. J. Biochem. 1989, 185, 485).
21. International Union of Biochemistry. Nomenclature Committee, “Nomenclature of Iron-Sulfur Proteins (Recommendations 1978)”, Eur. J. Biochem.
1979, 93, 427-430 (corrections: ibid. 1979, 95, 369 and 1979, 102, 315). Published previously as recommendations in Biochemistry 1973, 12, 3582-3583.
22. ——, “Nomenclature for Incompletely Specified Bases in Nucleic
Acid Sequences (Recommendations 1984)”, Eur. J. Biochem. 1985, 150, 1-5(corrections: ibid. 1986, 157, 1).

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23. ——, “Nomenclature of Electron-Transfer Proteins (Recommendations
1989)”, Eur. J. Biochem. 1991, 200, 599-611 (corrections: Eur. J. Biochem.
1993, 213, 2-3).
24. ——, “A Nomenclature of Junctions and Branchpoints in Nucleic
Acids”, Eur. J. Biochem. 1995, 230, 1-2.
25. International Union of Pure and Applied Chemistry. IUPAC-IUBMBIUPAB Inter-Union Task Group on the Standardization of Data Bases ofProtein and Nucleic Acid Structures by NMR Spectroscopy, “Recommendations for the Presentation of NMR Structures of Proteins and Nucleic Acids(IUPAC Recommendations 1998)”, Pure Appl. Chem. 1998, 70, 117-142.

¶ 298

Miscellaneous
41. International Union of Pure and Applied Chemistry and International
Union of Biochemistry. Commission on Biochemical Nomenclature, “Abbreviations and Symbols for Chemical Names of Special Interest in Biological
Chemistry (Revised Tentative Rules 1965)”, Biochemistry 1966, 5, 1445-1453.
42. ——, “Abbreviations and Symbols”, Eur. J. Biochem. 1977, 74, 1-5.
43. International Union of Nutritional Sciences. Committee 1/ I. Nomenclature, “Generic Descriptors and Trivial Names for Vitamins and Related
Compounds (Recommendations 1976)”, Nutrition Absts. and Revs., Series A:
Human and Experimental 1978, 48, 831-835.

Enzymes
26. International Union of Biochemistry and Molecular Biology Nomenclature Committee, Enzyme Nomenclature, 1992, Academic Press, Orlando,
Florida, 1992, 862 pp; Supplements 1, 2, 3, 4, and 5. Corrections and Additions, Eur. J. Biochem. 1994, 223, 1-5; 1995, 232, 1-6; 1996, 237, 1-5; 1997,
250, 1-6; 1999, 264, 610-650. (This edition includes corrections and additions
to “Enzyme Nomenclature, 1984”, published as three supplements in Eur. J.
Biochem. 1986, 157, 1-26; 1989, 179, 489-533; 1990, 187, 263-281; the 1984
edition updated the 1978 edition by including corrections and additions published as four supplements in Eur. J. Biochem. 1980, 104, 1-4; 1981, 116, 423435; 1982, 125, 1-13; 1983, 131, 461-472.)
27. International Union of Pure and Applied Chemistry and International
Union of Biochemistry. Commission on Biochemical Nomenclature, “The Nomenclature of Multiple Forms of Enzymes (Recommendations 1976)”, Eur. J.
Biochem. 1978, 82, 1-3. Published previously as “Rules Approved 1974” inPure Appl. Chem. 1974, 40, 309-314.
28. International Union of Biochemistry. Nomenclature Committee, “Symbolism and Terminology in Enzyme Kinetics (Recommendations 1981)”, Eur.
J. Biochem. 1982, 128, 281-291 (corrections: Eur. J. Biochem. 1993, 213, 1).
29. ——, “Nomenclature for Multienzymes (Recommendations 1989)”,
Eur. J. Biochem. 1989, 185, 485-486 (supercedes “Multienzyme Proteins” in
Trends. Biochem. Sci. 1979, 4, N275).
Lipids, Vitamins, Coenzymes, and Related Compounds
30. International Union of Pure and Applied Chemistry and International
Union of Biochemistry. Commission on Biochemical Nomenclature, “The Nomenclature of Lipids (Recommendations 1976)”, Eur. J. Biochem. 1977, 79,
11-21. Previously published as recommendations in J. Biol. Chem. 1967, 242,4845-4849 (amendments: ibid. 1970, 245, 1511).
31. ——, “Trivial Names of Miscellaneous Compounds of Importance inBiochemistry (Tentative Rules)”, J. Biol. Chem. 1966, 241, 2987-2988. (Supersedes “Definitive Rules for the Nomenclature of the Vitamins”, J. Am.
Chem. Soc. 1960, 82, 5581-5583.)
32. ——, “Nomenclature of Quinones with Isoprenoid Side Chains (Recommendations 1973)”, Eur. J. Biochem. 1975, 53, 15-18. Published previouslyas tentative rules in J. Biol. Chem. 1966, 241, 2989-2991. (Supersedes Rule V4 in J. Am. Chem. Soc. 1960, 82, 5581-5583.)
33. ——, “Nomenclature and Symbols for Folic Acid and Related Compounds (Recommendations 1986)”, Pure Appl. Chem. 1987, 59, 833-836. Published as “Tentative Rules” in J. Biol. Chem. 1966, 241, 2991-2992 which
superseded Rule V-13 in J. Am. Chem. Soc. 1960, 82, 5581-5583.
34. ——, “Nomenclature of Corrinoids (Rules Approved 1975)”, Pure
Appl. Chem. 1976, 48, 495-502. Published previously as recommendations in
Biochemistry 1974, 13, 1555-1560 and as tentative rules in J. Biol. Chem. 1966,
241, 2992-2994. (Supersedes Rule V-15 in J. Am. Chem. Soc. 1960, 82, 55815583; tentative rules for which appeared in “Nomenclature of Organic Chemistry, 1957”, Butterworths Scientific Publications, London, 1958, pp. 83-87.)
35. ——, “Nomenclature for Vitamins B6 and Related Compounds (Recommendations 1973)”, Biochemistry 1974, 13, 1056-1058. Published previously as tentative rules in Biochemistry 1970, 9, 4019-4021. (SupersedesSection M-7 in J. Biol. Chem. 1966, 241, 2987-2988; see item 29 above.)
36. International Union of Pure and Applied Chemistry and International
Union of Biochemistry. Joint Commission on Biochemical Nomenclature,“Nomenclature of Tocopherols and Related Compounds (Recommendations
1981)”, Pure Appl. Chem. 1982, 54, 1507-1510 and in Eur. J. Biochem. 1982,
123, 473-475. Published previously as “Recommendations 1973” in Eur. J.
Biochem. 1974, 46, 217-219 and as provisional recommendations in IUPAC
Inf. Bull. Append. No. 47, September, 1975. (Supersedes Section M-3 in J.
Biol. Chem. 1966, 241, 2987-2988; see item 29 above.)
37. ——, “Nomenclature of Vitamin D (Provisional)”, Pure Appl. Chem.
1982, 54, 1511-1516. Published as “Recommendations 1981” in Eur. J.
Biochem. 1982, 124, 223-227.
38. ——, “Nomenclature of Retinoids (Provisional)”, Pure Appl. Chem.
1983, 55, 721-726. Published as “Recommendations 1981” in Eur. J. Biochem.
1982, 129, 1-5.
39. ——, “Nomenclature of Prenols (Recommendations 1986)”, Pure
Appl. Chem. 1987, 59, 683-689.
40. ——, “Nomenclature of Glycolipids (IUPAC Recommendations
1997)”, Pure Appl. Chem. 1997, 69, 2475-2487; Carbohydr. Res. 1998, 312,
167-175; Eur. J. Biochem. 1998, 257, 293-298; Glycoconjugate J. 1999, 16, 16; J. Mol. Biol. 1999 286, 963-970; Adv. Carbohydr. Chem. Biochem. 2000, 55,
311-326. Superseded the glycolipid section in the 1976 Recommendations on
lipid nomenclature (see item 30, above).

298. Inorganic chemistry
1. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division. Commission on the Nomenclature of Inorganic Chemistry, Nomenclature of Inorganic Chemistry Recommendations 1990, G. J. Leigh, ed.,Blackwell Scientific Publications, Oxford, UK, 1990, 289 pp. These recommendations revise and extend the 2nd ed., “Nomenclature of Inorganic Chemistry, 1970”, Butterworths, London, 1971, 110 pp., which also appeared inPure Appl. Chem. 1971, 28, 1-110, and the 1st ed., “Nomenclature of Inorganic
Chemistry” (1957 Report of the Commission on the Nomenclature of Inorganic Chemistry), Butterworths Scientific Publications, London, 1958, 93 pp. (inFrench and English); the latter also appeared with comments in J. Am. Chem.
Soc. 1960, 82, 5523-5544. The 1970 edition incorporated “Tentative Proposals
for Nomenclature of Absolute Configurations Concerned with Six-Coordinated Complexes Based on the Octahedron”, Inorg. Chem. 1970, 9, 1-5; π-Complexes (Tentative), IUPAC Inf. Bull. No. 35, June, 1969, pp. 31-35; and Isoand Heteropolyanions (Rules 5.1 and 5.2, Tentative), IUPAC Inf. Bull. No. 35,
June, 1969, pp. 22-27.
2. ——, “Nomenclature of Inorganic Boron Compounds”, Pure Appl.
Chem. 1972, 30, 681-710 (see also ¶ 302, item 16).
3. ——, How to Name an Inorganic Substance. A Guide to the Use of Nomenclature of Inorganic Chemistry: Definitive Rules, 1970, Pergamon Press,
New York, 1977, 36 pp.
4. ——, “Nomenclature of Inorganic Chemistry: II.2. The Nomenclatureof Hydrides of Nitrogen and Derived Cations, Anions, and Ligands (Recommendations 1981)”, Pure Appl. Chem. 1982, 54, 2545-2552. Published previously as provisional recommendations in IUPAC Inf. Bull. 1978, (2), 151-160.
5. ——, “Recommendations for the Naming of Elements of Atomic
Numbers Greater than 100 (Definitive)”, Pure Appl. Chem. 1979, 51, 381-384.
Previously published as “Recommendations for the Naming of Elements ofAtomic Numbers Greater Than 105 (Provisional)” in IUPAC Inf. Bull. Append.
No. 55, December, 1976.
6. ——, “Nomenclature of Inorganic Chemistry: II.1. Isotopically
Modified Compounds (Recommendations 1981)”, Pure Appl. Chem. 1981, 53,
1887-1900. Previously published as provisional recommendations in Pure
Appl. Chem. 1979, 51, 1981-1994.
7. ——, “Nomenclature of Polyanions, Recommendations 1987”, Pure
Appl. Chem. 1987, 59, 1529-1548.
8. ——, “Names and Symbols of Transfermium Elements (IUPAC Recommendations 1997)”, Pure Appl. Chem. 1997, 69, 2471-2473. Superseded“Names and Symbols of Transfermium Elements (Recommendations 1994)”,
Pure Appl. Chem. 1994, 66, 2419-2421 (subsequently reclassified by the
IUPAC Bureau as provisional in August, 1995). See K. I. Zamaraev, “IUPAC
Recommendations on Names and Symbols of Transfermium Elements”, Chem.
Int. 1996, 18(1), 34.
9. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division, “New Notations in the Periodic Table”, Pure Appl. Chem. 1988,
60, 431-436.
10. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division, Commission on High Temperature and Solid State Chemistry,“Nomenclature and Terminology of Graphite Intercalation Compounds (Recommendations 1994)”, Pure Appl. Chem. 1994, 66, 1893-1901.
11. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division. Working Party on IUPAC Glossary of Terms Used in Bioinorganic Chemistry, “Glossary of Terms Used in Bioinorganic Chemistry(IUPAC Recommendations 1997)”, Pure Appl. Chem. 1997, 60, 1251-1303.
12. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division. Commission on Nomenclature of Inorganic Chemistry,“Nomenclature of Inorganic Chains and Ring Compounds (IUPAC Recommendations 1997)”, Pure Appl. Chem. 1997, 69, 1659-1692.
13. ——, “Nomenclature of Organometallic Compounds of the Transition
Elements (IUPAC Recommendations 1999)”, Pure Appl. Chem. 1999, 71,
1557-1585.
14. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division, Commission on High Temperature Materials and Solid State
Chemistry, “Terminology for Compounds in the Si-Al-O-N System (IUPAC
Recommendations 1999)”, Pure Appl. Chem. 1999, 71, 1765-1769.
15. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division. Commission on Nomenclature of Inorganic Chemistry, “Names
for Inorganic Radicals (IUPAC Recommendations 1999)”, Pure Appl. Chem.
2000, 72, 437-446.
16. ——, “Names for Muonium and Hydrogen Atoms and Their Ions
(IUPAC Recommendations 2001)”, Pure Appl. Chem. 2001, 73, 377-380.

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17. ——, Nomenclature of Inorganic Chemistry II: Recommendations
2000, J. A. McCleverty and N. G. Connelly, eds., Royal Society of Chemistry,
Oxford, UK, 2001, 130 pp.
18. ——, “Naming of New Elements (IUPAC Recommendations 2002)”,
Pure Appl. Chem. 2002, 74, 787-791.
19. International Union of Pure and Applied Chemistry. Chemistry and
Human Health Division. Clinical Chemistry Section. Commission on Toxicology, “ ′Heavy Metals′ - A Meaningless Term? (IUPAC Technical Report)”,Pure Appl. Chem. 2002, 74, 793-807.
20. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division. Commission on Nomenclature of Inorganic Chemistry, "On the
Claims for Discovery of Elements 110, 111, 112, 114, 116, and 118 (IUPAC
Technical Report)", Pure Appl. Chem. 2003, 75, 1601-1611.
21. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division, “Name and Symbol of the Element with Atomic Number 110(IUPAC Recommendations 2003)”, Pure Appl. Chem. 2003, 75, 1613-1615.
299. Macromolecular chemistry
1. International Union of Pure and Applied Chemistry. Physical Chemistry Division. Commission on Macromolecules. Subcommission on Nomenclature, “Report on Nomenclature in the Field of Macromolecules (1951)”, J.
Polym. Sci. 1952, 8, 257-277 [modifications and additions (tentative): J.
Polym. Sci., Part B: Polym. Lett., 1968, 6, 257-260].
2. ——, “Report on Nomenclature Dealing with Steric Regularity in HighPolymers”, Pure Appl. Chem. 1966, 12, 645-656 (Authors often cited as M. L.
Huggins, G. Natta, V. Desreux, and H. Mark); published previously as a preliminary version in J. Polym. Sci. 1962, 56, 153-161.
3. International Union of Pure and Applied Chemistry. Division ofApplied Chemistry. Plastics and High Polymers Section, “Recommendations
for Abbreviations of Terms Relating to Plastics and Elastomers”, Pure Appl.
Chem. 1969, 18, 583-589.
4. International Union of Pure and Applied Chemistry. Macromolecular
Division. Commission on Macromolecular Nomenclature, Compendium ofMacromolecular Nomenclature, Blackwell Scientific Publications, Oxford,
UK, 1991, 171 pp. (a collection of the recommendations given as items 5-12
and 18 below). For a bibliography of translations of this compendium preparedby W. V. Metanomski see http://www.chem.qmw.ac.uk/iupac2/bibliog/
purp.html
5. ——, “Nomenclature of Regular Single-Strand Organic Polymers(Rules Approved 1975)”, Pure Appl. Chem. 1976, 48, 373-385. Published previously as provisional recommendations in Macromolecules 1973, 6, 149-158 andin IUPAC Inf. Bull. Append. No. 29, November, 1972 (see also ¶ 302, item 15).
Superseded by item 18, below.
6. ——, “Glossary of Basic Terms in Polymer Science (Recommendations 1996)”, Pure Appl. Chem. 1996, 68, 2287-2311. Supercedes “Basic Definitions of Terms Relating to Polymers (1974)”, Pure Appl. Chem. 1974, 40,
477-491, and “Basic Definitions Relating to Polymers”, IUPAC Inf. Bul.
Append. No. 13, February 1971.
7. ——, “Stereochemical Definitions and Notations Relating to Polymers(Recommendations 1980)”, Pure Appl. Chem. 1981, 53, 733-752. Publishedpreviously as provisional recommendations in Pure Appl. Chem. 1979, 51,
1101-1121.
8. ——, “Source-Based Nomenclature for Copolymers (Recommendations 1985)”, Pure Appl. Chem. 1985, 57, 1427-1440.
9. ——, “Use of Abbreviations for Names of Polymeric Substances (Recommendations, 1986)”, Pure Appl. Chem. 1987, 59, 691-693. (Supersedes“List of Standard Abbreviations (Symbols) for Synthetic Polymers andPolymer Materials 1974” Pure Appl. Chem. 1974, 40, 473-476 and “List of Abbreviations for Synthetic Polymers and Polymer Materials”, IUPAC Inf. Bull.
Append. No. 12, February, 1971).
10. ——, “A Classification of Linear Single-Strand Polymers (Recommendations 1988)”, Pure Appl. Chem. 1989, 61, 243-254.
11. ——, “Definitions of Terms Relating to Individual Macromolecules,
Their Assemblies, and Dilute Polymer Solutions (Recommendations 1988)”,
Pure Appl. Chem. 1989, 61, 211-241.
12. ——, “Definition of Terms Relating to Crystalline Polymers (Recommendations 1988)”, Pure Appl. Chem. 1989, 61, 769-785.
13. ——, “Nomenclature of Regular Double-Strand (Ladder or Spiro)
Organic Polymers (Recommendations 1993)”, Pure Appl. Chem. 1993, 65,
1561-1580.
14. ——, “Graphic Representations (Chemical Formulae) of Macromolecules (Recommendations 1994)”, Pure Appl. Chem. 1994, 66, 2469-2482.
15. ——, “Structure-Based Nomenclature for Irregular Single-Strand
Organic Polymers (Recommendations 1994)”, Pure Appl. Chem. 1994, 66,
873-889 (Erratum: Pure Appl. Chem. 1994, 66 (9), insert).
16. ——, “Source-Based Nomenclature for Non-Linear Macromolecules
and Macromolecular Assemblies (IUPAC Recommendations 1997)”, Pure
Appl. Chem. 1997, 69, 2511-2521; in Polymer Networks, R. F. T. Stepto, ed.,Blackie Academic, London, 1998, pp. 316-328.
17. ——, "Generic Source-Based Nomenclature for Polymers (IUPAC
Recommendations 2001)", Pure Appl. Chem. 2001, 73, 1511-1519. Errata,
Pure Appl. Chem. 2002, 74, 2002.
18. ——, "Nomenclature of Regular Single-Strand Organic Polymers"(IUPAC Recommendations 2002)", Pure Appl. Chem. 2002, 74, 1921-1956.
Superseded item 5, above.
19. International Union of Pure and Applied Chemistry. Macromolecular
Division. Commission on Macromolecular Nomenclature and Inorganic
Chemistry Division. Commission on Nomenclature of Inorganic Chemistry,

128“Nomenclature for Regular Single-Strand and Quasi-Single-Strand Inorganic
and Coordination Polymers (Recommendations 1984)”, Pure Appl. Chem.
1985, 57, 149-168. Published previously as provisional recommendations inPure Appl. Chem. 1981, 53, 2283-2302.
300. Miscellaneous
1. International Union of Pure and Applied Chemistry. Interdivisional
Committee on Nomenclature and Symbols, “Use of Abbreviations in theChemical Literature (Recommendations 1979)”, Pure Appl. Chem. 1980, 52,
2229-2232. Previously published as provisional recommendations jointly with
the Physical Chemistry Division Commission on Molecular Structure andSpectroscopy in IUPAC Inf. Bull. Append. No. 58, July, 1977
2. International Union of Pure and Applied Chemistry. Analytical Chemistry Division, Compendium of Analytical Nomenclature, Definitive Rules
1997, 3rd ed., Blackwell Science, Oxford, UK, 1998, 840 pp. Superseded Compendium of Analytical Nomenclature, Definitive Rules 1987, 2nd ed., Blackwell Scientific Publications, Oxford, UK, 1978, 279 pp. The 1977 Definitive
Rules were published by Pergamon Press, Oxford, UK 1978, 223 pp.
3. International Union of Pure and Applied Chemistry. Analytical Chemistry Division. Commission on Analytical Nomenclature, “Guide to Trivial
Names, Trade Names, and Synonyms for Substances Used in Analytical Nomenclature”, Pure Appl. Chem. 1978, 50, 339-370. Previously published asprovisional recommendations under the title “List of Trivial Names andSynonyms (for Substances Used in Analytical Chemistry)” in IUPAC Inf. Bull.
Append. No. 45, September, 1975.
4. International Union of Pure and Applied Chemistry. Physical Chemistry Division. Commission on Symbols, Terminology and Units, Quantities,
Units, and Symbols in Physical Chemistry, 2nd. ed., Blackwell Scientific Publications, Oxford, UK, 1993, 166 pp. [An abbreviated list, 4 pp. A4 laminatedcard, is published by Blackwell Scientific Publications, Oxford, 1993]. Thisreplaces the 1988 edition which in turn replaced “Manual of Symbols and Terminology for Physicochemical Quantities and Units”, Pure Appl. Chem. 1979,
51, 1-41. A 1973 edition was published by Butterworths, London, 1975 and a1969 edition appeared in Pure Appl. Chem. 1970, 21, 1-44. (Supersedes rulesin J. Am. Chem. Soc. 1960, 82, 5517-5522.)
5. International Union of Pure and Applied Chemistry. Physical Chemistry Division. Commission on Colloid and Surface Chemistry, “Chemical Nomenclature and Formulation of Compositions of Synthetic and Natural Zeolites(Definitive)”, Pure Appl. Chem. 1979, 51, 1091-1100. Previously published asprovisional recommendations jointly with the Inorganic Chemistry Division
Commission on Nomenclature of Inorganic Chemistry in IUPAC Inf. Bull.
Append. No. 41, January, 1975.
6. International Union of Pure and Applied Chemistry; Compendium of
Chemical Terminology (IUPAC Recommendations), 2nd ed., A. D. McNaught
and A. Wilkinson, compliers, Blackwell Science, Oxford, UK, 1997, 336 pp.
Superseded Compendium of Chemical Technology (IUPAC Recommendations), V. Gold, K. L. Loening, A. D. McNaught, and P. Sehmi, compilers,Blackwell Scientific Publications, Oxford, UK, 1987, 456 pp.
7. International Union of Pure and Applied Chemistry and International
Union of Pure and Applied Physics. Transfermium Working Group, “Discovery of the Transfermium Elements (criteria that must be satisfied for the discovery of a new chemical element to be recognized)”, Part I, Pure Appl. Chem.
1991, 63, 879-886; Part II: Introduction to Discovery Profiles; Part III: Discovery Profiles of the Transfermium Elements, Pure Appl. Chem. 1993, 65, 17571814. [All three parts have been published together in Prog. Part. Nucl. Phys.
1992, 29, 453-530.] “Responses on the Report ‘Discovery of the Transfermium
Elements’ Invited by the Transfermium Working Groups from Lawrence
Berkeley Laboratory, California, the Joint Institute for Nuclear Research,
Dubna, and Gesellshaft für Schwerionenforschung, Darmstadt, and the Reply
to the Responses by the Transfermium Working Group”, Pure Appl. Chem.
1993, 65, 1815-1824.
8. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division, Commission on Atomic Weights and Isotopic Abundances,“Atomic Weights of the Elements 2001 (IUPAC Technical Report)”, Pure
Appl. Chem. 2003, 75, 1107-1122. Superseded “Atomic Weights of the
Elements 1999”, Pure Appl. Chem. 2001, 73, 667-683; “Atomic Weights of the
Elements 1997”, Pure Appl. Chem. 1997, 71, 1593-1607; “Atomic Weights ofthe Elements 1995”, Pure Appl. Chem. 1996, 68, 2339-2359; and “Atomic
Weights of the Elements 1993”, Pure Appl. Chem. 1994, 66, 2423-2444.
9. International Union of Pure and Applied Chemistry; Clinical Chemistry Division and the International Federation of Clinical Chemistry (IFCC),
Compendium of Terminology and Nomenclature of Properties in Clinical Laboratory Sciences (Recommendations 1995), Blackwell Science, Oxford, UK,1995, 304 pp.
10. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division. Commission on Atomic Weights and Isotopic Abundances,“History of the Recommended Atomic-Weight Values from 1882 to 1997: A
Comparison of Differences from Current Values to the Estimated Uncertainties
of Earlier Values”, Pure Appl. Chem. 1998, 70, 237-257.
11. International Union of Pure and Applied Chemistry, Principles ofChemical Nomenclature. A Guide to IUPAC Recommendations, G. J. Leigh, H.
A. Favre, and W. V. Metanomski, G. J. Leigh, ed., Blackwell Science, Oxford,
UK, 1998, 133 pp.
12. International Union of Pure and Applied Chemistry. Inorganic Chemistry Division, Commission on Atomic Weights and Isotopic Abundances,“Atomic Weights of the Elements. Review 2000 (IUPAC Technical Report)”,Pure Appl. Chem. 2003, 75, 683-799.

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American Chemical Society Nomenclature

301. Chemical Abstracts Service Index Nomenclature
Introductions to Subject Indexes and Name Selection Manuals
1. American Chemical Society. Chemical Abstracts Service, “The
Naming and Indexing of Chemical Compounds from Chemical Abstracts” [areprint of the Introduction to the Subject Index to Volume 56 (January-June,
1962)], Chemical Abstracts Service, Columbus, Ohio, 1962. A previous
edition was reprinted from the Introduction to the 1945 Subject Index (Chemical Abstracts 1945, 39, 5867-5975) which was combined with revisions introduced in 1957 (Subject Index 1957, 51, 1R-28R).
2. ——, “Combined Introductions: Subject, Formula, Ring System, and
HAIC Indexes to Volume 66, January-June, 1967”, Chemical Abstracts
Service, Columbus, Ohio, 1968.
3. ——, Naming and Indexing of Chemical Compounds, 1969 edition,
Chemical Abstracts Service, Columbus, Ohio, 1969.
4. ——, “Naming and Indexing of Chemical Substances for Chemical
Abstracts during the Ninth Collective Period (1972-1976)” [a reprint of
Section IV (Selection of Index Names for Chemical Substances) from theVolume 76 Index Guide], Chemical Abstracts Service, Columbus, Ohio, 1973.
5. ——, Chemical Substance Name Selection Manual for the Ninth Collective Period (1972-1976), Chemical Abstracts Service, Columbus, Ohio, 1973.
6. ——, “Selection of Index Names for Chemical Substances” in theVolume 76-85 Cumulative Index Guide (1972-1976), Chemical Abstracts
Service, Columbus, Ohio, 1977, Appendix IV.
7. ——, “Naming and Indexing of Chemical Substances for Chemical
Abstracts” [a reprint of Appendix IV (Selection of Index Names for Chemical
Substances) from the 1977 Index Guide], Chemical Abstracts Service, Columbus, Ohio, 1978.
8. ——, Chemical Substance Name Selection Manual, 1978 edition,
Chemical Abstracts Service, Columbus, Ohio, 1978.
9. ——, “Selection of Index Names for Chemical Substances” in the
1977-1981 Index Guide, Chemical Abstracts Service, Columbus, Ohio, 1982,
Appendix IV.
10. ——, “Naming and Indexing of Chemical Substances for Chemical
Abstracts” [a reprint of Appendix IV (Chemical Substance Index Names) fromthe 1982 Index Guide], Chemical Abstracts Service, Columbus, Ohio, 1982.
11. ——, Chemical Substance Name Selection Manual, 1982 edition,
Chemical Abstracts Service, Columbus, Ohio, 1982.
12. ——, “Chemical Substance Index Names” in the 1984 Index Guide,
Chemical Abstracts Service, Columbus, Ohio, 1984, Appendix IV.
13. ——, “Naming and Indexing of Chemical Substances for Chemical
Abstracts” [a reprint of Appendix IV (Chemical Substance Index Names) fromthe 1985 Index Guide], Chemical Abstracts Service, Columbus, Ohio, 1985.
14. ——, “Chemical Substance Index Names”, in the 1982-1986 Index
Guide, Chemical Abstracts Service, Columbus, Ohio, 1987, Appendix IV.
15. ——, “Naming and Indexing of Chemical Substances for Chemical
Abstracts” [a reprint of Appendix IV (Chemical Substance Index Names) fromthe 1987 Index Guide], Chemical Abstracts Service, Columbus, Ohio 1987.
16. ——, “Chemical Substance Index Names”, Appendix IV in the 1989
Index Guide, Chemical Abstracts Service, Columbus, Ohio, 1989.
17. ——, “Chemical Substance Index Names”, Appendix IV in the 1990
Index Guide, Chemical Abstracts Service, Columbus, Ohio, 1990.
18. ——, “Chemical Substance Index Names”, in the 1987-1991 Index
Guide, Chemical Abstracts Service, Columbus, Ohio, 1992, Appendix IV (alsoappears in the “12th Collective Index on CD-ROM, Index Guide Appendixes
I-IV [a reprint of Appendixes I-IV from the Index Guide to the 12th Collective
Index], Chemical Abstracts Service, Columbus, Ohio, 1993).
19. ——, “Naming and Indexing of Chemical Substances for Chemical
Abstracts” [a reprint of Appendix IV (Chemical Substance Index Names) fromthe 1992 Index Guide], Chemical Abstracts Service, Columbus, Ohio, 1992.
20. ——, Chemical Substance Name Selection Manual, 1982 edition (Revised, 1989) Chemical Abstracts Service, Columbus, Ohio.
21. ——, “Chemical Substance Index Names”, Appendix IV in the 1994
Index Guide, Chemical Abstracts Service, Columbus, Ohio, 1994.
22. ——, “Chemical Substance Index Names” in the 1992-1996 Index
Guide, Chemical Abstracts Service, Columbus, Ohio, 1997, Appendix IV.
23. ——, “Chemical Substance Index Names” in the 1997 Index Guide,
Chemical Abstracts Service, Columbus, Ohio, 1997, Appendix IV.
24. ——, “Naming and Indexing of Chemical Substances for CHEMICAL
ABSTRACTS” [A reprint of Appendix IV (Chemical Substance Index Names)from the CHEMICAL ABSTRACTS 1997 Index Guide], Chemical Abstracts
Service, Columbus, Ohio, 1997.
25. ——, “Chemical Substance Index Names” in the 1999 Index Guide,
Chemical Abstracts Service, Columbus, Ohio, 1999, Appendix IV.
26. ——, “Chemical Substance Index Names” in the 1997-2001 Index
Guide, Chemical Abstracts Service, Columbus, Ohio, 2002, Appendix IV.
27. ——, “Chemical Substance Index Names” in the 2002 Index Guide,
Chemical Abstracts Service, Columbus, Ohio, 2002, Appendix IV.
Ring Nomenclature Handbooks
1. A. M. Patterson and L. T. Capell, The Ring Index, Rheinhold, New
York, 1940, 661 pp.

¶ 302

2. A. M. Patterson, L. T. Capell, and D. F. Walker, The Ring Index, 2nded., American Chemical Society, Washington, D. C., 1960, 1425 pp.; Supplement 1, 1963, 371 pp.; Supplement 2, 1964, 515 pp.; Supplement 3, 1965, 581
pp.; “New Ring Systems from Chemical Abstracts Volumes 60-63”, Chemical
Abstracts Service, Columbus, Ohio, 1967, 285 pp.
3. Parent Compound Handbook, American Chemical Society, Washington, D. C., 1977 (Annual supplements appeared through 1983).
4. Ring Systems Handbook, 1984 edition, Chemical Abstracts Service,
Columbus, Ohio, 1984 (Six cumulative supplements were published, the last in
November 1987).
5. Ring Systems Handbook, 1988 edition, Chemical Abstracts Service,
Columbus, Ohio, 1988 (Eight cumulative supplements were published, the lastin November, 1992).
6. Ring Systems Handbook, 1993 edition, Chemical Abstracts Service,
Columbus, Ohio, 1993 (Eight cumulative supplements were published, the lastin November 1997).
7. Ring Systems Handbook, 1998 edition, Chemical Abstracts Service,
Columbus, Ohio, 1998 (Eight cumulative supplements were published, the lastin November 2002).
8. Ring Systems Handbook, 2003 edition, Chemical Abstracts Service,
Columbus, Ohio, 2003.
Nomenclature Publications
1. A. M. Patterson, L. T. Capell, and D. F. Walker, The Ring Index, 2nded., American Chemical Society, Washington, D.C., 1960. Introduction. pp. ixxxvi; Suppl. 1, 1963, Introduction, pp. x-xiii.
2. J. E. Blackwood, C. L. Gladys, K. L. Loening, A. E. Petrarca, and J. E.
Rush, “Unambiguous Specification of Stereoisomerism about a Double Bond”,
J. Am. Chem. Soc. 1968, 90, 509-510.
3. J. E. Blackwood, C. L. Gladys, A. E. Petrarca, W. H. Powell, and J. E.
Rush, “Unique and Unambiguous Specification of Stereoisomerism about a
Double Bond in Nomenclature and Other Notation Systems”, J. Chem. Doc.
1968, 8, 30-32.
4. K. L. Loening, W. Metanomski, and W. H. Powell, “Indexing ofPolymers in Chemical Abstracts”, J. Chem. Doc. 1969, 9, 248-251.
5. N. Donaldson, W. H. Powell, R. J. Rowlett, Jr., R. W. White, and K.
Yorka, “Chemical Abstracts Index Names for Chemical Substances in theNinth Collective Period (1972-76)”, J. Chem. Doc. 1974, 14, 3-15.
6. R. J. Rowlett, Jr. and F. A. Tate, “A Computer-Based System for
Handling Chemical Nomenclature and Structural Representations”, J. Chem.
Doc. 1972, 12, 125-128.
7. R. J. Rowlett, Jr. and D. W. Weisgerber, “Handling Commercial
Product Names at Chemical Abstracts Service”, J. Chem. Doc. 1974, 14, 92-95.
8. J. E. Blackwood and P. M. Giles, Jr., “Chemical Abstracts Stereochemical Nomenclature of Organic Substances in the Ninth Collective Period (19721976)”, J. Chem. Inf. Comput. Sci. 1975, 15, 67-72.
9. M. F. Brown, B. R. Cook, and T. E. Sloan, “Stereochemical Notationin Coordination Chemistry. Mononuclear Complexes”, Inorg. Chem. 1975, 14,1273-1278.
10. M. F. Brown, B. R. Cook, and T. E. Sloan, “Stereochemical Notationin Coordination Chemistry. Mononuclear Complexes of Coordination
Numbers Seven, Eight, and Nine”, Inorg. Chem. 1978, 17, 1563-1568.
11. A. C. Isenberg, J. T. LeMasters, A. F. Maxwell, and G. G. Vander
Stouw, “Procedures for Sorting Chemical Names for Chemical Abstracts’ Indexes”, J. Chem. Inf. Comput. Sci. 1985, 25(4), 410-412.
12. J. E. Blackwood, P. E. Blower, Jr., S. W. Layten, D. H. Lillie, A. H.
Lipkus, J. P. Peer, C. Qian, L. M. Staggenborg, and C. E. Watson. “Chemical
Abstracts Service Chemical Registry System. 13. Enhanced Handling of Stereochemistry”, J. Chem. Inf. Comput. Sci. 1991, 31, 204-212.
13. C. L. Gladys and A. L. Goodson, “Numbering of Interior Atoms in
Fused Ring Systems”, J. Chem. Inf. Comput. Sci. 1991, 31, 523-526.
14. P. M. Giles, Jr. and W. V. Metanomski, “The History of Chemical Substance Nomenclature at Chemical Abstracts Service (CAS)” in Organic Chemistry: Its Language and its State of the Art, M. Volkan Kisakürek, ed., Verlag
Helvetica Chemica Acta, Basel, 1993, pp. 173-196.
15. L. M. Staggenborg, “Stereochemistry in the CAS Registry File”, Spec.
Publ. - R. Soc. Chem. 1993, 120, 89-112. (Recent Advances in Chemical Information II).
16. A. L. Goodson, C. L. Gladys, and D. E. Worst, “Numbering andNaming of Fullerenes by Chemical Abstracts Service”, J. Chem. Inf. Comput.
Sci. 1995, 35, 969-978.
17. D. W. Weisgerber, “Chemical Abstracts Service Chemical SubstanceIndex Nomenclature” in Chemical Nomenclature, K. J. Thurlow, ed., Kluwer
Academic Publishers, Dordrecht, The Netherlands, 1998, pp. 66-102.
18. C. E. Carraher, Jr., “Chemical Abstracts Based Polymer Nomenclature”, J. Polym. Mater. 2000, 18, 1-6.
19. S. J. Teague, “Siloxanes and Silicones in the CAS Databases”, Polym.
Prepr. 2001, 42(1), xviii-xxii.
302. American Chemical Society Committee
1. American Chemical Society, “Recommendations of the Nomenclature
Committee of the Organic Division of the ACS to the Nomenclature Committee of the National Society”, J. Am. Chem. Soc. Proc. 1931, 40-41.
2. ——, “The Pronunciation of Chemical Words”, Ind. Eng. Chem., News
Ed. 1934, 12, 202-205.

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3. ——, “Nomenclature of the Hydrogen Isotopes and Their Compounds”, Ind. Eng. Chem., News Ed. 1935, 13, 200-201.
4. ——, “Report of the Committee for the Revision of the Nomenclatureof Pectic Substances”, Chem. Eng. News 1944, 22, 105-106.
5. ——, “Nomenclature of Carotenoid Pigments”, Chem. Eng. News
1946, 24, 1235-1236.
6. ——, “The Naming of cis and trans Isomers of Hydrocarbons Containing Olefin Double Bonds”, Chem. Eng. News 1949, 27, 1303.
7. ——, “The Designation of ‘Extra’ Hydrogen in Naming Cyclic Compounds”, Chem. Eng. News 1949, 27, 1303.
8. ——, “The Naming of Geometric Isomers of Polyalkyl Monocycloalkanes”, Chem. Eng. News 1950, 28, 1842-1843.
9. ——, “The Report of the ACS Nomenclature, Spelling, and Pronunciation
Committee for the First Half of 1952”, Chem. Eng. News 1952, 30, 4513-4526.
A. “Arene and Arylene”, p. 4513.
B. “Halogenated Derivatives of Hydrocarbons”, pp. 4513-4514.
C. “The Use of ‘Per’ in Naming Halogenated Organic Compounds”, pp.
4514-4515.
D. “The Use of ‘H’ to Designate the Positions of Hydrogens in Almost
Completely Fluorinated Organic Compounds”, p. 4515.
E. “Organic Compounds Containing Phosphorus”, pp. 4515-4522.
F. “Organosilicon Compounds”, pp. 4517-4522. (These rules supersede
the ACS 1946 rules which appeared in Chem. Eng. News 1946, 24,
1233-1234.)
G. “Nomenclature of Natural Amino Acids and Related Substances”, pp.
4522-4526. (These rules were reprinted in J. Am. Chem. Soc. 1960,
82, 5575-5577. They replaced the 1947 ACS rules which appearedin Chem. Eng. News 1947, 25, 1364-1367. See also ¶ 297, item 16.)
10. ——, “A New General System for the Naming of Stereoisomers”, G.
E. McCasland, included with the “Report of the Advisory Committee on Configurational Nomenclature”, July 14, 1953, H. B. Vickery, Chairman, to theNomenclature Committee, Division of Organic Chemistry, American Chemical Society, Washington, D.C.
11. ——, “Addendum to Definitive Rules for the Nomenclature of Natural
Amino Acids and Related Substances”, J. Org. Chem. 1963, 28, 291-293. (Seealso ¶ 297, item 16 and item 9G above).
12. ——, “A Proposed System of Nomenclature for Terpene Hydrocarbons”, Chem. Eng. News 1954, 32, 1795-1797.
13. ——, “Nomenclature for Terpene Hydrocarbons”, a report of the Nomenclature Committee of the Division of Organic Chemistry of the American
Chemical Society, American Chemical Society, Washington, D.C., 1955, 98
pp. (Advances in Chemistry Series No. 14.)
14. ——, “Rules of Carbohydrate Nomenclature”, J. Org. Chem. 1963, 28,281-291. (This report was the result of a cooperative effort by the Nomenclature Committee of the Division of Carbohydrate Chemistry of the American
Chemical Society and a British Committee on Carbohydrate Nomenclature [aSubcommittee of the Publications Committee of the Chemical Society,London]. They are sometimes referred to as the “Anglo-American Rules” andwere accepted by the Council of the American Chemical Society in 1962. They
replaced the ACS 1953 rules which appeared in Chem. Eng. News 1953, 31,
1776-1782, which in turn replaced the ACS 1948 Carbohydrate Nomenclature
Rules published in Chem. Eng. News 1948, 26, 1623-1629. These rules precede
the tentative IUPAC carbohydrate rules, see ¶ 297, item 5.)
15. ——, “A Structure-Based Nomenclature for Linear Polymers”, Macromolecules 1968, 1, 193-198. These rules precede the IUPAC rules; see ¶ 299,
item 5.
16. ——, “The Nomenclature of Boron Compounds”, Inorg. Chem. 1968,
7, 1945-1964. These rules precede the IUPAC rules; see ¶ 298, item 2.
17. ——, “ACS Committee on Nomenclature Recommendations”, J.
Chem. Doc. 1973, 13, 45 (News and Notes) (On the use of the diagonal, thehyphen, and the dash in chemical names).
18. American Chemical Society. Division of Carbohydrate Chemistry. Nomenclature Committee and the British Carbohydrate Nomenclature Committee, “Rules for Conformational Nomenclature for Five- and Six-Membered
Rings in Monosaccharides and Their Derivatives”, J. Chem. Soc., Chem.
Commun. 1973, 505-508. These rules precede the IUPAC recommendations;see ¶ 297, item 6.
19. American Chemical Society. Division of Polymer Chemistry. Nomenclature Committee, “Abbreviations for Thermoplastics, Thermosets, Fiber,
Elastomers, and Additives”, Polym. News 1983, 9, 101-110; 1985, 10, 169172.
20. J. A. Young, “Revised Nomenclature for Highly Fluorinated Organic
Compounds”, J. Chem. Doc. 1974, 14, 98-100.
21. W. C. Fernelius and W. H. Powell, “Confusion in the Periodic Tableof the Elements”, J. Chem. Educ. 1982, 59, 504-508.
22. K. L. Loening, “Recommended Format for the Periodic Table of the
Elements”, J. Chem. Educ. 1984, 61, 136.
23. K. L. Loening, “Activities in the United States Relating to Chemical
Terminology and Nomenclature”, TermNet News 1987, (18), 3-6.
24. B. P. Block, W. C. Fernelius, and W. H. Powell, Inorganic Chemical
Nomenclature: Principles and Practice, American Chemical Society, Washington, D.C., 1990, 210 pp.

130

Chem. Educ. 1931, 8, 1335-1340. (Contains references.)
2. A. D. Mitchell, British Chemical Nomenclature, Edward Arnold &Co., London, 1948, 156 pp.
3. E. J. Crane, “Chemical Nomenclature in the United States” in Chemical
Nomenclature, American Chemical Society, Washington, D.C., 1953, pp. 5564. (Advances in Chemistry Series No. 8.)
4. R. S. Cahn and A. D. Mitchell, “Chemical Nomenclature in Britain
Today” in Chemical Nomenclature, American Chemical Society, Washington,
D.C., 1953, pp. 49-54. (Advances in Chemistry Series No. 8.)
5. K. A. Jensen, “Problems of an International Chemical Nomenclature”
in Chemical Nomenclature, American Chemical Society, Washington, D.C.,
1953, pp. 38-48. (Advances in Chemistry Series No. 8.)
6. H. S. Nutting, “Nomenclature in Industry” in Chemical Nomenclature,
American Chemical Society, Washington, D.C., 1953, pp. 95-98. (Advances in
Chemistry Series No. 8.)
7. G. M. Dyson, “Development of Chemical Symbols and their Relation
to Nomenclature” in Chemical Nomenclature, American Chemical Society,
Washington, D.C., pp. 99-105. (Advances in Chemistry Series No. 8.)
8. J. W. Perry, “The Role of Terminology in Indexing, Classifying, andCoding” in Chemical Nomenclature, American Chemical Society, Washington, D.C., 1953, pp. 106-112. (Advances in Chemistry Series No. 8.)
9. A. M. Patterson, Words About Words, American Chemical Society,
Washington, D.C., 1957, 86 pp. (A compilation of the column by A. M. Patterson which appeared in Chem. Eng. News 1951-1956.)
10. L. T. Capell, “Effect of Changes in Nomenclature on the Use of
Indexes” in Searching the Chemical Literature, American Chemical Society,
Washington, D.C., 1961, pp. 58-66. (Advances in Chemistry Series No. 30.)
11. J. D. Scott and K. L. Loening, “Inorganic-Organic Nomenclature”, J.
Chem. Doc. 1964, 4, 66-69.
12. O. C. Dermer, G. Gorin, and K. L. Loening, “The Standardization ofChemical Language”, Int. J. Sociol. Lang. 1976, 11, 61-83.
13. R. S. Cahn and O. C. Dermer, Introduction to Chemical Nomenclature,
5th, ed., Butterworths, London, 1979, 200 pp.
14. K. L. Loening, “Nomenclature” in Kirk-Othmer Encyclopedia of
Chemical Technology, 3rd ed., John Wiley & Sons, New York, Vol. 16, 1981,
pp. 28-46; 2nd ed., Vol. 14, 1967, pp. 1-15.
15. R. Lees and A. F. Smith eds., Chemical Nomenclature Usage, Ellis
Horwood, Ltd., Chichester, UK, 1983, 172 pp.
16. R. Fennell, History of IUPAC, 1919-1987, Blackwell Science, Oxford,
UK, 1994 354 pp.
17. Council of Biology Editors. Style Manual Committee, Scientific Styleand Format; CBE Manual for Authors, Editors, and Publishers. E. Huth, ed.,
6th ed., Cambridge University Press, Cambridge, UK, 1995. 825 pp.
18. P. A. S. Smith, “Nomenclature” in Kirk-Othmer Encyclopedia of
Chemical Technology, 4th ed., John Wiley & Sons, New York, Vol. 17, 1996,
pp. 238-259.
19. K. J. Thurlow, ed., Chemical Nomenclature, Kluwer Academic Publishers, Dordrecht, The Netherlands, 1998, 247 pp.
20. E. D. Godly, “The Need for Good Nomenclature” in Chemical Nomenclature, K. J. Thurlow, ed., Kluwer Academic Publishers, Dordrecht, The
Netherlands, 1998, pp. 1-26.
21. S. S. Brown, History of IUPAC 1988-1999. Supplement to History of
IUPAC 1919-1987, IUPAC, 2001, pp. 355-442 (Update of item 16, above).
22. J. Simon, “Authority and Authorship in the Method of Chemical Nomenclature”, Ambix 2002, 49, 206-226.
304. Organic chemistry
Geneva Rules
1. A. Pictet, “Le Congres International de Geneve pour la Reforme de laNomenclature Chimique”, Arch. Sci. Phys. Nat. 1892, [3] 27, 485-520.
2. M. Hanriot, “Congres de Nomenclature Chimique, Geneve 1892”,
Bull. Soc. Chim. Paris Suppl. 1892, s. 3, 7, XIV-XXIV.
3. H. E. Armstrong, “The International Conference on Chemical Nomenclature”, Nature, 1892, 46, 56-58.
4. F. Tiemann, “Ueber die Beschluesse des Internationalen, in Genf von
19 bis 22 April 1892, versammelten Congresses zur Regelung der chemischen
Nomenklatur”, Ber. Dtsch. Chem. Ges. 1893, 26, 1595-1631.
Liege Rules
1. International Union of Chemistry. Commission on the Reform of theNomenclature of Organic Chemistry, “Definitive Report, Liege Meeting,1930”. (Translation with comments by A. M. Patterson, J. Am. Chem. Soc.
1933, 55, 3905-3925. Appeared also in English, J. Chem. Soc. 1931, 16071616.)
2. International Union of Chemistry. Commission on the Reform of theNomenclature of Organic Chemistry, “Full Text of the New Organic Nomenclature Rules”. Reported by A. M. Patterson, Science 1938, 87, 215-216 (Rules
34 and 49 of the Liege Report are given in full).
Amsterdam Rules

History and Development of Chemical Nomenclature
303. General
1. E. J. Crane, “The Standardization of Chemical Nomenclature”, J.

1. International Union of Pure and Applied Chemistry. Organic Chemistry Division. Commission on the Nomenclature of Organic Chemistry, “Nomenclature of Organosilicon Compounds”, C. R. de la Quinzieme Conference,
Amsterdam, 1949, 127-132.

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2. ——, “Changes and Additions to the Definitive Report [of the Liege
Meeting]”, C. R. de la Quinzieme Conference, Amsterdam, 1949, 132-185.
Proposals and Reviews
1. A. Hantzsch and J. H. Weber, Ber. Dtsch. Chem. Ges. 1887, 20, 31183132.
2. O. Widman, J. Prakt. Chem. 1888, 38, 185-201.
3. A. Baeyer, “Systematik und Nomenklatur Bicyclischer Kohlenwasserstoffe”, Ber. Dtsch. Chem. Ges. 1900, 33, 3771-3775.
4. E. Buchner und W. Weigand, “Bornylen und Diazoessigester [Nebst
einer Nomenklatur Tricyclischer Kohlenstoff-Ringsysteme nach Adolf von
Baeyer]”, Ber. Dtsch. Chem. Ges. 1913, 46, 2108-2117.
5. A. M. Patterson and C. E. Curran, “A System of Organic Nomenclature”, J. Am. Chem. Soc. 1917, 39, 1623-1638.
6. A. M. Patterson, “Proposed International Rules for Numbering
Organic Ring Systems”, J. Am. Chem. Soc. 1925, 47, 543-561.
7. ——, “The Nomenclature of Parent Ring Systems”, J. Am. Chem. Soc.
1928, 50, 3074-3087.
8. ——, “The Nomenclature of Organic Compounds of Complex Function”, Rec. Trav. Chim. 1929, 48, 1012-1017.
9. P. E. Verkade, “La revision recente de la nomenclature des combinaisons organiques”, Rec. Trav. Chim. 1932, 51, 185-217.
10. A. M. Patterson and L. T. Capell, “The Ring Index”, Reinhold, New
York, 1940, pp. 20-27.
11. F. Richter, “Basic Features of Nomenclature in Organic Chemistry” in
Chemical Nomenclature, American Chemical Society, Washington, D.C.,
1953, pp. 65-74. (Advances in Chemistry Series No. 8.)
12. P. E. Verkade, “Organic Chemical Nomenclature, Past, Present, andFuture” in Chemical Nomenclature, American Chemical Society, Washington,
D.C., 1953, pp. 75-82. (Advances in Chemistry Series No. 8.)
13. L. T. Capell and K. L. Loening, “Principles of Organic Nomenclature”
in Treat. Anal. Chem., I. M. Kolthoff and P. J. Elving, eds., Interscience, New
York, Vol. 11, 1965, Part II, Section B, pp. 1-44.
14. D. R. Eckroth, “Method for Manual Generation of Correct von Baeyer
Names of Polycyclic Hydrocarbons”, J. Org. Chem. 1967, 32, 3362-3365.
15. A. D. McNaught, “The Nomenclature of Heterocycles” in Advances in
Heterocyclic Chemistry, A. R. Katritzky and A. J. Boulton, eds., Academic
Press, New York, 1976, Vol. 20, pp. 175-247.
16. A. Balaban and P. von Rague Schleyer, “Systematic Classification and
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134

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45. N. V. Chukanov, I. V. Pekov, and A. P. Khomyakov, “Recommended
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46. W. H. Koppenol, “NO Nomenclature”, Nitric Oxide 2002, 6, 96-98.
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307. Macromolecular chemistry
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7. N. M. Bikales, “Nomenclature” in Concise Encyclopedia of Polymer
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22. ——, “A Nomenclature and Structural Representation System for
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23. L. H. Sperling, “Nomenclature and Notational Problems in the Phase
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Systems Used by CAS, IUPAC, MDL, and duPont. 1. Regular Single-Strand
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25. ——, “2. Aftertreated (Post-treated), Alternating/Periodic, and Block
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26. ——, “3. Comb/Graft, Cross-Linked, and Dendritic/Hyperconnected/
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29. ——, “Improved Indexing of Chemical Abstracts Service PostTreated Polymers”, J. Chem. Inf. Comput. Sci. 1997, 37, 436-442.
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34. E. S. Wilks, “Whither Nomenclature?”, Polym. Prepr. 1999, 40(2), 6-11.
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40(1), 6-11; Polym. Mater. Sci. Eng. 1999, 80(Spring), 640-641.
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37. L. H. Sperling, W. V. Metanomski, and C. E. Carraher, Jr., “Polymer¶ 308

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Chem. Soc. 1984, 106, 3319-3328.
9. J. H. Brewster, “On the Distinction of Diastereoisomers in the CahnIngold-Prelog (RS) Notation”, J. Org. Chem. 1986, 51, 4751-4753.
10. P. Mata, A. M. Lobo, C. Marshall, and A. P. Johnson “The CIP
Sequence Rules: Analysis and Proposal for a Revision”, Tetrahedron: Asymmetry, 1993, 4, 657-668.
11. E. L. Eliel, S. H. Samuel, and L. N. Lewis, Stereochemistry of Organic
Compounds, John Wiley & Sons, New York, 1994. (Chapter 5. Configuration,
pp. 101-113. Glossary. pp. 1191-1210).
12. G. Helmchen, “Glossary of Problematic Terms in Organic Stereochemistry”, Enantiomer 1996, 1(1), 84A-84D; ibid. 1997, 2, 315-318.
13. S. Reichelt, A. Reichelt, N. Muller, and I. Ugi, “Topology and Group
Theory-Tools for Determining the Stereochemistry of Molecules”, Croat.
Chem. Acta 1996, 69, 813-825.
14. C. Thilgen, A. Herrmann, and F. Diederich, “Configurational Description of Chiral Fullerenes and Fullerene Derivatives with a Chiral Functionalization Pattern”, Helv. Chim. Acta 1997, 80, 183-189.
15. E. L. Eliel, “Infelicitous Stereochemical Nomenclature”, Chirality
1997, 9, 428-430.
16. E. L. Eliel and M. B. Ramirez, “(-)-Quinic Acid: Configurational (Stereochemical) Descriptors”, Tetrahedron: Asymmetry 1997, 8, 3551-3554.
17. S. B. Elk, “Redefining the Terminology of Stereoisomerism To Produce a Mathematics-Based Taxonomy Paradigm”, THEOCHEM 1998, 431,
237-247.
18. J. Gal, “Problems of Stereochemical Nomenclature and Terminology.
1. The Homochiral Controversy. Its Nature and Origins, and a Proposed Solution”, Enantiomer 1998, 3, 263-273.
19. J. Michl and R. West, “Conformations of Linear Chains. Systematics
and Suggestions for Nomenclature”, Acc. Chem. Res. 2000, 33, 821-823.
20. A. Berces, D. M. Whitfield, and T. Nukada, “Quantitative Descriptionof Six-Membered Ring Conformations Following the IUPAC Conformational
Nomenclature”, Tetrahedron 2001, 57, 477-491.
21. J. Caldwell and I. W. Wainer, “Stereochemistry: Definitions and a Note
on Nomenclature”, Hum. Psychopharmacol. Clin. Exp. 2001, 16, S105-S107.
22. K. C. Nicolau, C. N. C. Boddy, and J. S. Siegel, “Does CIP Nomenclature Adequately Handle Molecules with Multiple Stereoelements? A Case Studyof Vancomycin and Cognates”, Angew. Chem., Int. Ed. 2001, 40, 701-704.

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Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Inorganic Compounds
1. W. Thewalt, K. A. Jensen, and C. E. Schaeffer, “A Nomenclature Symbolism for Chiral and Achiral Isomers of Bridged Inorganic Complexes”,
Inorg. Chem. 1972, 11, 2129-2136.
2. T. E. Sloan and D. H. Busch, “Stereochemical Description andNotation for Coordination Systems” in Stereochemistry of Optically Active
Transition Metal Compounds, B. E. Douglas and Y. Saito, eds., American
Chemical Society, Washington, D.C., 1980, pp. 397-419. (ACS Symposium
Series No. 119.)
3. T. E. Sloan, “Stereochemical Nomenclature and Notation in Inorganic
Chemistry” in Topics in Inorganic and Organometallic Stereochemistry”, G.
Geoffroy, ed., John Wiley & Sons, New York, 1981, pp. 1-36.
4. T. Damhus and C. E. Schaeffer, “Three Reference Systems for Chirality Specification, Application, Geometric Properties, and Mutual Relationships”, Inorg. Chem. 1983, 22, 2406-2412.
5. M. Brorson, T. Damhus, and C. E. Schaeffer, “Exhaustive Examinationof Chiral Configurations of Edges on a Regular Octahedron: Analysis of the
Possibilities of Assigning Chirality Descriptors within a Generalized ∆/ΛSystem”, Inorg. Chem. 1983, 22, 1569-1573.
6. T. E. Sloan, “Nomenclature of Coordination Compounds” in Comprehensive Coordination Chemistry, G. Wilkinson, R. D. Gillard, and J. A. McCleverty, eds., Pergamon Press, London, 1987, Part 1, Vol. 1, Chapter 3, pp.
109-134.

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Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 309

K. CHEMICAL PREFIXES
309. Miscellaneous chemical prefixes. The following list of prefixes
most often encountered in the chemical literature (though not necessarily employed in CA index names) is intended to supplement Section H (Illustrative
List of Substituent Prefixes); items in Section H are therefore not repeated here.
Also excluded are prefixes derived from individual element or compound
names, e.g., phospho-, ferri-, aceto-, oxa-, thiazolo-. Prefixes usually italicized
are so shown.
The lower-case Greek alphabet is supplied in a separate list below (¶ 310).
Greek and Latin multiplicative prefixes are also listed separately (¶ 311).
ac- abbreviation of alicyclic; as, ac-amino derivatives of Tetralin. Cf. ar-.
ace- from acetylene; as, acenaphthene.
aci- the acid form: as aci-acetoacetic ester, CH 3 C(OH):CHCOOC 2 H 5 ; acinitro group HON(O):.
aldo-, ald- from aldehyde; as, aldohexose, aldoxime.
allo- (Greek allos, other) indicating close relation; as, allo-telluric acid, alloocimene (a structural isomer of ocimene). Specifically, designating the morestable of two geometrical isomers; as, allomaleic acid (fumaric acid).
amphi- (Greek, both, around) relating to both sides or both kinds; as, amphinaphthoquinone (2,6-naphthalenedione), amphiphile.
andro-, andr- (Greek) relating to man, male; as androgen, androsterone.
ang- having an angular alignment of rings; as, ang-2′,3′-naphth-1,2-anthracene (pentaphene). Cf. lin-.
anhydro- (Greek anhydros, without water) denoting abstraction of water, anhydride of; as, anhydroglucose. Cf. dehydro-.
antho-, anth- (Greek) of flowers; as, anthocyanin, anthoxanthin.
anthra-, anthr- (Greek, anthrax, coal) of coal or anthracene; as, anthracite, anthraquinone, anthrapyrrole.
anti- (Greek, against) opposite, opposed to; as, antioxidant; specifically, equivalent to trans- (which see) as, anti-benzaldoxime.
apo- (Greek, from) denoting formation from, or relationship to, another compound; as, apomorphine, C17H17NO2 (morphine is C17H19NO3).
ar- abbreviation of aromatic; as, ar-derivatives of Tetralin.
as- abbreviation of asymmetric; as, as-trichlorobenzene (1,2,4-Cl3C6H3).
benzo-, benz- of benzene; as, benzoic; specifically, denoting fusion of a benzene ring; as, benzoquinoline.
bi- (Latin) twice, two, double; specifically: (a) in double proportion; as, bicarbonate (no longer considered good usage); (b) denoting the doubling of anorganic radical or molecule; as, biphenyl, C6H5C6H5; bipyridine,
C5H4N.C5H4N.
bicyclo- of two rings; specifically, designating certain bicyclic bridged compounds, as; bicyclo[2.2.1]heptane.
bili- (Latin) of bilirubin, as, biliverdin.
bisnor-, dinor- indicating removal of two CH2 groups; as, bisnorcholanic acidor dinorcholanic acid C22H36O2 (cholanic acid is C24H40O2).
bufo-, buf- (Latin bufo, toad) derived from the toad; as, bufotalin.
chole-, cholo, chol- (Greek) of bile; as, cholesterol, choline.
chromo- (Greek chroma, color) color, colored; as, chromophore, chromoprotein, chromoisomer (a colored isomer of a colorless compound).
chryso-, chrys- (Greek) gold, golden yellow, yellow; as chrysophanic acid,chrysazin.
cincho-, cinch- of cinchoma or cinchonine; as cinchomeronic acid, cinchonan.
cis- (Latin, on this side) an isomer in which certain atoms or groups are on thesame side of a plane; as, cis-1,4-cyclohexanediol.
copro- (Greek) of dung or excrement; as, coprosterol.
cyclo- (Greek kyklos, circle) of ring structure, cyclic; as, cyclohexane.
D- denoting configurational relationship to D-glyceraldehyde; as, D-fructose.
d- (a) abbreviation of dextro or dextrotatory; as, d-strychnine; (b) less properly= D.
de-, des- (Latin) indicating removal of something from the molecule; as, deoxybenzoin, C6H5CH2COC6H5 (benzoin with one oxygen atom removed).
dehydro- denoting (a) removal of hydrogen; as, dehydrocholic acid; (b) sometimes, removal of water; as, dehydromucic acid.
dextro- (Latin dexter, right) rotating the plane of polarization to the right; as,dextropinene. Abbreviation, d; as, d-valine.
dl-; d,l- denoting a racemic form. Cf. dextro-, levo-.
dvi- (Sanskrit, two, twice) designating provisionally an element of the samefamily, in the second place beyond; as dvi-manganese (rhenium).
eka- (Sanskrit, one) designating provisionally an element of the same family,in the first place beyond; as, eka-manganese (technetium).
endo- (Greek, within) indicating an inner position, specifically: (a) in the ringand not in a side chain; (b) attached as a bridge within a ring; as, 1,4-endomethylenecyclohexane (bicyclo[2.2.1]heptane).
epi- (Greek, upon, on, to) denoting (a) the 1,6-positions in naphthalene; as, epidichloronaphthalene; (b) in aldoses and related compounds identity ofstructure except arrangement about the α-carbon atom; as, epirhamnose(epimer of rhamnose); (c) a bridge connection; as, 9,10-epidioxyanthracene(anthracene 9,10-peroxide).
ergo-, ergot- relating to ergot; as, ergosterol, ergotamine.
erythro-, erythr- (Greek) red; as erythromycin, erythrosine.
eso- (Greek, within) denoting immediate attachment to a ring atom. Cf. exo-.
etio-, aetio- (Greek aitia, cause) denoting a degradation product; as, etiocholanic acid, etiocobalamin.
exo- (Greek) outside, out of; as, exotoxin (an excreted toxin); specifically, denoting attachment in a side chain. Cf. endo, eso-.

flavo-, flav- (Latin flavus, yellow) yellow; as, flavoprotein, flavone; specifically, designating certain series of coordination compounds.
fuco-, fuc- of fucus (a seaweed); as, fucoxanthin, fucose.
gala-, galacto-, galact- (Greek, milk, milky) relating to: (a) milk; as, galactase,galactose; (b) galactose; as, galactocerebroside, galactolipin.
gallo-, gall- relating to gallnuts or gallic acid; as, gallotannic acid, gallocatechin.
gem- abbreviation of geminate (said of two groups attached to the same atom);as, a gem-diol (e.g., 1,1-ethanediol), the gem-dimethyl grouping in camphor.
gluco-, gluc- (a) of glucose; as, glucopyranose, glucuronic acid; (b) less properly = glyco-, glyc-.
glyco-, glyc- (Greek) sweet, or relating to sugars or glycine; as, glycogen, glycoside, glycocholic acid.
hemato-, hemat-, hemo-, hem- (also haemato-, etc.) (Greek) of blood or its color; as, hematoporphyrin, hematein, hemoglobin, hemin.
hetero-, heter- (Greek heteros, other) other, different; as, heteropoly acids, heterocyclic.
holo- (Greek) whole, complete; as, holocellulose; holophosphoric acid, H5PO5.
homo- (Greek) same, similar; as, homocyclic, homologous (differing by an increase of CH2; as, homophthalic acid).
hydro-, hydr- (Greek) (a) denoting presence or addition of hydrogen; as, hydrochloric, hydracrylic; (b) sometimes, relating to water; as hydrate.
hyo- (Greek) of swine; as, hyodeoxycholic acid (from hog bile), hyoscyamine(from Hyoscyamus (hog bean)).
hypo- (Greek, under, beneath) indicating a lower (or the lowest) state of oxidation; as, hypochlorous acid, hypoxanthine.
i- abbreviation of (a) inactive; as, i-tartaric acid; (b) iso-; as, i-pentane.
iso- (Greek) equal, alike; as, isomer; usually, denoting an isomer of a compound; as, isocyanic acid; specifically, denoting an isomer having a single,
simple branching at the end of a straight chain; as, isopentane,(CH3)2CHCH2CH3.
keto-, ket- from ketone; as, ketohexose, ketoxime.
L- configurationally related to L-glyceraldehyde; as, L-fructose.
l- (a) abbreviation of levo or levorotatory; as, l-strychnine; (b) less properly =L-.
lano- (Latin) of wool; as, lanosterol (from wool fat).
leuco-, leuc- (Greek) colorless, white; as, leucine; specifically, a colorless reduced derivative of a triphenylmethane dye; as, leucomethylene blue.
levo-, laevo- (Latin laevus, left) rotating the plane of polarization to the left; as,levovaline. Abbreviation, l-; as, l-valine.
lin- denoting a straight, linear alignment of rings; as lin-naphthanthracene(pentacene). Cf. ang-.
litho-, lith- (Greek lithos, stone) related to stone or calculus; as, litharge, lithocholic acid (from gallstones).
luteo- (Latin luteus) orange-yellow, brownish yellow; as luteolin; specifically,
the coordination compounds [M(NH3)6]Cl3.
m- abbreviation of meta (sense c).
meso-, mes- (Greek) middle, intermediate; specifically; (a) an intermediate hydrated form of an inorganic acid; as, mesoperiodic acid, H3IO6; (b) opticallyinactive owing to internal compensation; as, mesotartaric acid; (c) (abbreviated µ-) centrally substituted; as, meso-chloroanthracene (9-chloroanthracene), meso-phenylimidazole (2-phenylimidazole); (d) (abbreviatedms-) centrally fused; as, mesonaphthodianthrene (phenanthro[1,10,9,8opqra]perylene).
meta-, met- (Greek) indicating changed relation; specifically, designating (a)a low hydrated form of an acid (usually that derived from the “ortho” form
by loss of one molecule of water); as, metaphosphoric acid, HPO3; (b) aclosely related compound (sometimes, a polymer); as, metaldehyde (trimerof ordinary (acet)aldehyde); (c) (abbreviated m-) the 1,3-positions in benzene; as, m-xylene.
n- abbreviation of normal (unbranched); as, n-butane, n-butyl.
naphtho-, naphth- (Greek naphtha) relating to naphthalene; as, naphthoquinone.
neo- (Greek) new; designating new or recent; as, neoarsphenamine; (of a hydrocarbon) having one carbon atom connected directly to four others; as,neopentane, (CH3)4C.
nor- from normal; (a) a lower homologue; as, norcamphane (of which camphane is a trimethyl derivative); (b) a normal (straight-chain) isomer; as,norleucine.
o- abbreviation of ortho (sense d).
oligo-, olig- (Greek oligos, small) meaning few; as, oligosaccharide.
ortho- (Greek, straight, right, true) (a) the fully hydrated form of an acid; as,orthonitric acid, H5NO5; (b) the highest-hydrated stable form; as, orthophosphoric acid, H3PO4; (c) the common or symmetrical molecular form of
an element; as, orthohydrogen; (d) (abbreviated o-) the 1,2-positions inbenzene; as, o-xylene.
p- abbreviation of para (sense c).
para-, par- (Greek, beside, alongside of, beyond) indicating a relationship; asparaxanthine (1,7-dimethylxanthine). Specifically, (a) a higher hydrated
form of an acid; as, paraperiodic acid, H3IO5 (preferably called orthoperiodic); (b) a polymer; as, paraldehyde; (c) (abbreviated p-) the 1,4-positions
in benzene; as, p-xylene.
per- (Latin) complete, thorough, extreme; (a) the highest (or a high) state of oxidation; as, perchloric acid, manganese peroxide (better, dioxide); (b) pres-¶ 309Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

ence of the peroxide group (O2); as, barium peroxide, perbenzoic acid, peracid (better, peroxy acid); (c) exhaustive substitution or addition; as, perchloroethylene, C2Cl4; perhydronaphthalene, C10H18.
peri- (Greek, around, about) (a) the 1,8-positions in naphthalene; as peri-dinitronaphthalene (b) in polycyclic ring systems, fusion of a ring to two or
more adjoining rings: as, perinaphthindene (phenalene).
peroxy- containing the peroxide group (O2); as, peroxymonosulfuric acid,
HOSO2OOH.
pheno-, phen- (from phene, benzene) related to phenyl or benzene; as, phenacyl; specifically, an anthracene analogue having two hetero atoms in thecentral positions; as, phenazine, phenothiazine.
phloro-, phlor- relating to phlorizin; as, phloroglucinol, phloretin.
phthalo-, phthal- relating to phthalic acid; as, phthalocyanine, phthalide.
phyllo-, phyll- (Greek phyllos) of leaves; as, phylloporphyrin.
phyto-, phyt- (Greek) relating to plants; as, phytosterol, phytohormones.
picro-, picr- (Greek) bitter; as, picrotoxin, picric acid.
pino-, pin- (Latin pinus, pine) relating to pine or pinene; as, pinic acid, pinocarvone.
poly- (Greek) many; as, polymer, polysulfide, polysaccharide.
pro- (Greek, before) a precursor; as proenzyme, provitamin.
proto-, prot- (Greek) first; specifically, designating: (a) first in an inorganic series; as, protoxide (lowest in oxygen content); (b) parent or immediate antecedent; as, protactinium, protochlorophyll.
pseudo-, pseud- abbreviated ψ or ps (Greek, false) indicating resemblance to,or relation (especially isomerism) with; as, ψ-cumene, pseudaconitine,
pseudobase. Abbreviation: as, ψ-cumene.
purpuro- (Latin purpura, purple) indicating purple or red color; as, purpurogallin.
pyo- py- (Greek) relating to pus; as, pyocyanine.
pyro-, pyr- (Greek pyr, fire) indicating formation by heat; as, pyrocinchonic acid, pyrene; specifically, designating an acid derived from two molecules ofan “ortho” acid by loss of 1H2O; as, pyrophosphoric acid, H4P2O7(2H3PO4-H2O).
pyrrolo-, pyrro-, pyrr- containing the pyrrole ring; as, pyrrolopyridine, pyrrocoline.
reso-, res- relating to resorcinol; as, resorufin, resazurin.
rhodo-, rhod- (Greek rhodon, rose) rose-red; as, rhodoporphyrin, rhodamine.
s- abbreviation of (a) symmetric(al); (b) secondary.
sapo- (Latin, soap) relating to soap or soap bark; as saponin, sapogenin.
sec- abbreviation of secondary; as, sec-butyl.
seco- (Latin secare, to cut) denoting ring cleavage; as, 16,17-secoandrostane.
sub- (Latin, under, below) denoting (a) a low proportion (or deficiency, as in abasic salt); as, subiodide, suboxide, aluminum subacetate.
super- (Latin, above, over) denoting a high proportion (or superfluity, as in anacid salt); as, superoxide (peroxide), superphosphate.
sym- abbreviation of symmetric(al); as sym-dichloroethylene (1,2-dichloroethene).
syn- (Greek, with, together) equivalent to cis (which see); as, syn-benzaldoxime.
t- abbreviation of tertiary; as, t-butyl.
tauro- (Latin taurus, bull) relating to bulls or to taurine; as, taurocholic acid,taurocyamine.
tere- (Latin terebinthus, terebinth) relating to terebene or terpenes; as, terephthalic, teresantalic.
tert- abbreviation of tertiary; as, tert-butyl.
thymo-, thym- relating to (a) thyme; as, thymoquinone, thymol; (b) the thymus;
as, thymonucleic.
trans- (Latin, across) an isomer in which certain atoms or groups are on opposite sides of a plane; as, trans-cinnamic acid.
uns-, unsym- abbreviations of unsymmetrical; as, uns-dichloroethane,
CH3CHCl2.
uro-, ur- (Greek ouro-, our-) relating to urine or urea; as, urobilin, urethane,uric acid.
urso-, urs- (Latin ursus, bear) relating to bears or the bearberry; as, ursolic acid.
v- abbreviation of vicinal; as, v-triazine.
verdo- (French, verd, vert, green) indicating green color; as, verdohemin.
vic- abbreviation of vicinal; as, vic-triazole.
xantho-, xanth- (Greek) yellow; as, xanthotoxin, xanthic acids, xanthine.
xylo-, xyl- (Greek xylon, wood) relating to wood, xylene, or xylose; as, xylan,
xylidine, xyloquinone, xylocaine.
zymo-, zym- (Greek zyme, leaven) relating to a ferment or fermentation; as, zymosterol, zymase.
310. Greek alphabet. Lower-case Greek letters are employed in the chemical literature to number carbon chains and to indicate the size of lactone rings(a γ-lactone generally contains a furan ring, a δ-lactone a pyran ring, and so on).
In CA names, Greek letters are reserved for the acyclic portion of conjunctive
index parents (see ¶ 124), while cyclic portions are numbered with arabic numbers. Of Greek capital letters, ∆ (delta) is sometimes encountered in the literature to denote a double bond); Τ (tau) indicates a triple bond. Some lowercase letters have additional meanings; ϕ (phi) is a shorthand version of “phenyl” or “Ph”; see also “meso” and “pseudo” in ¶ 309.

αβγδεζ
ηθικλµ-

alpha
beta
gamma
delta
epsilon
zeta
eta
theta
iota
kappa
lambdamu138νξοπρστυϕχψω-nuxi
omicron
pi
rho
sigma
tau
upsilon
phi
chi
psi
omega

311. Multiplicative prefixes. In CA index names, Greek prefixes are preferred, except for nona- (for nine), and undeca- (for eleven). The terms hemi(Greek) and sesqui- (Latin) were employed by CA in hydrate and ammoniatenames prior to the Twelfth Collective period (1987-1991) (see ¶¶ 192, 265A).
For use of the special terms bis-, tris-, tetrakis-, etc., with complex terms andto avoid ambiguity, see ¶¶ 110 and 266.

1/
2

1
11/2
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
40
50
60
70
80
90
100
101
102
110
120
132
200
300
400
1000

Greek

Latin

hemimono-, mon-semiunisesquibitri-, terquadri-, quadr-,
quaterquinque-, quinqusexi-, sexsepti-, sept-ditritetra-, tetr-

penta-, penthexa-, hexhepta-, heptocta-, oct-, octo-, octinona-, non-, noviennea-, ennedeca-, dec-, deciundeca-, undechendeca-, hendecdodeca-, dodectrideca-, tridectetradeca-, tetradecpentadeca-, pentadechexadeca- hexadecheptadeca-, heptadecoctadeca-, octadecnonadeca-, nonadeceicosa-, eicosheneicosa-, heneicosdocosa-, docostricosa-, tricostetracosa-, tetracospentacosa-, pentacoshexacosa-, hexacosheptacosa-, heptacosoctacosa-, octacosnonacosa-, nonacostriaconta- triaconthentriaconta-, hentriacontdotriaconta-, dotriaconttritriaconta-, tritriaconttetraconta-, tetracontpentaconta-, pentaconthexaconta-, hexacontheptaconta-, heptacontoctaconta-, octacontnonaconta-, nonaconthecta-, hecthenhecta-, henhectdohecta-, dohectdecahecta-, decahecteicosahecta-, eicosahectdotriacontahecta-, dotriacontahectadicta-, dicttricta1
tetracta1
kilia1

1 International Union of Pure and Applied Chemistry, Organic Chemistry
Division, Commission on Nomenclature of Organic Chemistry, “Extension ofRules A-1.1 and A-2.5 Concerning Numerical Terms Used in Organic Chemical Nomenclature (Recommendations 1986)”, Pure Appl. Chem. 1986, 58,
1693-6.

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Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

¶ 315

L. CHEMICAL STRUCTURAL DIAGRAMS FROM CA INDEX NAMES

Introduction
Form of CA index names
Deriving a chemical structural diagram
Index heading parents

¶ 312
313
314
315

Example:Basic skeleton nameLocantPrincipal functional suffix

2- Pyridine carbothioamideS1=

312. Introduction. The foregoing sections of this document are concernedwith selection of index names for chemical substances, but the user of CA printed indexes and computer-readable files often needs to proceed from a CA index
name to the structure diagram of a chemical substance. The aim of this sectionis therefore to describe succinctly the form of CA index names, to illustrate theprocedure for deriving a chemical structural diagram from a CA index name,and to show where in CAS publications structural data can be found. The structural diagrams accurately represent the positions of atoms relative to each otherin a molecule but because of molecular flexibility, crowding, and/or the needto draw a three-dimensional structure in two dimensions, some structural diagrams are, of necessity, distorted. For example, some bond lengths and angles
may differ from those in the molecule represented.1
313. Form of CA index names. The complexity of chemical substances
generally dictates the complexity of CA index names. The CA index name consists of up to five fragments, namely, the index heading parent alone or followed successively by the substituent, modification, and stereochemistryfragments (compare ¶104), as necessary. Some index heading parents are followed by synonym line formulas (compare ¶¶219, 315.II). Every name contains
an index heading parent and it is by citing the parent first (i.e., in an inverted
format) that the names of related chemical substances are listed together in theprinted indexes.
314. Deriving a chemical structural diagram from a CA index name proceeds by taking each name fragment sequentially, converting it into a structural
fragment, and then placing each structural fragment in its proper position in the
diagram, using the appropriate positional information. The complete derivationof a chemical structural diagram may require up to four steps, depending upon
the complexity of the chemical substance, each based on one of the four possible CA index name fragments. This process is illustrated in the remaining paragraphs of this section.
315. Index heading parents include the largest or most important molecular skeleton and (when present) the highest function in a chemical substance(see ¶¶ 130, 164).
I. Index heading parents that stand alone.
The simplest index heading parents may be illustrated by examples such as
the following:

¶ 316
317
318

Substituent prefixes
Modifications
StereochemistryN

6

C−N H 2
2

The Chemical Substance Index contains the following entry for pyridine.
Pyridine

1

N

6

The carbothioamide principal function suffix is discussed in detail with other amide groups in ¶¶ 171 and 233. The locant, 2, indicates where the carbothioamide group is attached to the pyridine ring (¶ 115).
Another type of two-part name, known as a “conjunctive name” (see ¶ 124),
is a combination of the name of a cyclic molecular skeleton and the name(s) of
one or more identical, saturated acyclic hydrocarbon chains, each terminatedby the same functional group.
Example:LocantGreek multiplicative prefix

Cyclic molecular skeleton

Acyclic hydrocarbon chain
terminated by a functional
group

Butane[1,1′:3′,1′′-Terphenyl] -4,4′′- di methanethiol

Chlorine

4

H SCH 22-Hexene

1 1′

3′
1 ′′

4 ′′

CH 2 SH

NickelThe names of acyclic hydrocarbons are discussed in ¶ 141 and the multiplicative terms that indicate the number of carbon atoms in a hydrocarbon are listed in ¶ 311. Element names are discussed in ¶ 219.
Some index heading parents are made up of two parts: a basic skeletonname and a principal functional suffix. Principal functional suffixes are discussed in detail in Section C (¶¶ 164-177).
Example:Basic skeleton namePrincipal functional suffix

Methan amine
MeNH2

The structure of the phenyl group is found in the Illustrative List of Substituent Prefixes (¶ 294). That “ter” is a Latin prefix meaning “three” is found in¶ 311. The first set of locants (1,1′:3′,1′′) indicates that the three benzene rings
are connected as shown. The second set of locants (4,4′′) shows that the two
methanethiol groups (see ¶¶ 141 and 175) are attached as shown to the first andthird benzene rings. Such “ring assembly” names are described in ¶ 157.
Polymers are named either on the basis of the monomers from which they
are formed (see ¶ 317) or on the basis of their structure, as represented by astructural repeating unit (compare ¶ 222). In the latter, the multivalent radicals
are cited in sequence, following the term “Poly”, and can be drawn from left toright. Each radical retains its own numbering and is oriented, if possible, so thatthe point of attachment at the left of the radical is assigned the lowest possible
locant.
Example:Poly[(4,4-dimethyl-2,5-dioxo-1,3-imidazolidinediyl)-1,4-phenyleneoxy-1,4-phenylene]O

The basic skeleton is the one-carbon unit “Methane” (¶ 141), the final “e”
being elided before a vowel. The principal (here, the only) functional group is
the amine (¶ 176).

1A. L. Goodson, “Graphical Representation of Chemical Structures in
Chemical Abstracts Service Publications”, J. Chem. Inf. Comput. Sci. 1980, 20,
212-217.

1

N

2

3

O

1

N

5 4

Me

4

O

1

4

Me
n

In this chemical structural diagram, the multivalent radicals are separated
by dashed vertical lines and the numbering of each radical is shown, where appropriate. The structures of the radicals (e.g., oxy, phenylene) are found in ¶294 or can be inferred from the chemical structural diagrams associated withparent names (e.g., imidazolidine) in the Ring Systems Handbook or the Chemical Substance Index. The meanings of the methyl and oxo terms can also be
determined from ¶ 294.

¶ 315

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

II. Index heading parents with synonym line formulas.
Synonym line formulas are molecular formulas which follow the index
heading parent. They are printed in boldface and are enclosed in parentheses.
They are often useful for resolving ambiguity, where two or more substances,usually inorganic (see ¶ 219), have the same name.
Examples:140

Cyclic stereoparent:
Rifamycin ((2S,12Z,14E,16S,17S,18R,19R,20R,21S,22R,
23S,24E)-21-(acetyloxy)-5,6,9,17,19-pentahydroxy-23methoxy-2,4,12,16,18,20,22-heptamethyl-2,7-(epoxypentadeca[1,11,13]trienimino)naphtho[2,1-b]furan-1,11(2H)dione)

Aluminum calcium titanium oxide (Al2CaTiO6)
Aluminum calcium titanium oxide (Al2Ca4Ti2O11)
Lack of a synonym line formula in such a case means that the author did notprovide the necessary specificity in the original document.
Example:

31

Me
20

HO
AcO

33

25
14

Aluminum calcium titanium oxide

Me

MeO

III. Index heading parents with chemical structural diagrams.
A chemical structural diagram is provided in the Chemical Substance Index where the structure of an inorganic substance (¶ 219) may not be readily
apparent from the name.
Example:

32

Me

35

O
Me OH
OH
OH

15

1

NH

9

Me 30
N

Me
34

29

O

O

5
11

12

Me

10
4

OH

O

13

Phosphorodihydrazidothioic acid
O

S

2

1

= −

= −

H 2 N− NH− P− SH

H 2 N−NH −P −OH

or

2

NH −NH 2

1

NH− NH 2

2′

1′

1′

316. Substituent prefixes (see ¶ 10A) follow the “comma of inversion”(see ¶ 104) in CA index names and their structures can be determined from ¶294, the Illustrative List of Substituent Prefixes.
Example:2′

A similar procedure is followed for other types of index heading parents
such as cage parents, ring parents, and stereoparents. Here, however, thestructural diagrams are published in the Ring Systems Handbook as well as the
Chemical Substance Index.
Examples:Cage Parent:

2H-Pyran-2,4(3H)-dione,
3-[[(4-aminophenyl)amino]phenylmethylene]6-phenylThe structure of the chemical substance represented by this name is derived
by first obtaining the structure of 2H-Pyran from the Chemical SubstanceIndex or, better, from the Ring Systems Handbook. The Ring Name Index of
the 1993 edition of the Ring Systems Handbook reveals that the Ring File (RF)number for 2H-Pyran is RF 2133. Entry RF 2133 in the Ring Systems
Handbook is as follows:

1,12-Dicarbadodecaborane(12)RF 2133
2H-Pyran
C5H6O

H
C1
6

B
H

5

HB

H

10 B

H

HB

H
B

9

1

2

B11
H

The index heading parent contains two functional groups which ¶ 174
identifies as ketone groups. However, putting an oxygen on position 4 requires“adding” a hydrogen at position 3. The indicated and added hydrogen terms(see ¶¶ 135 and 136) in the index heading parent thus define the bonding in thering (the bonding could also be defined by “3,4-dihydro” but that would be partof the substituent fragment of the name and not of the index heading parent,
which must be able to stand alone). The complete index heading parent (2HPyran-2,4(3H)-dione) is therefore:

BH
7

8

O

6

BH

H
B3

4B

289-66-7

C 12
HRing Parent:
Phenanthrene

1
6

2

10a 1

8
4b

O

O

9

4

3

4a

O

As stated in ¶ 313, the complexity of chemical substances generally dictates
the complexity of CA index names. This is particularly true for natural products
whose names must imply standard orientation and stereochemical representation as well as structure and numbering (compare ¶ 318). Such complexity
makes it desirable to use a simple, nonsystematic (“trivial”) name, or stereoparent name, as the index heading parent and to define the stereoparent nameby means of a chemical structural diagram.
Examples:The substituent fragment of the name indicates that a simple substituent (i.e.,“phenyl”, see ¶ 294) is attached to the ring at position 6:
1

O

O

6

2
4

3

O

Acyclic stereoparent:
ψ,ψ-Carotene((6E,8E,10E,12E,14E,16E,18E,20E,22E,24E,26E)2,6,10,14,19,23,27,31-octamethyl-2,6,8,10,12,
14,16,18,20,22,24,26,30-dotriacontatridecaene)

A complex substituent is attached to the ring at position 3. The second phenylgroup is attached through the methylene group (see ¶ 294) to position 3 toyield:
1

18 ′

17

18

Me Me

19

20

Me

Me
11

1
6

15

6′
15′

Me
18

6

Me

Me
20′

11′

Me
19′

4

2
3

CH

1′

Me Me
16′

O

O

17′

O

141

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

The third phenyl group has an amino group (¶ 294) attached to the 4-position
and is itself attached through an amino group to the methylene group of thepartial structure. The complete structure is therefore:

The homopolymer is represented as follows:( M e 2 CH CM e =CH 2 )x318. Stereochemistry for the heading parent is the last structural information described in a CA name. The various symbols used to describe the spatial
arrangement of atoms are discussed in ¶ 203.
Example:

1

O

O

6

¶ 318

3

C
O

1

NH

4

NH 2

317. Modifications of the principal functions or other groups follow thesubstituent(s) (¶ 104). Where derivatives of more than one functional groupmust be named, the derivative terms are cited in the order described in ¶ 113.
Example:8-Azabicyclo[3.2.1]octan-3-ol,
8-methyl-,(3-exo)The structure corresponding to the basic skeleton name, principal functionalsuffix, and substituent is determined as described above. The stereochemistry of
the hydroxy group (the methyl group rocks back and forth about the nitrogenatom, eliminating the effects of asymmetry there) is denoted by “(3-exo)-”, themeaning of which is determined from ¶ 203 I. The structure is therefore:

2H-Benzo[g]indazole-2-propanamine,
3,3a,4,5-tetrahydro-N,N-dimethyl-3-phenyl-,hydrochloride (1:3)

8

NMe
1

7
5

Only the form 1H-Benzo[g]indazole is illustrated in the Chemical
Substance Index and the Ring Systems Handbook:
1H-Benz[g]indazole
1

2

HN

N

9a

9b

3
4

6

5

The structure is converted into the 2H-isomer and the propanamine group (¶¶141 and 176) is attached at the 2-position. (It should be noted that, in conjunctive nomenclature, the function is located at the end of the saturated, acyclic
chain furthest from the ring system of the index heading parent (see ¶ 124).)

9a

1

2

N

NCH 2 CH 2 CH 2 NH 2
3

9b
4
5

6

The four hydrogens are added to the 3, 3a, 4, and 5 positions to saturate the two
double bonds; then, when the phenyl and two methyl substituents (see ¶ 294)
are attached, the structure becomes:
N

NCH 2 CH 2 CH 2 NMe 2

3OH

As stated in ¶ 315, stereoparent names (see ¶ 203 II) in the Chemical Substance Index imply (in the absence of cited stereochemical descriptors) a standard structure, including specific stereochemistry, as illustrated by anaccompanying structural diagram complete with the numbering system fromwhich locants for substituents and derivatives are derived. With the exceptionof monosaccharide and some peptide stereoparents, italicized systematicnames (and in some cases one or more trivial names) appear as synonyms inparentheses immediately following the (preferred) boldface stereoparent name.
In the following examples these systematically named synonyms (1) illustrate
the various types of stereochemical descriptors found in CA indexes and (2)show how the use of stereoparents as the preferred CA names for many natural
products avoids citation of (often necessarily complicated) stereochemical descriptors.
Stereochemical descriptors in the CA index names of coordination compounds reflect the geometry of ligand attachments around one or more central
metal atoms (compare ¶ 215).
Example:Nickel(1+),
bis[[2-(diphenylstibino-κSb)phenyl]diphenylarsine-κ As]iodo-,(T-4)-tetraiodonickelate(2-) (2:1)
In this example, the central atom is nickel. The structure of the two large
ligands can be determined by reference to ¶ 294. The italicized element symbols (As,Sb) identify the ligating atoms. The stereochemistry symbol (T-4)
along with the Kappa indicates that the anion is tetrahedral (see ¶ 203 III). The
structure of this coordination compound is therefore:+

The “hydrochloride (1:3)” modification completes the structure:N

NCH 2 CH 2 CH 2 NMe 2
2−• 3HClI
Ph2As

The modification is also used in naming polymers (¶ 222) on the basis of
the monomers from which they are formed.
Example:1-Butene,
2,3-dimethyl-,
homopolymer
The structure of 1-Butene is deduced from ¶ 141. When the two methylgroups (¶ 294) are attached at positions 2 and 3, the structure becomes:
Me Me
−

−

3

2

Me −CH −C= CH 2
4

1

2

Ni

Ni

I
Ph2As

I

SbPh2
SbPh2

I

I

Abeo

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

142

M. INDEX

The references are to paragraphs, not to pages. Trivial and former CA
names, general terms and name fragments are listed along with current CA
index names. Locants and other numerals, etc., have generally been omitted.
Abeo, 212
Acenaphthylene, 148, 152
Acetaldehyde, 173
hydrate, 192
oximes, 195
Acetals, 169, 196of carbohydrates, 208
retrospective index searching for, 226of stereoparents, 202
Acetamide, 171
Acetate fibers, 222
Acetatesof amines, 198
Acetato, 215
Acetic acid, 165
anhydride-esters, 186
anhydrides, 179
esters, 185
hydrazides, 189
locants for substituents, 117
molecular addition compds., 192
multiplication of, 118
order of precedence of, 106
polymers containing, 222
Acetoacetic acid, 167
Acetone, 174
hydrazone, 190
retrospective index searching for, 262
Acetonitrile, 172
Acetoxy, 175, 283
Acetyl, 134, 168, 174
free radical, 1-oxoethyl as name for, 187
Acetylamino, 134, 171
Acetyl chloride, 170
as substituent, 134
Acetylides, 180of elements, 219
Acetyloxy, 175, 283
Acid azides, 170
order of precedence of, 106
Acid chlorides. See Acid halides
Acid halides, 170of arsenic and phosphorus acids, 197of carbohydrates, 208
inorganic, 219
order of precedence of, 106
retrospective index searching for, 227
Acid isocyanates, 183
order of precedence of, 106
Acid radicals, 134, 168, 287
from amino acids, 205
from arsenic acids, 197
from phosphorus acids, 197, 219, 276
hetero-atom-attached, 163, 171, 174
Acids. See also Carboxylic acids; Imidic acids;
Sulfonic acids; etc.
acyclic, with cyclic substituents, 166
anhydrides—see Anhydridesof arsenic end phosphorus, 197of carbohydrates, 208
of chlorine, nitrogen, phosphorus, etc., orderof precedence of, 106
Class I and Class II, 185
conjunctive names for, 166
epoxy derivs., 166
expressed as suffixes, 164-177
functional derivs., 169
halogen oxo, 188
inorganic “oxo”, 219, 273
isopoly end heteropoly, 219
labeled, 220
ligands from, 215
of metals, 219, 273
order of precedence of, 106, 167
radicals from—see Acid radicals
retrospective index searching for, 228, 273
as substituents, 167
Acinitro, 132, 193
Acridineanalogs, 149
numbering of, 152

ACS. See American Chemical Society
Actinomycins, 206
Acyclic compounds, 141-144
nonfunctional, order of precedence of, 106
Acyl radicals. See Acid radicals
Added hydrogen, 136, 256
in cyclic ketones, 174
in ring assemblies, 157
in spiro systems, 156
Additional index entries
for anions, 198, 281A
for coordination compds., 215
for cyclic peptides, 206
for molecular addition compds., 192, 265A
Addition compounds. See Molecular addition
compounds
Additive nomenclature, 123, 228A
Additive terms, 113
locants for, 119
Adducts, 192
Adenine, 122
Adenosine, 210
Adenosine triphosphatase, 218
Adenylic acid, 210
homopolymer, 222
Agar, 208
-al, 173
Alanine, 205
peptides containing, 206
Alanine aminotransferase, 218
Alcohols, 175
carbohydrates as, 208
Class 1, 185esters, 185labeled, 220
metal salts, 198
order of precedence of, 106
retrospective index searching for, 229
Aldaric acids, 208
Aldehydes, 173
order of precedence of, 106
oximes, 195
retrospective index searching for, 230
Aldehydic acids, 167, 228
Alditols, 208
Aldonic acids, 208
Aldoses, 208
Alkaline earth metals, 219
Alkaloids, 204
retrospective index searching for, 231
stereochemistry of, 202
steroidal, 211
Alkanes, 141
Alkenes, 141
locants for, 113
Alkenyl radicals
locants for, 116
Alkoxy radicals
elision in names of, 107
Alkyl radicals, 161
1-imino and 1-oxo derivs., 134, 168
allo, 209
Alloys, 214labeled, 220
retrospective index searching for, 232α (alpha), 203, 208, 212
Alphabetizationof index names, 121
Alpha particle, 217
Alternating polymers, 222, 277
Aluminate, 215, 219
Aluminumlabeled complexes, 220
Aluminum chloride
and dimer, 215, 219
Alums, 219
American Chemical Society
nomenclature reports of, 302
nomenclature rules of, 296—300
American Mineralogist, 219
Amic acids, 167, 228

Amides, 171of amino acids, 205of arsenic and phosphorus acids, 197of carbohydrate acids, 208, 240
N-hydroxy, 193
order of precedence of, 106
oxides, 268
oximes, 171
peptides, 206
radicals from, 134, 171
retrospective index searching for, 233
tautomerism with imidic acids, 122, 165
unexpressed, 171
Amidines. See Imidamides
Amidine tautomerism, 122
Amido, 215
Amidodiphosphoric acid, 219
Amidodiphosphoryl chloride, 219
Amidogen, 187, 219
Amidoimidodisulfuric acid, 219
Amidoimidosulfurous chloride, 219
Amidoselenic acid, 219
Amidoselenonyl fluoride, 219
Amidosulfenyl chloride, 200, 219
Amidosulfoxylic acid, 219
Amidothiodiphosphoric acid, 219
Amidoximes, 171
Amines, 176boron complexes, 182
N-hydroxy, 193
order of precedence of, 106, 271
retrospective index searching for, 235
salts with acids, 198
Aminium compounds, 184hydroxides, inner salts, 112
present and former indexing rules for, 270
salts, 198
ylides, 201
Amino, 176
Amino acids, 205
ACS rules for, 302
amides of, 171
homopolymers, 206
polymers, 222
IUPAC-IUB tentative nomenclature rule for,297
retrospective index searching for, 236
Aminobutyryl
in peptide names, 206
Aminocarbonyl, 134
Amino group
tautomerism of, 122
Ammines, 215
labeled, 220
Ammonia, 219
Ammoniates, 192
of inorganic salts, 219
Ammonio, 184
Ammonium chloride, 219
Ammonium salts
inorganic, 219
organic, 184, 270
Ammoniumyl, 184, 219
Amylopectin, 208-anin mineral names, 219
Androstane, 211
Androstanol
esters, 202-ane, 146
Aneurine, 224
Angiotensins, 206
Anhydride-esters, 186
Anhydrides, 179of amino acids, 205of carbohydrates, 208
of carbonic acid derivs., 183of cyanic acid, 183
of halogen oxo acids, 188of inorganic with organic acids, 219
as modification terms, 112, 113

143

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

with partial esters, 186retrospective index searching for, 237
anhydro, 208
Anhydro, 139
Anhydrosulfides, 179, 197, 200“bis” and parentheses used with, 110of inorganic acids, 219
of thiocyanic acid, 183
Anilic acids, 167, 228
Anilides, 171, 233
Anils, 176
Anions, 180
additional index entries, 198, 281A
citation in modifications, 113
common, 198, 281A
complex, 215
of elements, 219
in modifications, 198-anium, 184“a” nomenclature. See Replacement nomenclature
Anthracene
in fused systems, 148, 151
numbering of, 152preferred to phenanthrene, 138
Anthracenedione, 136anti, 203
Antielements, 217
Antihelium, 217
Antimonate, 215
Antimonide, 180
Antimony
defined as metal, 101, 181, 215, 219, 257
Antimony compounds, 181
monocyclic, 146
order of precedence of, 106
Von Baeyer systems, 155
Antimony hydroxide, 181, 219
Antiparticles, 217
Antiproton, 217
Apamin, 206
Apiose, 208
Apocarotenes, 212
Aqua, 219
ar, 120
Arabinan, 208
arabinose, 208
Arrow nomenclature, 208, 210
Arsenamldic acid, 197
Arsenenic acid, 197
Arsenenous acid, 197
Arsenic acids, 197, 273
anhydrides, 179
inorganic, and salts, 219
Arsenic compounds, 197
order of precedence of, 106
tautomeric, 122Arsenic triamide, 197
Arsenides, 180of elements, 219
Arsenido, 215
Arsenous acid, 197
Arsindole, 149
Arsine, 143, 197
Arsine selenide, 197
Arsine sulfide, 197, 200
Arsinic acid, 197
Arsino, 161, 197
Arsinous acid, 197
Arsinous cyanide, 197
Arsinyl, 197
Arsonic acid, 197
derivs., 271
Arsonimidous acid, 129
Arsonium compounds, 184
Arsonous acid, 197
Arsorane, 140, 143, 197
as, 108
Ascorbic acid, 208, 224-ase, 218
Asparaginase, 218
Aspartic acidpeptides containing, 206
Aspartoyl, 205
Assumptions
for amino acid end peptide stereochemistry,
205, 206for biline stereochemistry, 223
for coordination stereochemistry, 203
for polymer SRU names, 222-ate, 219
Atisane, 212-ato ligands, 215
Aurate, 215
Aza, 128
Azacycloundecane, 146
Azahomoandrostane, 211
Azete, 146Azi, 161
Azidesacid, 170
acid, order of precedence of, 106
Azidodisulfuric acid, 219
Azidosulfuric acid, 219
Azines, 190
Azino, 161, 193
Aziridine, 146Azo, 161, 193
Azo compounds, 193, 218dyes, 216
retrospective index searching for, 238
Azomethines, 176
Azonia, 184
Azoxy compounds, 193
retrospective index searching for, 238
Balata, 222
Barbituric acid, 122
Baryon, 217
Base components
carbocyclic, of fused systems, 148
heterocyclic, of fused systems, 149, 281
selection of, 150
Benzaldehyde, 173
Benzenamine, 176
Benzenaminiumhydroxide, inner salts, 201
Benzenealkoxy derivs., 196
in fused systems, 149, 151
multiplication of, 118preferred to cyclohexane, 138
radicals from, 161ring assemblies of, 157, 163
Benzenecarbothioic acid
hydrazide, 189
Benzenecarbothioyl chloride, 170
Benzenecarboximidic acid, 129, 165
Benzenediacetic acidderivs., 124
Benzenediazonium compounds, 198
Benzenedicarboxylic acidpolymers, 222
Benzenedipropanoic acid, 166
Benzenemethanol, 124derivs., 131
Benzenepropanal
hydrazones, 190
Benzenesulfonamide, 171
Benzenesulfonic acidanhydrides, 179
Benzenethiol
esters, 185
Benzenide, 180
Benzeno, 154
Benzimidazole
tautomers, 122Benzimidazolium compounds, 184
Benzindene, 150
Benzisothlazole
abnormal valency in, 158
Benzo, 149elision of, 107Benzodioxaborole, 182
Benzofuran, 149
Benzogermole, 194
Benzoic acid, 165
anhydrides, 179
derivs., 131esters, 185order of precedence of, 106Benzonitrile, 172
Benzopyran
as fusion component, 152
Benzopyranol
vitamin E derivs., 224
Benzopyranone, 185Benzothiazolium compounds, 184dyes, 216
Benzothienyl, 161

Bori

Benzoxazine, 149
Benzoxazole, 149
Benzoyl, 134, 168, 174
Benzoyl isocyanide, 170
Benzyl alcohol, 124derivs., 131
Benzyne, 145
Beryllium chloride, 219
β (beta), 203, 208, 212
Beta particle, 217
Bibicyclo, 157
Bibliographyof nomenclature of chemical substances,295-308
Bicyclodecasilane, 155
Blcycloheptyl“bis” and parentheses used with, 110
Bicyclohexadienyldiylidene, 161
Bicyclohexenyl, 157
Bicyclohexyl, 157
Bicyclo systems. See Von Baeyer systems
Bicyclotetrasilazane, 155
Bicyclotetrasiloxanyl, 157
Bicycloundecane, 155
Biguanidine, 251
Biisoquinoline, 157
Bile pigments, 223
retrospective index searching for, 278
Biline, 223, 278“Bimol.”in anhydride names, 179
Bi names. See Ring assemblies
Binaphthalene, 157, 266, 281
Binaphthalenediyl, 161
Binary compounds, 219
Biochemistry
nomenclature of, history and developmentof, 305
nomenclature rules for, 297
Bipentaborane, 159
Biphenyl, 114, 157, 281
locants in, 113
Biphenyldlyl, 125, 161
Biphenylyl, 161
punctuation for, 109, 110
Biphenylylcarbonyl, 168
Bipiperidine, 157
Bipyridinedlyl, 161
Bis, 110, 266
alphabetization rules for names containing,121
enclosing marks following, 109
in multiplicative names, 125
in ordering of substituents, 121
Bismuth compounds, 181
monocyclic, 146
order of precedence of, 106
Bismuth hydroxide, 181
Bismuthine, 143, 181
Bismuthine imide, 181
Bismuthine oxide, 181
Bismuthino, 161, 181
Bisulfite addition compounds, 192
Bithiazole
polymers, 222
Bithiazolyl, 161
Bitriazole, 157
Block polymers, 222,277
Bohrium, 219
Bonds
metal-metal, 203
multiple—see Unsaturated compounds
Bora, 128
Boranamine, 182
Borane, 159, 182
free radicals from, 187
order of precedence of, 106
oxybis-, derivs., 179
trifluoro-, 257
Boranetriamine, 182
Boranthrene, 149
Borate (1-), 106, 182
Boratesaminium, 201
complex, 215
Borazine, 146, 182
Boric acid, 182, 219
anhydride-esters, 186
anhydrides, 179
Borinic acid, 182

BoroNaming and Indexing of Chemical Substances for Chemical Abstracts 2007

Borole, 182
Boron acids, 182
anhydrides, 179, 182
esters, 185
hydrazides, 182
Boron complexes, 201
Boron compounds, 159, 182
inorganic, IUPAC report on, 298
molecular skeletons, 159
order of precedence of, 106
retrospective index searching for, 239
zwitterionic, 201
Boronic acid, 182
Boron metaphosphate, 219
Boron phosphate, 219
Boroxin, 146
Borthiin, 146
Boryl, 161
Boson, 217
Boughton system
for isotopes, 220
Brackets, 109
around complex radicals, 132
around locants in spiro names, 156
in multiplicative names, 125
Bradykinin, 206
Brass, 214
Bridged fused systems, 154
Bridged systems, 140, 147, 155
choice between, 138
fused, 154
indicated hydrogen in, 135
Von Baeyer names for, 155
Bromic acid, 188
Bromo, 131
Bromous acid, 219
Bronze, 214
Bufanolide, 211
Butanedioic acidanhydride-esters, 186
Butanediol
fibers from dioic acids and, 222
Butenone, 137
Butynemetal derivs., 219
Butyrylin peptide names, 206
14C, 220

CA. See Chemical Abstracts
Cadinane, 212
Caerulein, 206
Caffeine, 122
Cahn-Ingold-Prelog rule. See Sequence rule
Calciferol, 224
Calcitonin, 206
Calcium carbide, 219
Camphor, 212
Carbaboranes, 160, 182
Carbamic acid, 183
conjunctive names not formed from, 124
as elided name, 107esters, 185hydroxy, 193
multiplication of, 118
Carbamic chloride, 183
Carbamimidic acid, 183
Carbamoyl, 134
Carbapolyboranes
order of precedence of, 106
Carbazole
numbering of, 152
Carbide, 219
Carbocyclic compounds, 145, 147, 148monocyclic, radicals from, 161order of precedence of, 106
spiro, 156
Carbodiimide, 177, 191
Carbodithioic acids, 165, 200
Carbohydrates, 208
ACS nomenclature rules for, 302
IUPAC tentetive nomenclature rules for, 296
retrospective index searching for, 240
Carbohydrazide, 252
Carbohydrazones, 190
Carbohydrazonic acids, 165
Carbon compounds. See also Carbocyclic
compounds
acyclic, 141

acyclic and cyclic, order of precedence of,106
ions, 180, 184, 219
Carbon dioxide, 219
Carbon disulfide, 219
Carbonic acid, 183
cyclic esters, 196
anhydrides, 179
anhydride with silicic acid, 199
derivs., retrospective index searching for,241
order of precedence of, 106, 271
and related compounds, 183
replacement names from, 129
Carbonic bromide chloride, 183
Carbonic dihydrazide, 183, 189
Carbonimidic acid, 183
Carbonimidoyl, 134, 168, 174
in multiplicative names, 125
Carbonitriles, 172
Carbonium compounds, 184
Carbon monoxide, 219
Carbonochloridic acid, 183
Carbonochloridothioic acidanhydrosulfides, 170
Carbonodiperoxoic acid, 129, 183
Carbonodithioic acidanhydrosulfides, 200
Carbonohydrazonic acid, 129
Carbonohydrazonoyl, 134
Carbonothioic dichloride, 183
Carbonothioyl, 134, 168, 174
in multiplicative names, 125
Carbon oxide sulfide, 219
Carbon tetrachloride, 272
Carbonyl, 134, 168, 174
free radicals containing, 187
hetero-atom-attached, 163
in multiplicative names, 125
Carbonyldiimino, 134
Carbonyls
metal, 215, 219
Carbostyril, 122
Carbothioamides
elision in names of, 107
Carbothioic acids, 165
Carboxaldehydes, 173, 230
Carboxamides, 171, 233
tautomerism of, 122
Carboximides, 191
Carboximidic acids, 129, 165
tautomerism of, 122
carboxy, 220
Carboxy, 134
Carboxyamino, 183
Carboxylato, 215
Carboxylic acids, 165
acyclic with cyclic substituents, 166aminium salts, 198
anhydrides with inorganic acids, 219
of carbohydrates, 208
esters, 185
free radicals from, 187
functional derivs., 169labeled, 220
molecular addition compds., 192
order of precedence of, 106, 167
retrospective index searching for, 228
salts, 198
as substituents, 167
Cardanolide, 211
Carotene, 212
Carotenoids, 212
ACS report on nomenclature of, 302
IUPAC tentative nomenclature rules for, 296
Carrageenan
mixtures containing, 221
Cast iron, 214
Categories
for elements, 219
Catena compounds, 192
Cations, 184
complex, 215
elementary and inorganic, 219
order of precedence of, 106
present and former indexing rules for, 270
salts, 198
Cellulose, 208, 240
Centrality

144

in amines, 176
in index name selection, 138, 255
Cephalosporins
stereochemistry of, 203
Cermets, 214
Cevane, 211
Chemical Abstracts
index nomenclature for, reports on, 301
Chicle, 222
Chirality. See Stereochemistrychiro, 209
Chloramido, 215
Chloramine, 219
Chloric acid, 219
metal salts, 219
Chloridesof arsenic and phosphorus acids, 197of elements, 219
glycosyl, 208
Chlorine compounds, 188
Chlorine nitrate, 219
Chlorine oxide, 219
Chloro, 132
Chlorocarbonyl, 131
Chloroimidosulfuric acid, 219
Chloronium, 219
Chlorophylls, 233
Chlorosulfuric acid, 129, 219
Chlorosyl, 219
Chloryl, 188, 219
Chloryl fluoride, 219
Chloryloxy, 188
Cholane, 211
Cholecalciferol, 224
Cholestane, 211
Chromates
complex, 215
Chromatite, 219
Chrome alums, 219
Chromic acid, 219, 273
Chromium carbonyl, 219
Chromium hydroxide, 219
Chromyl, 219
Chymotrypsin, 218
cis, 203, 209
C.I. names, 216
Cinchonanol
salts, 202
Cinnoline, 149
35Cl, 220Class I acids, 185, 247
Class I alcohols and thiols, 185, 247
Cluster compounds, 203, 215, 219
Cobalamin, 224
Cobaltlabeled complexes, 220
Cobaltate, 219
Cobalt nitrate sulfate, 219
Cobamic acid, 224
Cobamide, 224
Cobinamide, 224
Cobinic acid, 224
Cobyrinic acid, 224
Cocarboxylase, 224
Coenzyme A, 210
Colons, 108
in coordination names, 215
in index names, 108
Colour Index, 216
Commas, 108of inversion, 104
in modifications, 108
Common componentsof addition compds., 192, 265A
of salts, 198, 281A
Complexes. See Coordination compounds
Complexity
principle of, discontinuance of, 255
Compound classes
order of precedence of, 106
Compound radicals, 133, 162
Conanine, 211
Configuration. See Stereochemistry
Configuration numbers
for coordination compds., 203
Conjugate acids, 184labeled, 220
Conjunctive nomenclature, 124, 315
for acids, 166

145

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

present and former policies of, 255
Constitutional repeating units, 222
Coordination compounds, 215
amino acid transition metal salts as, 205
labeled, 220order of precedence of, 106
polymers of, 222
porphyrin complexes, 223
retrospective index searching for, 242
stereochemistry of, 203
structural diagram derivation for, 318
sulfur complexes as, 200
Copolymers, 222
Coppermonocysteine complex, 205
Corrin, 224
Corrinoids. See also Vitamin B12
IUPAC-IUB tentative nomenclature rules
for, 297
Corticotropins, 206
Coumarins, 185
Cuprates
complex, 215
Cyanamide, 183, 267
Cyanatesof arsenic and phosphorus acids, 197
Cyanato, 183, 188, 215
Cyanic acid, 183, 188, 219
anhydrides, 170, 179
esters, 185, 188
Cyanidesof arsenic and phosphorus acids, 197
Cyanine dyes, 216
Cyano, 172
Cyanocobalamin, 224
Cyanosulfurous acid, 219
Cyclic(glycylglycylglycyl), 206
Cyclitols, 209
IUPAC tentative nomenclature rules for, 296
Cycloalkanes, 145
Cycloalkenes, 145
Cycloalkenyl radicals
locants for, 116
Cycloandrostane, 211
Cyclodisilazane, 146
Cyclohexadienyne, 145
Cyclohexanamine
salts, 198
Cyclohexane, 130
benzene preferred to, 138
polyhydroxy derivs., 209
terpene derivs., 212
Cyclohexasiloxane, 146
Cyclohexastannane, 199
Cyclohexene, 145
no locant used with, 113
Cyclohexenone, 174
Cyclohexenylylidene, 161
Cyclohexyl, 161
Cyclopentadiene, 145
Cyclopentadienide, 180
Cyclopentadienyl, 161
in metal complexes, 215
Cyclopentane
fused derivs., 151
Cyclopentaphenanthrene
bridged derivs., 154
derivs., 211
and derivs., numbering of, 152
Cyclopregnane, 211
Cyclopropenyl, 161
Cyclosecopregnane, 211
Cyclosiloxanes, 146
Cyclotrisiloxanol, 199
Cysteine, 205
Cytidine, 210
Cytidylic acid, 210
Cytochalasan, 202
Cytochrome c, 207
Cytosine, 122din deuterium-labeled compds., 220
D, 108, 205, 208, 209

De, 206
Decaborane, 159
Decaborano, 159
Decyl“tris” and parentheses used with, 110
Dehydro, 139, 146, 158, 208

in phorbine names, 223
Dehydrogenase, 218
Deoxo, 204
Deoxy, 139, 204, 208
Depsipeptides, 206
Derivatives. See Functional derivatives
Desulfo, 206
Deuterium, 220
Di, 110
Diarsene, 143
Diarsine, 197
Diarsonous acid, 179
Diazadiphosphetidine, 197
Diazane. See Hydrazine
Diazaporphine, 223
Diazeneand derivs., 193
order of precedence of, 106
Diazenecarboxaldehyde
hydrazones, 190
Diazenecarboxylic acid
hydrazides, 189
Diazenyl, 161
Diazenyloxy
free radical, 187
Diazo, 132“bis” and parentheses used with, 110
Diazoamino tautomerism, 122
Diazo compounds, 193
retrospective index searching for, 243
Diazonio, 184
Diazonium compounds, 184
double salts, 216
salts, 198
Dibismuthine, 143
Diborane, 159, 182
Dicarbadodecaborane, 160, 182
Dicarbaheptaborane, 160
Dicarbonic acid, 179
Dicarbonic dichloride, 183
Dicarboxylic acids
esters and hydrazides, 119
Didehydro, 139, 146, 208
in phorbine names, 223
Diels-Alder adducts, 192
Diene adducts, 192
Diethylaminoalphabetization of, 121
Digermaselenane, 144
Diimidotricarbonimidic acid, 183
Diimidotriphosphoramide, 197
Dilmidotrisulfuric acid, 219
Dimersof aluminum chloride, 215, 219
of boranamines, 182
Dinorcholestanoic acid, 211
Dioic acids, 165
Diols
esters, 119, 185
Diones, 174
cyclic, 136
derivs., 119
Dioxaazadispirododecene, 156
Dioxacyclopentindene, 153
Dioxagermanin, 199
Dioxastannin, 146
Dioxy, 196
in free radical names, 187
Diphosphine, 197
order of precedence of, 106
sulfides, 200
Diphosphinediyl, 161
Diphosphinium, 219
Diphosphinyl, 161, 197
Diphosphonic acid, 179
Diphosphorane, 143
Diphosphoric acid, 197, 219
esters, 119
nucleotide esters, 210
Diphosphoric(III,V) acid, 219
Diphosphorous acid, 219
Diphosphorous tetramide, 219
Diphosphoryl, 219
Diphosphoryl, chloride, 197
Diphosphoryl chloride fluoride, 219
Diplumboxane, 199
Diselenides, 200
Diselenious acid, 219
Disilane, 199
order of precedence of, 106

epin

Disilanehexol, 219
Disilathiane, 199
order of precedence of, 106
Disilazane, 144, 199
radicals from, 144
Disilazanedlyl, 161
Disilanyl, 199
Disilazanyl, 144, 199
Disilene, 143
Disiloxane, 199
order of precedence of, 106
Disiloxanediol, 131
Disiloxanediyl, 125
as hetero unit, 127
Disiloxanyl, 161
Distannane, 140
Distannazane
radicals from, 144Distibene, 181
Distibenediyl, 161
Distibine, 181
Disulfamide, 219(Disulfate), 109
Disulfides, 200
acyl, 179
chloro, 170
order of precedence of, 106
phosphono sulfo, 219
Disulfones
order of precedence of, 106
Disulfonothioic acids, 165
Disulfonyl, 219
Disulfoxides, 200
order of precedence of, 106
Disulfuric acidand salts, 109, 219
Dithiastibabicyclononatriene, 155
Dithiazine, 146
Dithiin, 135
Dlthioas hetero unit, 127
Dithiocarboxy, 134
Dithioperoxoic acids, 165, 200
Diylidene, 161
Diyl, 161
DL, 108, 205, 208
Double bonds. See Unsaturated compounds
Double salts, 219
Dyes, 216
retrospective index searching for, 244
E, 203report on, 301
Earliest index position
principle of, 122of radical names, 133of total index names, 138
E.C., 218
-ecane, 146-ecin, 146-ecine, 146
Egg White
mixtures containing, 221
Element, 104, 219
Element, 105, 219
Elementary particles, 217
retrospective index searching for, 245
Elements, 219
of atomic number 104 and higher, 101
isotopes of, 220
Elisionof vowels and syllables, 107, 283
enantio, 206
Enclosing marks, 109
in complex radicals, 132
in indefinite names, 132
in labeled radicals, 220
in ligand names, 215
in uninverted multiplicative names, 192
endo, 154, 203, 206-ene, 139, 141, 155
no elision of “a” before, 142-enyl, 161
Enzymes, 218
retrospective index searching for, 246-epane, 146
epi, 209
Epidioxy, 154, 211-epin, 146-epine, 146

EpitNaming and Indexing of Chemical Substances for Chemical Abstracts 2007

Epithio, 154, 208
Epoxidesoxirane names for, 166
Epoxy, 154, 211
Ergocalciferol, 224
Ergostane, 211
erythro, 108, 208
Ester-anhydrides, 186
Esters, 185. See also Functional derivativesof amino acids, 205
anions of, 180of carbohydrates, 208
of halogen oxo acids, 188of hetero-atom-attached hydroxyl groups,
175
as modification terms, 112, 113
of polyalkylene glycols, 222
retrospective index searching for, 247
of stereoparents, 202of thio acids, 200η(eta)
for pi-bonded ligands, 215-etane, 146-ete, 146
Ethanamine, 131
Ethane, 130, 163
Ethanedinitrile, 172
Ethanedioic acid, 165
Ethanediol
esters, 185
Ethanedione, 190
Ethanedithioic acid, 129
Ethane(dithioperoxoic) acid, 129
Ethanediyl, 125
Ethanethioamide
S-oxide, 200
Ethanimidic acid, 165
Ethanimine, 177
Ethano, 154
Ethanol, 175
esters, 185
Ethanylylidene, 154
Ethenol
polymers, 222
Ethenone, 174
Ethers, 196“a” names for poly, 142of polyalkylene glycols, 222
retrospective index searching for, 248, 271
Ethoxyelision in spelling of, 107
free radical, 187
Ethyl, 161
free radical, 187
Ethylene glycol
polymers, 222
Ethylides, 201
Ethylium, 184
Ethynemetal derivs., 219-etidine, 146
Eudesmane, 212
Ewens-Bassett numbers, 215, 219
in vitamin B12 names, 224
exo, 203
Farnoquinone, 224
Fermion, 217
Ferrates, 215
porphine complexes, 223
Ferrobyrinic acid, 224
Ferrocene, 215
order of precedence of, 271
retrospective index searching for, 264
Fiberssynthetic, 222
Fibrinopeptide B, 206
Fluoresceins, 216
Fluorimide, 219
Fluorine compounds, 117, 188
Fluorocarbons
locants for, 117
Fluoroselenious acid, 219
Formaldehyde, 183
oximes, 195
polymers, 222
Formamide, 183
Formamidine, 234, 280
Formazan, 193
retrospective index searching for, 249

Formazano, 193
Formazanyl, 193
Formic acid, 183
anhydrides, 179
order of precedence of, 106
replacement analogs, 183
formyl, 220
Formyl, 134, 173
Formyl isocyanate, 183
Free radicals, 187
cationic, 184
Friedo, 212
Fructose, 208
valine deriv., 202
Fullerenes, 163A
Fulminic acid, 188, 219
Functional compounds
described by suffixes, 164-177
Functional derivativesof acids, 169of amino acids, 205
commas between names of, 108
locants for, 119order of citation of, 113
retrospective index searching for, 250
of stereoparents, 202, 204of steroids, 286
Functional parent compounds, 130, 131
acids, order of precedence of, 106
Functionsorder of precedence of, 106
Furan, 146
in fused systems, 149, 151
Furandione
polymers containing, 222
Furandiylidene, 161
Furanimine, 185
Furanium compounds, 184
Furano, 154-furanose, 208
Furanosides, 208
Furazan, 281
Furostan, 211
Furylium compounds, 184
Fused ring systems, 147, 148
Fused systems
base components for, 148, 149, 150, 281
boron-containing, 159
bridged, 154
carbocyclic, 148, 151
heterocyclic, 149, 151, 281
numbering of, 152
replacement nomenclature for, 153
Galactitol, 208
Galactose, 208
Gammacerane, 212
Gastrin, 206
Geometryof coordination complexes, 203
Germanamine, 199
Germanate, 215
Germane, 143, 199, 219
Germanium compounds, 199
cyclic, 146, 194
order of precedence of, 106
Germanium hydroxide, 199
Germaselenanes, 144
Gibbane, 212
Glucagon, 206
Glucitol, 208
gluco, 208
Gluconoyl chloride, 208
Glucopyranose, 208
Glucopyranosyl, 208
Glucopyranosylamine, 208
Glucopyranuronic acid, 208
Glucose, 208
mixtures containing, 221
polymers, 222
Glucosides, 208
Glucuronan, 208
Glutamic acid, 205
peptides containing, 206
Glutamoyl, 205
Glycerides, 185
glycero, 208
Glycerolesters, 185

146

Glycine, 205
peptides containing, 206
Glycols
polymers, 222
Glycolic acid, 167
Glycosides, 208, 240
Glycosylamines, 208
Glycosyl halides, 208
Glycosyl radicals, 208
in nucleosides and nucleotides, 210
Glycyl, 205
Gonane, 211
Gonatriene, 211
Gorgostane, 211
Graft polymers, 222, 277
Gramicidin S, 206
Graphite, 219
Graphite nitrate, 219
Graphitic acid, 219
Greek lettersalphabet, 310
order of citation of, 113
Guanidine, 183
derivs., retrospective index searching for,251
Guanine, 122
Guanosine, 210
Guanylic acid, 210
polymers, 222gulo, 208
Gutta-percha, 222
H. See Added hydrogen; Indicated hydrogen
Hadron, 217
Hahnium, 219
Halides. See also Acid halides
of germanium, lead, etc., 272
of metals, 219
of silicon, 282
Halogen compounds, 188
Halogenoid compounds, 188
Halogens, 219
Hantzsch-Widman system, 146
order of precedence of, 138
Helium-group gases, 219
Hematin, 223
Hemi, 192, 265A, 311
Hemiacetalsof carbohydrates, 208
Heptenepolymers, 222
Hetero-atom chains
acyclic, 142
acyclic, radicals from, 161
heterogeneous, 144
homogeneous, 143
homogeneous, breaking of, avoided, 138
Hetero atoms
lowest locants for, 137
order of precedence of compds. containing,
106, 138
Heterocyclic compounds
fused, 149, 281
numbering of, 152
spelling of names of, 107order of precedence of, 106preferred to carbocycles, 138
Heterogeneous hetero chains, 144
Heteropoly acids, 219
Hetero polyboranes, 160
Hetero units, 127, 176, 196, 279
Hexaborane, 159
Hexadiene, 141
Hexanedioic acidpolymers with diols, 222
Hexapropylene glycol, 222
Hexenepolymers, 222
Hexodialdose, 208
Hexopyranosulose, 208
Hexoses, 208
Hexosulofuranose, 208
Hexosulose, 208
Hexulose, 208
Hexyne, 141
Histidinenumbering of, 205
Homo, 204, 211
Homocysteine, 205
Homogeneous hetero chains, 143

147

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Homoglycans, 208
Homonorpregnane, 211
Homonorursene, 212
Hormones, 206
Hydantoin, 122
Hydrates, 192, 265A, 311
citation in modification, 113
labeled, 220of metal salts, 219
Hydrazi, 161, 211
Hydrazide
as index parent, 180, 219
Hydrazides, 189. See also Functional
derivativesof amino acids, 205of arsenic and phosphorus acids, 197of boron acids, 182
of elements, 219
Hydrazine, 143, 193, 219
acyl—see Hydrazides
alkylidene—see Hydrazones
alkylthio, 189
boryl, 182
derivs., 189, 193
derivs., retrospective index searching for,252
order of precedence of, 106
Hydrazinecarbothioamide
derivs., 190
Hydrazinecarboxamide
derivs., 193, 202
Hydrazinecarboxylic acid, 183, 189, 193
Hydrazinedicarboxylic acid, 165
Hydrazinedisulfonyl dichloride, 219
Hydrazinium, 184, 219
Hydraziniumyl, 184
Hydrazino, 161, 189, 193
tautomerism of, 122
Hydrazinosulfonyl, 189
Hydrazinylylidene, 161, 193
Hydrazo, 161, 193
Hydrazoic acid, 219
Hydrazonamides, 171
Hydrazones, 190. See also Functional
derivativesof carbohydrates, 208of stereoparents, 204
tautomerism of, 122
Hydrazonic acids, 165, 169, 190
hydrazides, 122
tautomerism with hydrazides, 165
Hydrazono, 161, 190, 193
Hydrazyl, 187
Hydrideas index parent, 219
Hydrides, 219
labeled, 220
Hydriodic acid, 219
Hydro
abnormal-valency ring systems, 158
locants for, 117
Hydrobromic acid, 219
Hydrocarbons
acyclic, 141
fused systems, 148, 152labeled, 220monocyclic, 145
monocyclic, radicals from, 161order of precedence of, 106
polycyclic, 147
spiro, 156
Hydrochloric acidand dimer, 219
Hydrochlorides, 198
Hydrocyanic acid, 183
Hydrodisulfides, 200
Hydrofluoric acid, 219
Hydrogenadded—see Added hydrogenindicated—see Indicated hydrogenisotopes of, 220
in partial ester names, 185
subtraction of, from ring systems, 139
Hydrogenase, 218
Hydrogenobyrinic acid, 224
Hydrogen peroxide, 219
Hydrogen sulfide, 219
Hydrogen triiodide, 219
Hydrogen trioxide, 219
Hydroisocyanic acid, 219

Hydrolytic polymers, 222, 277
Hydroperoxides, 126, 196of elements, 219
order of precedence of, 106
Hydroperoxo, 219
free radical, 187
Hydroperoxy, 196
Hydrotrioxides, 196
Hydrotrioxo, 219
Hydrotrisulfides, 200
Hydroxamic acids, 167, 228
Hydroxides
inner salts, 293A
inorganic, 219
Hydroximic acids, 167, 228
Hydroxyl, 219
free radical, 187
hetero-atom-attached, 163, 175
Hydroxylamine, 193, 219
0-acyl, 171
N-alkyl and N-aryl, 176
N-alkylidene—see Oximes
derivs., retrospective index searching for,253
order of precedence of, 106
Hydroxylaminesulfonic acid, 193, 195
Hydroxylase, 218
Hypernuclei, 217
Hyperon, 217
Hyphens, 108
in hydroperoxide names, 126
Hypoboric acid
esters, 182, 185
Hypochlorous acid, 188, 219
Hypofluorous acid, 188
Hypoiodous acidanhydrides, 188
Hyponitric acid, 219
Hyponitrous acidand metal salts, 219
Hypophosphoric acid, 197, 219-ianin mineral names, 219-ide, 219
ido, 208
Illustrated structural diagrams, 135
for stereoparents, 204, 211
Imidamides, 171
N-hydroxy, 171
radicals from, 134retrospective index searching for, 234
tautomerism of, 122
Imidazole, 146
Imidazolidine, 146
Imides, 191of arsenic and phosphorus acids, 197oxides, 268
Imidic acids, 129, 183, 228
amides preferred to, 122radicals from, 134
tautomerism of, 122, 165
Imido, 215
Imidodicarbonic acid, 129
Imidodiphosphoric acid, 197, 219
Imidodiselenic diamide, 219
Imidodisulfuryl fluoride
metal salts, 219
Imidogen, 187
Imidosulfamic acid, 219
Imidosulfamide, 129, 219
Imidosulfurous acid, 200
Imidotetraphosphoric acid, 219
Imidotriphosphoric acid, 129-iminein fused systems, 154
Imines, 177
N-alkyl derivatives, 176order of precedence of, 106
retrospective index searching for, 254
Iminio, 184
Iminium compounds, 184
Imino
as bridge, 154
in multiplicative nomenclature, 125
as substituent, 177
in tautomers, 122
Iminodiimidotriphosphoramide, 219
Iminomethyl, 168, 177-in, 146, 149

Ions

Indefinite compounds, 120
cationic, 184
coordination compds., 215
Indene, 135
Index names
choice of, 101, 103, 105, 138with functional suffixes, 164-177
inversion of, 104preferred, definition of, 192
retrospective searching of, 225-293
structural diagrams from, 312-318
Index name selection. See also Order ofprecedence
CAS policies (previous and present) for,255, 301
CAS policy revision for, 101, 255
for compds., 138
for fused ring systems, 151
necessity of rules for, 103
principles of, 105
for radicals, 133
Index parents
definition of, 130, 164, 315
inversion of substituent prefixes at, 104
nonfunctional, molecular skeletons as, 140,
163
nonfunctional, order of precedence of, 106,271
structural diagrams from, 312-318
Indicated hydrogen, 135, 317
in abnormal-valency ring systems, 158
to accommodate bridges, 154
ACS report on, 302
for cyclic ketones, 174
for cyclic sulfur compds. with abnormal
valencies, 158of fusion components, ignored, 152lowest locants for, 122, 137, 138present and former rules for, 256
in ring assemblies, 157
in spiro systems, 156
Indoleanalogs, 149
Indolylidene, 161-ine, 146, 149
Inner salts, 112, 201, 224, 293A
vitamin B12 derivs., 224
Inorganic compounds, 219
indexing policy changes for, 225, 239, 257,
273
labeled, 220
nomenclature of, history and developmentof, 306
nomenclature rules for, 298
Inosine, 210
Inosinic acid, 210
Inositols, 209
retrospective index searching for, 258
Inosose, 209
Insulins, 206, 274
Intermetallic compounds, 219
labeled, 220
International Mineralogical Association, 219
International Union of Biochemistry, 218
nomenclature rules of, 296-297
International Union of Pure and Applied
Chemistry, 101, 219
nomenclature rules of, 296-300
Inversionof index names, 104
Iodatedichloro, 219
Iodic acid, 219
Iodineas index parent, 188
Iodine acids, 219
anhydrides, 188
Iodine compoundswith abnormal valencies, 259
addition compds., 192
cyclic, 158
retrospective index searching for, 259
Iodonium, 184
Iodyl, 188
Ion(1-)
as modification term, 113, 198
Ionscomplex, 215
inorganic, 219
negative, 180

Ions

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

negative, in modifications, 198
negative, of elements, 219
order of citation of, in modifications, 113
positive, 184, 219, 270-io radicals
from metals, 215-irane, 146-irene, 146-iridine, 146-irine, 146
Iron compounds, 215, 219
hemes, 223
Iron oxide, 219
Iron zinc oxide, 219
Iso
in boron-compd. names, 159
Isobenzofurancarboxylic acid, 186
Isobenzofurandione, 179
Isocyanates
acid, 170
acid, order of precedence of, 106
Isocyanato, 183, 188
Isocyanides, 188of arsenic and phosphorus acids, 197
retrospective index searching for, 260
Isocyano, 188
Isocytidylic acid, 210
Isoguanylic acid, 210
Isohypophosphoric acid, 197, 219
Isoindolein fused systems, 149, 151
Isoneuraminic acid, 208
Isopoly acids, 219
Isoselenazole, 146
Isosemicarbazones, 190
Isothiazole, 146
Isotopes, 220
in alloys, 214compds. labeled with, 220
elementary particles, 217
of hydrogen, ACS report on, 302
metastable, 220
Isoxazole, 146
Italics, 108-ite, 219
-itol, 208
IUB. See International Union of Biochemistry
Ium compounds, 184, 215
borates, 201
retrospective index searching for, 270
salts, 198
zwitterionic, 201-iumdiyl, 184-iumyl, 184
IUPAC. See International Union of Pure andApplied Chemistry
Kaurane, 212
Ketenes, 174
thio, 183
retrospective index searching for, 261
Keto-enol tautomers
stereochemistry of, 203
Ketones, 174
added hydrogen in cyclic, 136
hetero-atom-attached, 163
indicated hydrogen in cyclic, 135
nitrogen-containing cyclic, 171of nitrogenous heterocycles, 122order of precedence of, 106
oximes, 195
retrospective index searching for, 262
Ketoses, 208
Kraystay K, 221
Kromycin, 202
Krypton fluoride, 219
L, 108, 205, 208, 209
Labeled compounds. See Isotopes
Lactam-lactim tautomerism, 122
Lactams
carbohydrates, 208
Lactate dehydrogenase, 218
Lactoflavine, 224
Lactones, 185of amino acids, 205of carbohydrate acids, 208
cyclic peptides, 206
steroidal, 211
Lactose, 208

Lactoylin peptides, 206
Ladder polymers, 222
Lakes, 216
λ (lambda)
in heterocyclic ring systems, 158
Langham, Cecil C., 102
Lanostane, 212
Latin prefixes, 311
Lead compounds, 199
cyclic, 158
monocyclic, 146
order of precedence of, 106
Lepton, 217
Leptonic molecules, 217
Letter locantsin coordination names, 215
in labeled compds., 220order of citation of numerals and, 114
Leucomycin V, 202
Ligands, 215, 242
Like treatment of like things, discontinuanceof, 138, 255
Linearityof bridged fused systems, 154of fused systems, 138, 150
Line formulaswith binary names, 219
for carbonic anhydride sulfur analogs, 183
containing isotope symbols, 220
for inorganic compds., 219, 257, 315
with polyphosphorus acids, 197
synonym line formulas, 109, 129
LipidsIUPAC-IUB tentative rules fornomenclature of, 297
Lithian, 219
Lithio, 215
Lithium compounds
organic, 194
Locants, 114
all cited when one is needed, 117, 119
in “a” names, 128
effect on alphabetization, 121
for bridged fused systems, 154
capital italic letters, in coordination
nomenclature, 215
enclosing marks between like, 132
in ester names, 185
for functional derivs., 119
for fused systems, 115, 152
for indefinite compds., 120
for isotopes, 220
lowest, definition of, 137
lowest, principle of, 255
in modifications, 185
for molecular skeletons, 137, 138
in multiplicative nomenclature, 118present and former rules for, 263
primed, 114, 151, 152
in radicals, 116, 133
in rings and chains, 137
for suffixes, 115
for sulfides of hetero atoms, 200
Lowest locants, 137, 255
for indicated hydrogen, 122, 135, 152
for multiple bonds, 138
in radicals, 133
in tautomers, 122
Lupane, 212
Lysozyme, 218
Macromolecular chemistry
nomenclature of, history and developmentof, 307
nomenclature rules for, 299
Magnesatephorbine complexes, 223
Magnesiumcations, 219
Magnesium compounds
chlorophylls, 223
Malonic acid. See Propanedioic acid
Manganese hydroxide oxide, 219
Manganic acid, 219, 273
Mannan, 208
Mannopyranosyl bromide, 208
Maximum substitution, 122, 133, 138
Melamine, 122
polymers with formaldehyde, 222

148

Melanocyte-stimulating hormone, 206
Menthane, 212
Mercapto
free radical, 187
hetero-atom-attached, 175
Mercuryorganic derivs., 194
Mercury chloride, 219
Meso-ionic compounds, 201, 293A
Meson, 217
Mesonic atom, 217
Metaborates
cyclic, 219
Metal complexes. See Coordination compounds
Metal carbonyls, 215
Metallic compounds
organo-, 194
monocyclic, 146retrospective index searching for, 272
Metallocenes, 215
retrospective index searching for, 264, 271
stereochemistry of, 203
Metal-metal bonds, 203, 215
Metal oxides
radicals from, 219
Metal radicals, 215
Metals, 215
complexes of, 215
definition of, 219
hydroxides and oxides, 219
isotopes, 217
Metal salts, 198of amino acids, 205
Metaphosphinic acid, 197
Metaphosphoric acid, 197, 219
Metaphosphorous acid, 197
Methanamine, 176boron complexes, 182
Methanaminium, 184
salts, 198
ylides, 201
Methane, 130, 140, 141
multiplication of, 118
Methanediimine, 177
Methane(dithioic) acid, 183
Methaneperoxoic acid, 183
Methanethial, 183
Methanethioamide, 183
Methanethione, 174, 183
Methanimidoyl isocyanate, 183
Methanimine, 183
Methano, 154
Methanoic acidreplacement analogs, 183
Methanone, 174, 183
oximes, 195
Metheno, 154
Methines, 216
Methiodides, 184
Methoxides, 180
Methoxy, 107, 287
free radical, 187
Methyl, 161
free radical, 187
Methylene, 125, 161
parentheses around, 110
Methylethyl, 162
Methylides, 201
Methylidyne, 161
free radical, 187
Methylium, 184
Methyliumyl, 184
Methylthio
free radical, 187
Methylphenyl, 162
Minerals, 219
labeled, 220(−) (minus), 203
Mixed salts, 219
Mixtures, 221of dyes, 216
order of citation of, in modifications, 113
retrospective index searching for, 265of stereoisomers, 203
Modifications
enclosing marks in, 109
format of, 104, 317
locants for terms in, 119order of citation of terms in, 113
Molecular addition compounds, 192, 265A

149

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

See also Saltsof amino acids, 205of borane, 182, 239
citation in modification, 113
of polymers, 222
stereochemistry of, 203of stereoparents, 202
Molecular skeletons, 140-163
boron, 159
definition of, 140, 315
as index parents, 130
numbering of, 137
order of precedence of, 106, 271
radicals from, 161
Molybdateiron sodium oxide, 219
Mono, 111, 120, 192, 311
in anhydride names, 179
in ester names, 185
Monoprotonatedas modification term, 184
Morpholine, 146
Morpholinyl, 161µ (mu), 215
in polyborane names, 182
muco, 209
Multiple bonds. See also Unsaturated
compounds
maximum number of, in parent radicals, 133
Multiplicative nomenclature, 125
brackets around parent in, 109
for ester names, 185
locants in, 118
for fused systems, 151preferred, 138retrospective index searching for, 255
ylidene radicals in, 125, 255
Multiplicative prefixes, 110, 311
alphabetization rules for, 121present and former ruleo for, 266
Muonic molecule, 217
Muonium, 217
Muramic acid, 208
myo, 209
N, 108order of citation of, in locant sets, 114

15N, 220

Name selection. See Index name selection
Naphthacene
numbering of, 152
Naphthalene
in fused systems, 148, 151
numbering of, 137
Naphthalenedione
vitamin K derivs., 224
Naphthalenimine, 154
Naphthaleno, 154
Naphthalenone
added hydrogen in, 136
Natural products. See Stereoparents
neo, 209
Neo
in boron compd. names, 159
in terpene names, 212
Neogammacerane, 212
Neoonocerane, 212
Neuraminic acid, 208
Neutrino, 217
Neutron, 217
Nickelibyrinic acid, 224
Nielsbohrium, 219
Ninth Collective Index
substance name revision in, 101
Niobate, 215
Nitramide, 219
Nitrateas index parent, 219
Nitric acidand metal salts, 219
Nitric acidium, 219
Nitridesof arsenic and phosphorus acids, 197
Nitrido, 215
Nitridotriphosphoric acid, 219
Nitriles, 172of carbohydrate acids, 208
order of precedence of, 106
retrospective index searching for, 267
Nitrilimine, 172, 201, 267

Nitrilio, 184
Nitrilo, 125
aci-Nitro, 193
Nitrogen acids, 219
Nitrogen compounds, 193
N-glycosyl derivs., 208
heterocyclic, N-acyl derivs., 171
monocyclic, 146
order of precedence of, 106
peptides as, 206
phosphorus-, 197
order of precedence of, 106
quaternary, 184, 270
salts, 198
tautomeric, 122
Nitrogen hydrides, 219
Nitrolic acids, 167, 228
Nitroneretrospective index searching for, 268
Nitrosamide, 219
Nitrosolic acids, 228
Nitrososulfonyl fluoride, 219
Nitrosyl, 219
Nitrosyl chloride, 219
Nitrosyl (disulfate), 219
Nitrosyls
metal, 215
Nitrous acid, 219
anhydrides, 179
Nitroxide, 187
Nitryl, 219
NNO, 193
Nomenclature
history of chemical, 303-308
IUPAC, IUB, and ACS rules of chemical,
296-300
retrospective index searching of CAS, 225
Nonfunctional compounds
order of precedence of, 106
Nor, 139
in alkaloid names, 204in peptide names, 206
in steroid names, 211
in terpene names, 212
Norcholenedioic acid, 211
Norlupane, 202
Normalizationof tautomeric structures, 122, 184
Nucleon, 217
Nucleosides, 210
retrospective index searching for, 269
Nucleotides, 210
polymers, 222
retrospective index searching for, 269
Numbering. See also Locantsof fused systems, 152of molecular skeletons, 137
Numeralsin alphabetization, 121order of citation of letters and, 114
Nylon, 222oelision of, 107
0, 108
17O, 220-oanin mineral names, 219-ocane, 146
Occurrencesmaximum number of parent, 122, 125, 138-ocin, 146-ocine, 146
Octaphene, 148-oic acids, 165-olane, 146-ol, 175-ole, 146
Oleanane, 212-olidine, 146
Oligomers, 222of arsenic and phosphorus acids, 197of boranamines, 182
of carbohydrates, 208
clusters, 219
of nucleotides, 210
Oligonucleotides, 210
Oligosaccharides, 208-onane, 146-one, 174

Oxon

elision of “e” before, 107-onin, 146-onine, 146
Onium compounds, 184. See also Cations
inner salts, 112, 293A
present and former indexing rules for, 270
salts, 198
ylides, 201
ONN, 193
Ophiobolane, 212
Optical rotation. See Stereochemistryor, 120
Order of citation. See also Alphabetizationof locants, 114
of modification terms, 113of substituent prefixes, 121
Order of precedenceof acids, 167of arsenic and phosphorus acids, 197of base components in ring systems, 148,281
of carbonic acid and related compds., 183
of cations, 184of compd. classes, 106
in index name selection, 105present and former, 271
of ring systems, 138of silicon compds., 106, 199
Organic chemistry
nomenclature of, history and developmentof, 304
nomenclature rules for, 296
Organic hetero chains, 142
Organometallic compounds, 194
monocyclic, 146retrospective index searching for, 272
Orientation. See also Linearityof fused ring systems, 152
Orotidylic acid, 210
Ortho acids
esters, 185
Ortho-fusion, 148
Ortho-peri fusion, 148
Osazones, 190-osyl, 208
Oxa, 128“Oxa-aza” nomenclature. See Replacement
nomenclature
Oxadiazolidinone, 201
Oxaspirodecane, 156
Oxatetragermolane, 146
Oxathiaazabicyclohexane, 155
Oxathiadisilaoctane, 142
Oxathiolane, 146
Oxatricycloheptane, 155
Oxazole, 146
Oxetane, 196
Oxetanone, 196
Oxidase, 218
Oxides. See also Additive termsof amides and imides, 268
of amines, 176of azo compds., 193of cyclic nitrogen and sulfur compds., 158of cyclic phosphorus compds., 185of cyclic sulfur compds., 171, 179
of elements, 219
of hetero atoms, 158
locants for, 119of nitrogen atoms, 113, 176, 193, 268
of phosphorus compds., 175of thioacids, thioamides and thiones, 200of thio esters, 185
Oximes, 195. See also Functional derivativesof amides, 171of carbohydrates, 208of stereoparents, 204
tautomerism of, 122
Oxirane, 196
polymers, 222
Oxirene, 146
Oxirenoland derivs., no locants used with, 117
Oxireno systems, 281
Oxo, 174
in terminal positions, 173
Oxo acids. See Acids
Oxonia, 184
Oxonium chloride, 219
Oxonium compounds, 184OxyNaming and Indexing of Chemical Substances for Chemical Abstracts 2007

Oxy, 125
free radical, 187
Oxygen compounds, 196
monocyclic, 146
order of precedence of, 106
Oxytocin, 206
Ozonides, 192of elements, 219
P-, 108, 219
Papain, 218
Pantothenic acid, 224
Paraformaldehyde, 222
Parent compounds, 130
Parentheses, 109
around compound radicals, 132
Particle resonances, 217
Pectic substances
ACS report on nomenclature of, 302
Penicillins
stereochemistry of, 203
Pentaborane, 159
Pentacene, 148
Pentacyclooctasiloxane, 155
Pentalene, 148
Pentanedioic acid, 165
Pentaoxaheptadecanediol, 222
Pentasilane, 143
Pentazadienyl, 161
Pentoses, 208
Pentuloses, 208
Pentyloxy, 132
Peptides, 206, 222“a” names not used for, 127
IUPAC-IUB tentative rules fornomenclature of, 297
retrospective index searching for, 274
Perchlorato, 215
Perchloric acidand ammonium salt, 219
esters, 185
Perchloryl, 188, 219
Perhalic acids, 188
Periodic acid, 219
Periods
in spiro and Von Baeyer names, 108
Permanganic acid, 219, 273
Peroxides, 126, 131, 196
carboxy, 179
of elements, 219
order of precedence of, 106
retrospective index searching for, 275
Peroxoic acids, 165
Peroxy acid halides, 170
Peroxy acids, 165of arsenic and phosphorus, 197
from carbonic acid, 183
esters, 185, 196
inorganic, 219
order of precedence of, 106, 167
retrospective index searching for, 271, 280of sulfur, 200
Peroxychromic acid, 219
Peroxydicarbonic acid, 183, 219
Peroxydicarbonic difluoride, 196
Peroxydiphosphonic acid, 196
Peroxydiphosphoramide, 219
Peroxydisulfuric acid, 219
Peroxyhypofluorous acid
esters, 196
Peroxymonosulfuric acid, 219
Perylenein fused systems, 148, 151
Phenanthrene
anthracene preferred to, 138
numbering of, 152
Phenazine, 149amino derivs., 216
Pheno, 149
Phenolpolymers with formaldehyde, 222
Phenolphthalein, 216
Phenols, 175
Class I, 185
metal salts, 198
order of precedence of, 106
retrospective index searching for, 229, 271
salts, 198
Phenolsulfonephthalein, 216
Phenothiazine

amino derivs., 216
Phenothiazinium, 184
Phenoxasilin, 149
Phenoxazine
amino derivs., 216
Phenoxide, 180
Phenoxy
elision in spelling of, 107
Phenylalaninamide, 206
Phenylalanine, 205
peptides containing, 206
Phenylalanyl, 205
Phenylazo, 131
Phenylene, 125
Phenylenedicarbonyl, 168
Phenylsulfinyl
free radical, 187
Phenylsulfonyl, 168
Phenylthio, 168
Phorbine, 223
Phospha, 128
Phosphaborocine, 182
Phosphatase, 218
Phosphate, 180
as index parent, 219
as modification term, 180
Phosphazines, 190
Phosphenic acid, 197
Phosphenimidous chloride, 197
Phosphenous acid, 197
Phosphide
as modification term, 180
Phosphidesof elements, 219
Phosphido, 215
Phosphine, 130, 143, 197
order of precedence of, 106, 271
Phosphinecarboxylic acid, 197
Phosphine imide, 197
order of precedence of, 106, 271
Phosphine oxide, 197
order of precedence of, 106, 271
Phosphine sulfide, 200
order of precedence of, 106, 271
Phosphinic acid, 197
Phosphinic cyanate, 179
Phosphinidene, 161
Phosphinidyne, 161
Phosphinimine, 177
Phosphino, 161, 197
free radical, 187
Phosphinyl, 197
Phosphinothioyl, 197
Phosphinous acid, 197
Phosphonate, 180
Phosphonia, 184
Phosphonic acid, 197
anhydrides, 179
Phosphonium, 184
inorganic, 219
mercury derivs., 194
salts, 198
ylides, 201, 276
Phosphonium cyanide, 219
Phosphonocyanatidic acid, 179
Phosphonous acid, 197
Phosphorane, 143, 197
order of precedence of, 106, 271
and phosphonium ylides, 201
Phosphoranyl, 161
Phosphoric acid, 197
anhydrides, 179
esters, 185inorganic salts, 219
replacement names from, 129
Phosphorin, 146
Phosphorochloridic acid, 129
Phosphorodiamidic acid, 197
Phosphorodithioic acid
esters, 185
Phosphorothioic acid
esters, 185
Phosphorothioic triamide, 129
Phosphorous acid, 197, 219
esters, 185
Phosphorous trichloride, 197
Phosphorus(1+), 215
Phosphorus acids, 197, 219
anhydride-esters, 186
anhydrides, 179

150

inorganic, and salts, 219
nucleotide esters, 210
replacement names for, 129
salts, 198
Phosphorus compounds, 197
monocyclic, 146
order of precedence of, 106, 271
retrospective index searching for, 276
spiro, abnormal valency in, 158
tautomeric, 122
Phosphoryl, 276
Phosphoryl chloride, 276
Phthaleins, 216
Phthalocyanine, 223, 278
copper complex, 215
Phylloquinone, 224
Physicochemical units
manual of, 300
Pi-bonded ligands, 215
Picrasane, 202
Picrates, 180, 192
Pigments
organic, 216
Pinane, 212
Piperazine, 146
Piperazinium, 184
Piperidine
pyridine preferred to, 138
Platinum metals, 219
Plumba, 158
Plumbane, 143, 199
iodo derivs., 219
Plumboxanes, 199(+) (plus), 203
Plutonyl ion, 219
Polyalkylene glycols, 222
Polyamides“a” names for, 171
fibers, 222
Polyboranes, 159
hetero, 160
radicals from, 161
Polycyclic systems, 147. See also Ringsystems
Poly(dioxobutanediyl), 222
Polyesters, 222
Polyethylene glycols, 222
Polymers, 222of amino acids, 206“a” names not used for, 127of carbohydrates, 208of coordination compds., 215
nomenclature of, history and developmentof, 307
order of citation of, in modifications, 113
retrospective index searching for, 277
stereochemistry of, 203
structural diagram derivation for, 315
Poly(methylene), 220
Polynucleotides, 222
IUPAC-IUB recommendations fornomenclature of, 297
Poly(oxyethanediyl), 222
Poly(oxymethylene), 222
Polyphenyls, 157
branched, 163
functional derivs., 163
radicals from branched, 162
radicals from unbranched, 161
Polypropylene glycols, 222
Polysaccharides, 208
Polysulfides, 200
order of precedence of, 106
Polyvalent radicals
in multiplicative names, 125
Porphine, 223
Porphyrazine, 223
Porphyrins, 223
retrospective index searching for, 278
Positron, 217
Positronium, 217
Potassium phosphate sulfate, 219
P,P′, 219
Precedence
order of—see Order of precedence
Preferred index names
definition of, 192
Prefixes
miscellaneous, 309
multiplicative—see Multiplicative prefixes

151

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

substituent—see Substituent prefixes
Pregnane, 211
and derivs., stereochemistry of, 203
Pregnenedione
mixtures containing, 221
Primary components
in fused systems, 151
Primed locants, 114
in fused systems, 151, 152
Principal chemical groups, 104, 164-177
esters of, 185
hetero-atom-attached, 163
lowest locant for, 137
as suffixes, 131
Proline, 205
salts, 202
Pronunciationof chemical words, ACS report on, 302
Propadiene, 141
Propanamine, 176
Propanebis(thioic) acid, 165
Propanedioic acidanhydride-esters, 186
anhydrides, 179
cyclic esters, 185esters, 185
hydrazides, 189
Propanesulfonic acid, 131
Propanetriol
esters, 185
Propanimine, 177
Propanoic acid, 131, 165
anhydrides, 179
Propanone, 174
hydrazone, 190
retrospective index searching for, 262
Propene(dithioic) acid, 165
Propenoic acidpolymers containing, 222
Propenol, 141
Propoxide, 180
Prostaglandins, 202
Prostane, 202
Proteinases, 218
Proteins, 207
enzymes, 218, 246
Proton, 217
Punctuation, 108
Purinamine
derivs., 210
glycosyl, 208
Purinenucleoside and nucleotide derivs., 210
numbering of, 152
tautomeric derivs. of, 122
Purinium, 184
Purinonederivs., 210
Pyran, 135, 146
Pyranone, 135, 136
Pyranoses, 208
Pyranosides, 208
Pyrazine, 146
Pyrazole, 146
tautomeric derivs., 122, 180
Pyrazolidine, 146
Pyrenenumbering of, 152
Pyridazine, 146
Pyridine, 146preferred to piperidine, 138
Pyridinecarboxamide, 224
Pyridinium, 184
acyloxy derivs., 185
ylides, 201
Pyridinone
hydrazones and oximes, 122
Pyridinyl, 161
Pyridoxal, 224
Pyridoxamine, 224
Pyridoxol, 224
Pyrimidine, 146
nucleoside and nucleotide derivs., 210
tautomeric derivs., 122
Pyrindine, 281
Pyrophosphoric acid, 197, 273
Pyrrole, 135, 146
Pyrrolidine, 135, 146
Pyrylium, 184

Quark, 217
Quater, 157
Quaterphenyl
radicals from, 162
Question marks, 120
Quinoline
analogs, 149
Quinolinium, 184
Quinolizinium, 184
Quinoxaline
in fused systems, 149, 151
Quinquephenyl, 157
radicals from, 162
R, 203, 212
Radical ions, 180
Radicals. See Free radicals; Substituent
prefixes
Radicofunctional nomenclature, 126
Ratiosin addition-compd. names, 192
in anhydride names, 179
in ester names, 185
Rayon, 222
Reductase, 218
Replacement nomenclature
for acids, 165
for acyclic skeletons, 127, 140, 142
for amides, 171
for amines, 176
for anhydrides, 179
for arsenic and phosphorus acids, 197
for boron compds., 182
for cations, 184
in cocarboxylase names, 224
for esters, 185
for ethers and peroxides, 196
for functional groups, 129
for fused systems, 149, 153
for hetero chains, 142, 144
for heterosteroids, 211
for hydrazides, 189
for ketones, 174
lowest locants in, 137
for minerals, 219
prefixes for, 128present and former rules for, 279, 280
for radicals, 133, 161, 287
for silicon (etc.) compds., 199
for spiro systems, 156
for sulfur compds., 200
for urea derivs., 183
for Von Baeyer systems, 155
Replacement prefixes, 128elision of “a” in, 146
Resonance-stabilized compounds
anions, 180
cations, 184
phenazine and phenothiazine amino derivs.,
216
Retinoic acid, 212
Retinol, 212
retro, 206, 211, 212
Retrocarotenes, 212
Retrospective searchingfor index names, 225-293
Retrosteroids, 211
Ribitol, 208
riboflavin deriv., 224
ribo, 208
Riboflavin, 224
Ribofuranosyl, 210
Ribonic acid, 208
Ribonuclease A, 207
Ribose, 208
Ring assemblies, 147, 157, 266, 281
added hydrogen in, 136
indicated hydrogen in, 135
locants for, 114
punctuation for, 109
radicals from, 161, 287
retrospective index searching for, 281
Ring contraction
in alkaloids, 204
in steroids, 211
in terpenes, 212
Ring expansion
in alkaloids, 204
in steroids, 211
in terpenes, 212

Semi

Ring-size descriptors, 108
Ring systems
additional index entries for, 138, 163, 281
base components of fused, 150, 281
bridged fused, 154
carbocyclic fused, 148with functional side chains, 124
fused steroidal, 211
heterocyclic, 199
arsenic- and phosphorus-containing, 197
cyclic esters named as, 185
fused, 149
imides named as, 191
oxygen-containing, 196
indicated hydrogen in, 135
locants for, 137
metal-containing, 194
monocyclic hetero, 146
monocyclic hydrocarbon, 145
nitrogenous, N-acyl derivs., 171
order of precedence of, 138
polycyclic, 147preferred to acyclic skeletons, 138, 271
radicals from, 161
replacement names for fused, 153
retrospective index searching for, 281
Von Baeyer, 155
Roman letters
as locants, order of citation of, 114
Rotaxanes, 192
Rubber, 222s, 108S, 203, 212
35S, 220
SIV, 140, 158
Saccharides, 208
in nucleosides and nucleotides, 210
Salamandra alkaloids, 211
Salt-type parents, 219
Salts, 198. See also Molecular addition
compoundsof amino acids, 205of cations, 180
citation of, in modifications, 113
common anions of, 198, 281A
double and mixed, 219
of germanium, lead, and tin, 199
inorganic, 219
locants not used for, 119of stereoparents, 202
Sanbornite, 219
Schiff bases, 176
scyllo, 209
Searchingretrospective, for index names, 225-293
Seco, 204, 212
Secocholestanol, 211
Secocholestatrienol, 224
Secoergostatetraenol, 224
Secostrychnidinoic acid, 204
Selectionof index names—see Index name selection
Selenals, 173
order of precedence of, 106
Selenic acid, 219
Selenic diamide, 219
Selenides, 200, 271
di and poly, order of precedence of, 106of elements, 219
Seleninic acids, 165
Selenious acid, 219
Selenium compounds, 200
order of precedence of, 106
Seleno, 200
Selenols, 175
order of precedence of, 106
Selenonic acids, 165
Selenonyl chloride, 219
Selenophene, 146
Selenosulfuric acid, 129
Selenotelluroarsenious acid, 219
Selenoxo, 174
Selenyl, 219
free radical, 187
Selones, 174
order of precedence of, 106
Semicarbazones, 190
of stereoparents, 202

Semi

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Semicolons, 108
Semioxamazones, 190
Septanoses, 208
Sequence rule, 203
Sesqui, 192, 265A, 311
Sigma-bonded ligands, 215
Sila, 128
Silabenzene, 146
Silacyclopentane, 199
Silacyclopropane, 146
Silanamine
derivs., 144, 176
multiplication of, 118
N-silyl, 199
Silane, 143, 199
acyl derivs., 163
order of precedence of, 106
polymers, 222, 277
tetrachloro, 257
Silano, 154
Silanol, 175, 199
multiplication of, 118
Silathianes, 199, 282
Silazanes, 144, 146, 199
Spiro systems, 156
Von Baeyer systems, 155
Silica, 219
Silicic acids, 199, 282
Silicide
as index parent, 180
Silicon compounds, 199, 282“a” names for acyclic, 142
fused systems, 149
monocyclic, 146
order of precedence of, 106
polymers, 222, 277
retrospective index searching for, 282
Von Baeyer systems, 155
Siloxanes, 144, 199
cyclic, 146
polymers, 222, 277
ring assemblies, 157
Spiro systems, 156
multiplicative radicals from, 125
Von Baeyer systems, 155
Silylene
free radical, 187
Silylidyne, 161
Sodio, 215
Sodium chloride, 219
labeled, 220
mixtures containing, 221
Sodium chloride sulfate, 219
Sodium hydride, 219
Sodium oxide, 219
Sodium peroxide, 219
Solanidane, 211
Solanidenol, 211
Solanidine, 211
Solasodine, 211
Solid solutionsof inorganic compds., 219
Solvates, 192
Spacesin uninverted names, 108
Species names
for peptides, 206
Spelling, 107present and former rules for, 283
Spirobi, 156
Spirohexasiloxane, 156
Spirooctane, 156
Spirosolane, 211
Spirostan, 211
Spiro systems, 140, 147, 156
added hydrogen in, 136
cationic, 184
indicated hydrogen in, 135
punctuation in names of, 108, 109
radicals from, 161steroidal, 211
SRUs, 222
Stainless steel, 214
Stannane, 130, 143, 199
Stannanetetrayl, 161
Stannate
dipotassium, 219
Stannathianes, 144
Stannazanes, 144

Stannoxanes, 199
Starch, 208
Steel, 214
Stereochemical descriptors, 203, 284, 318
for alkaloids, 204
for amino acids and peptides, 205, 206
for carbohydrates, 208
chirality symbols, 203
for inositols, 209
for polymers, 222
for steroids, 211
for terpenes, 212
Stereochemistry, 202-212, 284, 318
ACS reports on, 302
assumptions, 205of biline, 223
at double bonds, reports on, 301, 302
of inositols, 209
IUPAC tentative rules for, 296
of octahedral inorganic compds., IUPAC
tentative proposals for, 298
of polymers, IUPAC nomenclature reporton, 299
present and former rules for, 284
Stereoparents, 101, 202-212, 285, 318
addition compds. of, 192
copolymers, 222
definition of, 202
mixtures containing, 221
midified stereochemistry cited for, 203present and former indexing rules for, 285
Steroids, 211with modified stereochemistry, 203
retrospective index searching for, 286
Stibinamine, 181
Stibine, 143, 181
boryl derivs., 182
Stibine oxide, 181
Stibine sulfide, 181, 200
Stibino, 161, 181
Stibole, 181
Stibylene, 161
Stigmastane, 211
Stock numbers, 219
in vitamin B12 names, 224
Streptamine, 209
Structural diagrams, 135
in CA indexes, 315
derivation from index names, 312-318
Structural repeating units, 222
Strychnidine, 204
Subdivisionsof large index headings, 104
Substituent prefixes, 161, 294, 316
from acids-see Acid radicals
alphabetic list of, 294“a” names for, 128
cationic, 184
compound and complex, 133, 162elision in, 283
enclosing marks for, 109
ester groups as, 112
functional groups expressed as, 250
inversion of, 104
locants for, 117
locants in, 116
lowest locants for, 137
maximum number of, 122, 133, 138from metals, 215
multivalent, as structural repeating units,
222
order of citation of, 121
polyvalent, in multiplicative names, 125present and former rules for, 287
from steroids, 211
Substituent suffixes, 131
locants for, 115
order of precedence of, 106
principal groups as, 131, 164-177, 315
Substitutive nomenclature, 130, 139, 164
Substitutive parent compounds, 130
Subtractive nomenclature, 139
Succinic acid. See Butanedioic acid
Sucrose, 208
Suffixes. See Substituent suffixes
Sugars. See Carbohydrates
Sulfamic acid, 219
as elided name, 107
metal salts, 219

152

Sulfamide, 219
derivs., 219
as elided name, 107
Sulfanilic acid, 167
Sulfato, 215
Sulfenic acids, 165
esters, 196
Sulfenoselenoic acids, 200
Sulfenothioic acids, 165, 188, 196, 200
Sulfides, 200, 271
of elements, 219
di and poly, order of precedence of, 106of hetero atoms, 158of nitrogen and phosphorus compds., 200
retrospective index searching for, 288
Sulfilimine, 200
Sulfimide, 200, 219
Sulfinic acids, 165
Sulfinimidic acids, 165, 200
Sulfinyl, 168, 200, 219
Sulfinylamino, 200
Sulfinylsulfonyl, 200
Sulfonamides, 171
Sulfonefluorescein, 216
Sulfonephthaleins, 216
Sulfones
retrospective index searching for, 289
di and poly, order of precedence of, 106
Sulfonic acids, 165
acyclic with cyclic substituents, 166
anhydrides with inorganic acids, 219
esters, 185
free radicals from, 187
order of precedence of, 106, 167
Sulfonimidic acids, 165
Sulfonimidoyl, 200
Sulfonium, 184, 219
ylides, 201
Sulfoniumyl, 184
Sulfonohydrazonic acids, 165
Sulfonohydrazonimidic acids, 129
Sulfonothioic acids
esters, 200
Sulfonyl, 168, 200, 219
Sulfonyl halides, 170
Sulfonyloxy
in free radical names, 187
Sulfoxides, 200
retrospective index searching for, 289
Sulfoximine, 200
Sulfoxylic acid, 219
selenium analogs not recognized, 219
Sulfurcoordination complexes, 131, 200
tetravalent, in ring systems, 140
Sulfur acids, 219
order of precedence of, 106
Sulfur compounds, 200
cyclic, with abnormal valencies, 158dyes, 216
retrospective index searching for, 288
thio carbohydrates, 208
Sulfur diimide, 106, 200
Sulfur dioxide, 219
Sulfuric acid, 219
ammonium iron salt, 219
anhydrides, 179
esters, 185
and metal salts, 219
uranium complex, 219
Sulfurous acid, 219
monosodium salt, addition compds., 192
Sulfur oxides, 219
Sulfur trilmide, 200
Sulfur trioxide, 219
Sulfuryl, 219
Sulfuryl chloride, 219
Superoxides
of elements, 219
Superoxido, 215
Superscripts
abnormal valency indicated by, 158
in Von Baeyer names, 155
Superscripts, 114, 137
Sydnones, 201, 293A
syn, 203
Synonym line formulas. See Line formulas
Synthetic fibers, 222
System indicators

153

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

for coordination compds., 203tin tritium-labeled compds., 220
Tachyon, 217
Tacticityof polymers, 222
Tantalateheptapotassium, 219
Tartaric acidaddition compds. of, 192
Tautomeric compounds, 122
acetoacetanilide and pyrazolinone dyes, 216
amides and imidic acids, 165
anions, 180
cations, 184
cyclic amines and imines, 177
histidine, 205
hydrazides and hydrazonic acids, 165
tropolones, 122, 180
urea and carbamimidic acid, 183
Tellones, 174
order of precedence of, 106
Tellurals
order of precedence of, 106
Tellurenic acids, 165
Telluric acid, 219
Tellurides, 200, 271
of elements, 219
order of precedence of, 106
Tellurinic acids, 165
Tellurinyl, 200
Tellurium compounds, 200
order of precedence of, 106
Telluro, 200
Tellurols, 175
order of precedence of, 106
Tellurophene, 146
Telluroxo, 174
Telomers, 222
Tercyclopropane, 157
Terpenes, 212
ACS proposed system of nomenclature for,302
retrospective index searching for, 290
Terphenyl, 157
Terphenylcarboxylic acid, 163
Terphenyldiyl, 161
Terphenylyl, 162
Terpyrazolidine, 157
Tetra, 110
tetrahedro, 108
Tetrakis, 110
Tetraoxatetradecapentaene, 142
Tetraoxatetradecene, 142
Tetraoxatridecane, 142
Tetraoxatridecyl, 161
Tetraoxides, 196
Tetrapyrroles, 223
Tetrasiladecenylidene, 161
Tetrasilatetradecane, 142
Tetrasiloxane, 199
Tetrazadiene, 143
Tetrazane, 143
Tetrazene, 143
Theophylline, 122Thia, 128
Thiaandrostane, 211
Thiadiazole
abnormal valency in, 158
Thials, 173
order of precedence of, 106
Thiamine, 224
Thiaporphine, 223
Thiazolium
vitamin B12 deriv., 224
Thiireno systems, 281
Thio, 200
Thio acids, 165, 200of arsenic and phosphorus, 197
esters, 200
esters, S-oxides, 185retrospective index searching for, 280
Thioamides, 171
S-oxides, 200
Thioboric acid, 219
Thiocyanic acid, 183, 219
anhydrosulfides, 183, 188
Thiodicarbonic acid, 129, 200
Thiodiphosphonic acid, 179

Thiodiphosphoric acid, 219
Thiohydroperoxides, 129, 196
Thiohypochlorous acidanhydrosulfides, 170, 188
Thiohydroxylamine, 129
order of precedence of, 106
Thioic acids, 129, 165
Thiols, 175
Class I, 185order of precedence of, 106
retrospective index searching for, 291
Thiometaphosphimic acid, 197
Thiomorpholine, 146
Thiones, 174
order of precedence of, 106
S-oxides, 200thiono, 108
Thionyl, 219
Thionyl chloride cyanide, 219
Thionyl imide, 200
Thioperoxides, 129, 196
Thioperoxy acids
esters, 185
Thioperoxydicarbonic acid, 183
Thioperoxydicarbonic diamide, 200
Thioperoxydiphosphoric acid, 197, 219
Thioperoxydiphosphoric tetrafluoride, 200
Thioperoxymonosulfuric acid, 219
and esters, 200
Thiophene, 146
abnormal valency in, 158
Thiophene-ol, 175
Thiopheniumyl, 184
Thiophosphoryl chloride, 276
Thiosemicarbazones, 190
Thiosilicic acid, 199, 219
Thiosulfuric acidanhydrosulfides, 200
Thiosulfuric acidium, 219
Thiosulfurous acid, 219
Thiosulfuryl chloride, 219
Thiotrithiazyl, 219
Thiourea, 129, 183
Thioxanthene, 149
Thioxo, 131, 174
in terminal position, 173
Thioxomethyl, 134, 173, 174
Thorium hydride iodide, 219
threo, 208
Thromboxane, 202
Thymidine, 210
Thymidylic acid, 210
Tin chloride, 219
Tin compounds, 199
cyclic, 139
monocyclic, 146
order of precedence of, 106
Titanyl, 219
Tocopherols, 224
Tomatidlne, 211
Trade names
for polymers, 222
trans, 203
Transition metals, 219
amino acid salts of, 205
Tri, 110
Triazane, 143, 193
order of precedence of, 106
Triazanium, 184
Triazanyl, 161
Triazatriphosphorine, 158, 197
Triazenyl, 193
tautomerism of, 122
Triazinetriamine
polymers with formaldehyde, 222
Tribismuthine, 181
Triborane, 159
Trichlorodiphosphoric acid, 219
Trichothecane, 212
Tricyclododecane, 155
Triguanide, 280
Triiodidesof elements, 219
Trimersof sulfimide, 219
Trioxatriphosphorinane, 197, 219
Trioxides, 196
order of precedence of, 106
Trioxopropanediyl, 168
Triphenylene, 148

Vita

Triphosphonic acid, 179
Triphosphoric acid, 219
Triple bonds. See Unsaturated compounds
Tris, 110
Trisilaneorder of precedence of, 106
Trisiloxane, 140, 144
Trisiloxanetriyl, 161
Tristannane, 143
Tristannathiane, 144
Tristannoxane, 199
Trisulfides, 200
order of precedence of, 106
Trisulfones, 200
order of precedence of, 106
Trisulfuric acid, 219
Trisulfuryl chloride, 219
Trithiaazatetradecenediyl, 161
Trithiatristannacyclohexane, 146
Trithiatriazine
hexaoxide, 219
Tritium
compds. labeled with, 220
Trivial names, 101
for monocyclic hetero systems, 146
Tropine, 204
Tropolones, 122, 180
Tyrosine
peptides containing, 206
Ulosaric acids, 208
Ulosonic acids, 208
Ulosuronic acids, 208-ulosyl, 208
Uninverted index names, 104, 108
brackets around index parent in multiplicative, 109of esters, 104of salts, 198
Unnilpentium, 219
Unsaturated compounds
acyclic, 141
carbohydrates, 208
conjunctive names not formed from acyclic,
124
double vs. triple bonds in, 138
greater number of multiple bonds in parentof, 138
locants for, 114, 137
monocyclic hydrocarbons, 145
spiro systems, 156
steroids, 211
Von Baeyer systems, 155
Ununnilium fluoride, 219
Uracil, 122
Uranate, 219
Uranium
complexes, 219
Uranium chloride oxide, 219
Uranyl, 219
Urea, 183
derivs., retrospective index searching for,292
hydroxy, 193
no locants for monosubstituted, 117
polymers with formaldehyde, 222
tautomerism of, 183
Urethanes, 185
Ureylenecarbonyldiimino as name for, 134
Uric acid, 122
Uridine, 210
Uridylic acid, 210
Uronamides, 208-uronamidosyl, 208
Uronic acids, 208-uronosyl, 208
Ursane, 212
Valencyabnormal, in ring systems, 158, 161, 163
Valine, 205
peptides containing, 206
Vanadyl, 219
Vasopressin, 206
Veratraman, 211
Veratrum alkaloids, 211
Vinyl acetal polymers, 222
Vinyl alcohol polymers, 222
Vitamin A, 212, 224

Vita

Naming and Indexing of Chemical Substances for Chemical Abstracts 2007

Vitamin B12, 224. See also Corrinoids
Vitamins, 224
IUPAC-IUB tentative rules for, 297
retrospective index searching for, 293
Von Baeyer systems, 140, 155
cationic, 184
choice between, 138
oxygen-containing, 196
punctuation in, 108, 109, 155
radicals from, 161
Vowelselision of, 107, 146
Water, 219
in coordination compds., 219
hydrates, 113, 192, 265A, 311
labeled, 220
Willemite, 219

Xanthene, 149amino derivs., 216
numbering of, 152
Xanthic acids, 185
Xanthine, 210
derivs., 122
Xanthophylls, 212
Xanthosine, 210
Xanthylic acid, 210
Xenonate, 219
Xenon compounds, 219-yl, 161-ylene, 161
Ylic acids
nucleotides, 210-ylidene, 161
added hydrogen for cyclic, 136

in multiplicative names, 125, 255
Ylides, 201, 276-ylidyne, 161-ylium, 184-ylylidene, 161-yne, 139, 141, 155-ynyl, 161
Z, 203report on, 301
Zincatedye derivs., 216
Zinc chloride
double salts with dyes, 216
Zinc sulfide, 219
Zirconyl, 219
Zwitterionic compounds, 201, 293A

154