Library, N.W. Bldg //

OCT 5 196| ^

" E*- NBS MONOGRAPH 54

Analytical Standards

For Trace Elements

In Petroleum Products

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

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Outside Journals 1950 to 1959) ($2.25); available from the Superintendent of Documents, Government Printing Office, Washington, D.C.
UNITED STATES DEPARTMENT OF COMMERCE . Luther H. Hodges, Secretary

NATIONAL BUREAU OF STANDARDS • A. V. Astin, Director

Analytical Standards for Trace Elements

in Petroleum Products

H. S. Isbell, R. Stuart Tipson, J. L. Hague, B. F. Scribner,

W. Harold Smith, Clarence W. R. Wade, and Alex Cohen

National Bureau of Standards Monograph 54

Issued October 1, 1962

For sale by the Superintendent of Documents, U.S. Government Printing Office Washington 25 D.C. Price 25 cents

Contents

Page

1. Introduction 1

1.1. Origin and history of the project 1

1.2. Outline of the problem I

1.3. Outline of the project 2

2. Discussion of the work done 2

2.1. Exploratory study of available compounds 2

2.2. Compounds prepared and studied 2

2.2.1. Metal salts of carboxylic acids and of

dialkyldithiocarbamic acids 3

2.2.2. Chelate compounds 4

a. Chelate compounds of azomethines (SchifT bases) 4

b. Chelate compounds of dike- tones and hydroxy ketones 5

2.2.3. Miscellaneous compounds 5

2.3. Evaluation of compounds 5

2.3.1. Cooperative tests 5

2.3.2. Spectrographic analysis 5

2.3.3. Chemical analysis 6

2.3.4. Weight-stability of standard com- pounds 6

2.3.5. Dissolution in petroleum oils 6

3. Experimental procedures 7

3.1. Materials 7

3.2. Drying of products 7

3.3. Preparation of solubilizing agents 7

3.3.1. Bis (2-ethylhexyl) dithiocarbamic

acid 7

3.3.2. 6-Methyl-2,4-heptanedione 7

3.4. Preparation of compounds chosen as standards 7

3. Experimental procedures—Continued

3.4. Preparation of compounds, etc. —Con.

3.4.1. Cyclohexanebutyrates 8

a. Preparation 8

b. Recovery of cyclohexanebutyric

acid - 13

3.4.2. Miscellaneous compounds 13

3.5. Other compounds investigated 15

3.5.1. Erucates and 2-ethylhexanoates 15

3.5.2. Dialkyldithiocarbamates 15

3.5.3. Azomethine chelates 15

3.6. Spectrographic analysis 16

3.7. Chemical analysis 16

3.7.1. Wet-ashing: ignition 17

3.7.2. Wet-ashing 18

3.7.3. Ignition 18

3.7.4. Other procedures 18

3.8. Weight-stability of standards 18

3.9. Dissolution in petroleum oils 19

3.9.1. Metal 2-ethylhexanoates 20

3.9.2. Metal erucates 20

3.9.3. Metal dialkyldithiocarbamates 20

3.9.4. Metal chelates of azomethines 21

3.9.5. Metal chelates of diketones and

hydroxy ketones 21

3.9.6. Metal cyclohexanebutyrates 21

3.9.7. Miscellaneous compounds 21

3.9.8. Preparation of an oil solution containing one element of interest, at the desired concentration 21

3.9.9. Preparation of an oil solution containing several elements of interest, at the desired concentration. 22

4. References 23

iii

Analytical Standards for Trace Elements in Petroleum Products'

H. S. Isbell, R. Stuart Tipson, J. L. Hague, B. F. Scribner, W. Harold Smith,^

Clarence W. R. Wade, and Alex Cohen

A search has been conducted for stable, oil-soluble, organic compounds of metals (and

other elements) for use in the spectrographic analysis of petroleum products. Compounds

having suitable physical properties have been selected as standards in the determination of the following 24 elements: aluminum, barium, boron, cadmium, calcium, chromium, cobalt,

copper, iron, lead, lithium, magnesium, manganese, mercury, nickel, phosphorus, potassium,

silicon, silver, sodium, strontium, tin, vanadium, and zinc. The compounds have been

purified and analyzed, and are available as certified standards.^

These stable, oil-soluble standards were selected from over 150 prospective compounds

described in the Monograph. Methods are given for preparation of the compounds and

for the spectrographic and chemical analysis of the chosen standards. Procedures are described for the preparation of stable solutions thereof in petroleum oils. Xylene, together

with 2-ethylhexanoic acid, 6-methyl-2,4-heptanedione, and 2-ethylhexylamine (and specified

mixtures thereof) are used as additives to render the various samples soluble. The resulting

solutions are all compatible with each other, so that blends containing a known amount of

each element of interest can be prepared as needed.

1. Introduction

1.1. Origin and History of the Project

Technological advances in the petroleum industry during the past 15 years have occasioned a need for quantitative determination of metallic

and other constituents present in petroleum and

related products. For example, spectrographic

determination of the content of certain elements in

lubricating oils after use of the oUs in engines

provides a simple means for judging engine wear

and serves as a guide in maintaining the equipment in a satisfactory operating condition. The

research laboratories of petroleum companies have

devoted much attention to developing spectrographic methods for determination of trace elements in petroleum products, but have been

handicapped by a lack of suitable, pure, oil-soluble

compounds (containing the elements of interest)

that could be used as standards.

Recognizing the need for standards for instrumental and chemical analysis for metals and other

elements in petroleum products, the Committee

on Analytical Research, Division of Refining,

American Petroleum Institute, proposed that the

National Bureau of Standards develop and distribute a series of reproducible, stable, nonvolatile,

oil-soluble compounds (preferably solid) suitable

for use as analytical, spectrographic standards.

' This Monograph is based on woric partly supported by the Committee on

Analytical Research, Division of Refining, American Petroleum Institute.

2 Deceased, May 14, 1959.

3 These standard samples, prepared in solid form for easy weighing and

handling, may be purchased for $10.00 per 5 g of material. A certificate of

analysis, plus directions for preparing a solution of the substance, is distrib- uted with each sample. Orders should be directed to the Standard Samples

Clerk, National Bureau of Standards, Washington 25, D.C.

As the result of informal conferences and corre- spondence, the Committee on Analytical Research

prepared an outline of the work desired and made

a contract with the Chemistry Division of the

National Bureau of Standards for the development

of a series of 24 such analytical standards containing, respectively, aluminum, barium, boron, cadmium, calcium, chromium, cobalt, copper, iron,

lead, lithium, magnesium, manganese, mercury,

nickel, phosphorus, potassium, silicon, silver,

sodium, strontium, tin, vanadium, and zinc. These

standards were to be distributed under the NBS

standard-materials program.

1.2. Outline of the Problem

Certain trace elements are present in petroleum

products, as residues from crudes carried over in

the refining process or as constituents of materials

added to improve the lubricating properties or to

lessen corrosive effects or oxidation. For many

years, analytical chemists in the petroleum industry have had the problems of (a) determining

minor elements, particularly metals, in petroleum

and (b) establishing the accuracy and reliability of

their methods. The analysis usually involves the

addition of an accurately known amount of an oilsoluble compound of the element in question to an

oil which contains none of this element; the resulting standard solution is carried through all the

steps of the method and the amount of the element

added is determined. The same procedure is applied to the "unknown" oil, and its content of

the element is determined by comparison.

1
The problem of finding suitable metaUo-organic

compounds for use as standards has increased as more additives have been introduced and as a more exact knowledge of the trace constituents of

petroleum and related products has been needed.

However, the commercial metaUo-organic compounds available were found to be not completely

satisfactory as standards because (1) metallic and

other contaminants are often present in these

compounds in amoxmts greater than that of the

trace element to be determined in the petroleum

product; (2) some of the compoimds are not

sufiiciently soluble in petroleum products; (3)

some of the compounds are sufficiently volatile

that considerable loss occmrs during (or even

before) the analysis; and (4) when combinations

of the elements (as their respective compounds)

were dissolved in a single oil, the compoimds often

gave incompatible mixtures.

In 1955, the Committee on Analytical Research,

Division of Refining, American Petroleum Institute realized that the development of suitable

standards for chemical analysis and for analysis

by emission spectrography. X-ray fluorescence,

flame photometry, or colorimetry was a pressing

need. A survey revealed that 24 elements,

mainly metals, were of particular interest in the

analysis of crudes, charge stocks, and finished

petroleum products.

1.3. Outline of the Project

When this project was started, oil-soluble

naphthenates, sulfonates, or hexanoates of most

of the metals of interest were available, as were

compounds of boron, phosphorus, and silicon.

However, few of these were spectroscopically pure,

many were unstable under conditions of use, and

most of them were unsuitable as standards for

analytical determinations. Moreover, methods

for the preparation of the pure compounds were

unavailable.

Although certain naphthenates and petroleum

sulfonates had been used as standards, naphthenic

2. Discussion of

2.1. Exploratory Study of Available

Compounds

The literature submitted to us by the Project

Study Group of the Committee was reviewed,

and requests were made tc all prospective suppliers of oU-soluble, metallo-organic compounds

for information concerning potentially useful

compounds that they might be able to supply.

About 40 samples of commercial compounds were

obtained and preliminary tests were made in

order to ascertain whether these might prove

suitable for use as standards.

2.2. Compounds Prepared and Studied

In order to form an opinion as to the kinds of

compounds most likely to be suitable for use as

acids and petroleum sulfonic acids are mixtures i having a composition which may difler from

batch to batch, and commercial products now

available might well differ from materials avail- i able in the future. To secure standards that i would not differ according to the source, it was i decided to prepare a series of more-readily

duplicated standards. Consequently, attention i was directed to the preparation of definite, reproducible, oil-soluble compounds (preferably solid)

of the 24 elements selected by the Committee.

Another object of the project was to develop ' methods for preparing suitable blends of the

standards in an appropriate base oil, so that possession of an adequate collection of oil-soluble

compounds wovdd permit preparation of any i desired blend (of known concentrations) at any i time and make it unnecessary to maintain a i variety of standardized blends. I After consultation with the Advisory Com- j mittee, the following program was developed. I (1) Tentative selection of general classes of 1 compounds having the desired properties, from

indications obtained by a search of the literature I and by correspondence with industry. !, (2) Qualitative examination of available materials to ascertain their suitability for use as standards.

(3) Preparation and purification of potentially

useful compounds.

(4) Determination of pertinent properties of

potentially useful compounds.

(5) Selection of specific compounds for use as I standards.

[ (6) Development of methods for preparing oil \ solutions of the standard compounds.

(7) Preparation of large batches of the standard

compounds.

(8) Spectroscopic and chemical analysis of

the standard compounds. i

(9) Sale and distribution, through the NBS

standard-materials program, of the selected compounds as certified standards for analytical use.

! the Work Done j

standards, the chemical literature was studied,

j a large number of potentially useful compounds j were prepared, and qualitative tests of their ' solubility and stability were made. From the !, results of these studies, the compounds that

seemed most suitable were then selected for i further study; these are brieflj^ discussed in the | next three sections.

| Table 1 lists the salts prepared and examined. | Those italicized were distributed to cooperators

| in the petroleum industr}^, for qualitative evalu- i ation. From the results of these and other tests,

^ the compounds listed in table 2 were selected as the most promising; those italicized were prepared and distributed in 1958 to workers wishing

to examine them for possible use as standards.

2
I Table 1. Exploratory study of salts of metals *

ball 01 A 1 x>d Or- r t3 X D

T ; IVlg ivin IN 1 or on V

A. uarboxylic Acids

1, Naphthenic acids Yb V'' u\ -A. -A. Y Yh

2. Cyclohexanebutyric acid X X X X X X X X X X X X X X X X X

3. 2-Ethylhexanoic acid X X X X X X X X X X X X X X X X X

4. Palmitic acid Y AY -AY Y Y A

5. Oleic acid Y Y -AY

6. Erucic acid Y -A. V" -A Y Y Y Y Y A' -A A'" Y Y

D, IJ 111 ilULd.ru aiLUiL iVLlUb

1. Diethyl- X X X X X X X X X X X X X

2. Diisopropyl- X X X X X X X X

o. xJiuuiyi- x^ I" -AY Y -A" Yb Y -AY X Y X Y

4. Diisopcntyl- Y -A. Y Y -AY

Y Y

D. j^mepiyi- -A. -A. Y Y

7. Dicyclohexyl- X X X X X X X X X X X A' A' X X

8. Bis(2-ethylhexyl)- X X X X X X X X X A' A' X

9. 2-Ethylhexyl- X X X X X X X X

10. Hexadecyl- X X X X X X X X X X X

11. Cyclohexyl- X X X X

» The symbol X indicates that this salt was prepared; an italic Vindicates that a sample of this salt was evaluated by cooperators in the petroleum industries.

•> Oily product which did not crystallize.

Table 2. First set of compounds selected as possible

standards *

(April 11, 1958)

Element Compound

1. Aluminum 2-ethylhexanoate

2. Barium (a) enicai.e; (b) bis(2-ethylhexyl)dithiocarbamate

3, Boron (a) tTis{2-cyclohexylcyclohexyl) borate; (b) tris(diiso- butylcarbinyl) borate

4. Cadmium dibutyldithiocarbamate

5. Calcium (a) erucate; (b) 2-ethylhexanoate

6. Chromium (a) oleate; (b) erucate

7. Cobalt (a) dibutyldithiocarbamate; Qi) bis(2-ethylhexyl)dithio- carbamate

8. Copper (a) dibutyldithiocarbamate; (b) bisQ^-salicylidene-2- ethylhexylamine) chelate

9. Iron (a) dibutyldithiocarbamate; (b) diisopropyldithiooarba- mate

10. Lead dibutxjldithiocarbamate

11. Lithium (a) erucate; (b) dicyclohexyldithioearbamate

12. Magnesium erucate

13. Manganese (a) cyclohexanehutyrate; (b) oleate

14. Mercury dibutyldithiocarbamate

15. Nickel (a) dibutyldithiocarbamate; (b) bis(,2-ethylhexyl)dithio- carbamate; (c) bis(Ar.salicylidene-2-ethylhexylamlne) chelate

16. Phosphorus triphenyl phosphate

17. Potassium (a) erucate; (b) bis(2-ethylhexyl)dithiocarbamate;

(c) dicyclohexyldithioearbamate

18. Silicon octaphenylcyclotetrasiloxane

19. Silver

20. Sodium (a) erucate; (b) dicyclohexyldithioearbamate

21. Strontium erucate

22. Tin dibutyldithiocarbamate

23. X^anadium bis(salioylaldehyde oxime) chelate

24. Zinc dibutyldithiocarbamate

» The compounds italicized were evaluated by cooperators in the petro- leum industries.

As a result of these tests, the compounds listed

in table 3 were selected for further study. (Ultimately, the compounds listed in table 6 were

chosen as standards.)

2.2.1. Metal Salts of Carboxylic Acids and Dialkyldithiocarbamic Acids

Salts of carboxylic acids (see table 1) were

prepared by one or other of the following methods.

Table 3. Second set of compounds selected for consideration

as standards

(Sept. 30, 1958)

Element Compound

1. Aluminum (a) 2-ethylhexanoate; (b) cyclohexanehutyrate

2. Barium (a) erucate; (b) 2-ethylhexanoate

3. Boron menthyl borate

4. Cadmium (a) dibutyldithiocarbamate; (b) cyclohexanebutyrate

5. Calcium 2-ethyIhexanoate

6. Chromium (III) (a) 2-ethylhexanoate; (b) cyclohexanehutyrate

7. Cobalt (II) cyclohexanehutyrate

8. Copper (a) dibutyldithiocarbamate; (b) cycloliexanebutyrate; (c) bis(iV-salicylidene-2-ethylhexylamine)

9. Iron (III) (a) dibutyldithiocarbamate; (b) cyolohexanebutyrate

10. Lead (a) dibutyldithiocarbamate; (b) erucate

11. Lithium erucate

12. Magnesium (a) erucate; (b) cyclobexauebutyrate

13. Manganese cyclohexanehutyrate

14. Meroviry cyclohexanebutyrate

15. Nickel (a) bis(2-ethylhexyl)dithiocarbamate; (b) bis(Wsalicylidene-2-ethylhexylamine); (c) cyclohexanehutyrate

16. Phosphorus triphenyl phosphate

17. Potassium erucate

18. Silicon octaphenylcyclotetrasiloxane

19. Silver cyclohexanebutyrate

20. Sodium (a) erucate; (b) cyclohexanebutyrate

21. Strontium erucate

22. Tin (IV)

23. Vanadium bis (W-salicylidene-2-ethylhexylamine) chelate

24. Zinc (a) dibutyldithiocarbamate; (b) erucate; (c) cyclo- hexanebutyrate

(a) Sodium salt of the acid plus a salt of the

metal

7iRC00Na+M"+^(RC00)„M+ 7iNa+.

(b) The acid plus the metal hydroxide

n RCOOH+M(OH) (RCOO) „M +n H^O.

(c) The acid plus the metal oxide

2n RCOOH+M20„-^2 (RCOO)„M+H.O.
(d) (For aluminum) The acid plus aluminum

isopropoxide

3IICO2H +Al (OCaHv)3^(RCO2)3AI +SCaHvOH

.

(e) The acid plus the metal acetate

n RC00H+M(0Ac)„-^(IlC00)„M+7i HOAc.

Although the naphthenates were found to have

suitable oil-solubilities, they were not chosen as standards because of lack of uniformity of naphthenic acid. In addition to the salts listed in

table 1, silver erucate, dibutyltin 2-ethylhexanoate, and silver cyclohexanebutyrate were prepared.

The salts of 2-ethylhexanoic acid and cvclohexanebut3T:'ic acid were found to be much less soluble

than the salts of naphthenic acid, but most of

them had the advantage of being definite, reproducible compounds.

Most of the compounds listed in table 1 were

obtamed as solids, many of them crystalline.

Before and after purification, the approximate

solubility in such common organic solvents as benzene, xylene, chloroform, alcohol, and ether

was ascertained. (This information also served

as a guide to the probable degree of solubility in

petroleum oUs.) For purification of carboxylic

acid salts, butyl acetate was found to be a general

solvent, but chloroform, ethanol, aqueous acetone, and water were preferable in some instances.

Acetone was used as a general precipitant for all of the cyclohexanebutyrates.

Many salts of the dialkyldithiocarbamic acids

were prepared according to the following equations.

R R s \ 6-10 °c \ 11 N—H+CS2 + NaOH » N—C—SNa + HjO

R R

S S

II II n R2N—C—SNa + M"+-^(R2NC —S)„M + raNa+

where M=Cu++, A1+++, etc.

Because of their ease of preparation, low

solubility in water, and characteristic colors,

these salts have been extensively used as organic

reagents for the detection and quantitative

estimation of many metals. Their solubilities

in paraffin or lubricating oUs have not, however,

been recorded in the literature.

Some of these salts lack stability, but others

seemed promising. In general, the heavy-metal

salts are insoluble in water but soluble in such

low-polarity solvents as benzene, chloroform,

carbon tetrachloride, and carbon disulfide. Benzene, chloroform, and ethanol were satisfactory

solvents for recrystallization.

The salts of diethyldithiocarbamic acid crystallize readily, but are only slightly soluble in

hot parafiin oil. The salts of dicyclohexyldithiocarbamic acid also have low solubility in paraffin

oil. The salts of dibutyldithiocarbamic acid are more soluble; crystalline dibutyldithiocarbamates

of cadmium, cobalt, copper, iron, lead, mercury,

nickel, and zinc were prepared and found to have

many desirable properties, but salts of the other

metals were less satisfactory. Salts of bis(2-

ethylhexyl)dithiocarbamic acid have excellent

solubility, but are much more difficult to isolate

and purify than the salts of the other carbamic

acids mentioned; only the nickel salt was satisfactory. In addition to the salts listed in tables

1, 2, and 3, some salts of 1,1,3,3-tetramethylbutyldithiocarbamic acid were prepared, but their

properties were unsuitable.

The solubility of dialkyldithiocarbamates in

lubricating oils is increased by the addition of

bis(2-ethylhexyl) dithiocarbamic acid.

2.2.2. Chelate Compounds

For a given metal, a variety of metaUo-organic

complexes were prepared and studied, in order to

evaluate (1) the methods of preparation; (2) the

increase or decrease in solubility caused, in a given class of chelates, by change of the bonding

groups and by branching or lengthening of the

alkyl side-chain; and (3) the relative stability of

various chelates.

Compounds examined in a cursory fashion

included metal derivatives of cupferron, dimethylglyoxime, a,Q;-(ethylenedinitrLlo)di-o-cresol, 1-nitroso-2-naphthol, 8-quinolinol, picolinic acid, rhodanilic acid, and the oximes of salicylaldehyde,

l'-hydroxy-2'-acetonaphthone, and 2'-hydroxyacetophenone.

Compounds prepared and examined in more

detail were various metal derivatives of (a) A^-

salicylidenebutylamine and A7'-salicylidene-2-ethylhexylamine, and (b) l,3-diphenyl-l,3-propanedione, 2,4-hexanedione, 1 '-hydroxy-2'-acetonaphthone, 2'-hydroxyacetophenone, 6-methyl-2,4-

heptanedione, 2,4-pentanedione, and l-phenyl-1,3-

butanedione.

a. Chelate Compounds of Azomethines (SchiS Bases)

The azomethines axid their metal complexes were prepared by the following reactions:

/

H

0=0

H R

+RNH2-

OH

+H2O

\ OH

H R

+M+

OH

M

R H

where Il =alkyl, and M+"'"=a metal ion.

Work was conducted on these chelates of cadmium, cobalt, copper, iron, nickel, vanadium, and

zinc. Of these, the crystalline complexes of cop4
per, nickel, and vanadium seemed the most

promising. However, the vanadium compounds

are not sufficiently stable for use as standards.

b. Chelate Compounds of Diketones and Hydroxy Ketones

In general, chelates of the ketones were prepared

according to one of the following equations:

R

H2C

\

c /

\c

0=0

+M++

c=o

R'

R R \ /

C=0 0=0

/ \ \

HC M CH

/ \ ^

C—0 O—

C

/ \

R' R'

R

I C=0

I

R

I C===0

-OH

-t-M+

M —O 0=0

I R

where R=H or CH3, and R' =alkyl or phenyl.

For aluminum and chromium, liquid chelates

of 6-methyl-2,4-heptanedione were prepared [1]''; efforts to crystallize these compounds were

imsuccessful.

The 2,4-pentanedione chelates of aluminum,

cadmium, chromium, cobalt, copper, iron, nickel,

and vanadium were prepared; the solubilities of

these compounds in lubricating oils were found to

be unsatisfactory.

Finally, the l-phenyl-l,3-butanedione chelates

of chromium, cobalt, iron, lead, and vanadium

were prepared. Of these compounds, the chelates

of cobalt, lead, and vanadium seemed the most

promising. Only the vanadium compound was

then studied in detail because (a) a suitable vana- dium compound had high priority and (b) this

diketone is too expensive for consideration unless

no other suitable derivative could be found.

2.2.3. Miscellaneous Compounds

A number of miscellaneous compounds were

studied.

(a) Triphenyl phosphate. A supply of triphenyl

phosphate was purchased. The ester was purified

by recrystallization from ethanol and from aqueous

ethanol, and its solubilities were studied. A

spectrographic analysis of the material indicated

that it would make a satisfactory standard.

(b) Borates. 2-Cyclohexylcyclohexyl borate was

prepared. It was found to contain impurities that

separated from solutions of the material in oil. Since the impurities were not readily removed,

other borates were examined. Menthyl borate

was prepared, and it was found to have satisfactory solubility in lubricating oils.

(c) Octaphenylcyclotetrasiloxane. Use of this

compound as a standard for silicon was suggested

* Figures in brackets indicate the literatiire references at the end of this Monograph.

by E. G. Tajkowski of the SUicone Products

Department, General Electric Company, Waterford, N.Y., and he kindly supplied the material

tested. The sample was found to be exceptionally

pure and to be suitable for use without further

treatment. It had certain desirable properties,

but low solubility in lubricating oils. (d) Other compounds studied included ferric 2-

methylpentanoate, mercm-ic 2-methylpentanoate,

aluminum 2-ethylhexanoate, calcium 2-ethylhexanoate, iron 2-ethylhexanoate, silver 2-ethylhexanoate, and potassium erucate.

2.3. Evaluation of Compounds

2.3.1. Cooperative Tests

In the evaluation of samples of our compounds

in laboratories of the petroleum industries, the

following were the cooperative tests made and the

cooperators.

Solubility, stability, and compatibility. California Researcla (R. L. LeTourneau), Esso Research

and Engineering (H. L. Leland), Gulf Research

(R. 0. Clark), Phillips Petroleum (B. J. Heinrich),

Shell Development (E. D. Peters), Standard Oil

of Indiana (E. B. Tucker), Texaco Research (F. M.

Roberts), Union OU (G. R. Lake).

Volatility. E. I. du Pont de Nemours (G. H.

Patterson), Ethyl Research (C. M. GambrUl).

At the meeting of our group with the Advisory

Committee on January 16, 1959, the following

decisions were then reached:

(1) To discontinue study of salts of naphthenic

acid, because the acid is a variable mixture of

acids that may differ from batch to batch.

(2) To avoid use of dithiocarbamates, because,

in some projected uses of the standards, introduction of sulfur would be undesirable, particularly

in X-ray fluorescence studies.

(3) To continue study of salts of cyclohexanebutyric acid (in preference to salts of erucic acid

and 2-ethylhexanoic acid), because they are more

readily isolated as solid materials.

(4) To continue search for a suitable compound

of vanadium.

(5) To proceed with preparation of large

batches of compounds selected as standards, and

to purify, analyze, and issue them as provisional

standards.

These decisions were then acted on. In connection with item 4, bis(l-phenyl-l,3-butanediono)-

oxovanadium (IV) was prepared, tested, and se- lected as the vanadium standard.

2.3.2. Spectrographic Analysis

Qualitative tests on the compounds prepared

dm"ing the exploratory part of the project indicated that there would be no particular difficulty

in obtaining reasonably pure materials for use as standards. After the program had become re- stricted to products to be used as standards,

semiquantitative spectrographic measurements

640506—62-
(and chemical analyses) were made on a sample

taken from the final, highly pm-ified batch of each

standard compound. The procedure for, and

results of, spectrographic analysis of the standard

compounds are given in section 3.6.

2.3.3. Chemical Analysis

Each standard sample was analyzed by appropriate methods, the details of which are given in

section 3.7. Table 4 lists the various methods

employed for decomposing the standard samples,

prior to analysis. The analytical results are given

in table 6.

TaBLE 4. Methods used fov decoTnpositioTi of stQ^7idQ,rd

samples

Method Standard Sample No. a

Sulfuric-nitrie acids 1050, 1051, 1052, 1052a, 1053, 1054, 1056, 1056a, 1057, 1057a, 1058, 1059, 1060, 1061, 1061 a, 1062, 1062a, 1065, 1065a 1066, 1067, 1070, 1071, 1072, 1073, 1076.

Ignition 1050, 1051, 1051a, 1062, 1062a, 1054, 1055,

1055a, 1056, 1058, 1059, 1059a, 1060a, 1061, 1062, 1065, 1067, 1068, 1069, 1069a, 1070, 1070a, 1073, 1073a, 1074, 1075 1076 1077

Peroxide fusion 1063, 1063a

Extraction with chloroform 1064

Perchloric-nitric acids 1071a

" The name of each standard sample is given in tal)le 6. Tlie letter a after the number of a standard sample indicates material obtaiaed in a second,

large-scale preparation.

2.3.4. Weight-stability of Standard Compounds

The weight-stability of each standard sample

was determined by (a) exposing the sample to

an atmosphere of 75 percent humidity for various

periods of time, and then, after equilibrium had

been reached, (b) drying the same sample over phosphorus pentaoxide. From the results, the

drying times recommended in table 6 were obtained

.

For those compounds which require only a

2-hr drying time, the maximum gain in weight

on exposure to 75 percent humidity was 0.08

percent. The maximum loss in weight when these

compounds were then dried over phosphorus

pentaoxide was 0.05 percent.

From the results of this work, it is recommended

that all specimens of the standard samples should

be stored in closed containers in desiccators

containing phosphorus pentaoxide.

2.3.5. Dissolution in Petroleum Oils

Since most of the solid, metallo-organic compounds that are stable in humid air are, for the

intended use, too insoluble in lubricating oil, and

since simple methods of dissolving these substances

to give stable solutions had not been discovered,

it had (before this project was undertaken) been

customary to prepare oil solutions of the various

compounds without isolating the solids.

TaBLE 5. Time recommended for drying over phosphorus

pentaoxide at room temperature

Time Standard Sample No."

hr

0 1066

1050, 1052a, 1066, 1056a, 1057, 1057a, 1069a,

1063, 1063a, 1064, 1071, 1071a, 1076, 1077

1051, 1051a, 1055, 1058, 1060, 1060a, 1068, 1070, 1070a, 107:^

1053, 1064, 1056a, 1069, 1061, 1061a, 1062, 1065, 1065a, 1069, 1069a, 1072, 1073a, 1074, 1075

1062a

2

24

48 1

72

» See footnote a to table 4.

However, use of solid materials, which may be

conveniently dried handled, and weighed, is advantageous. Nevertheless, successful application of the set of solid compounds we have developed is contingent on a simple reproducible method

of preparing stable solutions of them in petroleum

j oils.In many instances, application of heat causes the I compound to dissolve in oil, but, on cooling to i room temperature and standing for several days,

gellation or precipitation often occurs in the

solution.

For preparing stable oil-solutions containing

the desired concentration of the respective element, several organic solubilizing agents were

developed. These could be used in small proportions, and proved satisfactory for preparing single

solutions or blends of the 24 metallo-organic I standards. These agents may be loosely classi- I fied on the basis of their chemical properties and

according to the types of compound they solubilize.

j Xylene, which has a rather low volatility (high

boiling point; was found to be satisfactory for

predissolving the selected compounds of boron, ^ phosphorus, silicon, and tin, and it was used, in

combination with the other solubilizing agents

found necessary, for predissolving all of the standard compounds. ! Oil-soluble organic acids, especially naphthenic : acid and 2-ethylhexanoic acid, were found to be

j excellent agents for dissolving the salts (soaps) of | lead, manganese, mercury, nickel, zinc, and the : alkali and alkaline-earth metals. To maintain ' compatibility of blends, it was foimd advisable to ' employ 2-ethylhexanoic acid with many of the ; non-soaps. Use of naphthenic acid was discon- i tinned because of variability of the material. !' 2-Ethylhexylamine was found to solubilize

j salts of metals that form complexes with ammonia,

for example, the salts of cadmium, cobalt, copper,

'

nickel, and silver. Even in daylight, the oil ! solutions of silver formed in this way are stable , for months. In order to stabilize solutions of

vanadium for long periods of time, addition of

j 2,2'-diethyldihexylamine proved satisfactory. i
6-Methyl-2,4-heptanedione gives metal derivatives that are difficult to crystallize, and it was

found excellent for predissolving the compounds of

iron and chromium and for preventing formation

of, or dissolving, gels of aluminum salts.

After a compound had been dissolved by use of

one or more solubilizers, the solution could be

diluted to the desired concentration with lubricating oU or with such hydrocarbons as mineral

spirits, paraffin oil, gasoline, or heptane.

3. Experimental Procedures

3.1. Materials

The inorganic salts were reagent or analytical

grade. The acetone, chloroform, absolute ethanol,

and absolute methanol were reagent grade, and

the butyl acetate was commercial material of

90- to 92-percent purity; all organic solvents were

used without further purification. Cyclohexanebutyric acid (obtained from Distillation Products

Industries, Eastman Organic Chemicals Department, Rochester 3, New York) was redistilled,

and the fraction boiling at 134 °C (3ram) was

collected and used for the preparation of its salts.

Scrupulous precautions were taken to avoid

contamination of all materials; apparatus was

thoroughly cleaned, and dust was removed and

excluded.

3.2. Drying of Products

After recrystallization or reprecipitation from

an appropriate solvent, each purified product was

air-dried overnight (with exclusion of dust),

dried in a vacuum desiccator (enclosed in a Desiguard) over phosphorus pentaoxide at 0.5 mm,

ground with an agate mortar and pestle, and sieved

to pass a 40-mesh screen. (For certain hard,

noncrystalline, or slightly sticky products, it was

necessary first to grind to pass a 20-mesh sieve,

redry, and then grind to pass a 40-mesh sieve.)

The compound was redried in a vacuum desiccator over phosphorus pentaoxide at 0.5 mm, and, if necessary, large quantities were then placed in a rotary cylinder and dried at room temperature

at 0.5 mm, under continuous rotation, for at

least 48 hr (or until condensate was no longer

formed in a dry-ice trap included in the system).

Immediately preceding analysis (see sections 3.6

and 3.7), each sample was further dried, as described in section 3.S.

3.3. Preparation of Solubilizing Agents

3.3.1. Bis(2-ethylhexyl)dithiocarbamic Acid

Cold carbon disulfide (7.6 g, 0.1 mole) was

added dropwise, with stirring, to 44.3 g (0.2 mole)

of cold bis (2-ethylhexyl) amine in an ice bath, at

such a rate that the temperature of the mixture

did not exceed 10 °C. Stirring was continued for an additional 10 min, after which the reagent was

poured into a bottle which was then stoppered.

For many of the metallo-organic compounds.

dissolution was facilitated by diluting the reagent

with an equal volume of xylene.

3.3.2. 6-Methyl-2,4-heptanedione [2] *

Anhydrous, ethanol-free sodium ethoxide (2

moles, prepared from 46 g of granular sodium),

anhydrous ethyl acetate (352.4 g, 4 moles), and

1 liter of sodium-dried toluene were placed in a

5-liter, 3-necked, round-bottomed flask equipped

with a drying tube, a powerful mercury-sealed

stirrer, and a 300-ml dropping funnel equipped

with a drying tube. The mixture was stirred for

30 min at room temperature, cooled in an ice

bath, and vigorously stirred while 4-methyl-2-

pentanone (200.3 g, 2 moles) was added slowly over a period of 30 to 60 min. The progress of

the reaction was determined by the disappearance

of the solid sodium ethoxide.

After the ketone had been added, the mixture

was stirred for 3 hr in the ice bath, allowed to

stand overnight at room temperature, recooled in

an ice bath, and diluted with an equal volume

(or more) of cold water to dissolve the solid that

had precipitated. After separation of the resulting layers, the aqueous layer was washed with

four lOO-ml portions of ether, and the toluene

layer was extracted with four 100-ml portions of

water. The aqueous layer and washings were

combined and acidified with 130 ml (65 ml per

mole of sodium ethoxide used) of glacial acetic

acid, yielding the ketone as the upper, oily layer.

This layer was separated, and the lower aqueous

layer was extracted with four 100-ml portions of

ether. The diketone and the ether extracts were

combined, washed successively with three 50-ml

portions of water and three 50-ml portions of a saturated solution of sodium bicarbonate, and

dried with calcium chloride. The ether was

removed by evaporation, and the ketone was

fractionally distlUed under duninished pressure;

yield, 171 g (60 percent), bp, 71-76° C (18 mm).

3.4. Preparation of Compounds Chosen as Standards

Table 6 lists the compounds selected as standards, together with their foi'mulas, molecular

weights, and results of analysis for the pertinent

element in each.

5 This compound may now be jiurcliasod from Chemicals Procurement

Laboratories, Inc., College Point, N.Y.

7
Table 6. Formulas, molecular weights, and analyses of compounds chosen as standard samples

I

Serial No. NBS Standard Sample No. Compound Formula Molecular weight

Element

bymDol Calculated Found •

12

3

4

5

7

8

9

10

11

12

13

14

15

10

17

18

19

20

21

22

23

24

25

26

2728

1050

Cyclohexanebutyrate Aluminum _ .. _ _ C20H35AIO5

C2oH;34Ba04

382. 45

475. 82

A 1

/o %

6.9

28.1

29.1 23.9

10.5

17.1 17.5

16.0

16.1 19.3

37.5

36.9 4.0

4.1 6.9

6.8

13.9

13.8 36.2

17.6

16.8

19.0 38.7

12.0

11.9

19.8 20.7

18.5

16.7

2.27

2.4

10.6

9.5

9.5

14.1 23.6

2.3.2 13.1

13.1 13.4

7.5

10.1 42.4

1051 Barium

1051a

1053 Cadmium C2oH3iCd04

C2oH34Ca04

b unknown

450. 87

378. 54

24.93

1054 Calcium ... _ \^3, lu. oy

1055 Cobalt (ous) 1055a

1056 CoDDer (ic) C20H34CUO4 402. 00 r'n 1 SI 10. ox 1056a

1058 Iron.. _ " unlcnown

1059 Lead _ C20H3.|O4Pb 545. 67 1 I) 37. 97 1059a

1060 Lithium _ CioHi7Li02 176. 17 T i 0. 1060a

1061 Magnesium. C20H34MgO4 362. 78 iVig 6.70 1061a

1062 Manganese (ous) C2oH34Mn04 393. 40 A/Tn 07 1062a

1064 Mercury (ic) - - . C20H34HgO4 539. 07 TT(T Xlg 37. 21 1065 Niclfel (ous) . . d unkno\vn XTi 1065a

1067 Potassium .. C10H17KO2

CioH,7Ag02

CioHi7Na02

208. 33

277. 11

192. 22

K_ 18. 77 38.93

11. 96

1068 Silver

_

. . Ag ---

1069 Sodium Na

1069a

1070. Strontium

_

. C2oH3404Sr-1.5 H2O 453. 15 or 19.34 1070a

1073 Zinc -- . e unknowai

C2oH3404Zn

C30H57BO3

1073a 403. 84

476. 58

ZjII ID. ly

1063 2.27

Miscellaneous Menthyl borate T?x> 1063a

1072. Tris(2'-hydroxyacetoplienono)-chromium(III)

Triphenyl phosphate

C24n2lCr06

C18H15O4P

457. 41

326. 28

11 ^7

1071 L - _ 9. 49

1071a_ 1066 Octaphenyloyclotetrasiloxane _ C48H4o04Si4 C24H4804Sn

793. 21

619. 34

Si 14. 15 1057 -. Dibutyltin bis(2-ethylhexauoate) Sn 22.86

1057a

1052 Bis(l-phenyl-l,3-butanediono)oxovanadium(IV) . . C2oH,803V 389^ 29 V 13. 09 1052a

1074

CieHsiAlOs C22H41KO2 C8Hi5Ag02

Ca

1075 Aluminum 2-ethylhexanoate 330. 41

376. 67

251. 09

Al 8.17

10. 38

42. 96

1076 Potassium erucate _ . _ ... K

1077 Silver 2-ethylhexanoate Ag

» By analysis of the compound dried at 25° over phosphorus pentaoxide in a desiccator. ' b Calculated for C20H34C0O4 (M.W., 397.40): Co, 14.83.

« Calculated for CioHi702Fe(OH)2 (M.W., 259.11): Fe, 21.55. d Calculated for C2oH34Ni04 (M.W., 397.17): Ni, 14.78.

• Calculated for C2oH3404Zn (M.W., 403.84): Zn, 16.19.

' Calculated for C,6H3oCa04 (M.W., 326.50): Ca, 10.82.

!

7), the solution was now heated to 70 to 75 °C

on the steam bath. For all salts except that of I 'ron (see detailed description), an aqueous solution | of the metal compound (see table 7) at the prej scribed temperature was then added dropwise, i with stirring, and the preparation was continued ; as described in the individual descriptions.

This general method was later improved by

first converting the cyclohexanebutyric acid to

the sodium salt (method b) , and this procedure was

employed for preparation of the other cyclohex- i anebutyrates (compounds 2,3,4, 6, 8, 10, 11, 12, 15,

and 17). Sodium hydroxide (81.6 g of 98 percent; 2.0 moles) was placed in a large Pyrex

beaker (equipped with an electric stirrer and

j 1 -liter dropping funnel) and 2 liters of water was

added, with stirring. Into the resiilting solution

was rapidly poured, with stirring, 340.5 g (2.0

|

3.4.1. Cyclohexanebutyrates

a. Preparation

Table 7 gives a summary of the compounds

used in the preparation of the cyclohexanebutyrates and the yields of the respective, purified

products.

Aluminum cyclohexanebutyrate (table 6, compound 1) was prepared by the reaction of cyclohexanebutyric acid with aluminum isopropoxide

in boiling toluene.

Seven other cyclohexanebutyrates (compounds

5, 7, 9, 13, 14, 16, and 18) were prepared from

the free acid (method a). Absolute ethanol (2

liters) was placed in a large Pyrex beaker equipped

with an induction-type, electric stirrer, 340.5 g

(2 moles) of cyclohexanebut3iTic acid was added,

and the mixture was stirred untU all of the acid

had dissolved. In some preparations (see table

8
Table 7. Experimental details in the preparation of cyclohexanebutyrates

Starting material Water

used Temp, b

Yield of pure product

Serial No. of

iVlLUl, W t. Amount used v^aiou- product

lated Actual

S

" TTlOtCS ° C Q /o

Z.Kt't. O 136.

2

0. 66 0.0 zoo 249 97 1 Zoo. o ZD!5. o I, uo 2. 0 60-70 t/0. 0 333 70 2

OUo. O QUO. 0 1. u l!3 25 4*^0 'ioxj. Qy

'i'iA 74 3

y^ai\\J.i\.L }2 -0-2

V

176 2 IBO. Z 1, uo 1.9 25 0/0. 0 295 78 4 C>0(UAc)2-4H2U 249.

1

261.

6

1 nr 1.8 70-75 270 5

v-* U.O W4 0X12'-' 262.2 1.05 2.3 25 ^uz. u 368 91 6 FpPli.fiTToO 270 3 180 2 0. 66 0.5 70-75 lo* 7

0 PhfT* I U A f'^o.^TTo^ \, w-fxt^y 2 Oxlj'-' oiii. t 417^3 i. 1 2. 0 60-70 oto. / 463 85

J_/ 1 wIII • JQ2

83.9 2.0 0! 965 25 OOZ. 0 314 89 9 Mg(OAc)2-4H20 214.5 214.5 1.0 0.5 25 362. 8 287 79 10 MnOl9.4R'30 197.

9

197.9 1.0 1.0 25 393. 4 315 80 11 Hg(OAo)2 sis!? 334.6 1. 05 2.0 25 539^1 380 70 12 Ni(OAc)2-4H20 248.9 261. 4 1.05 2.5 70-75 312 13 KOH 56. 1 » 132. 0 2.0 0. 449 25 416.6 358 86 14 AgNOs 169.9 356.8 2.1 6.0 25 554.2 520 94 15 NaOH 40.0 d 81.6 2.0 0.72 25 384.5 322 84 16 SrCl2-6H20 266.6 266.6 1.0 0.5 25 453.2 354 78 17 Zn(OAc)2-2H20 219.5 219.5 1.0 2.0 25 355 18

« Per 2.0 moles (340.5 g) of cyclohexanebutyric acid.

b Of reaction and, unless otherwise noted, of the aqueous solution.

" Of 85 percent.

<i Of 98 percent.

moles) of warm, molten cyclohexanebutyric acid,

and the mixture was stirred until an essentially

clear solution resulted (4 min). In some preparations (see table 7) , the solution was now heated to 65 to 70° on the steam bath. An aqueous solution of the metal compound (see table 7) at the

prescribed temperature was then added dropwise, with stirring, usually during 20 to 30 min,

and the preparation was continued as described

in the individual descriptions.

(1) Aluminum cyclohexanebutyrate. Aluminum

isopropoxide (204.3 g, 1 mole), cyclohexanebutyric acid (512.4 g, 3.01 moles), and 1 liter of

toluene were placed in a 3-liter, 2-necked, roundbottomed flask fitted with a 1-liter dropping

funnel (filled with toluene) and with a reflux

condenser to the top of which was attached a connecting tube equipped with a thermometer

and a water-cooled condenser set for distillation.

The mixture was refluxed for 1 hr; the flow of

water through the reflux condenser was then

stopped and the water was drained out, ihe temperature of the heater was regulated to give a

reflux ratio of about 1:7, and the stopcock of the

dropping funnel was carefully opened and so adjusted that the number of drops of toluene

entering the flask equaled the number of drops

of distillate collected. During 3 hr, the vapor

temperature rose from 80 to 88° and 400 ml of

distillate was collected; during a total time of

5 hr, the temperature rose to 110° and 900 ml of

distillate was collected (and discarded)

.

The hot solution was filtered through toluenewashed, filter-paper pulp, and the filtrate was

cooled to room temperature, transferred to a

6-liter, Pyrex jar, and vigorously stirred while 4

liters of acetone was gradually added, producing

a turbid solution. Stirring of the solution was

continued during 30 min, while 1 liter of acetone

containing 18 g of water was added, precipitating

a white, spongy product. The mixcure was

refrigerated overnight, and the precipitate was

collected on a Biichner funnel, washed with

acetone, and dried and powdered in the usual

way.

(2) Barium cyclohexanebutyrate. By use of

method b and the quantities of reactants given in

table 7, a sticky, soft precipitate resulted. After

the mixture had been stirred for about 30 min at

60 to 70 °C, the solution was decanted from the

precipitate and discarded; the precipitate was

washed successively with four 300-ml portions of

water at 60 to 70 °C, and two 300-ml quantities

of absolute ethanol at 25 °C, and then stirred with

500 ml of acetone for 30 min, during which time

the precipitate became hard and granular. The

solid was collected on a Biichner funnel, air dried,

and dissolved in a hot solution of 600 ml of methanol and 50 ml of water in 2.5 liters of butyl

acetate. The hot, clear solution was filtered

transferred to a 4-liter beaker (placed on a cork

mat and equipped with a stirrer), and allowed to

cool while being rapidly stirred. After the solution had been stirred for about 30 min, the barium

salt began to separate as a finely divided precipitate; when the temperature of the solution

had reached about 25 °C, the precipitate was

collected by suction filtration. The filtrate was

refrigerated overnight, affording a second batch of

precipitate which was collected, combined with

the first batch, and air dried. A second purification of the salt was carried out by redissolving

in the butyl acetate-methanol-water mixture and

cooling, after which the salt was collected on a Biichner funnel, and dried and powdered as usual.

(3) Cadmium cyclohexanebutyrate. To a so- lution of the acid (see table 7) in 667 ml of absolute

ethanol was added a solution of the sodium hydroxide (see method b) in 667 ml of water, followed

by the solution of cadmium nitrate; a white

precipitate was obtained. After bemg stirred for a further 30 min, the mixture was filtered by

9
suction, and the precipitate was washed by

stirring with water, refiltering, and repeating the

process twice. The moist precipitate was added

to boUing absolute methanol (in the ratio of 500 g

of precipitate to 2 liters of methanol) and the

resulting suspension was filtered. The insoluble

precipitate remaining was dissolved by suspending

it in hot methanol and adding, with stirring,

sufficient cyclohexanebutyric acid to give complete

dissolution. The two solutions were combined,

water was added to turbidity, and the solution

was refrigerated, giving a precipitate which was

removed with suction. The product was re- crystaUized as previously described, but excess water was added to the heated solution whenever

an oil (instead of crystals) settled out on refrigeration. The product was filtered off, and dried

and powdered in the usual way.

Analysis. Calculated for C2oH34Cd04: C,

53.28; H, 7.6. Found: C, 53.35; H, 7.7.

(4) Calcium cyclohexanebutyrate. The calcium

acetate solution (see table 7) was added to a

solution of the sodium cyclohexanebutyrate (see

method b) in 700 ml of water plus 700 ml of absolute ethanol; a white precipitate was formed.

The mixture was refrigerated overnight; the precipitate was then collected in a Biichner fimnel,

transferred to a 4-liter beaker (equipped with a

stirrer), and washed by stirring with several

200-ml portions of water. The solid was collected

by suction filtration, air dried, crushed, and dried over phosphorus pentaoxide; weight, 372 g. The

dry salt (372 g) was dissolved, with stirring, in a

sufficiency of 43:57 (vol/vol) aqueous ethanol at

70 to 75 °C on the steam bath, filtered, cooled to

25 °C, and refrigerated overnight. The salt

separated as short, needlelike crystals which were

collected by suction filtration and washed with

water. The salt was recrystaUized once by the

same procedure, and dried and powdered as

usual.

(5) Cobalt cyclohexanebutyrate. By use of

method a and the quantities of reactants given in

table 7, a soft, lavender precipitate was obtained.

After the mixture had been stirred for about 30

min at 65 to 70 °C, the supernatant solution was

decanted and discarded, and the precipitate was

stirred with 500 ml of acetone for 20 min, during

which time the precipitate solidified. The solid

was collected by suction filtration, washed successively with water and acetone, and dissolved

at 60 to 70° in 1.5 liters of 1 : 1 (vol/vol) methanolbutyl acetate. The hot solution was filtered

through absorbent cotton, cooled to 45 °C,

stirred whUe acetone was added dropwise to

incipient turbidity, cooled to 25 °C, and refrigerated. The salt separated as a finely divided

precipitate which was collected on a Biichner

funnel, washed with absolute ethanol, air dried,

repurified (by the same procedure) from 1.2 liters

of 1:1 (vol/vol) methanol-butyl acetate, and dried

and powdered as usual.

(6) Copper cyclohexanebutyrate. A solution of

the sodium cyclohexanebutyrate (see method b)

in 4 liters of water plus 1 liter of absolute ethanol

was added dropwise to the solution of copper

sulfate (see table 7); a finely divided, blue precipitate resvdted. The mixture was kept at 25 °C j overnight; the precipitate was then collected by I suction ffitration, transferred to a 4-liter beaker

j equipped with a stirrer, and washed successively,

with stirring, with three 300-ml portions of water, , two 300-ml quantities of 50-percent (vol/vol) I aqueous ethanol, and 500 ml of acetone (for 20 i min). The solid was collected on a Biichner 1 funnel, air dried, powdered, sieved (20-mesh), and ! dried over phosphorus pentaoxide at 2 mm; weight,

| 398 g The copper cyclohexanebutyrate (398 g) i was dissolved, with stirring, in 1 liter of absolute

ethanol at 65 to 70 °C on the steam bath. The } hot, blue solution was filtered through filter-paper

pulp, and the filtrate was cooled to room temperature and refrigerated. After the solution had been | refrigerated for 3 days (with intermittent scratchj ing of the sides of the flask and warming of I the solution to 25 °C), the copper salt precipitated ] from solution. A second purification of the salt ! was carried out by redissolving the precipitate in | 1 liter of absolute ethanol, refrigerating, and | nucleating the solution. The salt was collected j on a Biichner funnel, and dried and powdered in

the usual way.

(7) Iron cyclohexanebutyrate. To a solution of i the acid (see table 7) in 333 ml of absolute ethanol

at 25 °C was added 134 ml of concentrated

ammonium hydroxide (sp gr 0.90) and then, with

vigorous stirring, the hot solution of ferric chloride, j A red-brown oil was precipitated. The super- i natant liquor was decanted and set aside, and the | oil was transferred to a 2-liter separatory funnel,

washed with four 200-ml portions of hot water I (70 to 80 °C), filtered twice (with difficulty)

| through absorbent cotton, and transferred to a 4-

| liter beaker equipped with a stirrer. Aqueous ac- I etone (2 liters of 10-percent) was gradually added

during 30 min, with the formation of a brown

granular precipitate which was dissolved in a. solution of 13.5 ml of cyclohexanebutyric acid m i 667 ml of chloroform and vigorously stirred while '

2.7 liters of acetone was added dropwise during ; 50 min. The solid was collected on a Biiclmer j funnel, washed successively with absolute ethanol i and acetone, and dried and powdered as usual, i [The filtrate was concentrated and unreacted

| cyclohexanebutyric acid (213 g, 1.25 moles) was i recovered (see section 3.4.1.b).] _

i,

(8) Lead cyclohexanebutyrate. The hot solution !'

of lead acetate (see table 7) was added to a hot '

solution of the sodium cyclohexanebutyrate (see

method b) in 1.5 liters of water plus 1 liter of

absolute ethanol, and a sticky, soft precipitate was ' produced. The mixture was diluted with 2 liters

j of water and stirred for 2 hr, during which time the

precipitate solidified. The white salt was col- ! lected by suction filtration, transferred to a 4- i liter beaker, washed successively with three 300-ml i portions of water at 60 to 70 °C and two 30q-ml

j quantities of absolute ethanol, and dissolved in 7 ;

10
i liters of butyl acetate at 70 to 80 °C. The hot

solution was filtered twice, by suction, through

filter-paper pulp on ordinary filter paper, placed in a 10-liter, cylindrical, Pyrex jar, and vigorously

stirred while 3 liters of a 2:1 (vol/vol) solution of

acetone in butyl acetate was slowly added.

After the solution had been stirred for about 10

min, the lead salt began to separate as a stringy

precipitate, and, after about a further 30 min, the

\ suspension became a gel which was too viscous to

be stirred. The mass was transferred to a large

Biichner fimnel, pressed free of most of the butyl

acetate, washed with absolute ethanol, and air

dried. In like manner, the filtrate (not mixed with

the ethanol washings) was stirred untU the solution gelled; the butyl acetate solution was pressed

out of the precipitate and refrigerated, yielding

more precipitate. The precipitates were combined, washed with absolute ethanol, air dried,

redissolved in butyl acetate, collected by the same

procedure, and dried and pulverized as usual; mp

85-86 °C.

_ (9) Lithium cyclohexanebutyrate. Use of method

a and the quantities of reactants given in table 7

gave a solution. The solution was evaporated to

700 ml on the steam bath, and butyl acetate (2

liters) was added to the mixture, which was then

heated slowly to 95 to 105 °C until most of the

water had evaporated, giving a slightly turbid

solution. Sufficient water was added to remove

the turbidity, and the mixture was filtered. The

filtrate was allowed to cool to room temperature,

nucleated, and refrigerated overnight, giving a

precipitate which was filtered off with suction and

dispersed in 2 liters of butyl acetate. The sus- pension was heated slowly, with occasional addition of a little water, until the solution showed a

slight turbidity at 95 °C. A slight excess of water

was added to remove the turbidity, and the clear

solution was filtered, cooled, and refrigerated,

giving a precipitate which was filtered with suction, washed twice with acetone, and dried and

powdered as usual.

(10) Magnesium cyclohexanebutyrate. By use of

method b and the quantities of reactants given

in table 7, a white precipitate was formed. After

being stirred for a further 30 min, the mixture

was refrigerated overnight. With the aid of a

fUter-flask containing several ml of butyl acetate

(to decrease foaming), the mixture was filtered

by suction; the filtrate was refrigerated for 3 to

4 hr (to give a second crop of white precipitate)

and refiltered. The precipitates were combined

and were washed by stirring with water, refUtering, and repeating the treatment twice.

Butyl acetate (1 liter) was now added to the

moist precipitate, and the suspension was slowly

heated to 85 to 93 °C and maintained at that

temperature until dissolution was complete. (At

this point, the solution was often slightly turbid

and was boiling gently.) The solution was

filtered into a 4-liter beaker, stirred, nucleated,

and allowed to cool to room temperature, affording a white precipitate. After the mixture had been

refrigerated overnight, the precipitate was filtered

off with suction, again recrystallized from 1 liter

of butyl acetate, as before, and dried and powdered

as usual.

(11) Manganese cyclohexanebutyrate. The solution of sodium cyclohexanebutyrate (see method

b) was added to the solution of manganous

chloride (see table 7) during 90 min. After being

stirred for a further 30 min, the mixture was

refrigerated overnight. The suspension was fil- tered by suction and the precipitate was twice

stirred with water and refiltered. The moist

product (ca. 2,000 g) was purified as follows.

To an aliquot (500 g) was added 143.5 ml of

absolute methanol followed by 1,092.5 ml of

chloroform, and the suspension was stirred until

most of the salt had dissolved. Butyl acetate

(1,316 ml) was now added and the mixture was

stirred until dissolution was complete. The solution was filtered, and to the clear filtrate was

added 865.5 ml of butyl acetate, followed by

108.5 ml of water. The resulting solution was

shaken, nucleated, and refrigerated ( —5 °C)

overnight. The resulting precipitate was filtered

off with suction, washed by stirring with acetone

and refUtering, and dried and powdered in the

usual way.

(12) Mercuric cyclohexanebutyrate. The mercuric

acetate solution (see table 7) was added to a

solution of the sodium cyclohexanebutrate (see

method b) in 1.5 liters of water plus 1 liter of

absolute ethanol, giving a milky-white suspension;

from this, a very small quantity of heavy oil

separated. After the mixture had been stirred

for about 15 min, the suspension was refrigerated

overnight, giving off-white, sticky crystals which

were collected by suction filtration, washed successively (in a 2-liter beaker) with two 200-ml

quantities of ice water and one 100-ml portion of

absolute ethanol, filtered, and air dried. The

crystals were carefidly added portionwise to 1.5

liters of vigorously stirred, hot (65 to 70 °C)

absolute ethanol containing 20 g of cyclohexanebutyric acid in a 4-liter beaker on the steam

bath, and stirring was continued for an additional

5 min, during which time most of the salt dissolved,

leaving a deep-orange, insoluble material that was

removed completely by three rapid fUtrations,

with suction, through a layer of filter-paper pulp

placed on ordinary filter paper.

The clear filtrate was transferred to a 4-liter

beaker equipped with a stirrer, and 40 to 60 ml

of water was gradually added, with stirring, to

give a faintly turbid solution which was refrigerated overnight. The salt separated as clumps of

crystals which were collected by suction filtration,

washed with cold absolute ethanol, air dried,

recrystallized (by the same procedure) from 1.1

liters of absolute ethanol, and dried and powdered

as usual; mp, 75.5-76.5 °C.

(13) Nickel cyclohexanebutyrate. By use of

method a and the quantities of reactants given in

table 7, a viscous, green oil was precipitated.

11
After the mixture had been stuTed lor about 30

min at 65 to 70 °C, the supernatant liquor was

decanted, and the oil was dissolved in 750 ml of

chloroform, transferred to a 3-liter separatory

funnel, washed three times with 200-ml portions

of water, and filtered twice thi'ough absorbent

cotton on ordinary filter paper. The clear, green

solution was added dropwise, with sthring, to

4 liters of absolute ethanol in a 6-liter cylindrical

jar. The salt separated as a finely divided, lightgreen precipitate which was collected by suction

filtration, washed with hot (70 °C), 10-percent

(vol/vol) aqueous ethanol, and aii- dried. The

dry product was dissolved in 1 liter of butyl ace- tate contaming 10 g of cyclohexanebutj'ric acid,

diluted dropwise with acetone to incipient turbidity, refrigerated, collected on a Biichner

funnel, and dried and powdered as usual.

(14) Potassium cyclohexanebutyrate. Usmg

method a, 20-percent aqueous potassimn hj^droxide solution (see table 7) was added to a solution

of the acid in 500 ml of absolute ethanol (faint

pink to phenolphthalein). The solution was

transferred to a large evaporating dish, concentrated on the steam bath, with frequent stirring,

to a volume of about 400 ml, and transferred to an

8-liter beaker equipped with a sthrer. The

viscous solution was cooled to 40 °C and stirred,

while 5 liters of acetone was added during 15 min,

with the formation of a bulky, white, granular

precipitate. After the mixture had been stirred

for 15 min, the precipitate was collected on a Biichner funnel, washed with acetone, air dried,

and mixed with 1.4 liters of 12-percent ethanolbutyl acetate at 60 to 70 °C ; 20 to 28 ml of water

was added to afford a clear solution. The hot,

clear solution was filtered, transferred to a 6-liter

beaker, and stirred while enough acetone was

added dropwise to form a turbid solution which

was then refrigerated overnight.

The salt separated as a soft, soaplike precipitate

which was collected by decantation of the supernatant liquor, and washed with 200-ml portions

of 5-percent (vol/vol) ethanol-acetone until a

finely divided solid was obtained. The filtrate

was mixed with more acetone and refrigerated,

affording more of the solid product. The precipitates were combined, washed with acetone,

air dried, redissolved as before (with the same

quantities of solvent), refrigerated, isolated, and

dried and powered as usual.

(15) Silver cyclohexanebutyrate. The silver nitrate solution (see table 7) was added to a solution

of the sodium cyclohexanebutyrate (see method

b) in 2 liters of water plus 2 liters of absolute

ethanol, and a white precipitate was formed.

The mixture was stirred for 30 min; the precipitate was then collected on a large Biichner funnel,

pressed free of much of the absorbed liquid,

transferred to an 8-liter, cylindrical jar, and

washed successively, with stirrmg, with five 1-

liter portions of water, thi'ee 1-liter quantities

of ethyl alcohol, and 1 liter of acetone (for 15

min). The salt was collected on a Biichner i fimnel, and dried and powdered as usual.

j The silver salt sometimes became dark brown I duiing the preparation and, to remove this color, | the following procedure was followed. A suspen-

'

sion of 260 g of dark-brown silver cyclohexane- i butyrate in 300 ml of 30-percent aqueous ethanol I in a 4-liter beaker was vigorously stirred whUe a i solution of 20 g of cyclohexanebutyric acid in

320 g of concentrated ammonium hydroxide | (sp gr 0.90) was slowly added, with the dissolution \ of most of the solid and the formation of a deep- \ amber solution. The mixture was filtered; the I filtrate was mixed with 4 g of acid-and-waterj washed, decolorizing carbon in a 4-liter beaker, | heated on the steam bath for 30 min, and filtered

[ twice through filter-paper pulp on ordinary filter

paper. Decolorizing carbon (4 g) was added to

the filtrate and the process was repeated; the '

filtrate was then placed in an 8-liter, cylindrical

j jar (equipped with a stirrer), and stirred while a | solution of 20 ml of concentrated nitric acid '

(sp gr 1.42) and 350 ml of glacial acetic acid in

2 liters of water was added during 45 min, precipitating silver cyclohexanebutyrate as a bulky,

off-white solid. The precipitate was collected on a Biichner funnel, washed with several 500-ml

portions of water, pressed free of most of the wash ' liquid, and dried and powered as usual; salt | recovered, 190 g. This procedure was repeated,

if necessary. | (16) Sodium cyclohexanebutyrate. Using methj od a, a 10-percent aqueous sodimn hydroxide \ solution (carbonate-free; see table 7) was added | to a solution of the acid in 500 ml of absolute

j ethanol (faint pmk to phenolphthalein). The | solution was placed in a large evaporating dish | and, with frequent stirring, was concentrated on | the steam bath to a viscous paste to which 200 | ml of 1 : 1 (vol/vol) aqueous ethanol was added,

giving a viscous solution. The solution was

filtered into a 6-liter beaker equipped with a I stirrer, and 1.6 to 2 liters of acetone was gradually ! added, with stirring, giving a faintly turbid solu- i tion which was inmiediately filtered; the filtrate

was refrigerated overnight. The salt separated

j as long, thin, needlelike crystals which were

collected by suction filtration and washed once with 400 ml of 1:3 (vol/vol) ethanol-acetone.

A second crop of crystals (about 40 g) was obtained

by adding acetone to the filtrate to incipient

turbidity and refrigerating the mixture. The salt i was recrystallized once by the same procedure,

collected, dried, and powdered as usual. During

j the drying, the crystaUinity of the salt was lost. I

(17) Strontium cyclohexanebutyrate hydrate. By

use of method b and the quantities of reactants

given in table 7, a white precipitate was formed.

After being stirred for a further 30 mm, the mixture was refrigerated overnight. The suspension

was filtered by suction and the precipitate was

washed by stirring with water, refiltermg, and

| repeating the process twice. Butyl acetate (1

12
liter) was now added to the moist precipitate, and

the suspension was slowly heated to 93 °C and

maiatained at that temperature until dissolution

was complete. (At this point, the solution was

boUing.) The solution was filtered through a heated funnel into a 4-liter beaker, and the filtrate

was stirred electrically, nucleated periodically,

and allowed to cool to room temperature, afi'ording a white precipitate. After the mixture had been

refrigerated overnight, the precipitate was filtered

off with suction, again recrystallized from 1 liter

of butyl acetate, as before, and dried and powdered

as usual.

Analysis. Calculated for C2oH.-!404Sr-1.5 H2O:

C, 53.01 ;_H, 8.2. Found: C, 52.77; H, 8.1.

(18) Zinc cyclohexanehutyrate. Using method

a, a solution of the acid (see table 7) in 1 liter of

absolute ethano] was added to the solution of

zinc acetate. A white precipitate was formed.

After stirring for a further 30 min, the suspension

was filtered by suction and the precipitate was

washed by stirring with 2 liters of water, refiltering,

and repeating the treatment. Butyl acetate

(1.334 liters) was now added to the moist precipitate, and the suspension was slowly heated to 70

to 80 °C and mamtained at that temperature untd

dissolution was complete. The solution was

filtered, nucleated, and refrigerated overnight,

giving a precipitate which was filtered off with

suction, again recrystallized from 1.334 liters of

butyl acetate, as before, and dried and powdered

as usual.

b. Recovery of Cyclohexanebutyric Acid

A mixtui'e of impm-e residues of salts of cyclohexanebutyric acid (crude solids and mother

liquors) was placed in a porcelain evaporating

dish on the steam bath and the solvents were

evaporated. Excess aqueous 50-percent phosphoric acid was added, and the mixture was heated

on the steam bath during 72 hr. The resulting

aqueous suspension was diluted with water and

the free acid was precipitated with ice. (Alternatively, it was extracted with chloroform, and

the extract was washed with thi-ee portions of

water. Decolorizing carbon was added to the

washed chloroform layer, and the suspension was

heated to boiling and filtered. The brown filtrate

was transferred to a porcelain evaporating dish,

and the chloroform and water were evaporated on

the steam bath.) The resulting moist, crude

cyclohexanebutyric acid was rapidly distilled at

3 mm (132-135 °C), and the main fraction of

distillate was redistilled twice, giving pure cyclohexanebutyric acid.

3.4.2. Miscellaneous Compounds

(19) Tijj-Menthyl borate. The method of preparation was essentially that described for l- menthyl borate [3]. A suspension of 61.8 g (1 mole)

of boric acid in a solution of 468.9 g (3 moles) of

DL-menthol in 2.6 liters of toluene (boiling stone)

in a 6-liter, 1-necked, round-bottomed flask

(equipped with a Barrett trap and a reflux condenser) was boiled until the acid had dissolved

(15 min) and for a fiu"ther 2.75 br; 53.4 ml of

water was collected in the trap (theoretical yield,

54.0 g). The reaction mixture was allowed to

cool to room temperature, and the reflux condenser

and trap were replaced by a water-cooled con- denser arranged for distillation. Two liters of

toluene was distilled off and the remaining hot

solution was filtered twice, by suction, and

refrigerated, yielding 458 g (dry) of colorless

crystals. This material was recrystallized twice

from 1.5 liters of a 1:1 (vol/vol) solution of acetone

in ethyl acetate, and dried and powdered as usual;

weight, 434 g (91 percent), mp, 151-152 °C.

(20) Tris {2' -hydroxyacetophenono)chromium

{III). 2 '-Hydroxyacetophenone (1361.4 g, 10

moles) was dissolved in 2 liters of absolute ethanol

in a 4-liter beaker equipped with a stirrer, and

vigorously stirred while 900 g of concentrated

ammonium hydroxide (sp gr 0.90) was slowly

added. The resulting pale-amber solution was

stirred while a solution of 954 g of a commercial

chromic acetate hydrate (corresponding to 3.0

moles of anhydrous acetate) in 3 liters of water

was added, with the formation of a purplish-red

solution; this solution was placed in an 8-liter,

cylindrical, Pjnrex jar and concentrated on the

steam bath during 5 days to a sticky, tarry residue.

The residue was mixed with 500 ml of absolute

ethanol, and the mixture was gently heated on

the steam bath while 200 g of concentrated

ammonium hydroxide (sp gr 0.90) was added

dropwise.

The mixture was reconcentrated to a tarry

residue, cooled to 40 °C, and dissolved in 3 liters

of chloroform, with the formation of a deepbrown solution which was filtered through filterpaper pulp, transferred to a separatory funnel,

and washed with 100-ml portions of water until

the aqueous washings were colorless. The chloroform solution was then concentrated to half volume, and stirred while 4 liters of petroleum ether

(bp, 38 to 67 °C) was added portionwise diu-ing

30 min, with the precipitation of a greenish-tan

solid. The solid was collected by suction filtration

and washed with petroleum ether; the filtrate was

placed in an evaporating dish, concentrated to a

paste, dissolved in chloroform, filtered, and treated

with petroleum ether as above, affording more

solid material. The precipitates were combined,

air dried, and dried and powdered as usual; weight,

840 g (61 percent).

(21) Triphenyl phosphate. Triphenyl phosphate (technical grade, from Fisher Scientific Cc.

;

978 g) was dissolved in 2 liters of absolute ethanol

in a 6-liter flask (equipped with a stirrer) on the

steam bath. The solution was kept at 60 to 70 °C

and vigorously stirred while 2 liters of water at

60 °C was gradually added, affording two layers.

Alost of the upper (aqueous) layer was removed

by decantation, and a further 2 liters of water at

60 °C was added, with stirring, to the lower layer.

The mixture was transferred to a separatory funnel,

and the lower layer was drawn off and cooled,

13
with stirriBg, until material crystallized. The

crystals were collected on a Biichner funnel, air

dried, and dissolved in 2 liters of absolute ethanol

in a 5-liter flask on the steam bath. The hot,

clear solution was filtered, cooled to room temperature, and refrigerated overnight, giving colorless

crystals which were collected by suction filtration.

Water was added to the filtrate, to incipient turbidity; on refrigeration, a second crop of crystals

was obtained. The two crops were combined,

recrystallized in the same way, and dried and powdered as usual; weight, 820 g (84 percent recovery)

;

mp 49-50 °C.

(22) Octaphenylcyclotetrasiloxane. This compound was purchased from the Silicone Products

Department, General Electric Company, Waterford, New York; it was found to need no fm"ther

purification or drying.

(23) Dibutyltin his{2-ethylhexanoate) . Commercial dibutyltin bis(2-ethylhexanoate)^ (2,500 g)

was dissolved in 2 liters of absolute methanol in a 6-liter flask on the steam bath. The hot solution

was filtered twice, transferred to a 6-liter, P3a'ex

jar (placed in an ice bath and equipped with a

stirrer), and vigorously stirred while precipitation

occurred. After the mixture had been stirred for

about 2 hr at 5 to 10 °C, the crystals were collected by suction filtration. The filtrate was

concentrated to half volume, filtered, and refrigerated overnight, yielding a second crop of crystals

that was combined with the first crop and air

dried. The compound was recrystaUized once by

the same procedure, and dried and powdered as usual; weight, 1,868 g (75-percent recovery).

(24) Bis {1 -phenyl-1 , 3-butanediono) oxo-vanadium

{IV). This compound had previously been prepared by a different method [4]. l-Phenyl-1,3-

butanedione (324.4 g, 2 moles) was dissolved in 2

liters of absolute ethanol in a 4-liter beaker

(equipped with a stirrer) on the steam bath.

The solution was maintained at 70 to 80 °C and

vigorously stirred whfle a hot (75°) suspension of

219.1 g (1.1 moles) of vanadyl sulfate dihydrate

in 1 liter of water was added rapidly, producing a

clear, green solution. After the solution had been

heated for 10 min, a solution of 313 g (2.3 moles)

of sodium acetate trihydrate in 700 ml of water

at 70 to 80 °C was added, with stirring, during

20 min, precipitating a small quantity of green

crystals. The mixture was carefully diluted with

water to incipient turbidity, refrigerated overnight, diluted with an equal volume of cold water,

and refrigerated for 4 hr.

The crystals were collected on a Biichner funnel,

washed successively with two 200-ml portions of

cold water and two 200-ml portions of cold absolute ethanol, and air dried on the filter. The

crude, dry product, weighing 379.4 g, was dissolved in 1.6 liters of chloroform in a 3-liter

beaker on the steam bath, and the solution was

diluted with 2 liters of absolute ethanol and

8 This compound was obtained from Metal & Thermit Corporation,

Eahway, New Jersey, under the trade name of M. & T. Catalyst T-8, Dibutyltin di-2-ethylhexoate.

transferred to a 5-liter, round-bottomed, one- necked (standard taper, 40/50) flask. The flask

was attached to a rotary still by means of a modifled adapter, and evaporated at 50° and 5 j mm to half volume or until crystals began to ! separate. The flask was kept in an ice bath for i 3 hr, with frequent shaking, and the crystals were | collected by suction and washed with cold absolute i ethanol; the filtrate was evaporated further in ' the rotary still, and cooled in an ice bath, affording

a second batch of crystals which was collected,

combined with the first batch, air dried, recrystallized in the same way, and dried and powdered as usual; weight, 340 g (87 percent), mp 214-215 °C.

(25) Calcium 2-ethylhexanoate. A solution of

176.2 g (1 mole) of calcium acetate hydrate in

600 ml of water was slowly added, with stirring,

to a solution of 344.4 g (2 moles) of 2-ethylhexanoic

acid in 500 ml of 95 percent ethanol that had been [ neutralized with 10 percent sodium hydroxide

j (using phenolphthalein as indicator). The clear

'

solution was vigorously stirred and heated on the ' steam bath, giving a white precipitate which was , removed at about 30-min intervals until precipita-

[ tion was complete. The precipitate was added to ' 1,500 ml of hot butyl acetate (95-100 °C) and

vigorously stirred while sufficient water was added

to produce a clear solution. The solution was

filtered, allowed to cool to room temperature, and I refrigerated overnight, giving a white precipitate I which was recovered by suction filtration, again j dissolved in butyl acetate, cooled, and reprecipij tated. The precipitate was filtered with suction, ' washed with acetone, dried, and powdered as usual ; weight 290 g. (26) Aluminum 2-ethylhexanoate. This compound was prepared according to the procedure

given for aluminum cyclohexanebutyrate. From

3 moles of 2-ethylhexanoic acid, 406 g (88.8

percent) of the compound was obtained. i

(27) Potassium erucate. Aqueous, 5-percent potassium hydroxide solution was added to a solution

of 338.6 g (1 mole) of recrystallized erucic acid in i 1,500 ml of 95-percent ethanol (faint pink to ' phenolphthalein). The solution was transferred j to a large evaporating dish, concentrated on the | steam bath, with frequent stirring, to a thick j paste, and transferred to an 8-liter beaker equipped i with a stirrer. The paste was mixed with 1 liter

{ of water and stirred while 3 liters of acetone wa.s added during 25 min, with the formation of a bulky, white precipitate. After the mixture had

been stirred for a few minutes, the precipitate was

collected on a Biichner funnel, washed with acetone, air dried, mixed with 2.5 liters of butyl

acetate, and heated (with stirring) to 90-100 °C; S sufficient water was added to afford a clear

| solution. The hot solution was filtered, allowed

to cool to room temperature, and refrigerated ! overnight, giving a fine, granular precipitate i which was filtered with suction, washed with ] acetone, dried, and powdered as usual; weight,

| 347 g (92 percent). ;

14
(28) Silver 2-ethylhexanoate. This compound

was prepared according to the procedure given

for silver cyclohexanebutyi'ate. From 2 moles

(288.4 g) of 2-ethylhexanoic acid, 360 g (91

percent) of the pure, dry salt was obtained.

3.5. Other Compounds Investigated

3.5.1. Erucates and 2-Ethylhexanoates

Most of the erucate salts were prepared by the

addition of an aqueous solution of the metal

hydroxide or acetate to an ethanol or acetone

solution of the required amount of purified erucic

acid [5]. Erucates not prepared by this method

were obtained by addition of an aqueous solution

of a salt of the desired metal to a warm methanol

solution of potassium erucate. This caused the

precipitation of crude product; the reaction mixture was then cooled in the refrigerator for several

hours, and the product was separated by filtration

and washed. The crude salt was triturated in a

large beaker with large amounts of water. After

thorough extraction, the product was filtered off,

air dried, dissolved in hot butyl acetate, the sus- pension filtered, and the solution cooled slowly.

After 18 hr, the product was separated, and washed

with a suitable solvent (acetone or methanol).

The material was recrystallized several times and

then dried in a rotary drier under diminished

pressure.

Freshly prepared stannic erucate dissolves in

mineral oU, but the salt, on drying and keeping,

becomes insoluble and no means has been found

for preparing solutions of this dried compound in

oUs.

The 2-ethylhexanoates were prepared by procedures analogous to those outlined for the erucates. However, acetone and methanol were

ineffective as precipitants for these salts, most of

which could only be isolated as oils.

3.5.2. Dialkyldithiocarbamates

The sodium salts of the dialkyldithiocarbamic

acids were prepared by slowly mixing a cold,

10-percent, alcoholic solution of the secondary

amine with an equimolar quantity of cold carbon

disulfide in ethanol and then slowly adding an

equimolar quantity of 10-percent aqueous sodium

hydroxide, with stirring untU. all turbidity disappeared.

Ordinarily, the sodium salt was used directly

(without isolation) for the preparation of other

salts, by mixing its aqueous solution with the

calculated quantity of a 10-percent aqueous solution of the appropriate metal salt of an inorganic

acid. However, it was observed that, if the

sodium dialkyldithiocarbamate is isolated by

removal of the solvent, the difficulty encountered

in obtaining certain of the salts as solids is greatly

lessened.

Most of the salts of the dialkyldithiocarbamic

acids crystallize readily and are easily purified by

recrystallization from ethanol, or from a mixture

of ethanol and chloroform or benzene.

The preparation of lead dibutyldithiocarbamate

is typical of the methods used.

Preparation oj lead dibutyldithiocarbamate. A

10-percent aqueous solution of lead nitrate

(0.05 mole) was added dropwise, with mechanical

stirring, to an aqueous solution of commercial

sodium dibutyldithiocarbamate (0.1 mole). Crude

lead dibutyldithiocarbamate separated as a gum,

from which the supernatant liquor was decanted:

the product was tritiu-ated with large amounts of

water, filtered, air dried, dissolved in hot isopropyl

alcohol, and the suspension filtered. The filtrate

was cooled, and the resulting crystals were filtered

off, air dried, and recrystallized in the same way.

Cold methanol was used for washing the crystals.

Finally, the pure product was dried in a rotary

drier at 60 °C and 1 mm; it had mp 78.5-79.0 °C.

3.5.3. Azomethine Chelates

The azomethines were prepared by mixing the

aldehyde or ketone with an equimolar quantity

of the appropriate amine, using methanol as the solvent. The metal chelate was then prepared

by adding an aqueous solution of the inorganic

salt to the Schiff base, followed by addition of

sodium acetate. The mixture was kept at incipient boiling for about 30 min and left under

refrigeration overnight.

The copper, nickel, and vanadium chelates of

A^-salicylidene-2-ethylhexylamine were obtained

as crystalline compounds having excellent solubility in oUs, but its iron, cobalt, and aluminum

chelates were only obtained as oils. Preparation oj Bis {N-salicylidene-2-ethylhexylamino)oxovanadium (IV). To prepare this compound [6], 12.9 g (0.1 mole) of 2-ethylhexylamine

was added to a solution of 12.2 g (0.1 mole) of

salicylaldehyde in 100 ml of absolute ethanol.

The mixture was allowed to stand for about 30

min, and 100 ml of a 5-percent aqueous solution

of vanadyl sulfate dihydrate (0.05 mole) was

added. After thorough mixing, 50 ml of a 10-

percent aqueous sodium acetate solution was

added, and the mixture was heated on the steam

bath for 30 min. A brown oil was precipitated;

it was separated by decantation and washed

several tunes with hot water. Finally, the crude

product (about 25 g) was dissolved in 80 ml of

ethanol and refrigerated overnight. The green

crystals were separated and dried in vacuo over phosphorus pentaoxide for 12 hr. The product

was recrystallized three times by the same method;

yield, 23 g; mp 93-93.5 °C. This compound

dissolves readily in bis(2-ethylhexyl)dithiocarbamic acid. The solution is stable for only a few days, but the stability is improved by the

addition of naphthenic acid and, possibly, by the

addition of 6-methyl-2,4-heptanedione.

Similar complexes of copper and nickel were

prepared in the same manner; both of these

chelates appeared to have satisfactory solubility

in oils.

15
Table 8. Spectrographic analysis of standard samples

Standard Sample

No.

Major

element Minor elements Standard Sample

No.

Major

element Minor elements

% %

1050 Al Fe, Si «0.01) 1063 B Si KO.Ol)

1051 Ba Sr «0.1); Ca, Si, Sn «0.01) 1063a B <0.01, of any

1051a Ba Sr «0.1); Ca, Na «0.01) 1064 Hg Na, Mg, Si «0.01)

1052 V Al «0.1) 1065 Ni Cu, Fe «0.01)

1052a V <0.01, of any 1065a Ni <0.01, of any

1066 Si <0.01, of any

1053 Cd <C0 01 of any

1054 Ca Sr kb.l); K, Si «0.01) 1067 K Na, Sr «0.1); Ca, Fe, Si «0.01)

1055 Co Ni, Sn (<0.1): Al, Cu, Fe, Mn «0.01) 1068 Ag Si (<0.01) lOSSa Co Ni (<0.1); Cu, Si «0.01) 1069 Na Al, Si «0.01)

1056 Cu Al, Si «0.01) 1069a Na <0.01, of any

1056a Cu <0.01, of any 1070 Sr Ca «0.1); Ba «0 01) 1057 Sn <0.01, of any 1070a Sr Ca «0.1); Ba «0.01)

1057a Sn <0.01, of any 1071 P <0.01, of any

1058 Fe Al, Mn, Mo, Si,Sn «0.01) 1071a P <0.01, of any

1059 Pb Sn «0.1); Fe «0.01) 1072 Cr Ba «0.1); Al, Si, Sr «0.01)

1059a Pb <0.01, of any 1073 Zn Ca, Mg, Ni, Si «0.01)

1060 LI Ca, Na «0.1); Al, K, Si «0.01) 1073a Zn <0.01, of any

1060a Li <0.01, of any 1074 Ca Ba, Na, Sr «0.01)

1061 Mn (<0.01) 1075 Al Si (<0 01) 1061a Mg <0.01, of any 1076 K Al, Ca, Mg, Si «0.01)

1062 Mn Sr «0.1); Al, Pb, Mo, Sn «0.01) 1077 Ag Si «0.01)

1062a Mn <0.01, of any

3.6. Spectrographic Analysis

Spectrographic analysis was applied in rapid

surveys of preliminary and final samples for qualitative or semiquantitative analysis for 50 or more

chemical elements. In this procedure, a small

sample was volatilized in an electric arc, the spectrum of the arc was photographed, and the spectrogram was examined for the presence of prominent

spectral lines of the various elements by comparison with a standard reference spectrum. Semiquantitative estimates of ranges of concentration

of the impurities were reported. For the elements

found present in significant amounts, quantitative

determinations were made subsequently by chemical analysis or by spectrographic analysis relative

to synthesized standards.

The detailed procedures and apparatus used for

the semiquantitative analyses were as follows.

A 5-mg portion of the powdered sample was mixed

with 2 mg of high-purity graphite powder, which

acted as a buffer to assist in volatilizing the sample.

The charge was placed in a graphite electrode

(having a shallow cup) and was vaporized and

excited in a direct-current arc, with a starting

current of 5 amp and a running current of 15 amp.

The light from the arc, passing through the slit of

the spectrograph, was dispersed into a spectrum

and this was photographed in the spectral range

from 2,200-4,800 A on Eastman 33 plates. The

spectrograph used for this work employed a Wadsworth mounting of a concave grating which had

15,000 lines per inch and a radius of curvature of

21 ft, and which produced a spectrum with linear,

reciprocal dispersion of 5 A per mm in the first

order. In some cases, where greater sensitivity

was desired for the alkali metals, the spectrum

was also photographed in the range 4,800-7,000 A,

with an Eastman I-N plate.

The elements searched for in all samples included

the following: Ag, Al, As, Au, B, Ba, Be, Bi,

Cu 0. 004 Ti <0. 0002 Fe .001 Mo < .0002 SL— — < .0006 Al < .0002 Co < .0004 Mg < .0002 Cr < .0002

Ca, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, Hf, Hg, In,

Ir, La, Mg, Mn, Mo, Nb, Ni, Os, P, Pb, Pd, Pt,

Rh, Ru, Sb, Sc, Si, Sn, Sr, Ta, Te, Th, Ti, Tl, U,

V, W, Y, Zn, and Zr. In addition, Cs, K, Li,

Na, and Rb were sought in alkali samples, using

the special conditions described in the preceding

paragraph.

The results of spectrographic semiquantitative

analyses of the final materials issued as standard

samples are given in table 8. As a check on the semiquantitative analysis,

quantitative spectroscopic analysis was made for

impurities in nickel cyclohexanebutyrate (Standard Sample 1065), using a procedure similar to

that of ASTM Tentative Method E129-57T,'

in which the sample is ignited to form the oxide,

and analysis is made by direct-current arc excitation relative to standard samples prepared in

oxide form. The results of this analysis, given in

percentage of the element in the original metalloorganic compound, are given below.

3.7. Chemical Analysis

For each determination, a sample (approximately 1 g) was dried over phosphorus pentaoxide

for the tuTie recommended in table 5, accurately

weighed, and analyzed. All analyses were performed in duplicate, at least. The analytical

results are given in table 6. ( For decomposition prior to analysis, two I methods were mainly employed. For 22 of the

standard samples, decomposition was accom- ! plished either by (a) wet-ashing with sulfuric !

' Methods for Emission Speotrochemical Analysis, 3d ed., pp 139-43 ! (American Society for Testing Materials, Philadelphia, 1960). j

16
and nitric acids, followed by determination of the

element in the solution by appropriate methods,

or (b) ignition. For 13 of the compounds, both

methods were applied. The residue obtained by

ignition was either (a) weighed as the oxide; (b)

treated with sulfuric acid and the sulfate weighed ; (c) reduced with hydrogen and the metal weighed ; or (d) dissolved in acid and the metal determined

by various means. However, menthyl borate

(Standard Sample 1063) was fused with sodium

peroxide, and the organic material of mercuric

cyclohexanebutyrate (Standard Sample 1064) was

extracted with chloroform. Triphenyl phosphate

(Standard Sample 1071a) was decomposed by

wet-ashing with perchloric and nitric acids.

The details of the methods of analysis for each

standard sample are given in the next four

subsections.

3.7.1. Wet-ashing; Ignition

Aluminum cyclohexanebutyrate {Standard Sample

1050) . Aluminum was determined by wet-ashing,

precipitating with ammonium hydroxide, and

igniting the filtered precipitate to aluminum oxide

at 1,100 °C. Determinations were also made by

direct ignition of a sample, %vrapped in filter paper

and covered with oxalic acid, to ahmiinmn oxide

at 1,100 °C.

Barium cyclohexanebutyrate {Standard Sample

1051) . Barimn was determined by wet-ashing,

filtering the barium sulfate, and weighing it after

ignition at 1,000 °C. Determinations were also

made by direct ignition of a sample wrapped in

filter paper and covered with oxalic acid. The

residue was converted into barium sulfate and

weighed after ignition at 900 °C.

Bis{l-phenyl-l ,3-butanediono)oxovanadium {IV)

{Standard Sample 1052). Vanadium was determined by wet-ashing, oxidizing the vanadium

with nitric acid, and titrating the vanadium with

ferrous ammonium sulfate solution. Determinations were also made by direct ignition of a sample

wrapped in filter paper and covered with oxalic

acid. The oxide was ignited at 800 °C and

weighed as vanadium pentaoxide.

Calcium cyclohexanebutyrate {Standard Sample

1054). Calcium was determined by wet-ashing,

precipitating the calcium sulfate in alcoholic

solution, and weighing the calcixun sulfate after

ignition at 600 °C. Determinations were also

made by direct ignition of a sample wrapped in

filter paper and covered with oxalic acid. The

oxide was converted into calcium sulfate, and

weighed after ignition at 700 °C.

Copper cyclohexanebutyrate {Standard Sample

1056). Copper was determined by wet-ashing,

depositing the copper by electrolysis, and weighing

as metallic copper. Determinations were also

made by direct ignition of a sample wrapped in

filter paper and covered with oxalic acid. The

oxide was ignited under hydrogen, and weighed as the metal.

Ferric cyclohexanebutyrate {Standard Sample

1058) . Iron was determined by wet-ashing,

precipitating with ammonium hydroxide, dissolving the precipate in hydrochloric acid, reducing

with stannous chloride, and titrating with potassium dichromate. Determinations were also made

by direct ignition of a sample, wrapped in filter

paper and covered with oxalic acid, to ferric oxide

at 1050 °C.

Lead cyclohexanebutyrate {Standard Sample

1059) . Lead was determined by wet-ashing,

filtering the lead sulfate through a porcelain frit,

and weighing the lead sulfate after ignition at

600 °C. Determinations were also made by direct

ignition of a sample wrapped in filter paper and

covered with oxalic acid. The oxide was dissolved

in nitric acid, precipitated with chromate, and

weighed as lead chromate after drying at 140 °C.

Magnesium cyclohexanebutyrate (Standard Sample 1061). Magnesium was determined by wetashing, precipitating twice as magnesium ammonium phosphate, and weighing the magnesium pyrophosphate after ignition at 1,000 °C. Determinations were also made by direct ignition of a sample wrapped in filter paper and covered with

oxalic acid. The residue was converted into magnesium sulfate and weighed after ignition at

700 °C.

Manganous cyclohexanebutyrate {Standard Sample 1062). Manganese was determined by wetashing, oxidizing the manganese with ammonium

persulfate, and titrating the manganese with

sodium arsenite solution. Determinations were

also made by direct ignition of a sample wrapped

in filter paper and covered with oxalic acid.

The residue was converted into manganous sulfate

and weighed after ignition at 700 °C.

Nickel cyclohexanebutyrate [Standard Sample

1065). Nickel was determined by wet-ashing,

precipitating with dimethyIglyoxime, and weighing

the nickel dmieth.ylglyoxime precipitate after

drying at 150 °C. Determinations were also made

by direct ignition of a sample wrapped in filter

paper and covered with oxalic acid. The oxide was

ignited under hydrogen and weighed as the metal.

Potassium cyclohexanebutyrate {Standard Sample

1067). Potassium was determined by wet-ashing,

removing the excess acid by evaporation, and

weighing the potassium as potassium sulfate after

ignition at 650 °C. Determinations were also

made by direct ignition of a sample wrapped in

filter paper and covered with oxalic acid. The

residue was converted either into potassium sulfate or potassium chloride and weighed after ignition

at 650 °C.

Strontium cyclohexanebutyrate {Standard Sample

1070). Strontium was determined by wet-ashing,

precipitating the strontium sulfate in alcoholic

solution, and weighing the strontium sulfate after

ignition at 600 °C. Determinations were also

made by direct ignition of a sample wrapped in

filter paper and covered with oxalic acid. The

residue was converted into strontium sulfate, iind

weighed after ignition at 700 °C.

17
Zinc cyclohexanebutyrate {Standard Sample 1073).

Zinc was determined by wet-ashing, precipitating

with hydrogen sulfide from 0.01 N acid, and igniting the filtered precipitate to zinc oxide at 950 °C.

Determinations were also made by direct ignition

of a sample, wrapped in filter paper and covered

with oxalic acid, to zinc oxide at 950 °C.

3.7.2. Wet-ashing

Cadmium cyclohexanebutyrate {Standard Sample

1053). Cadmium was determined by wet-ashing,

electrodepositing the cadmimn from an alkaline

cyanide solution, or from 0.5-percent sulfuric acid

solution, and weighing the metal.

Dihutyltin bis{2-ethylhexanoate) {Standard Sample 1057). Tin was determined by wet-ashing,

precipitating the tin with cupferron, and igniting

to stannic oxide at 1,000 °C. Determinations

were also made by wet-ashing, reducing the tin

with metallic nickel, and titrating the tin with

potassium iodate solution.

Lithium cyclohexanebutyrate {Standard Sample

1060). Lithium was determined by wet-ashing,

remo%dng the excess acid by evaporation, and

weighing the lithium as lithiiun sulfate after

ignition at 600 °C.

Octaphenylcyclotetrasiloxane {Standard Sample

1066). SUicon was determined by wet-ashing,

dehydrating the silica twice, igniting the silica at

1,100 °C, and volatilizing the silicon with hydrofluoric acid.

Triphenyl phosphate {Standard Sample 1071).

Phosphorus was determined by wet-ashing, twice

precipitating with magnesia mixture, and igniting

to magnesium pyrophosphate at 1,000 °C. Phospliorus was also determined (for Standard Sample

1071a) by wet-ashing with perchloric and nitric

acids, precipitating the phosphorus with quinoline

in the presence of sodium molybdate, drying the

precipitate at 250 °C, and weighing as (C9H,N)3-H3P04-12 M0O3.

Tris{2'-hy dr 0 xyac eta p hen on o)chromium{III)

(Standard Sample 1072). Chromium was determined by wet-ashing, oxidizing the chromium with

ammonium persulfate, and titrating the chromium

with ferrous ammonium sulfate solution.

3.7.3. Ignition

Cobalt cyclohexanebutyrate {Standard Sample

1055). Cobalt and nickel (minor constituent)

were determined by ignition of a sample wrapped

in filter paper and covered with oxalic acid. The

mixture of oxides was dissolved in hydrochloric

acid, electrodeposited as cobalt plus nickel from

ammoniacal solution, and weighed as the metals.

The oxide mixture was also ignited under hydrogen

and weighed as the metals. Nickel M^as separa ted

from a hydrochloric acid solution of the metals by

anion exchange, precipitated with dimethylglyoxime, and weighed.

Silver cyclohexanebutyrate {Standard Sample

1068). Silver was determined by direct ignition

of a sample wrapped in filter paper and covered

with oxalic acid. The oxide was ignited under

hydrogen and weighed as the metal. Determinations were also made by dissolving the ignited

oxide in nitric acid, precipitating with hydrochloric acid, and weighing the silver chloride.

Sodium cyclohexanebutyrate {Standard Sample i 1069). Sodium was determmed by direct ignition ' of a sample wrapped in filter paper and covered

j with oxalic acid. The residue was either con- 1 verted into sodimn sulfate and weighed after igni-

| tion at 900 °C or converted into sodium chloride , and weighed after ignition at 600 °C.

Calcium 2-ethylhexanoate {Standard Sample ! 1074). Calcimn was deteiTnined by direct ignition 1 of a sample wrapped in filter paper and covered

with oxalic acid. The residue was dissolved in

hydrocliloric acid, the calcium precipitated as calcium oxalate, and the calcium oxalate titrated

with potassium permanganate solution.

j

3.7.4. Other Procedures | Menthyl borate {Standard Sample 1063). Boron i was determined by bomb-fusing an 0.5-g sample

with sodium peroxide and titratmg the resulting

boric acid with standard sodium hydroxide after

the addition of mannitol.

^ Mercuric cyclohexanebutyrate {Standard Sample

1064). Mercury was determined in a sample by

j titration with ammonimn thiocyanate, after ex- \ traction of organic matter with chloroform. De- i terminations were also made by extracting a ; sample with chloroforai, precipitating the mercury 1 with hydrogen sulfide, drying the precipitate at | 110 °C, and weighing as mercuric sulfide. i

3.8. Weight-stability of Standard Compounds I

I Preliminary studies showed that some of the

j compounds chosen as standards are fairly hygroscopic. Furthermore, drying hy gentle heating | (e.g., to 60 °C) at atmospheric pressure or in a ! vacumn oven was, in some instances, deleterious. ' Consequently, in order to ascertain the time for

| maximimi absorption of moisture by each comj pound and the rate of drying after maximum | absorption, the following procedure was employed. | A specitnen (approximately 1 g) of the standard [ sample was transferred from the bottle to a weighj ing bottle (ground-glass stopper) and accurately I weighed. The stopper was then removed and the

material was exposed to an atmosphere of approxi- \ mately 75 percent humidit}' in a closed desiccator , containing a dish of saturated, aqueous sodium '. chloride solution. After the elapse of various ji periods of tinie, the stopper was replaced in the ^ weighing bottle and the weight was determined.

| When equilibrium had been reached, the sample

| was dried in a desiccator containing phosphorus

pentaoxide until the weight was constant. Most \ of the determinations were made in duplicate.

In addition, a 1-g specimen of each standard

sample, as received by the analyst, was dried to

constant weight over phosphorus pentaoxide in a

desiccator. The percent loss in weight is given in 1 column 4 of table 9.

18
Table 9. Loss in weight on drying, gain in weight at 75 percent humidity, and loss in loeight on drying humidified material,

for the standard samples

Serial No.

1_ 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.

NBS

Standard

Sample

No.

1050

1051 1051a

1053

1054

1055 1055a

1056 1056a

1058

1059

1059a

1060 1060a

1061 1061a

1062 1062a

1064

1065 1065a

1067

1068 1069 1069a

1070

1070a

1073 1073a

1063 1063a

1072

1071 1071a

1066

1057

1057a

1052a

1074

1075

1076

1077

Original material ' Humidified material '>

Dried over P2O5

Time

to equil

Loss in wt at equil

r

(77 24 1. 0 24 1. 0

OA 11 Q u. y 48 5.

7

48 0.

1

1 n AQ 1 0

0 U. Ui

0Zi no

24 . 6

24 .4

2 .02 24 .5

7 .4 216 2.6

48 0.3

144 1.9 24 0.5

2 .01 72 .7 24 .5

24 4.9 48 0.5

2 .01 2 .01 48 .8 24 .5

2 .05

2 .01 2 .01 48 .4

2 .01 2 .01 2 .0

2 .01

2 .01

2 .02 48 .4 48 .5 2 .01 2 .01

In 75% humidity

Time

to equil

hr

22

2

7

7

24

48

2

2

2

2

16 168

168 336

336

24

72

2

16848

* 48

24

168

1682

2

48

24

48

24

2

22

2

2

2

2

4824

24

24

Gain in wt

m

7hr

%

0. 08

1.

1

1.9

1.6 0.06

.06

.01 .03

.2

.2

.4

.3

.3

56

/I.

4.

0.8

2.5

0.04

.4

1.5

0.4

2.3

2.2 0.2

1.4 5.0 0.04

.04

.4

.01 .02

.0

.01 .04

.01

5.

1

0.

1

. 1 .4

at equil

0. 08

1.

1

1.9

1.6

0. 06

.1 1.1

0. 01

.02

.2

.2

.6 2.8

2.3

e 2.2

' 2.2

1.2 2.7

0.04

.9

1.9

* 30.0 0.6 28.0

28.0

0.2

1.8 6.9

0.2

. 1 .4

.01

.01 .0.01

.04

.02

Dried over P2O5

Time''

to equil

hr

224

24

48

48

24

48

2

224

48

224

24

48

48

72

248

48

' 430

2448

48

24

24

24

48

2

248

22

0

2

2

248

48

Loss in weight '

m

7hr

10.4

1.7 8.1 8.4

0.9

1.0

1.7

1.7

0. 01 .06

.01

.01 .0

.01 .02

.02 2.9

0.5

.2

.5

at equil '

% %

1.0 1. 0

2. 1 2. 5

2. 2 2. 8

1. 6 7. 2

0. 09 0.2

0. 08 LI

1.5 2.5 0.02 0. 02

.06 .05

.7 .8

.9 1.2

.03 0. 01 2.5 3.6

1.8 3.0

2.0 2.8

1.4 L6

0.8 2.9

1.1 3.3 0.03 0.03

1.0 1.7

1.2 2.2

23.5 2.0

28.0

28.0 0.9

1.2

3.6

7.2

0. 01 .04

1.0

0. 01

.01 .0

.01 .01

.02

4.5

0.7

.2

.5

' As received by analyst.

<> Kept in 75% humidity to equililirium.

' Calculated on the weight of original material taken. Eecommended drying time.

• The figure in this column should be approximately equal to the sum of the figures in columns 4 and 7, unless hydrolysis occurred during the humidification.

/ Gain of 3.5% after 48 hr.

« This compound initially gained weight and then lost some of this gain in

weight, at 75% humidity.

* Equilibrium not reached. This compound should not be exposed to moisture.

The percent gain in weight, at equUibrimn in

75-percent humidity, of a 1-g specimen of each

standard sample (as received by the analyst) is given in colimm 7 of table 9. The percent loss

in weight of this himiidified material, on drying to

constant weight over phosphorus pentaoxide in a

desiccator, is given in column 10 of table 9. The

figure in colimm 10 should be approximately equal

to the sum of the figures m columns 4 and 7,

unless hydrolysis occurred during the humidification. Standard Samples 1059a, 1061 and

1061a, 1067, and 1074 exhibit this behavior.

From table 9, it may be seen that the weightstabilities vary widely. It was concluded that, as a precautionary measure, bottles containmg

standard samples should be stored, tightly closed,

in desiccators containing phosphorus pentaoxide,

and that, before use, the required amount of a compound should be dried over phosphorus pentaoxide for the length of time recommended in

column 8 of table 9.

3.9. Dissolution in Petroleum Oils

In estunattng the oil-solubUity of the metalloorganic and other compounds, benzene, toluene,

xylene, mineral spirits, mineral oil, white paraffin

oil, and base oUs (which were supplied by several

oil companies) were used. One or more of the

following attempts at dissolvmg the compounds

were made.

(1) Dissolving directly in oil, without heat or other solvents.

19
(2) Dissolving in oil, with moderate heating

(below 100 °C).

(3) Dissolving in benzene, toluene, xylene, or mineral spirits, and diluting with the base oil.

(4) Dissolving in a solubilizing agent (such as a

free carboxjdic acid, a diketone, or an ester) and

diluting with the base oU.

Early in the project, it was found that very few

of the compounds could be dissolved by method 1. A slightly larger number of compounds could be

dissolved by method 2, but the solutions usually

redeposited material at room temperature.

Method 3 gave solutions that were more stable.

Method 4 gave the most stable and the most

concentrated solutions of a given element.

These solubility tests were used both for evaluating the solubility of each compound and for

comparing the solubilities of a variety of

compounds of one element. The solubility of a compound was considered to be "satisfactory" if, by method 4, a solution could be prepared that

had a concentration (of the element in question)

of 500 ppm. In the subsequent discussion, the

term "calculated weight" of a compound refers to

the weight of it which will provide 50 mg of the

element of interest per 100 g of the final solution.

The solution was regarded as "stable" if it re- mained clear and devoid of visible change during

several weeks at room temperature.

In the course of the work, a solution was developed which acts as both a solubUizer and a

stabilizer of compounds dissolved in oil. This

"solubilizing solution A" consists of a mixture of

equimolar proportions of bis (2-ethylhexyl) amine

and bis (2-ethylhexyl) dithiocarbamic acid in an

equal volunie of xylene.

3.9.1. Metal 2-Ethylhexanoates

Crude salts of 2-ethylhexanoic acid dissolved

readily in benzene or xylene, and these solutions

could be diluted with base oils to give stable

solutions.

The purified, solid 2-eth3dhexanoates of bariiun,

calciimi, copper, lead, lithiiun, and sodium gave

stable solutions (metal concentration, 500 ppm)

by dissolving the calculated weight in 3 to 6 ml of

2-ethylhexanoic acid and dilutmg to 100 g with

lubricating oU.

Silver 2-ethylhexanoate gave a solution (sUver

concentration, 500 ppm) by first dissolving in

2-ethylhexylamine and then diluting to 100 g

with base oU.

The iron (III) salt was dissolved by use of

6-methyl-2,4-heptanedione and 2-eth5dhexanoic

acid before addition of the oU.

The chromium salt underwent changes sunUar

to those shown by chi'omium erucate and, after

storage, could not be dissolved.

The solid salts of nickel and cobalt were practically insoluble in all solvents tested (with base

oil).

3.9.2. Metal Erucates

Erucates of the metals of interest were found to

be insoluble in the common organic solvents, f; Solutions having (a) the desired concentration oi\

metal and (b) satisfactory stability were prepared \ by dissolving the calculated weight of the given ti salt in 3 to 6 ml of hot naphthenic acid (or hott

2-ethylhexanoic acid) and diluting to 100 g with*

lubricating oil. ; Because of the high molecular weights of the

metal erucates, a relatively large sample of each ^

salt was needed in order to provide a final concentration (of metal) of 500 ppm; consequently, i concentrations of 200 ppm were tested instead. , Stable solutions of the erucates of barium, lead,

,

lithium, magnesium, potassimn, sodium, strontilun, and zinc, respectively, at a concentration of i 200 ppm of the metal, were obtained by use of • 4 to 6 ml of 2-ethylhexanoic acid as the solubilizing agent. L Silver erucate was dissolved in lubricating oil

' by use of solubilizing solution A.

By use of naphthenic acid or 2-ethylhexanoic

.

acid, freshly prepared chromiimi erucate dissolved

in base oils, but after the dry salt had been kept^

at room temperature for several days, it could no

longer be dissolved.

3.9.3. Metal Dialkyldithiocarbamates \

The calculated weight of each compound dis-|

solved readily in 3 to 5 ml of benzene, toluene, '. xylene, or mineral spirits at room temperature or,

!

in a few instances, on heating; the solution was ? then diluted to 100 ml with lubricating oil, andlj

the flask was stoppered. The solution was kept

at room temperature for many weeks and was

periodically observed for deposition of a precipitate or formation of a gel.

The following observations were made on dibutyldithiocarbamates: the cadmium and cobalt:

compounds formed gels in base oils; the iron (III)

compound had low solubility; but the copper,

lead, nickel, and zinc compounds were satisfactory.

As could be anticipated, highly purified samples ? of the metal dithiocarbamates were less soluble in

J oil, and showed a greater tendency to crystallize

from solution, than less pure samples. However, ^' by dissolving the calculated weight of the dithio- [ carbamate (of copper, lead, nickel, and zinc) in j 4 to 6 ml of solubilizing solution A and then ' adding sufficient lubricating oil to bring the

weight to 100 g, each compound remained dissolved and the stabilit}^ of the solution, on keeping,

was satisfactory in all cases but one. (After a

| solution of lead dibutyldithiocarbamate had been

kept at room temperature for several weeks, a \ precipitate was formed which could not be redis- i solved in organic solvents.) Nickel bis(2-ethyl-

[

hexyl)dithiocarbamate gave solutions that were)

stable for many months. I

20
3.9.4. Metal Chelates of Azomethines

The copper, nickel, and vanadium chelates of

A^-salicylidene(2-ethylhexyl) amine were soluble in

lubricating oil. However, the oil solution of the

vanadium chelate was not sufficiently stable, unless

used on the same d?y that the solution was prepared; but addition of 4 to 6 ml of solubilizer

A (per 100 g of final oU-solution) gave the desired

stability.

3.9.5. Metal Chelates of Diketones and Hydroxy Ketones

The metal chelates of the diketones having

low molecular weight are soluble in benzene or

xylene, and less soluble in mineral spirits, but

their solubility in lubricating oils is very low

The 2,4-pentanedione chelates of chromium,

cobalt, copper, and iron are practically insoluble

in oil, and solutions of the compounds in oil gave

crystalline precipitates on being kept overnight

at room temperature.

The 6-methyl-2,4-heptanedione chelates of aluminum and chromium were only obtained as oils,

which were, however, very soluble in lubricating

oil without addition of any solubilizer The

chromium, cobalt, iron, lead, and vanadium

chelates of l-phenyl-l,3-butanedione and 1,3-

diphenyl-l,3-propanedione were also tested for oilsolubility. The chromium and iron chelates of

1-phenyl-l,3-butanedione were too low in solubility (by method 4), but the cobalt, lead, and

vanadium chelates had satisfactory oil-solubility

by method 4. The stability of this solution of

this vanadium chelate in oil was satisfactory.

For the vanadium chelate of l-phenyl-1,3-

butanedione, a stable solution (metal concentration, 500 ppm) was prepared by dissolving the

calculated weight in a hot solution of 3 ml of bis-

(2-ethylhexyl) amine and 3 ml of 6-methyl-2,4-

heptanedione in 3 ml of xylene, adding 1 ml of

2-ethylhexanoic acid and 80 to 90 ml of lubricating oil, cooling to room temperature, and diluting

to 100 g with lubricating oil. Although this vanadium compound is less oil-soluble than his{Nsalicyiidene-2-ethylhexylamino)oxovanadium (IV)

,

it is superior to the latter as regards (a) stability

to light and air and (b) the stability of its

solutions.

An oil solution of the chromium chelate of 2'-

hydroxyacetophenone, at a metal concentration of

500 ppm, was prepared by heating the calculated

weight with a mixture of 3 ml of 2-ethylhexanoic

acid and 3 ml of 6-methyl-2,4-heptanedione until a clear solution formed and then diluting to 100 g

with lubricating oil.

3.9.6. Metal Cyclohexanebutyrates

The solid cyclohexanebutyrates of 19 metals

were tested for solubility. The salts of cadmium,

cobalt, copper, iron, lead, manganese, mercury,

nickel, and zinc dissolve readily in chloroform but

are less soluble in benzene or xylene.

With the exception of the chromium salt, all of

the cyclohexanebutyrates studied were, by use of a solubilizer, dissolved in lubricating oil to afford

stable solutions. For the salts of barium, calcium,

lead, lithium, magnesium, manganese, mercury,

nickel, potassium, sodium, and zinc, the calculated

weight was dissolved in 4 to 6 ml of 2-ethylhexanoic acid, and the solution was diluted to 100 g

with lubricating oil to afford a stable solution.

For the salts of cadmium, cobalt, copper, and

silver, the calculated weight was dissolved in 4 to

6 ml of 2-ethylhexylamine, and the solution was

diluted with oil. For the salts of aluminum and iron, the calculated weight was dissolved in a hot mixture of 2-

ethylhexanoic acid and 6-methyl-2,4-heptanedione,

and the solution was diluted with oil. Chromium cyclohexanebutyrate was unsatisfactory both as regards its physical state and its

low solubility in oil (with all solubilizers tested).

3.9.7. Miscellaneous Compounds

For the elements boron, phosphorus, and tin,

the compounds that (of those tested) had the

highest solubility in oil were menthyl borate,

triphenyl phosphate, and dibutyltin bis(2-ethylhexanoate), respectively. Each dissolved in hot

lubricating oil, at a concentration (of the element

of interest) of 500 ppm, to give a stable solution.

However, in routine work, it was found more

practical to dissolve the calculated weight of each

compound in 5 ml of hot xylene and dilute to

100 g with lubricating oil. For silicon, the only solid derivative studied

was octaphenylcyclotetrasiloxane, and this is practically insoluble in oils at room temperature.

However, certain of the petroleum laboratories

cooperating in testing the oil-solubility of the

compounds discovered that this silicon compound

gives a solution (silicon concentration, 200 ppm)

which can be used satisfactorily if prepared as described in section 3.9.8.

Preparation of a stable, oil solution of the

selected chromium compound has already been

described (see section 3.9.5).

3.9.8. Preparation of an Oil Solution Containing One

Element of Interest, at the Desired Concentration

The required weight of the standard sample

and the volume of each solvent needed, except

that of the lubricating oil, are given in table 10.

The procedure is exemplified by that for aluminum

cyclohexanebutyrate (Standard Sample 1050).

Transfer approximately 1.0 g of this compound from

the bottle to a small beaker and dry over fresh phosphorus

pentaoxide in a desiccator for two hours. (Tightly close the bottle containing the remainder of the compound.')

Quickly and accurately transfer 0.725 g of this dried salt to a weighed 200-ml flask. (This weight of salt is equivalent to 50 mg of aluminum.) Add 3 ml of xylene and

4 ml of 2-ethylhexanoic acid and heat the flask on a hot

plate, with swirling and without charring, until a clear

gel forms. Add 3 ml of 6-methyl-2,4-heptanediono and

21
Tabf-p: 10. Preparation of a solution of one Standard Sample, in lubricating oil, at a concentration {of the element of interest)

of 600 ppm »

Standard Sample

Serial No. NBS No. Element of interest •>

Approxi- mate weiglit taken for drying

Weight of dried material taken

Xylene

2-Ethyl- hexanoic

acid

6-Methyl2,4-heptane- dione

2-Ethylhexylamine

1 1050 Al

g

1.0

Q 0.725 ml

3 ml

4" ml

3

TJll

2 1051 Ba 0.2 . 178 3 5

3 1053 Cd .3 .209 2 c2 4

4 1054 Ca . 5 .476 3 5

5 1055 Co .3 .292 2 "2 4

6 1056 Cu .5 .313 2 «2 4

7 1058 Fe .3 .259 3 4 3

8 1059 Pb .2 .133 3 5 9 1060 Li 1.5 1.25 3 5 10 1061 MgMn

1.0 0.725 3 5

11 1062 0.5 .360 3 5

12 1064 Hg

Ni

.2 .138 3 5

13 1065 .3 .284 3 5 U 1067 K .3 .263 3 5

l.T 1068 Ag

Na

.2 . 129 2

c 2 4

16 1069 .5 .417 3 5

17 1070 Sr .3 .252 3 5

18 1073 Zn .3 .270 3 5

19 1063 B 2.5 2. 203 5 20 1072 Cr 0. 5 0. 472 3 3 21 1071 P .6 .526 5 22 <> 1066 Si .2 = .142 4g

23 1057 Sn .3 .212 5 24 1052 V .4 .383 3 0 i '3

25 1074 Ca .5 .373 3 5 26 1075 Al .8 .666 3 4 3

27 1076 K .6 .495 3 5 28 1077 Ag . 2 .118 2 « 2 4

Solubilizers added

» Except for compound 22 (Standard Sample 1066).

•> Wt of element, 60 mg, except for compound 22 (20 mg).

" Added just before addition of the lubricating oil.

continue heating and swirling until the gel disappears

and a clear solution forms. To the hot solution, add 80

to 90 ml of lubricating oil, and gently shake the flask to mix the contents. Allow the fiask to cool to room temperature and add enough lubricating oil to bring the total weight of the contents of the flask to 100 ±0.5 g. Stopper

the flask and shake gently to insure a homogeneous

solution. The concentration of aluminum in this solution

is 500 ppm.

Because of its low solubility, a special procedure

is necessary in order to prepare an oil solution of

octaphenylcyclotetrasiloxane (Standard Sample

1066).

Accurately transfer 0.142 g of this compound to a weighed 200-ml flask. (This weight of compound is equivalent to 20 mg of silicon.) Add 4 g of xylene and

heat the flask on a hot plate, with swirling and without

charring, until the solid dissolves. In a separate flask,

heat 95 g of lubricating oil to 75 °C, and carefully pour

this hot oil into the silicon-containing solution. Allow

the solution to cool to room temperature and add enough

cool lubricating oil to bring the total weight of the contents

of the flask to 100 ±0.5 g. Reheat the flask immediately

to 75 °C under a reflux condenser and keep the solution

under the condenser, at this temperature, during use. The

concentration of silicon in this solution is 200 ppm.

3.9.9. Preparation of an Oil Solution Containing Several

Elements of Interest, at the Desired Concentration

Stable solutions of a mixture of the compounds,

containing each element of interest at the desned

concentration, can be prepared.

Of the 24 compounds selected as standards, the

aluminum, chromimn, iron, and vanadimn compounds require (a) the most heating and (b) the

presence of at least two solubilizers (in xylene)

for dissolution in the oil. Consequently, one (or

i See separate description of procedure.

« Contains 20 mg of Si and gives a fmal concentration of 200 ppm.

' Plus 3 ml of bis-(2-ethylhexyl)amine.

more) of these compounds was dissolved first. Moreover, the compounds of silver and mercury

are sensitive to prolonged heating and, so, theyi

should be added last. For the other compounds,'

the order of addition is immaterial.

An appropriate solubilizer, or mixture thereof,

is chosen, and the calculated weight of one of the

compounds is added; this compound is dissolved!

completely. The other compounds are now!

added, one at a time, each being dissolved com-'

pletely before the next one is added. As a rule,|

the more compounds added, the greater the

solubility in the mixture. Finally, the cooled

solution is diluted to 100 g with lubricatmg oil. ' The volume of solubilizer needed depends on

the particular mixture of compounds to be dis-i solved, but in no instance exceeded 12 ml per|

100 g of final oil-solution.

The following is a precise description of the

preparation oj a blend containing nine elements oj. interest, each at a concentration of 250 ppm.

The solubilizing agent was prepared by placing

5 ml of 2-ethylhexanoic acid, 4 ml of 6-methyl2,4-heptanedione, and 2 ml of xylene in a weighed,

,

200-ml Erlenmeyer flask. The calculated weightj

of aluminum cyclohexanebutyrate (see table 11)!

was weighed into a small beaker and carefully

transferred to the flask (without permitting the

salt to touch the inside of the flask and without

creation of dust of the compound). The sus-' pension was gently heated on a hot plate, with'

swirling, until the salt had dissolved to a clear

solution. Using a clean spatula each time, and;

22
Table 11. Order of addition and weights of compounds used

for preparation of a blended solution of nine elements in

oil

Element

AlCrV

Ba

FeCu

CoMg

Ni

Compound

Aluminum cyclohexanebutyrate

Tris (2'-hydroxyacetophenono) chromium (III)... Bis (l-phenyl-l,3-butanediono) oxovanadium (IV) Barium cyclohexanebutyrate

Iron cyclohexanebutyrate

Cupric cyclohexanebutyrate Cobalt cyclohexanebutyrate

Magnesium cyclohexanebutyrate --- Nickel cyclohexanebutyrate

Wt of compound

used •>

9

0. 363

.236

.193 .089

.130

.157

.146 .363 .142

» Equivalent to 25 mg of the particular element.

b Per 100 g of final solution, to give a concentration (of the element) of 250 ppm.

with precautions to avoid contamination from

transfer of traces of one compound to a container

of another compound, the calculated weight of

each of the other compounds was added, one at a time (in the order given in table 11), and completely dissolved before the next compound was

added. After each addition, the mixture was

gently heated, tilted, and rotated in order to wash

down any particles adhering to the inside of the

flask.

After the last compound had been added and

dissolved, 2 ml of bis(2-ethylhexyl)amine was

added. The hot solution in the flask was now

poured into the small beaker, and back and forth,

until all traces of solid in the beaker had dissolved.

After returning the solution to the fl.ask, the

beaker was washed with six 15-ml portions of

lubricating oil, and these rinsings were all transferred to the flask. The oil solution was now

allowed to cool to room temperature, and cool

lubricating oil was added to the flask until tlie weight of the solution was 100 d=0.5 g. The

solution was reheated to 85 °C, allowed to cool to

room temperature, transferred to a bottle, and

tightly stoppered.

A precise determination of the maximum concentration attainable for each element of interest,

either individually in oil plus solubilizers, or as a mixture of the standard compounds in oil plus

solubUizers, has not been made. However, so- lutions having concentrations much higher than

those given have been prepared and found to be

stable. All solutions prepared from the standard

compounds (according to the directions given)

have, up to this time, shown no signs of deterioration on keeping.

The authors express their appreciation to all persons and firms who co-operated on this project.

They are especially indebted to W. T. Gunn,

Director of the Division of Refining, American

Petroleum Institute, and to the following members

of the Project Advisory Committee: C. M.

GambrUl, Ethyl Corporation, Chairman; R. O.

Clark, Gulf Research and Development Company;

G. H. Patterson, E. I. du Pont de Nemours and

Company, Inc.; E. D. Peters, Shell Development

Company; and E. B. Tucker, Standard Oil Company (Indiana). They also thank the following

members of the staff of the National Bureau of

Standards who collaborated on the work and made

many helpful suggestions: H. A. Bright ^ and E.

Wichers. Technical assistance was rendered by

A. D. Kuchta (summer student, 1957 and 1958).

Spectrographic analyses were performed by E. K.

Hubbard and R. Alvarez of the Spectrochemistry

Section. Chemical analyses were made by B. B.

Bendigo and L. A. Machlan of the Standard Reference Materials Section, and the determinations

of the weight-stabilities were made by B. B.

Bendigo.

The following companies supplied samples of

some of the materials used in this research and, in

some instances, gave valuable advice: Advance

Solvents & Chemicals, Division of Carlisle Chemical Works, Inc., New Brunswick, N.J. ; Carbide &

Carbon Chemicals Co., Division of Union Carbide

& Carbon Corp., Baltimore, Md., and Charleston,

W. Va.; Elastomer Chemicals Dept., E. I. du

Pont de Nemours & Co., Inc., Wilmington, Del.;

Ethyl Corporation, Detroit, Mich. ; General Electric Co., Chemical & Metallurgical Div. and Sili- cone Products Dept., Waterford, N.Y. ; Gulf Research & Development Co., Pittsburgh, Pa.;

Harshaw Chemical Co., Cleveland, Ohio, and

Gloucester City, N.J. ; Irvington Varnish & Insulator, Irvington, N.J. ; Metal & Thermit Corp.,

Rahway, N.J. ; Minnesota Mining & Mfg. Co.,

Newark, N.J. ; Monsanto Chemical Co., Organic

Chemicals Div., St. Louis, Mo.; Naftone, Inc.,

New York, N.Y. ; Nuodex Products Co., Div. of

Heyden Newport Chemical Corp., Elizabeth, N.J.

Pennsalt Chemicals Corp., Industrial Div., Pennsylvania Salt Mfg. Co., Philadelphia 2, Pa.;

Quaker State Oil & Refining Co., Oil City, Pa.;

Sharpies Chemical Div., Pennsylvania Salt Mfg.

Co., Philadelphia 2, Pa.; Shell Development Co.,

Emeryville, Calif.; Shell Oil Co., Inc., Martinez,

Calif. ; and Standard OU Co. of Indiana, Whiting,

Ind.

4. References

[1] R. G. Charles, J. Inorg. & Nuclear Chem. 6, 42 (1958).

[2] C. R. Hauser, F. W. Swamer, and J. T. Adams, Org.

Reactions 8, 115 (1954).

[3] G. L. O'Connor and H. R. Nace, J. Am. Chem. Soc. 77,

1578 (1955).

[4] G. T. Morgan and H. W. Moss, J. Chem. Soc. 103, 78

(1913).

[5] C. Doree and A. C. Pepper, J. Chem. Soc. 1942, 477.

[6] R. G. Charles, J. Org. Chem. 22, 677 (1957).

» Deceased, May 22, 1961.

23

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