ECOSAR Class Definition: Acid Halides

The Acid Halide class is identified by any of the following structures: 

 C

O

Halogen P

O

Halogen S

O

Halogen

The Halogens include chlorine (Cl), bromine (Br), fluorine (F) and iodine (I). 

The C(=O) carbon, P(=O) phosphorus and S(=O) sulfur can have other attachments. In 

the current ECOSAR program, these other attachments can be anything. 

SMILES String Identifications: 

C(=O)Br C(=O)Cl C(=O)F C(=O)I 

P(=O)Br P(=O)Cl P(=O)F P(=O)I 

S(=O)Br S(=O)Cl S(=O)F S(=O)I 

Associated ECOSAR Class(s): None 

Example Acid Halides: 

CAS No. Name SMILES Notation

75‐36‐5 Acetyl chloride O=C(Cl)C

506‐96‐7 Acetyl bromide O=C(Br)C

98‐88‐4 Benzoyl chloride O=C(c(cccc1)c1)Cl

98‐09‐9 Benzenesulfonyl chloride c1ccccc1S(=O)(=O)Cl

824‐72‐6 Phosphonic dichloride, phenyl‐  O=P(c(cccc1)c1)(Cl)Cl

 
ECOSAR Class Definition: Acrylamides

The Acrylamides class is identified by the following structure: 

 

N

C

C

O

C

R1

R2 R3

R1 and R2 - must be hydrogen or alkyl, olefinic, acetylenic or aromatic carbon atoms 

(no other atoms currently allowed). 

R3 - can be anything (no exclusions) ... There is no Methacrylamide class in ECOSAR. 

In the current ECOSAR program, the Acrylamides structure must meet the following 

criteria: 

(1) Exactly as depicted by the structure representation and R-substituents 

SMILES String Identifications: 

C=C(=O)N 

C=C(=O)NC 

C=C(=O)NC=C 

C=C(=O)NC#C 

C=C(=O)Nc1ccccc1 

Associated ECOSAR Class(s): 

Amides - the ECOSAR Amides class is a general class having a CC(=O)N or 

NC(=O)N group that occurs in other ECOSAR classes. In general, the Amides class is 

reported by ECOSAR in addition to the other classes (such as Acrylamides). 

Example Acrylamides: 

CAS No. Name SMILES Notation 

79-06-1 Acrylamide C=CC(=O)N 

94-62-2 Piperine O=C(N(CCCC1)C1)C=CC=Cc(ccc(OCO2)c23)c3 

107-58-4 t-Butylacrylamide O=C(NC(C)(C)C)C=C 

2210-25-5 N-Isopropylacrylamide O=C(NC(C)C)C=C 
ECOSAR Class Definition: Acrylates

The Acrylates class is identified by the following structures:

NOTE: The previous version of ECOSAR (1.0 and before) characterized anything with 

an acrylate alert, including chemicals with internal double bonds, within this class. In 

version 1.1 of ECOSAR, we have restricted the definition to represent only those 

chemicals with terminal double bonds which more correctly represent the acrylate 

moiety (as shown above). 

R1 - attachment to the olefinic carbon (adjacent to the carbonyl or thiocarbonyl) can be 

anything except a methyl group (CH3). If the R1 attachment is a methyl group (CH3), 

the structure is classified as a Methacrylate. 

R2 - attachment must be either an alkyl carbon, olefinic carbon, acetylenic carbon or 

aromatic carbon.

{O,S} - can be either oxygen (-O-) or sulfur (-S-)

Internally, the ECOSAR program initially detects a carbonyl function [C(=O)] or a 

thiocarbonyl function [C(=S)] with one olefinic attachment and one oxygen or sulfur 

attachment. If the olefinic carbon has a methyl (CH3) attachment, the classification will 

be a Methacrylate (instead of Acrylate). The oxygen or sulfur must have either an alkyl 

carbon, olefinic carbon, acetylenic carbon or aromatic carbon attachment to be 

classified as either an Acrylate or Methacrylate.

Associated ECOSAR Class(s):

Methacrylates - If the olefinic carbon has a methyl (CH3) attachment, the classification 

will be a possible Methacrylate (instead of Acrylate). 

Example Acrylates:

CAS No. Name SMILES Notation

96-33-3 Methyl acyrlate C=CC(=O)OC

140-88-5 Ethyl acrylate C=CC(=O)OCC

3066-71-5 Cyclohexyl acrylate C=CC(=O)OC1CCCCC1
ECOSAR Class Definition: Aldehydes (Mono)

The Aldehydes (Mono) class is identified by the following structure: 

 H

C

R1

O

R1 - attachment must be either an alkyl carbon, aromatic carbon, carbonyl or hydrogen. 

The structure can contain only one aldehyde functional group to be classified as 

Aldehydes (Mono). If a structure contains more than one aldehyde group, it will be 

classified as Aldehydes (Poly). 

If the R1 attachment is an olefinic carbon, acetylenic carbon or allyl group (-CC=C), the 

structure will be classified as a Vinyl/Allyl Aldehyde. In the current ECOSAR program, 

structures classified as Vinyl/Allyl Aldehydes are not additionally classified as Aldehydes 

(Mono). 

SMILES String Identifications: 

O=C or O=C[H] or O=CH 

O=CC ... (no other attachments to carbonyl) 

O=Cc1ccccc1 ... (no other attachments to carbonyl) 

Associated ECOSAR Class(s): 

Aldehydes (Poly) - If a structure contains more than one aldehyde group, it will be 

classified as Aldehydes (Poly) instead of Aldehydes (Mono) 

Vinyl/Allyl Aldehydes - If the R1 attachment is an olefinic carbon, acetylenic carbon or 

allyl group (-CC=C), the structure will be classified as a Vinyl/Allyl Aldehyde. In the 

current ECOSAR program, structures classified as Vinyl/Allyl Aldehydes are not

additionally classified as Aldehydes (Mono). 

Example Aldehydes (Mono): 

CAS No. Name SMILES Notation

75‐07‐0 Acetaldehyde O=CC

123‐72‐8 Butanal O=CCCC

555‐16‐8 Benzaldehyde, 4‐nitro‐  O=Cc(ccc(N(=O)(=O))c1)c1

148‐53‐8 o‐Vanillin O=Cc(c(O)c(OC)cc1)c1

454‐89‐7 Benzaldehyde, 3‐(trifluoromethyl)‐  O=Cc(cccc1C(F)(F)F)c1

 
ECOSAR Class Definition: Aldehydes (Poly)

The Aldehydes (Poly) class is identified by the more than one occurrence of following 

functional group in the structure: 

 H

C

R1

O

R1 - attachment must be either an alkyl carbon, olefinic carbon, acetylenic carbon, 

aromatic carbon, carbonyl or hydrogen. 

The structure must contain more than one aldehyde functional group to be classified as 

Aldehydes (Poly). If a structure contains only one aldehyde group, it will be classified 

as either an Aldehydes (Poly) or Vinyl/Allyl Aldehydes class depending on the R1 

attachment. 

In the current ECOSAR program, a structure can be classified as both Aldehydes (Poly) 

and Vinyl/Allyl Aldehydes. 

SMILES String Identifications: 

O=C or O=C[H] or O=CH 

O=CC ... (no other attachments to carbonyl) 

O=CC=C ... (no other attachments to carbonyl) 

O=CC #C ... (no other attachments to carbonyl) 

O=Cc1ccccc1 ... (no other attachments to carbonyl) 

 ... a combination of two or more of these partial SMILES strings must be present 

anywhere in the entire SMILES. 

Associated ECOSAR Class(s): 

Aldehydes (Mono) - If a structure contains only one aldehyde group, it will be classified 

as either an Aldehydes (Poly) or Vinyl/Allyl Aldehydes class depending on the R1 

attachment. 

Vinyl/Allyl Aldehydes - In the current ECOSAR program, a structure can be classified as 

both Aldehydes (Poly) and Vinyl/Allyl Aldehydes. 

Example Aldehydes (Poly): 

CAS No. Name SMILES Notation

111‐30‐8 Pentanedial O=CCCCC=O

542‐78‐9 1,3‐Propanedial O=CCC=O

 
ECOSAR Class Definition: Aliphatic Amines 

ECOSAR currently identifies several different types of structures as Aliphatic Amines 

which are described separately below. 

Normal Aliphatic Amines: 

 

C NH2

C

NH

C

N

C C

C

Carbon attachments to the nitrogen must be aliphatic carbons (alkyl, olefinic or 

acetylenic carbon); aromatic carbon is not allowed. 

SMILES String Identifications: 

 NH2 type (one attachment to N): 

 NC [equivalent to: N([H])([H])C or N(H)(H)C] 

 NC=C [equivalent to: N([H])([H])C=C or N(H)(H)C=C] 

 NC#C [equivalent to: N([H])([H])C or N(H)(H)C] 

 NH type (two attachments to N): 

 CNC [equivalent to: CN([H])C or CN(H)C] 

 N type (three attachments t N): 

 CN(C)(C) 

... for NH and N type, the carbons must be alkyl, olefinic or acetylenic 

Aliphatic Amines with Oxygen: 

 C

NH

O

R1

C

N

O

R1

C

R1 - can be anything including hydrogen. The carbon attachments to the nitrogen must 

be aliphatic carbons (alkyl, olefinic or acetylenic carbon); aromatic carbon is not 

allowed. 

SMILES String Identifications: 

 NH type (two attachments to N): CNO [equivalent to: CN([H])O or CN(H)O] 

 N type (three attachments t N): CN(C)O 

... for NH and N type, the carbons must be alkyl, olefinic or acetylenic 

Oximes as Aliphatic Amines: 
 C

N

OH C

N

O

C

Substitutions of the carbon can be anything including hydrogen. 

SMILES String Identifications: 

 C=NO 

 C=NOC 

Nitrosaminesas Aliphatic Amines: 

N

R

R

N O

R - at least one carbon attachment to the nitrogen. The carbon attachment must be 

aliphatic carbons (alkyl, olefinic or acetylenic carbon); aromatic carbon is not allowed. 

SMILES String Identifiactions: 

 O=N 

 O=N(C)C 

Amine Oxides and Nitrosyls as Aliphatic Amines: 

 

R – can be an aliphatic carbon (alkyl, olefinic or acetylenic carbon).Carbon chain 

lengths greater than 8 may result in surfactant-like effects. 

SMILES String Identifiactions: 

 O=N(C) 

 O=N(C)(C)C 

Amidines and Guanidines as Aliphatic Amines: 

O

N

R R R

O

R'
N

N

R

R'

R'

N N

N

R

R'

R' R'

R'

 

R- must be either hydrogen or carbon (alkyl, olefinic, acetylenic or aromatic carbon) ... 

R’ - can be anything (no exclusions) 

SMILES String Identifications: 

 N=C(C)N [ equivalent to: [H]N=C(C)N([H])[H] or HN=C(C)N(H)H ] 

 N=C(N)N 

Reducible Ammonium Salts as Aliphatic Amines:Like all salts in ECOSAR, the 

conjugate salt of ammonium salts should be replaced with a hydrogen; however, 

reduction of ammonium salts at a neutral pH results in a loss of hydrogens, and the 

resulting structure should be entered into ECOSAR as an aliphatic amine for the 

purpose of ECOSAR estimations (examples depicted below). Ammonium salts in which 

the ammonium cation has four bound carbons in the presence of a stabilizing anion 

(e.g., chloride ion) are excluded from this definition since reduction is less likely. 

Predictions for these more stable ammonium salts are based on analogous chemicals 

or the cationic surfactant QSAR R

H

C N

+

R

Anion

R - can be an aliphatic carbon (alkyl, olefinic or acetylenic carbon) or hydrogen 

Associated ECOSAR Class(s): 

Oxyamine - identified by H2N-O-C- structure. 

Triazine, Aliphatic – a 6-membered aliphatic ring structure with 3 alternating nitrogens. 

 

Example Aliphatic Amines: 

CAS No. Name SMILES Notation 

107-10-8 Propylamine NCCC 

111-42-2 Diethanolamine OCCNCCO 
107-15-3 1,2-Ethanediamine NCCN 

103-76-4 1-Piperazineethanol OCCN(CCNC1)C1 

107-11-9 Allyl amine NCC=C 
ECOSAR Class Definition: Alkoxy Silanes (or Silanes, alkoxy)

The Silanes (alkoxy) class is identified by the following example structure: 

 

R2 Si O

R3

R1

Alkyl Carbon

R1, R2 and R3 - must be either hydrogen, oxygen or carbon (alkyl, olefinic, acetylenic, 

aromatic or a carbonyl). 

In the current ECOSAR program, the Alkoxy Silane structure meets the following 

criteria: 

(1) Contains a silicon to oxygen attachment. The oxygen must also be attached to an 

alkyl carbon (or carbonyl). 

Notation: the R1, R2 and R3 attachments are limited to the atoms listed above ... Any 

other atom attachments (e.g. nitrogen, sulfur, halogen, etc) will not result in an Alkoxy 

Silane identification. 

SMILES String Identifications: 

[Si]OC 

SiOC ... (ECOSAR allows Silicon to be either with or without brackets) 

 ... other attachments to Silicon as defined above. 

Associated ECOSAR Class(s): 

None specifically. 

The Silamines class is the only other ECOSAR class specifically containing silicon. 

Example Alkoxy Silanes: 

CAS No. Name SMILES Notation 

78-62-6 Dimethyl diethoxysilane C[Si](OCC)(OCC)C 

18246-71-4 Silane, butoxyethoxydimethyl- CCCCO[Si](C)(C)OCC 

17841-46-2 Silane, methoxytripropyl- [Si](OC)(CCC)(CCC)CCC 
ECOSAR Class Definition: Amides 

The Amides class is identified by the following structures: 

 

R1

C [or S]

N

O

R2

R3

R1 can be an aliphatic carbon with a single bond to any atom other than a halogen, or 

an aromatic carbon. 

R1 can not contain the following atoms below: 

If R1 is an oxygen atom, ECOSAR will identify the structure as a carbamate ester 

or derivatives 

If R1 is a C=C, ECOSAR will identify the structure as an acrylamide 

If R1 is a sulfur atom, ECOSAR will identify the structure as a thiocarbamate, 

mono 

If R1 is a nitrogen atom, ECOSAR will identify the structure as a substituted urea. 

If R1 is C-halogen group, ECOSAR will identify the structure as a Haloacetamide. 

R2 and R3 can be anything other than a carbonyl group. 

If either R2 or R3 are carbonyl groups, ECOSAR will identify the structure as a 

carbonyl urea. 

SMILES String Identifications: 

O=CN ... ( equivalent to: O=C(H)N or O= C([H])N formamide-type) 

CC(=O)N 

NOTE: If R1 above is a benzene ring (6-member aromatic ring) with a nitro/nitroso 

attachment, then ECOSAR will also identify the structure as nitro/nitroso-Benzamides. 

There are very limited empirical data for this class (fish acute only) so this substitution 

rule for R1 has not been implement as an exclusion for the amides class so that the 

user is presented with QSAR results for both classes. 

 Example Amides: 

CAS No. Name SMILES Notation 

60-35-5 Acetamide NC(=O)C 

2620-63-5 Glycin-amide,N-acetyl CC(=O)NCC(=O)N 
Anilines (amino-meta)

The Anilines (amino-meta) class is identified by the following structure: 

In the current ECOSAR program, the Anilines (amino-meta) structure meets the 

following criteria: 

(1) A benzene ring (or any other six-member aromatic ring including hetero-aromatic 

rings) has amine substituent (as -NH2) in meta-position to each other. 

(2) The aromatic ring can be fused to another ring. 

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N< 

is not identified as an amine for this class. 

SMILES String Identifications: 

Nc1cc(N)ccc1 ... aliphatic nitrogens as NH2 attached to aromatic carbons 

 equivalent to: N(H)(H)c1cc(N(H)H)cc1 

 ... aromatic ring can contain non-carbon members as in: Nc1cc(N)ccn1 

Associated ECOSAR Class(s): 

Anilines (Aromatic Amine) - An aromatic ring has one (or more) amine substituent 

(NH2). If the Anilines (amino-meta) class is identified, ECOSAR excludes the Anilines 

(Aromatic Amines) identification. 

Anilines (amino-ortho) and Anilines (amino-para) - These classes are identified when a 

six-member aromatic ring has two -NH2 substituents in either a ortho- or para-position. 

When identified in conjunction with Anilines (amino-meta), they are both reported by 

ECOSAR. 

Example Anilines (amino-meta): 

CAS No. Name SMILES Notation 

108-45-2 m-Phenylenediamine Nc(cccc1N)c1 

608-32-2 1,2,3-Triaminobenzene Nc1c(cccc1N)N 

94-10-0 Ethoxazene Nc1cc(N)c(N=Nc2ccc(OCC)cc2)cc1 

95-86-3 2,4-Diaminophenol Nc1ccc(O)c(N)c1 
495-54-5 2,4-Diaminoazobenzene N(=Nc(cccc1)c1)c(c(N)cc(N)c2)c2 
Anilines (amino-ortho)

The Anilines (amino-ortho) class is identified by the following structure: 

In the current ECOSAR program, the Anilines (amino-ortho) structure meets the 

following criteria: 

(1) A benzene ring (or any other six-member aromatic ring including hetero-aromatic 

rings) has amine substituent (as -NH2) in ortho-position to each other. 

(2) The aromatic ring can be fused to another ring. 

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N< 

is not identified as an amine for this class. 

SMILES String Identifications: 

Nc1c(N)cccc1 ... aliphatic nitrogens as NH2 attached to aromatic carbons 

 equivalent to: N(H)(H)c1c(N(H)H)ccc1 

 ... aromatic ring can contain non-carbon members as in: Nc1c(N)cccn1

Associated ECOSAR Class(s): 

Anilines (Aromatic Amine) - An aromatic ring has one (or more) amine substituent 

(NH2). If the Anilines (amino-ortho) class is identified, ECOSAR excludes the Anilines 

(Aromatic Amines) identification. 

Anilines (amino-meta) and Anilines (amino-para) - These classes are identified when a 

six-member aromatic ring has two -NH2 substituents in either a meta- or para-position. 

When identified in conjunction with Anilines (amino-ortho), they are both reported by 

ECOSAR. 

Example Anilines (amino-ortho): 

CAS No. Name SMILES Notation 

95-54-5 o-Phenylenediamine Nc(c(N)ccc1)c1 

91-95-2 1,1'-Biphenyl -3,3',4,4'-tetramine Nc(c(N)cc(c(ccc(N)c1N)c1)c2)c2 

95-83-0 1,2-Benzenediamine, 4-chloro- Nc(c(N)cc(c1)Cl)c1 

608-32-2 1,2,3-Triaminobenzene Nc1c(cccc1N)N 
Anilines (amino-para)

The Anilines (amino-para) class is identified by the following structure:

In the current ECOSAR program, the Anilines (amino-para) structure meets the

following criteria:

(1) A benzene ring (or any other six-member aromatic ring including hetero-aromatic

rings) has amine substituent (as -NH2) in para-position to each other.

(2) The aromatic ring can be fused to another ring.

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N<

is not identified as an amine for this class.

SMILES String Identifications:

Nc1ccc(N)cc1 ... aliphatic nitrogens as NH2 attached to aromatic carbons

equivalent to: N(H)(H)c1ccc(N(H)H)c1

... aromatic ring can contain non-carbon members as in: Nc1ccc(N)cn1

Associated ECOSAR Class(s):

Anilines (Aromatic Amine) - An aromatic ring has one (or more) amine substituent

(NH2). If the Anilines (amino-para) class is identified, ECOSAR excludes the Anilines

(Aromatic Amines) identification.

Anilines (amino-ortho) and Anilines (amino-meta) - These classes are identified when a

six-member aromatic ring has two -NH2 substituents in either a meta- or ortho-position.

When identified in conjunction with Anilines (amino-para), they are both reported by

ECOSAR.

Example Anilines (amino-para):

CAS No. Name SMILES Notation

106-50-3 p-Phenylenediamine Nc(ccc(N)c1)c1

95-70-5 2,5-Diaminotoluene Nc(c(cc(N)c1)C)c1

615-71-4 1,2,4-Benzenetriamine Nc1c(N)cc(N)cc1
ECOSAR Class Definition: Anilines (Hindered) 

The Anilines (Hindered) class is identified by the following structure: 

 

A carbon-based functional group must be attached ortho to the amine group (can be an 

aliphatic carbon [including alkyl, olefinic, acetylenic, carbonyl] or an aromatic carbon 

[biphenyl-type attachment]). 

In the current ECOSAR program, the Aniline (Hindered) structure meets the following 

criteria: 

(1) A benzene ring (or any other aromatic ring including hetero-aromatic rings) that has 

an amine substituent as -NH2 

(2) The aromatic ring can be fused to another ring. 

(3) An aliphatic carbon is present in the ortho-position. 

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N< 

is not identified as an amine for this class. The Anilines (Hinderd) SAR Sheet notes that 

N-substituted amines are less toxic than the SARs for this class 

SMILES String Identifications: 

Nc1ccccc1C 

Nc1c(C)cccc1

Associated ECOSAR Class(s): 

Anilines (Unhindered) - an R-substituent is not an carbon-based ortho attachment. 

Dinitro Aromatic Amine (Dinitro Aniline)- If an aromatic ring has both the amine 

substituent (-NH2) and two or more nitro substituents (-NO2), ECOSAR classifies the 

ring as Dinitro Aromatic Amine and also reports the Anilines (Hindered) identification. 

Anilines (amino-ortho), Anilines (amino-meta), Anilines (amino-para) - These classes 

are identified when a six-member aromatic ring has two -NH2 substituents in either an 

ortho-, meta- or para-position. 

Example Anilines (Hindered): 

CAS No. Name SMILES Notation 

88-68-6 Benzamide, 2-amino- O=C(N)c(c(N)ccc1)c1 

24544--04-5 2,6-Diisopropylaniline Nc(c(ccc1)C(C)C)c1C(C)C 

2894-51-1 2-Amino-4'-chlorobenzophenone Nc1ccccc1C(=O)c2ccc(Cl)cc2 
ECOSAR Class Definition: Anilines (Unhindered) 

The Anilines (Unhindered) class is identified by the following structure: 

 

NH2

R

R can not be a carbon-based fragment (including alkyl, olefinic, acetylenic, carbonyl or 

an aromatic carbon). Allowed attachments include hydrogen atoms, chlorine, 

secondary or tertiary nitrogens, sulfur, etc. 

R can not be a primary amine. 

If R is a primary amine (NH2) then ECOSAR will identify the class as amino-ortho 

anilines 

In the current ECOSAR program, the Aniline (Unhindered) structure meets the following 

criteria: 

A benzene ring (or any other aromatic ring including hetero-aromatic rings) that has an 

amine substituent as -NH2. 

The aromatic ring can be fused to another ring. 

An excluded R-substituent is not present in the ortho-position. 

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N< 

is not identified as an amine for this class. The Anilines (Unhinderd) SAR Sheet notes 

that N-substituted amines are less toxic than the SARs for this class. 

SMILES String Identifications: 

Nc1ccccc1 

c1ccccc1N

Associated ECOSAR Class(s): 

Anilines (Hindered) - an R-substituent is an aliphatic or aromatic carbon-based 

attachment in the ortho position. 

Dinitro Aromatic Amine (Dinitro Aniline)- If an aromatic ring has both the amine 

substituent (-NH2) and two or more nitro substituents (-NO2), ECOSAR classifies the 

ring as Dinitro Aromatic Amine and also reports the Anilines (Unhindered) identification. 

Anilines (amino-ortho), Anilines (amino-meta), Anilines (amino-para) - These classes 

are identified when a six-member aromatic ring has two -NH2 substituents in either an 

ortho-, meta- or para-position. 

Example Anilines (Unhindered): 

CAS No. Name SMILES Notation 

62-53-3 Aniline Nc1ccccc1 

371-40-4 4-Fluoroaniline Nc1ccc(F)cc1 
106-49-0 4-Toluidine Nc1ccc(C)cc1 

3481-20-7 2,3,5,6-Tetrachloroaniline Nc1c(Cl)c(Cl)cc(Cl)c1Cl 
ECOSAR Class Definition: Aziridines

The Aziridines class is identified by the following ring structure: 

 

N

ECOSAR identifies an Aziridine ring as follows: 

(1) a three member aliphatic ring consisting of one aliphatic nitrogen and two aliphatic 

carbons 

(2) the carbon atoms cannot have double or triple bonds (excludes olefinic and 

acetylenic carbons or carbons with bonds such as C=N) 

(3) the Aziridine ring can be part of a fused-ring system 

SMILES String Identifications: 

N1CC1 ... (same as: C1NC1 or C1CN1 ) 

Associated ECOSAR Class(s): 

Aliphatic Amines - In the current ECOSAR program, the nitrogen in an aziridine ring is 

not additionally classified as an Aliphatic Amine.

Example Aziridines: 

CAS No. Name SMILES Notation 

151-56-4 Aziridine N1CC1 

1072-44-2 N-Methylaziridine CN1CC1 

75-55-8 2-Methylaziridine N1CC1C 

286-18-0 7-Azabicyclo[4.1.0]heptane N(C1CC2)C1CC2 

4055-40-7 Mitomycin B COC4=C(C)C(=O)C1=C(C(COC(N)=O)C2(O)C3C(CN12)N3C)C4=O

 
ECOSAR Class Definitions: Benzodioxoles

The Benzodioxoles class is identified by the following structure: 

 

O

O

In the current ECOSAR program, the Benzodioxole structure identification meets the 

following criteria: 

(1) The ECOSAR program identifies a five-member ring containing two aromatic carbon 

atoms, two aliphatic oxygen atoms and one alkyl carbon atom. Currently, the position of 

the atoms in the ring is not differentiated; for example, the two oxygen atoms could sideby-side and the structure will still be identified as Benzodioxoles (the two different 

structures would correspond to 1,3-benzodioxole and 1,2-benzodioxole). 

 (2) The aromatic ring that is fused to the five-member is not required to be a benzene 

ring; it can be any aromatic ring including hetero-aromatic rings. 

(3) The Benzodioxole ring structure can be fused to additional ring(s). 

SMILES String Identifications: 

Equivalent SMILES for 1,3-benzodioxole: 

 c1cccc2OCOc12 

 c1ccc2OCOc2c1 

 c1cc2OCOc1cc1 

 c12ccccc1OCO2 

 C1=CC=C2OCOC2=C1 

 O1c2ccccc2OC1O=CC 

Associated ECOSAR Class(s): 

None. 

Examples Benxodioxoles: 

CAS No. Name SMILES Notation 

274-09-9 1,3-Benzodioxole c1ccc2OCOc2c1 

51-03-6 Piperonyl butoxide O(c(c(O1)cc(c2CCC)COCCOCCOCCCC)c2)C1 
ECOSAR Class Definition: Benzotriazoles

The Benzotriazoles class is identified by the following structures (1H-Benzotriazole and 

2H-Benzotriazole): 

 

N

N

N

R

N

N

N R

R - can be anything (no exclusions) 

In the current ECOSAR program, the Benzotriazoles structure must meet the following 

criteria: 

(1) The triazole ring must be fused to a benzene ring. The ring to which the triazole 

ring is fused cannot be a hetero-aromatic ring. 

(2) The fused benzene ring can be fused to another ring 

SMILES String Identifications: 

c1ccc2nn[nH]c2c1 

c1ccc2n[nH]nc2c1 

c1ccc2nnnc2c1 

c1ccc2N=NNc2c1 

C1=CC2=NNN=C2C=C1 

Associated ECOSAR Class(s): 

None specifically. However, ECOSAR includes other “ring structure” classes such as 

Triazines, Imidazoles, Triazoles (Non-Fused), Triazole Pyrimidines and Thiazole, 

Benzo. 

With respect to structures containing a triazole ring: 

Triazoles (Non-Fused) - a structure containing either a 1,2,4-triazole, 1,2,3-triazole or 

1,3,4-triazole ring that is not fused to another aromatic ring. 

Triazole Pyrimidines - a triazole-pyrimidine fused ring structure 

Examples Benzotriazoles: 

CAS No. Name SMILES Notation 

95-14-7 1H-Benzotriazole c1ccc2nnnc2c1 

273-02-9 2H-Benzotriazole c1ccc2nnnc2c1 

36437-37-3 

Phenol, 2-(2H-benzotriazol-2-yl)-

4-(1,1-dimethylethyl)-6-(1-

methylpropyl)- Oc(c(cc(c1)C(C)(C)C)C(CC)C)c1n(nc(c2ccc3)c3)n2 
ECOSAR Class Definition: Benzoylcyclohexanedione

The Benzoylcyclohexanedione class is identified by the following structure: 

 

C

C C

O O

O

In the current ECOSAR program, the Benzoylcyclohexanedione structure meets the 

following criteria: 

(1) A linear carbonyl [-C(=O)-] is attached to both a phenyl ring and a 2,6-

cyclohexanedione ring at the position shown above. 

(2) The rings can be fused to other rings. 

Notation: The current identification in ECOSAR is very strict ... The phenyl ring must be 

a phenyl ring (a hetero-aromatic ring (e.g. pyridine) is not allowed) ... The 

cyclohexanedione ring must be a 2,6-dione only with the linear carbonyl attached at the 

1-position. 

SMILES String Identifications: 

c1ccccc1C(=O)C2C(=O)CCCC2=O 

equivalent SMILES: O=C(c1ccccc1)C2C(=O)CCCC2=O 

Associated ECOSAR Class(s): 

None specifically. 

Example Benzoylcyclohexaediones: 

CAS No. Name SMILES Notation 

99105-77-8 Sulcotrione O=C1CCCC(=O)C1C(=O)c2ccc(S(=O)(=O)C)cc2Cl
ECOSAR Class Definition: Benzyl Alcohols

The Benzyl Alcohols class is identified by the following structure: 

 

C

OH

In the current ECOSAR program, the Benzyl Alcohol structure meets the following 

criteria: 

(1) An alkyl carbon atom has both an hydroxyl (-OH) attachment and benzene ring 

attachment. 

(2) A strict definition of “benzyl” implies the single alkyl carbon is a -CH2- group and the 

aromatic ring is a benzene ring. However, in the current ECOSAR program, the single 

alkyl carbon can be -CH2-, -CH< or >C< and the aromatic ring can be any aromatic 

ring including hetero-aromatic rings. 

SMILES String Identifications: 

c1ccccc1CO ... ( equivalent to: c1ccccc1COH or c1ccccc1CO[H] ) 

Associated ECOSAR Class(s): 

None specifically. 

ECOSAR includes a variety of other Alcohol classes (such as Propargyl Alcohols, 

Vinyl/Allyl Alcohols, Ketone Alcohol, Halo Alcohols and Nitro Alcohols). ECOSAR also 

includes a variety of Benzyl classes. 

Example Benzyl Alcohols: 

CAS No. Name SMILES Notation 

100-51-6 Benzyl alcohol c1ccccc1CO 

4412-91-3 3-Hydroxymethylfuran OCc1ccoc1 

115-32-2 Dicofol OC(c1ccc(Cl)cc1)(c2ccc(Cl)cc2)C(Cl)(Cl)Cl 
ECOSAR Class Definition: Benzyl Halides

The Benzyl Halides class is identified by the following structure: 

 

C

Halogen

[ Halogen = Br, Cl or I ]

In the current ECOSAR program, the Benzyl Halide structure meets the following 

criteria: 

(1) An alkyl carbon atom has both a benzene ring attachment and a Halogen 

attachment. For this class, halogens are limited to bromine, chlorine and iodine ... 

Fluorine is excluded. 

(2) A strict definition of “benzyl” implies the single alkyl carbon is a -CH2- group and the 

aromatic ring is a benzene ring. However, in the current ECOSAR program, the single 

alkyl carbon can be -CH2-, -CH< or >C< and the aromatic ring can be any aromatic 

ring including hetero-aromatic rings. 

SMILES String Identifications: 

 with bromine: c(CBr) or c1CBr 

 with chlorine: c(CCl) or c1CCl 

 with iodine: c(CI) or c1CI 

 ... with a complete ring: c1ccccc1CBr or c1ccccc1CCl or c1ccccc1CI 

Associated ECOSAR Class(s): 

None specifically. 

ECOSAR includes other Halide classes (such as Propargyl Halides, Vinyl/Allyl Halides, 

Acid Halides, Halo Acetamides, Halo Ethers, etc). ECOSAR also includes a variety of 

Benzyl classes. 

Example Benzyl Halides: 

CAS No. Name SMILES Notation 

100-44-7 Benzene, (chloromethyl)- c(cccc1)(c1)CCl 

611-19-8 o-Chlorobenzyl chloride c(c(ccc1)Cl)(c1)CCl 

623-25-6 Benzene, 1,4-bis(chloromethyl)- c(ccc(c1)CCl)(c1)CCl 

30030-25-2 Chloromethyl styrene C=Cc1ccc(cc1)CCl 
ECOSAR Class Definition: Benzyl Imides 

The Benzyl Imides class is identified by the following structure: 

 R1

[S] O N

R2

R3

O [S]

R1 and R3 can be anything except a nitrogen atom 

If R1 or R3 are a nitrogen atom, ECOSAR will identify the class as carbonyl 

ureas. The carbonyl urea contains training set chemicals contain structures with 

the R1 or R3 as nitrogen atoms and the R2 as defined below. 

R2 must be an alkyl carbon that is attached to a phenyl or other aromatic ring. A strict 

definition of “benzyl” implies the single alkyl carbon is a -CH2- group and the aromatic 

ring is a benzene ring. However, in the current ECOSAR program, the single alkyl 

carbon can be -CH2-, -CH< or >C< and the aromatic ring can be any aromatic ring 

including hetero-aromatic rings. 

SMILES String Identifications: 

c(CN(C(=O))C(=O)) or c1CN(C(=O))C(=O) ...complete ring: c1ccccc1CN(C(=O))C(=O) 

c(CN(C(=S))C(=S)) or c1CN(C(=S))C(=S) ...complete ring: c1ccccc1CN(C(=S))C(=S) 

c(CN(C(=O))C(=S)) or c1CN(C(=O))C(=S) ...complete ring: c1ccccc1CN(C(=O))C(=S) 

Example Benzyl Imides: 

CAS No. Name SMILES Notation 

2142-01-0 2-Benzyl-isoindole-1,3-dione c12C(=O)N(Cc3ccccc3)C(=O)c1cccc2 

32000-70-7 Uracil, 3-benzyl-5-bromo-1,6-dimethyl- N1(C)C(=O)N(Cc2ccccc2)C(=O)C(Br)=C1C
ECOSAR Class Definition: Benzyl Nitriles 

The Benzyl Nitriles class is identified by the following structures: 

 

C

N

C

C

N

C

Aromatic Ring

In the current ECOSAR program, the Benzyl Nitrile structure must meet the following 

criteria: 

(1) A nitrile group (carbon triple-bonded to nitrogen; SMILES of C#N) is attached to an 

alkyl carbon which also has a phenyl or aromatic ring attachment. 

 (2) A strict definition of “benzyl” implies the single alkyl carbon is a -CH2- group and 

the aromatic ring is a benzene ring. However, in the current ECOSAR program, the 

single alkyl carbon can -CH2-, -CH< or >C< and the aromatic ring can be any aromatic 

ring including hetero-aromatic rings. 

SMILES String Identifications: 

c(CC#N) or c1CC#N ... with a complete ring: c1ccccc1CC#N 

 ... attachments to the alkyl carbon as defined above 

Associated ECOSAR Class(s): 

Nitriles, Polyaliphatic - Two or more nitrile groups are attached to aliphatic atoms in the 

whole structure. When two or more nitrile groups are attached to the same alkyl or 

olefinic carbon, the structure will be classified as both Vinyl/Allyl Nitriles and Nitriles, 

Polyaliphatic. 

Pyrethroids - One of the two potential identifying structures for pyrethroids contains the 

benzyl nitrile moiety. Due to the nature of the pyrethroid class as a pesticide class with a 

complex structure and mode of action, compounds that fit the pyrethroid definition are 

excluded from the benzyl nitriles class. 

Other SAR Nitrile classes include: Halo Nitriles, Nitrile Alpha-OH, Phthalonitriles, 

Vinyl/Allyl Nitriles, Malonitriles, and Nitriles, Polyaliphatic. 

Example Benzyl Nitriles: 

CAS No. Name SMILES Notation 

140-29-4 Benzyl nitrile c1ccccc1CC#N 
Carbamate Esters, Alkyl 

The Carbamate Esters class is identified by the following structure: 

R

N O

R'

O

R - can be anything except two hydrogens (making the nitrogen atom a primary amine). 

 

If R is a primary amine ECOSAR will identify the class as a simple ester 

R’- can be anything except a 6-member aromatic ring (c1ccccc1) or -N=C. 

If R’ is an aromatic ring ECOSAR will identify the class as carbamate esters, 

phenyl. 

If R’ is an -N=C group, ECOSAR will identify the class as carbamates esters, 

oxime 

In the current ECOSAR program, the Carbamate Esters class meets the criteria as shown 

in the structures above. 

Associated ECOSAR Class(es): 

Carbamate Esters, Oxime - if R’ is -N=C, the ECOSAR class becomes Oxime Carbamate 

Ester, and the Carbamate Ester class is excluded. 

Carbamate Esters, Phenyl - if R’ is a phenyl ring, the ECOSAR class becomes Phenyl 

Carbamate Ester, and the Carbamate Ester class is excluded. 

ECOSAR includes a variety of Thiocarbamate ester classes. 

Example Carbamate Esters: 

CAS No. Name SMILES Notation 

101-21-3 Chlorpropham CC(C)OC(=O)Nc1cccc(Cl)c1 

6135-31-5 N-Methylethylcarbamate O=C(OC)NCC 

539-71-9 Ethylidene O=C(OCC)NC(NC(=O)OCC)C 

Mechanism of Action Information: 

Carbamate esters act by inhibiting acetylcholinesterase (AChE) in the nervous system, as 

well as inhibition of other esterases (IPCS, 1986). Toxicity of carbamate esters, based on 

available data (presented in the Carbamate Esters, Alkyl Manual Sheets), appears to 

correlate with the substituent on the oxygen (O-alkyl, O-phenyl, or O-oxime); however, 
data available for modeling were limited to methylcarbamates and, thus, the trend may be 

specific to methylcarbamates. Additionally, compounds with a large substitution on the 

nitrogen may not fit into the active site of AChE and, thus, the mechanism of action may 

be inhibited. Hydrolysis of carbamate esters in aquatic conditions may factor in to the 

ultimate toxicity of the compound; however, hydrolysis as it pertains to O-alkyl 

substituted, O-phenyl substituted, and O-oxime substituted carbamate esters has not been 

fully characterized and correlated with standard endpoint effect levels (e.g., insufficient 

information). Fukuto (1990) indicates that carbamate esters with certain steric properties 

may be hydrolytically degraded before the carbamate ester has an opportunity to inhibit 

the enzyme. Additionally, Fukuto (1990) indicates “that methylcarbamate esters of 

alcohols are intrinsically unreactive [compared to methyl carbamates substituted with 

phenols or oximes] and, therefore, they are generally poor anticholinesterases [e.g., poor 

inhibitorsof AChE]. A good fit of a methylcarbamate ester in the enzyme active site, i.e., 

formation of the enzyme-inhibitor complex prior to carbamylation, is crucial for high 

anti-cholinesterase activity.” Thus, the Carbamate Ester, Alkyl QSAR is considered to 

represent the least toxic carbamate ester QSAR class based on available data and 

supporting information. Fukuto (1990) provides a more in depth discussion of the 

mechanism of inhibition of carbamate insecticides, which support ecotoxicity trends 

observed in available carbamate esters data. Datasets for the below determined equations 

have excluded any studies using static testing methods without analytical monitoring of 

test concentrations due to potential for hydrolysis. 

Desmedipham and phenmedipham were included in Carbamate Esters, Alkyl QSAR 

based on data that suggested poor inhibition of acetylcholinesterase, which may be a 

result of hydrolytic instability or poor formation of the enzyme-inhibitor complex, even 

though these compounds contain a carbamate ester conjugated with a phenyl in addition 

to a carbamate ester conjugated with an alkyl. Some instances of hydrolytic instability 

and poor formation of the enzyme-inhibitor complex may need to be assessed on a caseby-case basis. 

References: 

IPCS. 1986. Carbamate Pesticides: A General Introduction. International Programme on 

Chemical Safety (IPCS) Environmental Health Criteria (EHC) 64, ISBN: 92 4 154264 0. 

[http://www.inchem.org/documents/ehc/ehc/ehc64.htm] 

Fukoto T.R. 1990. Mechanism of Action of Organophosphorus and Carbamate 

Insecticide. Environmental Health Perspectives, 87:245-254. 
Carbamate Esters, Oxime 

The Oxime Carbamate Ester class is identified by the following substructure: 

R - can be anything except two hydrogens (making the nitrogen atom a primary amine). 

 

If R is a primary amine, ECOSAR will identify the class as a neutral organic. 

This is because for an ester classification, the functional group off the oxygen must be 

carbon based and therefore the –N=C does not qualify, nor do any other nitrogen 

functional group attachments. 

In the current ECOSAR program, the Oxime Carbamate Ester class meets the criteria as 

shown in the structure above. Substitutions on the oxime carbon are allowed. 

Associated ECOSAR Class(es): 

Carbamate Esters - if the -N=C attached to the oxygen is replaced by something else 

(excluding a phenyl ring), the ECOSAR class becomes Carbamate Esters. 

Phenyl Carbamate Esters - if the -N=C is replaced by a phenyl ring, the ECOSAR class 

becomes Phenyl Carbamate Ester, and the Carbamate Ester class is excluded. 

Example Oxime Carbamate Ester: 

CAS No. Name SMILES Notation 

23135-22-0 Oxamyl CNC(=O)ON=C(SC)C(=O)N(C)C 

16752-77-5 Methomyl CNC(=O)ON=C(C)SC 

116-06-3 Aldicarb O=C(ON=CC(SC)(C)C)NC 

References: 

IPCS. 1986. Carbamate Pesticides: A General Introduction. International Programme on 

Chemical Safety (IPCS) Environmental Health Criteria (EHC) 64, ISBN: 92 4 154264 0. 

[http://www.inchem.org/documents/ehc/ehc/ehc64.htm] 

Fukoto T.R. 1990. Mechanism of Action of Organophosphorus and Carbamate 

Insecticide. Environmental Health Perspectives, 87:245-254. 

Mechanism of Action Information: 

Carbamate esters act by inhibiting acetylcholinesterase (AChE) in the nervous system, as 

well as inhibition of other esterases (IPCS, 1986). Toxicity of carbamate esters, based on 

available data (presented in the Carbamate Esters, Oxime Manual Sheets), appears to 

correlate with the substituent on the oxygen (O-alkyl, O-phenyl, or O-oxime); however, 

data available for modeling were limited to methylcarbamates and, thus, the trend may be 
specific to methylcarbamates. Additionally, compounds with a large substitution on the 

nitrogen may not fit into the active site of AChE and, thus, the mechanism of action may 

be inhibited. Hydrolysis of carbamate esters in aquatic conditions may factor in to the 

ultimate toxicity of the compound; however, hydrolysis as it pertains to O-alkyl 

substituted, O-phenyl substituted, and O-oxime substituted carbamate esters has not been 

fully characterized and correlated with standard endpoint effect levels (e.g., insufficient 

information). Fukuto (1990) indicates that “[m]ethylcarbamates of substituted phenols 

and oximes with good complementary fit to the [AChE] enzyme active site are generally 

strong inhibitors of AChE.” Furthermore, substitution of “ phenols and oximes, each with 

pKa values in the region of 10, [make] methylcarbamates that are reactive to the degree 

that they are able to carbamylate the serine hydroxyl of AChE. Owing to the intrinsic 

reactivity of methylcarbamate esters, an electron-withdrawing substituent is not required 

in the aryl moiety for high anticholinesterase activity.” Fukuto (1990) provides a more in 

depth discussion of the mechanism of inhibition of carbamate insecticides, which support 

ecotoxicity trends observed in available carbamate esters data. Datasets for the below 

determined equations have excluded any studies using static testing methods without 

analytical monitoring of test concentrations due to potential for hydrolysis. 
Carbamate Esters, Phenyl 

The Phenyl Carbamate Ester class is identified by the following structure: 

N O

O

R

R - can be anything except two hydrogens (making the nitrogen atom a primary amine). 

 

If R is a primary amine, ECOSAR will identify the class as a simple ester 

In the current ECOSAR program, the Phenyl Carbamate Ester class meets the criteria as 

shown in the structure above. 

Substitutions on the phenyl ring are allowed. 

Associated ECOSAR Class(es): 

Carbamate Esters - if the phenyl ring attached to the oxygen is replaced by an aliphatic 

group, the ECOSAR class becomes Carbamate Esters. 

Oxime Carbamate Esters - if the phenyl ring attached to the oxygen is -N=C, the 

ECOSAR class becomes Oxime Carbamate Ester, and the Carbamate Ester class is 

excluded. 

Example Oxime Carbamate Ester: 

CAS No. Name SMILES Notation 

114-26-1 Propoxur CNC(=O)Oc1ccccc1OC(C)C 

63-25-2 Carbaryl O=C(Oc(c(c(ccc1)cc2)c1)c2)NC 

2686-99-9 Trimethacarb CNC(=O)Oc1cc(C)c(C)c(C)c1 

Mechanism of Action Information: 

Carbamate esters act by inhibiting acetylcholinesterase (AChE) in the nervous system, as 

well as inhibition of other esterases (IPCS, 1986). Toxicity of carbamate esters, based on 

available data (presented in the Carbamate Esters, Phenyl Manual Sheets), appears to 

correlate with the substituent on the oxygen (O-alkyl, O-phenyl, or O-oxime); however, 

data available for modeling were limited to methylcarbamates and, thus, the trend may be 

specific to methylcarbamates. Additionally, compounds with a large substitution on the 

nitrogen may not fit into the active site of AChE and, thus, the mechanism of action may 

be inhibited. Hydrolysis of carbamate esters in aquatic conditions may factor in to the 

ultimate toxicity of the compound; however, hydrolysis as it pertains to O-alkyl 

substituted, O-phenyl substituted, and O-oxime substituted carbamate esters has not been 
fully characterized and correlated with standard endpoint effect levels (e.g., insufficient 

information). Fukuto (1990) indicates that “[m]ethylcarbamates of substituted phenols 

and oximes with good complementary fit to the [AChE] enzyme active site are generally 

strong inhibitors of AChE.” Furthermore, substitution of “ phenols and oximes, each with 

pKa values in the region of 10, [make] methylcarbamates that are reactive to the degree 

that they are able to carbamylate the serine hydroxyl of AChE. Owing to the intrinsic 

reactivity of methylcarbamate esters, an electron-withdrawing substituent is not required 

in the aryl moiety for high anticholinesterase activity.” Fukuto (1990) provides a more in 

depth discussion of the mechanism of inhibition of carbamate insecticides, which support 

ecotoxicity trends observed in available carbamate esters data. Datasets for the below 

determined equations have excluded any studies using static testing methods without 

analytical monitoring of test concentrations due to potential for hydrolysis. 

Fukuto (1990) suggests that “introduction of a nitro substituent into the phenyl ring of 

phenyl methylcarbamate results in a compound of such high reactivity that it is 

hydrolytically degraded before it has an opportunity to inhibit the enzyme.” Aquatic 

toxicity data were not located for compounds such as this and, thus, the Carbamate 

Esters, Phenyl QSAR class does not account for this phenomenon. 

In comparing the rates of reaction of [m-isopropyl compound] and [m-tert-butyl 

compound] with [ammonium compound], Fukoto suggests that “replacement of the 

central carbon atom [in the side chain] with a positively charged quaternary nitrogen 

atom [similar to Ammonium, (3-(methylcarbamoyloxy) phenyl)trimethyl-, chloride (CAS 

# 64051-06-5)] resulted in about a 50-fold increase in anticholinesterase activity.” 

Aquatic toxicity data were not located for compounds such as this and, thus, the 

Carbamate Esters, Phenyl QSAR class does not account for this phenomenon. 

Additionally, compounds such as this are treated as cationic surfactants for the purpose of 

QSAR predictions. 

References: 

IPCS. 1986. Carbamate Pesticides: A General Introduction. International Programme on 

Chemical Safety (IPCS) Environmental Health Criteria (EHC) 64, ISBN: 92 4 154264 0. 

[http://www.inchem.org/documents/ehc/ehc/ehc64.htm] 

Fukoto T.R. 1990. Mechanism of Action of Organophosphorus and Carbamate 

Insecticide. Environmental Health Perspectives, 87:245-254. 

 
ECOSAR Class Definition: Carbonyl Ureas 

In ECOSAR V1 and early, carbonyl ureas were identified as both imides and substituted 

ureas. The Carbonyl Urea class is identified by the following example structure in 

ECOSAR V1.1. 

 

R1 N N

R4

O O

R2

R3

The nitrogens must be aliphatic nitrogen atoms 

R1 can be anything (no exclusions) 

If R1 is a sulfur atom, there may be overlap with the thiocarbamates, mono class 

based on the training set chemicals, but toxicity profiles are similar for both 

classes to all organisms and therefore no restrictions will be applied at this time 

since thiocarbamates, mono class define only the [S-C=ON] portion of the above 

base structure. 

R2, R3 and R4 can be anything except halogen atoms. 

If R2 or R3 or R4 are halogens, ECOSAR will identify the class as haloimides 

which show much higher toxicity to fish and daphnid than non-halogenated 

carbonyl ureas 

R4 can be anything (no exclusions) 

The oxygen in the carbonyl(s) can not to be replaced by S or N atoms, as is done in 

other related classes. 

In this case, compounds containing C=S are included in the thioureas class 

definition, though the effects of the repeating C=S (like the carbonyl does above) 

is unknown since simple thiourea (NC=SN) defines the training set. We have no 

structural analogs in ECOSAR for the C=N configuration of this molecule. 

A related class is sulfonyl ureas where a sulfone group [S(=O)(=O)] replaces the second 

carbonyl group off of the R1 above. 

SMILES String Identifications: Carbonyl Urea Group: C(=O)NC(=O)N 

Example Carbonyl Urea: 

CAS No. Name SMILES Notation 

314-40-9 Bromacil N1C(=O)N(C(C)CC)C(=O)C(Br)=C1C 

36734-19-7 Iprodione c1c(Cl)cc(Cl)cc1N2C(=O)CN(C(=O)NC(C)C)C2(=O)

78587-05-0 Hexythiazox c1cc(Cl)ccc1C2SC(=O)N(C(=O)NC3CCCCC3)C2C 

57-43-2 Amobarbital CCC1(CCC(C)C)C(=O)NC(=O)NC1=O 
ECOSAR Class Definition: Acid Halides

The Acid Halide class is identified by any of the following structures: 

 C

O

Halogen P

O

Halogen S

O

Halogen

The Halogens include chlorine (Cl), bromine (Br), fluorine (F) and iodine (I). 

The C(=O) carbon, P(=O) phosphorus and S(=O) sulfur can have other attachments. In 

the current ECOSAR program, these other attachments can be anything. 

SMILES String Identifications: 

C(=O)Br C(=O)Cl C(=O)F C(=O)I 

P(=O)Br P(=O)Cl P(=O)F P(=O)I 

S(=O)Br S(=O)Cl S(=O)F S(=O)I 

Associated ECOSAR Class(s): None 

Example Acid Halides: 

CAS No. Name SMILES Notation

75‐36‐5 Acetyl chloride O=C(Cl)C

506‐96‐7 Acetyl bromide O=C(Br)C

98‐88‐4 Benzoyl chloride O=C(c(cccc1)c1)Cl

98‐09‐9 Benzenesulfonyl chloride c1ccccc1S(=O)(=O)Cl

824‐72‐6 Phosphonic dichloride, phenyl‐  O=P(c(cccc1)c1)(Cl)Cl

 
ECOSAR Class Definition: Acrylamides

The Acrylamides class is identified by the following structure: 

 

N

C

C

O

C

R1

R2 R3

R1 and R2 - must be hydrogen or alkyl, olefinic, acetylenic or aromatic carbon atoms 

(no other atoms currently allowed). 

R3 - can be anything (no exclusions) ... There is no Methacrylamide class in ECOSAR. 

In the current ECOSAR program, the Acrylamides structure must meet the following 

criteria: 

(1) Exactly as depicted by the structure representation and R-substituents 

SMILES String Identifications: 

C=C(=O)N 

C=C(=O)NC 

C=C(=O)NC=C 

C=C(=O)NC#C 

C=C(=O)Nc1ccccc1 

Associated ECOSAR Class(s): 

Amides - the ECOSAR Amides class is a general class having a CC(=O)N or 

NC(=O)N group that occurs in other ECOSAR classes. In general, the Amides class is 

reported by ECOSAR in addition to the other classes (such as Acrylamides). 

Example Acrylamides: 

CAS No. Name SMILES Notation 

79-06-1 Acrylamide C=CC(=O)N 

94-62-2 Piperine O=C(N(CCCC1)C1)C=CC=Cc(ccc(OCO2)c23)c3 

107-58-4 t-Butylacrylamide O=C(NC(C)(C)C)C=C 

2210-25-5 N-Isopropylacrylamide O=C(NC(C)C)C=C 
ECOSAR Class Definition: Acrylates

The Acrylates class is identified by the following structures:

NOTE: The previous version of ECOSAR (1.0 and before) characterized anything with 

an acrylate alert, including chemicals with internal double bonds, within this class. In 

version 1.1 of ECOSAR, we have restricted the definition to represent only those 

chemicals with terminal double bonds which more correctly represent the acrylate 

moiety (as shown above). 

R1 - attachment to the olefinic carbon (adjacent to the carbonyl or thiocarbonyl) can be 

anything except a methyl group (CH3). If the R1 attachment is a methyl group (CH3), 

the structure is classified as a Methacrylate. 

R2 - attachment must be either an alkyl carbon, olefinic carbon, acetylenic carbon or 

aromatic carbon.

{O,S} - can be either oxygen (-O-) or sulfur (-S-)

Internally, the ECOSAR program initially detects a carbonyl function [C(=O)] or a 

thiocarbonyl function [C(=S)] with one olefinic attachment and one oxygen or sulfur 

attachment. If the olefinic carbon has a methyl (CH3) attachment, the classification will 

be a Methacrylate (instead of Acrylate). The oxygen or sulfur must have either an alkyl 

carbon, olefinic carbon, acetylenic carbon or aromatic carbon attachment to be 

classified as either an Acrylate or Methacrylate.

Associated ECOSAR Class(s):

Methacrylates - If the olefinic carbon has a methyl (CH3) attachment, the classification 

will be a possible Methacrylate (instead of Acrylate). 

Example Acrylates:

CAS No. Name SMILES Notation

96-33-3 Methyl acyrlate C=CC(=O)OC

140-88-5 Ethyl acrylate C=CC(=O)OCC

3066-71-5 Cyclohexyl acrylate C=CC(=O)OC1CCCCC1
ECOSAR Class Definition: Aldehydes (Mono)

The Aldehydes (Mono) class is identified by the following structure: 

 H

C

R1

O

R1 - attachment must be either an alkyl carbon, aromatic carbon, carbonyl or hydrogen. 

The structure can contain only one aldehyde functional group to be classified as 

Aldehydes (Mono). If a structure contains more than one aldehyde group, it will be 

classified as Aldehydes (Poly). 

If the R1 attachment is an olefinic carbon, acetylenic carbon or allyl group (-CC=C), the 

structure will be classified as a Vinyl/Allyl Aldehyde. In the current ECOSAR program, 

structures classified as Vinyl/Allyl Aldehydes are not additionally classified as Aldehydes 

(Mono). 

SMILES String Identifications: 

O=C or O=C[H] or O=CH 

O=CC ... (no other attachments to carbonyl) 

O=Cc1ccccc1 ... (no other attachments to carbonyl) 

Associated ECOSAR Class(s): 

Aldehydes (Poly) - If a structure contains more than one aldehyde group, it will be 

classified as Aldehydes (Poly) instead of Aldehydes (Mono) 

Vinyl/Allyl Aldehydes - If the R1 attachment is an olefinic carbon, acetylenic carbon or 

allyl group (-CC=C), the structure will be classified as a Vinyl/Allyl Aldehyde. In the 

current ECOSAR program, structures classified as Vinyl/Allyl Aldehydes are not

additionally classified as Aldehydes (Mono). 

Example Aldehydes (Mono): 

CAS No. Name SMILES Notation

75‐07‐0 Acetaldehyde O=CC

123‐72‐8 Butanal O=CCCC

555‐16‐8 Benzaldehyde, 4‐nitro‐  O=Cc(ccc(N(=O)(=O))c1)c1

148‐53‐8 o‐Vanillin O=Cc(c(O)c(OC)cc1)c1

454‐89‐7 Benzaldehyde, 3‐(trifluoromethyl)‐  O=Cc(cccc1C(F)(F)F)c1

 
ECOSAR Class Definition: Aldehydes (Poly)

The Aldehydes (Poly) class is identified by the more than one occurrence of following 

functional group in the structure: 

 H

C

R1

O

R1 - attachment must be either an alkyl carbon, olefinic carbon, acetylenic carbon, 

aromatic carbon, carbonyl or hydrogen. 

The structure must contain more than one aldehyde functional group to be classified as 

Aldehydes (Poly). If a structure contains only one aldehyde group, it will be classified 

as either an Aldehydes (Poly) or Vinyl/Allyl Aldehydes class depending on the R1 

attachment. 

In the current ECOSAR program, a structure can be classified as both Aldehydes (Poly) 

and Vinyl/Allyl Aldehydes. 

SMILES String Identifications: 

O=C or O=C[H] or O=CH 

O=CC ... (no other attachments to carbonyl) 

O=CC=C ... (no other attachments to carbonyl) 

O=CC #C ... (no other attachments to carbonyl) 

O=Cc1ccccc1 ... (no other attachments to carbonyl) 

 ... a combination of two or more of these partial SMILES strings must be present 

anywhere in the entire SMILES. 

Associated ECOSAR Class(s): 

Aldehydes (Mono) - If a structure contains only one aldehyde group, it will be classified 

as either an Aldehydes (Poly) or Vinyl/Allyl Aldehydes class depending on the R1 

attachment. 

Vinyl/Allyl Aldehydes - In the current ECOSAR program, a structure can be classified as 

both Aldehydes (Poly) and Vinyl/Allyl Aldehydes. 

Example Aldehydes (Poly): 

CAS No. Name SMILES Notation

111‐30‐8 Pentanedial O=CCCCC=O

542‐78‐9 1,3‐Propanedial O=CCC=O

 
ECOSAR Class Definition: Aliphatic Amines 

ECOSAR currently identifies several different types of structures as Aliphatic Amines 

which are described separately below. 

Normal Aliphatic Amines: 

 

C NH2

C

NH

C

N

C C

C

Carbon attachments to the nitrogen must be aliphatic carbons (alkyl, olefinic or 

acetylenic carbon); aromatic carbon is not allowed. 

SMILES String Identifications: 

 NH2 type (one attachment to N): 

 NC [equivalent to: N([H])([H])C or N(H)(H)C] 

 NC=C [equivalent to: N([H])([H])C=C or N(H)(H)C=C] 

 NC#C [equivalent to: N([H])([H])C or N(H)(H)C] 

 NH type (two attachments to N): 

 CNC [equivalent to: CN([H])C or CN(H)C] 

 N type (three attachments t N): 

 CN(C)(C) 

... for NH and N type, the carbons must be alkyl, olefinic or acetylenic 

Aliphatic Amines with Oxygen: 

 C

NH

O

R1

C

N

O

R1

C

R1 - can be anything including hydrogen. The carbon attachments to the nitrogen must 

be aliphatic carbons (alkyl, olefinic or acetylenic carbon); aromatic carbon is not 

allowed. 

SMILES String Identifications: 

 NH type (two attachments to N): CNO [equivalent to: CN([H])O or CN(H)O] 

 N type (three attachments t N): CN(C)O 

... for NH and N type, the carbons must be alkyl, olefinic or acetylenic 

Oximes as Aliphatic Amines: 
 C

N

OH C

N

O

C

Substitutions of the carbon can be anything including hydrogen. 

SMILES String Identifications: 

 C=NO 

 C=NOC 

Nitrosaminesas Aliphatic Amines: 

N

R

R

N O

R - at least one carbon attachment to the nitrogen. The carbon attachment must be 

aliphatic carbons (alkyl, olefinic or acetylenic carbon); aromatic carbon is not allowed. 

SMILES String Identifiactions: 

 O=N 

 O=N(C)C 

Amine Oxides and Nitrosyls as Aliphatic Amines: 

 

R – can be an aliphatic carbon (alkyl, olefinic or acetylenic carbon).Carbon chain 

lengths greater than 8 may result in surfactant-like effects. 

SMILES String Identifiactions: 

 O=N(C) 

 O=N(C)(C)C 

Amidines and Guanidines as Aliphatic Amines: 

O

N

R R R

O

R'
N

N

R

R'

R'

N N

N

R

R'

R' R'

R'

 

R- must be either hydrogen or carbon (alkyl, olefinic, acetylenic or aromatic carbon) ... 

R’ - can be anything (no exclusions) 

SMILES String Identifications: 

 N=C(C)N [ equivalent to: [H]N=C(C)N([H])[H] or HN=C(C)N(H)H ] 

 N=C(N)N 

Reducible Ammonium Salts as Aliphatic Amines:Like all salts in ECOSAR, the 

conjugate salt of ammonium salts should be replaced with a hydrogen; however, 

reduction of ammonium salts at a neutral pH results in a loss of hydrogens, and the 

resulting structure should be entered into ECOSAR as an aliphatic amine for the 

purpose of ECOSAR estimations (examples depicted below). Ammonium salts in which 

the ammonium cation has four bound carbons in the presence of a stabilizing anion 

(e.g., chloride ion) are excluded from this definition since reduction is less likely. 

Predictions for these more stable ammonium salts are based on analogous chemicals 

or the cationic surfactant QSAR R

H

C N

+

R

Anion

R - can be an aliphatic carbon (alkyl, olefinic or acetylenic carbon) or hydrogen 

Associated ECOSAR Class(s): 

Oxyamine - identified by H2N-O-C- structure. 

Triazine, Aliphatic – a 6-membered aliphatic ring structure with 3 alternating nitrogens. 

 

Example Aliphatic Amines: 

CAS No. Name SMILES Notation 

107-10-8 Propylamine NCCC 

111-42-2 Diethanolamine OCCNCCO 
107-15-3 1,2-Ethanediamine NCCN 

103-76-4 1-Piperazineethanol OCCN(CCNC1)C1 

107-11-9 Allyl amine NCC=C 
ECOSAR Class Definition: Alkoxy Silanes (or Silanes, alkoxy)

The Silanes (alkoxy) class is identified by the following example structure: 

 

R2 Si O

R3

R1

Alkyl Carbon

R1, R2 and R3 - must be either hydrogen, oxygen or carbon (alkyl, olefinic, acetylenic, 

aromatic or a carbonyl). 

In the current ECOSAR program, the Alkoxy Silane structure meets the following 

criteria: 

(1) Contains a silicon to oxygen attachment. The oxygen must also be attached to an 

alkyl carbon (or carbonyl). 

Notation: the R1, R2 and R3 attachments are limited to the atoms listed above ... Any 

other atom attachments (e.g. nitrogen, sulfur, halogen, etc) will not result in an Alkoxy 

Silane identification. 

SMILES String Identifications: 

[Si]OC 

SiOC ... (ECOSAR allows Silicon to be either with or without brackets) 

 ... other attachments to Silicon as defined above. 

Associated ECOSAR Class(s): 

None specifically. 

The Silamines class is the only other ECOSAR class specifically containing silicon. 

Example Alkoxy Silanes: 

CAS No. Name SMILES Notation 

78-62-6 Dimethyl diethoxysilane C[Si](OCC)(OCC)C 

18246-71-4 Silane, butoxyethoxydimethyl- CCCCO[Si](C)(C)OCC 

17841-46-2 Silane, methoxytripropyl- [Si](OC)(CCC)(CCC)CCC 
ECOSAR Class Definition: Amides 

The Amides class is identified by the following structures: 

 

R1

C [or S]

N

O

R2

R3

R1 can be an aliphatic carbon with a single bond to any atom other than a halogen, or 

an aromatic carbon. 

R1 can not contain the following atoms below: 

If R1 is an oxygen atom, ECOSAR will identify the structure as a carbamate ester 

or derivatives 

If R1 is a C=C, ECOSAR will identify the structure as an acrylamide 

If R1 is a sulfur atom, ECOSAR will identify the structure as a thiocarbamate, 

mono 

If R1 is a nitrogen atom, ECOSAR will identify the structure as a substituted urea. 

If R1 is C-halogen group, ECOSAR will identify the structure as a Haloacetamide. 

R2 and R3 can be anything other than a carbonyl group. 

If either R2 or R3 are carbonyl groups, ECOSAR will identify the structure as a 

carbonyl urea. 

SMILES String Identifications: 

O=CN ... ( equivalent to: O=C(H)N or O= C([H])N formamide-type) 

CC(=O)N 

NOTE: If R1 above is a benzene ring (6-member aromatic ring) with a nitro/nitroso 

attachment, then ECOSAR will also identify the structure as nitro/nitroso-Benzamides. 

There are very limited empirical data for this class (fish acute only) so this substitution 

rule for R1 has not been implement as an exclusion for the amides class so that the 

user is presented with QSAR results for both classes. 

 Example Amides: 

CAS No. Name SMILES Notation 

60-35-5 Acetamide NC(=O)C 

2620-63-5 Glycin-amide,N-acetyl CC(=O)NCC(=O)N 
Anilines (amino-meta)

The Anilines (amino-meta) class is identified by the following structure: 

In the current ECOSAR program, the Anilines (amino-meta) structure meets the 

following criteria: 

(1) A benzene ring (or any other six-member aromatic ring including hetero-aromatic 

rings) has amine substituent (as -NH2) in meta-position to each other. 

(2) The aromatic ring can be fused to another ring. 

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N< 

is not identified as an amine for this class. 

SMILES String Identifications: 

Nc1cc(N)ccc1 ... aliphatic nitrogens as NH2 attached to aromatic carbons 

 equivalent to: N(H)(H)c1cc(N(H)H)cc1 

 ... aromatic ring can contain non-carbon members as in: Nc1cc(N)ccn1 

Associated ECOSAR Class(s): 

Anilines (Aromatic Amine) - An aromatic ring has one (or more) amine substituent 

(NH2). If the Anilines (amino-meta) class is identified, ECOSAR excludes the Anilines 

(Aromatic Amines) identification. 

Anilines (amino-ortho) and Anilines (amino-para) - These classes are identified when a 

six-member aromatic ring has two -NH2 substituents in either a ortho- or para-position. 

When identified in conjunction with Anilines (amino-meta), they are both reported by 

ECOSAR. 

Example Anilines (amino-meta): 

CAS No. Name SMILES Notation 

108-45-2 m-Phenylenediamine Nc(cccc1N)c1 

608-32-2 1,2,3-Triaminobenzene Nc1c(cccc1N)N 

94-10-0 Ethoxazene Nc1cc(N)c(N=Nc2ccc(OCC)cc2)cc1 

95-86-3 2,4-Diaminophenol Nc1ccc(O)c(N)c1 
495-54-5 2,4-Diaminoazobenzene N(=Nc(cccc1)c1)c(c(N)cc(N)c2)c2 
Anilines (amino-ortho)

The Anilines (amino-ortho) class is identified by the following structure: 

In the current ECOSAR program, the Anilines (amino-ortho) structure meets the 

following criteria: 

(1) A benzene ring (or any other six-member aromatic ring including hetero-aromatic 

rings) has amine substituent (as -NH2) in ortho-position to each other. 

(2) The aromatic ring can be fused to another ring. 

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N< 

is not identified as an amine for this class. 

SMILES String Identifications: 

Nc1c(N)cccc1 ... aliphatic nitrogens as NH2 attached to aromatic carbons 

 equivalent to: N(H)(H)c1c(N(H)H)ccc1 

 ... aromatic ring can contain non-carbon members as in: Nc1c(N)cccn1

Associated ECOSAR Class(s): 

Anilines (Aromatic Amine) - An aromatic ring has one (or more) amine substituent 

(NH2). If the Anilines (amino-ortho) class is identified, ECOSAR excludes the Anilines 

(Aromatic Amines) identification. 

Anilines (amino-meta) and Anilines (amino-para) - These classes are identified when a 

six-member aromatic ring has two -NH2 substituents in either a meta- or para-position. 

When identified in conjunction with Anilines (amino-ortho), they are both reported by 

ECOSAR. 

Example Anilines (amino-ortho): 

CAS No. Name SMILES Notation 

95-54-5 o-Phenylenediamine Nc(c(N)ccc1)c1 

91-95-2 1,1'-Biphenyl -3,3',4,4'-tetramine Nc(c(N)cc(c(ccc(N)c1N)c1)c2)c2 

95-83-0 1,2-Benzenediamine, 4-chloro- Nc(c(N)cc(c1)Cl)c1 

608-32-2 1,2,3-Triaminobenzene Nc1c(cccc1N)N 
Anilines (amino-para)

The Anilines (amino-para) class is identified by the following structure:

In the current ECOSAR program, the Anilines (amino-para) structure meets the

following criteria:

(1) A benzene ring (or any other six-member aromatic ring including hetero-aromatic

rings) has amine substituent (as -NH2) in para-position to each other.

(2) The aromatic ring can be fused to another ring.

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N<

is not identified as an amine for this class.

SMILES String Identifications:

Nc1ccc(N)cc1 ... aliphatic nitrogens as NH2 attached to aromatic carbons

equivalent to: N(H)(H)c1ccc(N(H)H)c1

... aromatic ring can contain non-carbon members as in: Nc1ccc(N)cn1

Associated ECOSAR Class(s):

Anilines (Aromatic Amine) - An aromatic ring has one (or more) amine substituent

(NH2). If the Anilines (amino-para) class is identified, ECOSAR excludes the Anilines

(Aromatic Amines) identification.

Anilines (amino-ortho) and Anilines (amino-meta) - These classes are identified when a

six-member aromatic ring has two -NH2 substituents in either a meta- or ortho-position.

When identified in conjunction with Anilines (amino-para), they are both reported by

ECOSAR.

Example Anilines (amino-para):

CAS No. Name SMILES Notation

106-50-3 p-Phenylenediamine Nc(ccc(N)c1)c1

95-70-5 2,5-Diaminotoluene Nc(c(cc(N)c1)C)c1

615-71-4 1,2,4-Benzenetriamine Nc1c(N)cc(N)cc1
ECOSAR Class Definition: Anilines (Hindered) 

The Anilines (Hindered) class is identified by the following structure: 

 

A carbon-based functional group must be attached ortho to the amine group (can be an 

aliphatic carbon [including alkyl, olefinic, acetylenic, carbonyl] or an aromatic carbon 

[biphenyl-type attachment]). 

In the current ECOSAR program, the Aniline (Hindered) structure meets the following 

criteria: 

(1) A benzene ring (or any other aromatic ring including hetero-aromatic rings) that has 

an amine substituent as -NH2 

(2) The aromatic ring can be fused to another ring. 

(3) An aliphatic carbon is present in the ortho-position. 

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N< 

is not identified as an amine for this class. The Anilines (Hinderd) SAR Sheet notes that 

N-substituted amines are less toxic than the SARs for this class 

SMILES String Identifications: 

Nc1ccccc1C 

Nc1c(C)cccc1

Associated ECOSAR Class(s): 

Anilines (Unhindered) - an R-substituent is not an carbon-based ortho attachment. 

Dinitro Aromatic Amine (Dinitro Aniline)- If an aromatic ring has both the amine 

substituent (-NH2) and two or more nitro substituents (-NO2), ECOSAR classifies the 

ring as Dinitro Aromatic Amine and also reports the Anilines (Hindered) identification. 

Anilines (amino-ortho), Anilines (amino-meta), Anilines (amino-para) - These classes 

are identified when a six-member aromatic ring has two -NH2 substituents in either an 

ortho-, meta- or para-position. 

Example Anilines (Hindered): 

CAS No. Name SMILES Notation 

88-68-6 Benzamide, 2-amino- O=C(N)c(c(N)ccc1)c1 

24544--04-5 2,6-Diisopropylaniline Nc(c(ccc1)C(C)C)c1C(C)C 

2894-51-1 2-Amino-4'-chlorobenzophenone Nc1ccccc1C(=O)c2ccc(Cl)cc2 
ECOSAR Class Definition: Anilines (Unhindered) 

The Anilines (Unhindered) class is identified by the following structure: 

 

NH2

R

R can not be a carbon-based fragment (including alkyl, olefinic, acetylenic, carbonyl or 

an aromatic carbon). Allowed attachments include hydrogen atoms, chlorine, 

secondary or tertiary nitrogens, sulfur, etc. 

R can not be a primary amine. 

If R is a primary amine (NH2) then ECOSAR will identify the class as amino-ortho 

anilines 

In the current ECOSAR program, the Aniline (Unhindered) structure meets the following 

criteria: 

A benzene ring (or any other aromatic ring including hetero-aromatic rings) that has an 

amine substituent as -NH2. 

The aromatic ring can be fused to another ring. 

An excluded R-substituent is not present in the ortho-position. 

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N< 

is not identified as an amine for this class. The Anilines (Unhinderd) SAR Sheet notes 

that N-substituted amines are less toxic than the SARs for this class. 

SMILES String Identifications: 

Nc1ccccc1 

c1ccccc1N

Associated ECOSAR Class(s): 

Anilines (Hindered) - an R-substituent is an aliphatic or aromatic carbon-based 

attachment in the ortho position. 

Dinitro Aromatic Amine (Dinitro Aniline)- If an aromatic ring has both the amine 

substituent (-NH2) and two or more nitro substituents (-NO2), ECOSAR classifies the 

ring as Dinitro Aromatic Amine and also reports the Anilines (Unhindered) identification. 

Anilines (amino-ortho), Anilines (amino-meta), Anilines (amino-para) - These classes 

are identified when a six-member aromatic ring has two -NH2 substituents in either an 

ortho-, meta- or para-position. 

Example Anilines (Unhindered): 

CAS No. Name SMILES Notation 

62-53-3 Aniline Nc1ccccc1 

371-40-4 4-Fluoroaniline Nc1ccc(F)cc1 
106-49-0 4-Toluidine Nc1ccc(C)cc1 

3481-20-7 2,3,5,6-Tetrachloroaniline Nc1c(Cl)c(Cl)cc(Cl)c1Cl 
ECOSAR Class Definition: Aziridines

The Aziridines class is identified by the following ring structure: 

 

N

ECOSAR identifies an Aziridine ring as follows: 

(1) a three member aliphatic ring consisting of one aliphatic nitrogen and two aliphatic 

carbons 

(2) the carbon atoms cannot have double or triple bonds (excludes olefinic and 

acetylenic carbons or carbons with bonds such as C=N) 

(3) the Aziridine ring can be part of a fused-ring system 

SMILES String Identifications: 

N1CC1 ... (same as: C1NC1 or C1CN1 ) 

Associated ECOSAR Class(s): 

Aliphatic Amines - In the current ECOSAR program, the nitrogen in an aziridine ring is 

not additionally classified as an Aliphatic Amine.

Example Aziridines: 

CAS No. Name SMILES Notation 

151-56-4 Aziridine N1CC1 

1072-44-2 N-Methylaziridine CN1CC1 

75-55-8 2-Methylaziridine N1CC1C 

286-18-0 7-Azabicyclo[4.1.0]heptane N(C1CC2)C1CC2 

4055-40-7 Mitomycin B COC4=C(C)C(=O)C1=C(C(COC(N)=O)C2(O)C3C(CN12)N3C)C4=O

 
ECOSAR Class Definitions: Benzodioxoles

The Benzodioxoles class is identified by the following structure: 

 

O

O

In the current ECOSAR program, the Benzodioxole structure identification meets the 

following criteria: 

(1) The ECOSAR program identifies a five-member ring containing two aromatic carbon 

atoms, two aliphatic oxygen atoms and one alkyl carbon atom. Currently, the position of 

the atoms in the ring is not differentiated; for example, the two oxygen atoms could sideby-side and the structure will still be identified as Benzodioxoles (the two different 

structures would correspond to 1,3-benzodioxole and 1,2-benzodioxole). 

 (2) The aromatic ring that is fused to the five-member is not required to be a benzene 

ring; it can be any aromatic ring including hetero-aromatic rings. 

(3) The Benzodioxole ring structure can be fused to additional ring(s). 

SMILES String Identifications: 

Equivalent SMILES for 1,3-benzodioxole: 

 c1cccc2OCOc12 

 c1ccc2OCOc2c1 

 c1cc2OCOc1cc1 

 c12ccccc1OCO2 

 C1=CC=C2OCOC2=C1 

 O1c2ccccc2OC1O=CC 

Associated ECOSAR Class(s): 

None. 

Examples Benxodioxoles: 

CAS No. Name SMILES Notation 

274-09-9 1,3-Benzodioxole c1ccc2OCOc2c1 

51-03-6 Piperonyl butoxide O(c(c(O1)cc(c2CCC)COCCOCCOCCCC)c2)C1 
ECOSAR Class Definition: Benzotriazoles

The Benzotriazoles class is identified by the following structures (1H-Benzotriazole and 

2H-Benzotriazole): 

 

N

N

N

R

N

N

N R

R - can be anything (no exclusions) 

In the current ECOSAR program, the Benzotriazoles structure must meet the following 

criteria: 

(1) The triazole ring must be fused to a benzene ring. The ring to which the triazole 

ring is fused cannot be a hetero-aromatic ring. 

(2) The fused benzene ring can be fused to another ring 

SMILES String Identifications: 

c1ccc2nn[nH]c2c1 

c1ccc2n[nH]nc2c1 

c1ccc2nnnc2c1 

c1ccc2N=NNc2c1 

C1=CC2=NNN=C2C=C1 

Associated ECOSAR Class(s): 

None specifically. However, ECOSAR includes other “ring structure” classes such as 

Triazines, Imidazoles, Triazoles (Non-Fused), Triazole Pyrimidines and Thiazole, 

Benzo. 

With respect to structures containing a triazole ring: 

Triazoles (Non-Fused) - a structure containing either a 1,2,4-triazole, 1,2,3-triazole or 

1,3,4-triazole ring that is not fused to another aromatic ring. 

Triazole Pyrimidines - a triazole-pyrimidine fused ring structure 

Examples Benzotriazoles: 

CAS No. Name SMILES Notation 

95-14-7 1H-Benzotriazole c1ccc2nnnc2c1 

273-02-9 2H-Benzotriazole c1ccc2nnnc2c1 

36437-37-3 

Phenol, 2-(2H-benzotriazol-2-yl)-

4-(1,1-dimethylethyl)-6-(1-

methylpropyl)- Oc(c(cc(c1)C(C)(C)C)C(CC)C)c1n(nc(c2ccc3)c3)n2 
ECOSAR Class Definition: Benzoylcyclohexanedione

The Benzoylcyclohexanedione class is identified by the following structure: 

 

C

C C

O O

O

In the current ECOSAR program, the Benzoylcyclohexanedione structure meets the 

following criteria: 

(1) A linear carbonyl [-C(=O)-] is attached to both a phenyl ring and a 2,6-

cyclohexanedione ring at the position shown above. 

(2) The rings can be fused to other rings. 

Notation: The current identification in ECOSAR is very strict ... The phenyl ring must be 

a phenyl ring (a hetero-aromatic ring (e.g. pyridine) is not allowed) ... The 

cyclohexanedione ring must be a 2,6-dione only with the linear carbonyl attached at the 

1-position. 

SMILES String Identifications: 

c1ccccc1C(=O)C2C(=O)CCCC2=O 

equivalent SMILES: O=C(c1ccccc1)C2C(=O)CCCC2=O 

Associated ECOSAR Class(s): 

None specifically. 

Example Benzoylcyclohexaediones: 

CAS No. Name SMILES Notation 

99105-77-8 Sulcotrione O=C1CCCC(=O)C1C(=O)c2ccc(S(=O)(=O)C)cc2Cl
ECOSAR Class Definition: Benzyl Alcohols

The Benzyl Alcohols class is identified by the following structure: 

 

C

OH

In the current ECOSAR program, the Benzyl Alcohol structure meets the following 

criteria: 

(1) An alkyl carbon atom has both an hydroxyl (-OH) attachment and benzene ring 

attachment. 

(2) A strict definition of “benzyl” implies the single alkyl carbon is a -CH2- group and the 

aromatic ring is a benzene ring. However, in the current ECOSAR program, the single 

alkyl carbon can be -CH2-, -CH< or >C< and the aromatic ring can be any aromatic 

ring including hetero-aromatic rings. 

SMILES String Identifications: 

c1ccccc1CO ... ( equivalent to: c1ccccc1COH or c1ccccc1CO[H] ) 

Associated ECOSAR Class(s): 

None specifically. 

ECOSAR includes a variety of other Alcohol classes (such as Propargyl Alcohols, 

Vinyl/Allyl Alcohols, Ketone Alcohol, Halo Alcohols and Nitro Alcohols). ECOSAR also 

includes a variety of Benzyl classes. 

Example Benzyl Alcohols: 

CAS No. Name SMILES Notation 

100-51-6 Benzyl alcohol c1ccccc1CO 

4412-91-3 3-Hydroxymethylfuran OCc1ccoc1 

115-32-2 Dicofol OC(c1ccc(Cl)cc1)(c2ccc(Cl)cc2)C(Cl)(Cl)Cl 
ECOSAR Class Definition: Benzyl Halides

The Benzyl Halides class is identified by the following structure: 

 

C

Halogen

[ Halogen = Br, Cl or I ]

In the current ECOSAR program, the Benzyl Halide structure meets the following 

criteria: 

(1) An alkyl carbon atom has both a benzene ring attachment and a Halogen 

attachment. For this class, halogens are limited to bromine, chlorine and iodine ... 

Fluorine is excluded. 

(2) A strict definition of “benzyl” implies the single alkyl carbon is a -CH2- group and the 

aromatic ring is a benzene ring. However, in the current ECOSAR program, the single 

alkyl carbon can be -CH2-, -CH< or >C< and the aromatic ring can be any aromatic 

ring including hetero-aromatic rings. 

SMILES String Identifications: 

 with bromine: c(CBr) or c1CBr 

 with chlorine: c(CCl) or c1CCl 

 with iodine: c(CI) or c1CI 

 ... with a complete ring: c1ccccc1CBr or c1ccccc1CCl or c1ccccc1CI 

Associated ECOSAR Class(s): 

None specifically. 

ECOSAR includes other Halide classes (such as Propargyl Halides, Vinyl/Allyl Halides, 

Acid Halides, Halo Acetamides, Halo Ethers, etc). ECOSAR also includes a variety of 

Benzyl classes. 

Example Benzyl Halides: 

CAS No. Name SMILES Notation 

100-44-7 Benzene, (chloromethyl)- c(cccc1)(c1)CCl 

611-19-8 o-Chlorobenzyl chloride c(c(ccc1)Cl)(c1)CCl 

623-25-6 Benzene, 1,4-bis(chloromethyl)- c(ccc(c1)CCl)(c1)CCl 

30030-25-2 Chloromethyl styrene C=Cc1ccc(cc1)CCl 
ECOSAR Class Definition: Benzyl Imides 

The Benzyl Imides class is identified by the following structure: 

 R1

[S] O N

R2

R3

O [S]

R1 and R3 can be anything except a nitrogen atom 

If R1 or R3 are a nitrogen atom, ECOSAR will identify the class as carbonyl 

ureas. The carbonyl urea contains training set chemicals contain structures with 

the R1 or R3 as nitrogen atoms and the R2 as defined below. 

R2 must be an alkyl carbon that is attached to a phenyl or other aromatic ring. A strict 

definition of “benzyl” implies the single alkyl carbon is a -CH2- group and the aromatic 

ring is a benzene ring. However, in the current ECOSAR program, the single alkyl 

carbon can be -CH2-, -CH< or >C< and the aromatic ring can be any aromatic ring 

including hetero-aromatic rings. 

SMILES String Identifications: 

c(CN(C(=O))C(=O)) or c1CN(C(=O))C(=O) ...complete ring: c1ccccc1CN(C(=O))C(=O) 

c(CN(C(=S))C(=S)) or c1CN(C(=S))C(=S) ...complete ring: c1ccccc1CN(C(=S))C(=S) 

c(CN(C(=O))C(=S)) or c1CN(C(=O))C(=S) ...complete ring: c1ccccc1CN(C(=O))C(=S) 

Example Benzyl Imides: 

CAS No. Name SMILES Notation 

2142-01-0 2-Benzyl-isoindole-1,3-dione c12C(=O)N(Cc3ccccc3)C(=O)c1cccc2 

32000-70-7 Uracil, 3-benzyl-5-bromo-1,6-dimethyl- N1(C)C(=O)N(Cc2ccccc2)C(=O)C(Br)=C1C
ECOSAR Class Definition: Benzyl Nitriles 

The Benzyl Nitriles class is identified by the following structures: 

 

C

N

C

C

N

C

Aromatic Ring

In the current ECOSAR program, the Benzyl Nitrile structure must meet the following 

criteria: 

(1) A nitrile group (carbon triple-bonded to nitrogen; SMILES of C#N) is attached to an 

alkyl carbon which also has a phenyl or aromatic ring attachment. 

 (2) A strict definition of “benzyl” implies the single alkyl carbon is a -CH2- group and 

the aromatic ring is a benzene ring. However, in the current ECOSAR program, the 

single alkyl carbon can -CH2-, -CH< or >C< and the aromatic ring can be any aromatic 

ring including hetero-aromatic rings. 

SMILES String Identifications: 

c(CC#N) or c1CC#N ... with a complete ring: c1ccccc1CC#N 

 ... attachments to the alkyl carbon as defined above 

Associated ECOSAR Class(s): 

Nitriles, Polyaliphatic - Two or more nitrile groups are attached to aliphatic atoms in the 

whole structure. When two or more nitrile groups are attached to the same alkyl or 

olefinic carbon, the structure will be classified as both Vinyl/Allyl Nitriles and Nitriles, 

Polyaliphatic. 

Pyrethroids - One of the two potential identifying structures for pyrethroids contains the 

benzyl nitrile moiety. Due to the nature of the pyrethroid class as a pesticide class with a 

complex structure and mode of action, compounds that fit the pyrethroid definition are 

excluded from the benzyl nitriles class. 

Other SAR Nitrile classes include: Halo Nitriles, Nitrile Alpha-OH, Phthalonitriles, 

Vinyl/Allyl Nitriles, Malonitriles, and Nitriles, Polyaliphatic. 

Example Benzyl Nitriles: 

CAS No. Name SMILES Notation 

140-29-4 Benzyl nitrile c1ccccc1CC#N 
Carbamate Esters, Alkyl 

The Carbamate Esters class is identified by the following structure: 

R

N O

R'

O

R - can be anything except two hydrogens (making the nitrogen atom a primary amine). 

 

If R is a primary amine ECOSAR will identify the class as a simple ester 

R’- can be anything except a 6-member aromatic ring (c1ccccc1) or -N=C. 

If R’ is an aromatic ring ECOSAR will identify the class as carbamate esters, 

phenyl. 

If R’ is an -N=C group, ECOSAR will identify the class as carbamates esters, 

oxime 

In the current ECOSAR program, the Carbamate Esters class meets the criteria as shown 

in the structures above. 

Associated ECOSAR Class(es): 

Carbamate Esters, Oxime - if R’ is -N=C, the ECOSAR class becomes Oxime Carbamate 

Ester, and the Carbamate Ester class is excluded. 

Carbamate Esters, Phenyl - if R’ is a phenyl ring, the ECOSAR class becomes Phenyl 

Carbamate Ester, and the Carbamate Ester class is excluded. 

ECOSAR includes a variety of Thiocarbamate ester classes. 

Example Carbamate Esters: 

CAS No. Name SMILES Notation 

101-21-3 Chlorpropham CC(C)OC(=O)Nc1cccc(Cl)c1 

6135-31-5 N-Methylethylcarbamate O=C(OC)NCC 

539-71-9 Ethylidene O=C(OCC)NC(NC(=O)OCC)C 

Mechanism of Action Information: 

Carbamate esters act by inhibiting acetylcholinesterase (AChE) in the nervous system, as 

well as inhibition of other esterases (IPCS, 1986). Toxicity of carbamate esters, based on 

available data (presented in the Carbamate Esters, Alkyl Manual Sheets), appears to 

correlate with the substituent on the oxygen (O-alkyl, O-phenyl, or O-oxime); however, 
data available for modeling were limited to methylcarbamates and, thus, the trend may be 

specific to methylcarbamates. Additionally, compounds with a large substitution on the 

nitrogen may not fit into the active site of AChE and, thus, the mechanism of action may 

be inhibited. Hydrolysis of carbamate esters in aquatic conditions may factor in to the 

ultimate toxicity of the compound; however, hydrolysis as it pertains to O-alkyl 

substituted, O-phenyl substituted, and O-oxime substituted carbamate esters has not been 

fully characterized and correlated with standard endpoint effect levels (e.g., insufficient 

information). Fukuto (1990) indicates that carbamate esters with certain steric properties 

may be hydrolytically degraded before the carbamate ester has an opportunity to inhibit 

the enzyme. Additionally, Fukuto (1990) indicates “that methylcarbamate esters of 

alcohols are intrinsically unreactive [compared to methyl carbamates substituted with 

phenols or oximes] and, therefore, they are generally poor anticholinesterases [e.g., poor 

inhibitorsof AChE]. A good fit of a methylcarbamate ester in the enzyme active site, i.e., 

formation of the enzyme-inhibitor complex prior to carbamylation, is crucial for high 

anti-cholinesterase activity.” Thus, the Carbamate Ester, Alkyl QSAR is considered to 

represent the least toxic carbamate ester QSAR class based on available data and 

supporting information. Fukuto (1990) provides a more in depth discussion of the 

mechanism of inhibition of carbamate insecticides, which support ecotoxicity trends 

observed in available carbamate esters data. Datasets for the below determined equations 

have excluded any studies using static testing methods without analytical monitoring of 

test concentrations due to potential for hydrolysis. 

Desmedipham and phenmedipham were included in Carbamate Esters, Alkyl QSAR 

based on data that suggested poor inhibition of acetylcholinesterase, which may be a 

result of hydrolytic instability or poor formation of the enzyme-inhibitor complex, even 

though these compounds contain a carbamate ester conjugated with a phenyl in addition 

to a carbamate ester conjugated with an alkyl. Some instances of hydrolytic instability 

and poor formation of the enzyme-inhibitor complex may need to be assessed on a caseby-case basis. 

References: 

IPCS. 1986. Carbamate Pesticides: A General Introduction. International Programme on 

Chemical Safety (IPCS) Environmental Health Criteria (EHC) 64, ISBN: 92 4 154264 0. 

[http://www.inchem.org/documents/ehc/ehc/ehc64.htm] 

Fukoto T.R. 1990. Mechanism of Action of Organophosphorus and Carbamate 

Insecticide. Environmental Health Perspectives, 87:245-254. 
Carbamate Esters, Oxime 

The Oxime Carbamate Ester class is identified by the following substructure: 

R - can be anything except two hydrogens (making the nitrogen atom a primary amine). 

 

If R is a primary amine, ECOSAR will identify the class as a neutral organic. 

This is because for an ester classification, the functional group off the oxygen must be 

carbon based and therefore the –N=C does not qualify, nor do any other nitrogen 

functional group attachments. 

In the current ECOSAR program, the Oxime Carbamate Ester class meets the criteria as 

shown in the structure above. Substitutions on the oxime carbon are allowed. 

Associated ECOSAR Class(es): 

Carbamate Esters - if the -N=C attached to the oxygen is replaced by something else 

(excluding a phenyl ring), the ECOSAR class becomes Carbamate Esters. 

Phenyl Carbamate Esters - if the -N=C is replaced by a phenyl ring, the ECOSAR class 

becomes Phenyl Carbamate Ester, and the Carbamate Ester class is excluded. 

Example Oxime Carbamate Ester: 

CAS No. Name SMILES Notation 

23135-22-0 Oxamyl CNC(=O)ON=C(SC)C(=O)N(C)C 

16752-77-5 Methomyl CNC(=O)ON=C(C)SC 

116-06-3 Aldicarb O=C(ON=CC(SC)(C)C)NC 

References: 

IPCS. 1986. Carbamate Pesticides: A General Introduction. International Programme on 

Chemical Safety (IPCS) Environmental Health Criteria (EHC) 64, ISBN: 92 4 154264 0. 

[http://www.inchem.org/documents/ehc/ehc/ehc64.htm] 

Fukoto T.R. 1990. Mechanism of Action of Organophosphorus and Carbamate 

Insecticide. Environmental Health Perspectives, 87:245-254. 

Mechanism of Action Information: 

Carbamate esters act by inhibiting acetylcholinesterase (AChE) in the nervous system, as 

well as inhibition of other esterases (IPCS, 1986). Toxicity of carbamate esters, based on 

available data (presented in the Carbamate Esters, Oxime Manual Sheets), appears to 

correlate with the substituent on the oxygen (O-alkyl, O-phenyl, or O-oxime); however, 

data available for modeling were limited to methylcarbamates and, thus, the trend may be 
specific to methylcarbamates. Additionally, compounds with a large substitution on the 

nitrogen may not fit into the active site of AChE and, thus, the mechanism of action may 

be inhibited. Hydrolysis of carbamate esters in aquatic conditions may factor in to the 

ultimate toxicity of the compound; however, hydrolysis as it pertains to O-alkyl 

substituted, O-phenyl substituted, and O-oxime substituted carbamate esters has not been 

fully characterized and correlated with standard endpoint effect levels (e.g., insufficient 

information). Fukuto (1990) indicates that “[m]ethylcarbamates of substituted phenols 

and oximes with good complementary fit to the [AChE] enzyme active site are generally 

strong inhibitors of AChE.” Furthermore, substitution of “ phenols and oximes, each with 

pKa values in the region of 10, [make] methylcarbamates that are reactive to the degree 

that they are able to carbamylate the serine hydroxyl of AChE. Owing to the intrinsic 

reactivity of methylcarbamate esters, an electron-withdrawing substituent is not required 

in the aryl moiety for high anticholinesterase activity.” Fukuto (1990) provides a more in 

depth discussion of the mechanism of inhibition of carbamate insecticides, which support 

ecotoxicity trends observed in available carbamate esters data. Datasets for the below 

determined equations have excluded any studies using static testing methods without 

analytical monitoring of test concentrations due to potential for hydrolysis. 
Carbamate Esters, Phenyl 

The Phenyl Carbamate Ester class is identified by the following structure: 

N O

O

R

R - can be anything except two hydrogens (making the nitrogen atom a primary amine). 

 

If R is a primary amine, ECOSAR will identify the class as a simple ester 

In the current ECOSAR program, the Phenyl Carbamate Ester class meets the criteria as 

shown in the structure above. 

Substitutions on the phenyl ring are allowed. 

Associated ECOSAR Class(es): 

Carbamate Esters - if the phenyl ring attached to the oxygen is replaced by an aliphatic 

group, the ECOSAR class becomes Carbamate Esters. 

Oxime Carbamate Esters - if the phenyl ring attached to the oxygen is -N=C, the 

ECOSAR class becomes Oxime Carbamate Ester, and the Carbamate Ester class is 

excluded. 

Example Oxime Carbamate Ester: 

CAS No. Name SMILES Notation 

114-26-1 Propoxur CNC(=O)Oc1ccccc1OC(C)C 

63-25-2 Carbaryl O=C(Oc(c(c(ccc1)cc2)c1)c2)NC 

2686-99-9 Trimethacarb CNC(=O)Oc1cc(C)c(C)c(C)c1 

Mechanism of Action Information: 

Carbamate esters act by inhibiting acetylcholinesterase (AChE) in the nervous system, as 

well as inhibition of other esterases (IPCS, 1986). Toxicity of carbamate esters, based on 

available data (presented in the Carbamate Esters, Phenyl Manual Sheets), appears to 

correlate with the substituent on the oxygen (O-alkyl, O-phenyl, or O-oxime); however, 

data available for modeling were limited to methylcarbamates and, thus, the trend may be 

specific to methylcarbamates. Additionally, compounds with a large substitution on the 

nitrogen may not fit into the active site of AChE and, thus, the mechanism of action may 

be inhibited. Hydrolysis of carbamate esters in aquatic conditions may factor in to the 

ultimate toxicity of the compound; however, hydrolysis as it pertains to O-alkyl 

substituted, O-phenyl substituted, and O-oxime substituted carbamate esters has not been 
fully characterized and correlated with standard endpoint effect levels (e.g., insufficient 

information). Fukuto (1990) indicates that “[m]ethylcarbamates of substituted phenols 

and oximes with good complementary fit to the [AChE] enzyme active site are generally 

strong inhibitors of AChE.” Furthermore, substitution of “ phenols and oximes, each with 

pKa values in the region of 10, [make] methylcarbamates that are reactive to the degree 

that they are able to carbamylate the serine hydroxyl of AChE. Owing to the intrinsic 

reactivity of methylcarbamate esters, an electron-withdrawing substituent is not required 

in the aryl moiety for high anticholinesterase activity.” Fukuto (1990) provides a more in 

depth discussion of the mechanism of inhibition of carbamate insecticides, which support 

ecotoxicity trends observed in available carbamate esters data. Datasets for the below 

determined equations have excluded any studies using static testing methods without 

analytical monitoring of test concentrations due to potential for hydrolysis. 

Fukuto (1990) suggests that “introduction of a nitro substituent into the phenyl ring of 

phenyl methylcarbamate results in a compound of such high reactivity that it is 

hydrolytically degraded before it has an opportunity to inhibit the enzyme.” Aquatic 

toxicity data were not located for compounds such as this and, thus, the Carbamate 

Esters, Phenyl QSAR class does not account for this phenomenon. 

In comparing the rates of reaction of [m-isopropyl compound] and [m-tert-butyl 

compound] with [ammonium compound], Fukoto suggests that “replacement of the 

central carbon atom [in the side chain] with a positively charged quaternary nitrogen 

atom [similar to Ammonium, (3-(methylcarbamoyloxy) phenyl)trimethyl-, chloride (CAS 

# 64051-06-5)] resulted in about a 50-fold increase in anticholinesterase activity.” 

Aquatic toxicity data were not located for compounds such as this and, thus, the 

Carbamate Esters, Phenyl QSAR class does not account for this phenomenon. 

Additionally, compounds such as this are treated as cationic surfactants for the purpose of 

QSAR predictions. 

References: 

IPCS. 1986. Carbamate Pesticides: A General Introduction. International Programme on 

Chemical Safety (IPCS) Environmental Health Criteria (EHC) 64, ISBN: 92 4 154264 0. 

[http://www.inchem.org/documents/ehc/ehc/ehc64.htm] 

Fukoto T.R. 1990. Mechanism of Action of Organophosphorus and Carbamate 

Insecticide. Environmental Health Perspectives, 87:245-254. 

 
ECOSAR Class Definition: Carbonyl Ureas 

In ECOSAR V1 and early, carbonyl ureas were identified as both imides and substituted 

ureas. The Carbonyl Urea class is identified by the following example structure in 

ECOSAR V1.1. 

 

R1 N N

R4

O O

R2

R3

The nitrogens must be aliphatic nitrogen atoms 

R1 can be anything (no exclusions) 

If R1 is a sulfur atom, there may be overlap with the thiocarbamates, mono class 

based on the training set chemicals, but toxicity profiles are similar for both 

classes to all organisms and therefore no restrictions will be applied at this time 

since thiocarbamates, mono class define only the [S-C=ON] portion of the above 

base structure. 

R2, R3 and R4 can be anything except halogen atoms. 

If R2 or R3 or R4 are halogens, ECOSAR will identify the class as haloimides 

which show much higher toxicity to fish and daphnid than non-halogenated 

carbonyl ureas 

R4 can be anything (no exclusions) 

The oxygen in the carbonyl(s) can not to be replaced by S or N atoms, as is done in 

other related classes. 

In this case, compounds containing C=S are included in the thioureas class 

definition, though the effects of the repeating C=S (like the carbonyl does above) 

is unknown since simple thiourea (NC=SN) defines the training set. We have no 

structural analogs in ECOSAR for the C=N configuration of this molecule. 

A related class is sulfonyl ureas where a sulfone group [S(=O)(=O)] replaces the second 

carbonyl group off of the R1 above. 

SMILES String Identifications: Carbonyl Urea Group: C(=O)NC(=O)N 

Example Carbonyl Urea: 

CAS No. Name SMILES Notation 

314-40-9 Bromacil N1C(=O)N(C(C)CC)C(=O)C(Br)=C1C 

36734-19-7 Iprodione c1c(Cl)cc(Cl)cc1N2C(=O)CN(C(=O)NC(C)C)C2(=O)

78587-05-0 Hexythiazox c1cc(Cl)ccc1C2SC(=O)N(C(=O)NC3CCCCC3)C2C 

57-43-2 Amobarbital CCC1(CCC(C)C)C(=O)NC(=O)NC1=O 
ECOSAR Class Definition: Diazoniums, Aromatic

The Diazoniums, Aromatic class is identified by the following structure: 

 Aromatic Ring [N+] N

An aromatic ring is attached to a charged nitrogen that is triple bonded to another 

nitrogen. The SMILES notation representing a diazonium function required by 

ECOSAR is either of the following: 

(1) [N+]#N ... as in c1ccccc1[N+]#N 

(2) N#N ... as in c1ccccc1N#N 

SMILES String Identifications: 

N#N 

[N+]#N 

 ... (requires aromatic attachment) 

Associated ECOSAR Class(s): 

Diazoniums - the Aromatic Ring attachment to the charged nitrogen atom is replaced by 

an aliphatic atom attachment. 

Azides - the Aromatic Ring attachment is replaced by a nitrogen double bonded to the 

charged nitrogen (which will no longer be charged). 

Example Diazoniums, Aromatic: 

CAS No. Name SMILES Notation 

6087-56-5 Benzenediazonium,4-(dimethylamino)- c1cc(N(C)C)ccc1[N+]#N 

52572-38-0 4-Diazo-2-methylpyrrolidinobenzene ZnCl N1(c2c(C)cc([N+]#N)cc2)CCCC1 
Diketones

The Diketones class is identified by the following structure: 

To be classified as Diketones by the current ECOSAR program, the structure must meet 

the following criteria: 

(1) The diketone fragment must be a 1,3-diketone. The two carbonyl groups must be 

separated by one carbon atom; this carbon atom must be an alkyl or olefinic carbon. 

The carbon atoms on the ends of the diketone fragment must be alkyl, olefinic, 

acetylenic or aromatic carbons. 

(2) The diketone fragment must be acyclic. The carbon atom in the middle cannot 

occur in a ring. 

SMILES String Identifications: 

CC(=O)CC(=O)C 

CC(=O)CC(=O)C=C 

CC(=O)CC(=O)C#C 

CC(=O)CC(=O)c ... (aromatic attachment) ... full ring: CC(=O)CC(=O)c1ccccc1 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

In addition to the Diketones class, the ECOSAR program will add any of the classes 

below to the to the program output if identified in a structure. 

Vinyl/Allyl Ketones - a ketone with a vinyl (-C=C) or allyl (-C-C=C) attachment to the 

carbonyl 

Benzyl Ketones - a ketone with -C-aromatic ring attachment to the carbonyl 

Halo Ketones (2 Free H) - a ketone with a -CH2-Halogen attachment to a carbon atom 

at the alpha- or beta-position to the carbonyl 

Halo Ketones (0-1 Free H) - a ketone with a -CH-Halogen (or -C-Halogen) attachment 

to a carbon atom at the alpha- or beta-position to the carbonyl 

Example Diketones: 

CAS No. Name SMILES Notation

123‐54‐6 2,4‐Pentanedione CC(=O)CC(=O)C

3002‐24‐2 2,4‐Hexanedione CC(=O)CC(=O)CC

69725‐37‐7 3,5‐Octanedione, 2,2,7‐trimethyl‐  O=C(C(C)(C)C)CC(=O)CC(C)C
ECOSAR Class Definition: Epoxides, Mono

The Epoxides, Mono class is identified by the following ring structure: 

 

O

ECOSAR identifies an Epoxide ring as follows: 

(1) a three member aliphatic ring consisting of one aliphatic oxygen and two aliphatic 

carbons 

(2) the carbon atoms cannot have double or triple bonds (excludes olefinic and 

acetylenic carbons or carbons with bonds such as C=N) 

(3) the Epoxide ring can be part of a fused-ring system 

To be classified as Epoxides, Mono, a structure must contain only one epoxide ring. 

SMILES String Identifications: 

O1CC1 ... equivalent to: C1OC1 or C(O1)C1 

Associated ECOSAR Class(s): 

Epoxides, Poly - if a structure contains two or more epoxide rings, it will be classified as 

Epoxides, Poly instead of Epoxides, Mono 

Epoxides, Mono Acid Substituted - contains one epoxide ring plus an acid function. 

Structures classified as Epoxides, Mono Acid Substituted are not additionally classified 

as Epoxides, Mono 

Halo Epoxides - structures containing an epoxide ring and a halogen attached directly to 

the ring or on an alkyl carbon attached to the ring). In the current ECOSAR program, 

structures identified as Halo Epoxides are not additionally classified as Epoxides, Mono. 

Example Epoxides, Mono: 

CAS No. Name SMILES Notation 

75-21-8 Ethylene oxide O1CC1 

3266-23-7 Oxirane, 2,3-dimethyl- O(C1C)C1C 

122-60-1 Phenyl glycidyl ether O1CC1COc2ccccc2 

72-20-8 Endrin ClC4=C(Cl)C5(Cl)C3C1CC(C2OC12)C3C4(Cl)C5(Cl)Cl 

 
ECOSAR Class Definition: Epoxides, Poly

The Epoxides, Poly class is identified by more than one occurence the following ring 

structure: 

 

O

ECOSAR identifies an Epoxide ring as follows: 

(1) a three member aliphatic ring consisting of one aliphatic oxygen and two aliphatic 

carbons 

(2) the carbon atoms cannot have double or triple bonds (excludes olefinic and 

acetylenic carbons or carbons with bonds such as C=N) 

(3) the Epoxide ring can be part of a fused-ring system 

To be classified as Epoxides, Poly, a structure must contain two or more epoxide rings. 

SMILES String Identifications: 

O1CC1 ... equivalent to: C1OC1 or C(O1)C1 

Associated ECOSAR Class(s): 

Epoxides, Mono - if a structure contains only one epoxide ring, it will be classified as 

Epoxides, Mono instead of Epoxides, Poly 

Epoxides, Mono Acid Substituted - contains one epoxide ring and an acid function 

Halo Epoxides - structures containing an epoxide ring and a halogen attached directly to 

the ring or on an alkyl carbon attached to the ring). In the current ECOSAR program, 

structures can be classified as both Halo Epoxides and Epoxides, Poly. 

Example Epoxides, Poly: 

CAS No. Name SMILES Notation 

3568-29-4 Glycerin, 1,3-diglycidyl ether O(C1COCC(O)COCC(O2)C2)C1 

54208-63-8 Bisphenol, diglycidyl ether O(C1COc(c(ccc2)Cc(c(OCC(O3)C3)ccc4)c4)c2)C1 

 
ECOSAR Class Definition: Esters

ECOSAR includes a variety of structures identified in the Esters class. The various 

structures identified as Esters are listed below. 

Esters (as Formic Acid Esters)

Formic acid and thioformic acid esters are identified by the following structures 

 H

C

O

O

C H

C

S

O

C

The carbon must be alkyl, olefinic, acetylenic or aromatic carbon. 

SMILES String Identifications: 

O=COC ... equivalent to: O=C(H)OC or O=C([H])OC 

O=CSC ... equivalent to: O=C(H)SC or O=C([H])SC 

 ... (the carbon must be alkyl, olefinic, acetylenic or aromatic): 

O=COC=C 

O=COC#C 

O=COc 

Esters (as Carboxylic Acid Esters)

Carboxylic acid esters and thiocarboxylic acid esters [-C(=O)-S-] are identified by the 

following structures: 

 R1

C

O

O

R2 R1

C

S

O

R2

R1 - must be alkyl, acetylenic, or aromatic carbon or a carbonyl;. 

R2 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included); 

silicon allowed if attached to oxygen. 

Notation: If R1 is olefinic (-C=C), ECOSAR will classify the structure as an Acrylate (or 

Methacrylate), and the Esters class will be excluded from the ECOSAR report. 

SMILES String Identifications: 

C(=O)O or C(=O)S 

 ... (attachments as defined above) 

Esters (as Carbonates and Thiocarbonates)

Carbonic acid esters are identified by the following structures: 
 O

C

O

O

R R S

C

S

O

R R

O

C

S

O

R R

R - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included); silicon 

allowed if attached to oxygen. 

SMILES String Identifications: 

OC(=O)O or SC(=O)S or OC(=O)S 

 ... (attachments as defined above)

Esters (as Carbamic Acid Esters)

Carbamic acid esters are identified by the following structures: 

 N

C

O

O

R R1

N

C

S

O

R R1

R1 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included); 

silicon allowed if attached to oxygen. 

R - attachments to the nitrogen can be anything 

Notation: ECOSAR will classify the structure as a Carbamate Ester or Thiocarbamate. 

SMILES String Identifications: 

NC(=O)O or NC(=O)S {equivalent to: N(H)(H)C(=O)O or N(H)(H)C(=O)S 

 ... (attachments as defined above) 

Esters (as Carbamimidic Acid Esters)

Carbamimidic acid esters are identified by the following structures: 

 N

C

O

NH

R1 R2

N

C

O

N

R2

R3

R1

R1 and R3 - can be anything (no exclusions). 

R2 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). 

SMILES String Identifications: 

NC(=N)O 

 ... (attachments as defined above) 
Esters (as Thioformic Acid Esters)

 H

C

O

S

R H

C

S

S

R

R - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). 

SMILES String Identifications: 

S=CO or S=CS {equivalent to: S=C(H)O or S=C(H)S 

 ... (attachments as defined above) 

Esters (as Thiocarboxylic Acid Esters)

 R1

C

O

S

R2 R1

C

S

S

R2

R1 - must be alkyl, acetylenic, or aromatic carbon or a carbonyl. 

R2 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). 

Notation: If R1 is olefinic (-C=C), ECOSAR will classify the structure as an Acrylate (or 

Methacrylate) in addition to the Esters class ... Note: this differs from the Carboxylic 

acid esters which are excluded from the ECOSAR report when Acrylates (or 

Methacrylates) are identified. 

SMILES String Identifications: 

C(=S)O or C(=S)S 

 ... (attachments as defined above) 

Esters (as Thiocarbamic Acid Esters)

Thiocarbamic acid esters are identified by the following structures: 

 H2N

C

O

S

R

H2N

C

S

S

R

R - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). 

Notation: the amine (-NH2) must be -NH2 ... if a hydrogen is substituted by a carbon, 

ECOSAR will classify the structure as a Thiocarbamate or Dithiocarbamate, and the 

Esters class will be excluded from the ECOSAR report. 

SMILES String Identifications: 

NC(=S)O or NC(=S)S {equivalent to: N(H)(H)C(=S)O or N(H)(H)C(=S)S 

 ... (attachments as defined above) 
Esters (as Thiocarbonates [C(=S)] )

Thiocarbonate acid esters are identified by the following structures: 

 O

C

O

S

R R S

C

S

S

R R

O

C

S

S

R R

R - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). In 

addition, R can be an aromatic nitrogen. 

Notation: the carbonate and thiocarbonate Esters (where the carbonyl is C(=O) instead 

of C(=S)), do not allow the R attachment to be an aromatic nitrogen. 

SMILES String Identifications: 

OC(=S)O or SC(=S)S or OC(=S)S 

 ... (attachments as defined above) 

Esters (as Phosphate-type)

Phosphate esters are identified by the following structures: 

 

O P R3

O

R2

R1 S P R3

O

R2

R4

R1 - can be alkyl carbon, olefinic carbon, acetylenic carbon, aromatic carbon, a 

carbonyl, phosphorus, sulfur, oxygen or nitrogen. 

R2 and R3 - can be anything except a hydroxy group (-OH). 

R4 - can be alkyl carbon, olefinic carbon, acetylenic carbon, aromatic carbon, or 

phosphorus 

Notation: Esters (Phosphates) are a separate ECOSAR class. When identified, 

ECOSAR reports both Esters and Esters (Phosphates). 

SMILES String Identifications: 

P(=O)O or P(=O)S 

 ... (attachments as defined above) 

Esters (as Thiophosphate-type)

Thiophosphate esters are identified by the following structure: 

 

S P R3

S

R2

R1
R1 - can be alkyl carbon, olefinic carbon, acetylenic carbon, aromatic carbon, or 

phosphorus. 

R2 and R3 - can be anything except oxygen. 

Notation: Esters, Monothiophosphates and Esters, Dithiophosphates are separate 

ECOSAR classes from Esters. When either of the two separate classes are identified 

ECOSAR excludes the Esters identification. 

SMILES String Identifications: 

P(=S)S 

 ... (attachments as defined above) 

Esters (as Sulfuric Acid or Sulfonate Esters)

Sulfonate and sulfuric acid esters are identified by the following structures: 

 

O S O

O

O

R1 R1 R2 S O

O

O

R1

R1 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). In 

addition, R1 can be silicon. 

R2 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). 

SMILES String Identifications: 

OS(=O)(=O)O or S(=O)(=O)O 

 ... (attachments as defined above) 

Associated ECOSAR Class(s): 

Other ester classes reported in conjunction with the Esters class by ECOSAR: 

Esters (Phosphates) 

Vinyl/Allyl Esters 

Ester classes that explicitly exclude the Esters class or ECOSAR generally does not 

report both if both are identified: 

 Carbamate Esters 

 Oxime Carbamate Esters 

 Thiocarbamates ... (includes a variety of Thiocarbamate classes ... depending 

on structure, ECOSAR may report both). 

 Beta-Halo Esters 

 Propargyl Carbamates 

 Acrylates 

 Methacrylates 

 Esters (imidic) 

 Esters, Monothiophosphates 

 Esters, (Phosphinates) 

 Esters, Dithiophosphates 
 

Example Esters: 

CAS No. Name SMILES Notation 

 Formates 

107-31-3 Methyl formate O=COC 

 Carboxylates 

141-78-6 Ethyl acetate CC(=O)OCC 

138-22-7 Butyl lactate O=C(OCCCC)C(O)C 

131-11-3 Dimethyl phthalate O=C(OC)c(c(ccc1)C(=O)OC)c1 

 Carbonates 

105-58-8 Diethyl carbonate O=C(OCC)OCC 

 Carbamic Acid Esters 

51-79-6 Carbamic acid, ethyl ester O=C(OCC)N 

 Carbamimidic Acid Esters 

64037-23-6 Benzoxazoline, 5-chloro-2-imino-3-methyl- c12N(C)C(=N)Oc1ccc(Cl)c2 

 Thioformic Acid Esters 

 O-Methyl thioformate S=COC 

 Thiocarboxylic Acid Esters 

2168-84-5 Methyl dithioacetate CC(=S)SC 

 Thiocarbonates 

822-38-8 1,3-Dithiolane-2-thione S(C(SC1)=S)C1 

 Phosphates 

78-40-0 Triethyl phosphate O=P(OCC)(OCC)OCC 

62-73-7 Dichlorvos O=P(OC)(OC)OC=C(Cl)Cl 

 Thiophosphates 

996-05-4 Phosphonotrithioic acid, methyl-,dipropyl CCCSP(=S)(C)SCCC 

 Sulfonates & Sulfuric acid esters 

62-50-0 Methanesulfonic acid, ethyl ester O=S(=O)(OCC)C 

515-46-8 Ethylbenzene sulfonate S(=O)(=O)(OCC)c(ccc1)cc1 

64-67-5 Sulfuric acid, diethyl ester O=S(=O)(OCC)OCC 
ECOSAR Class Definition: Esters, Dithiophosphates

The Esters, Dithiophosphates class is identified by the following structure: 

 

R1 P O

S

R3

S

R2

R1 - can be anything except sulfur (additional sulfurs change the “dithio” class 

identification). 

R2 - must be hydrogen, carbon (alkyl, olefinic, acetylenic, aromatic, or carbonyl) or 

phosphorus. 

R3 - must be hydrogen, carbon (alkyl, olefinic, acetylenic, aromatic, or carbonyl), 

nitrogen, oxygen, phosphorus, or sulfur. 

In the current ECOSAR program, the Esters, Dithiophosphates class meets the criteria 

as shown in the structures above. 

Notation: Currently, ECOSAR does not identify compounds having a structure such as 

P(=O)(S)(S) as a possible Dithiophosphate. 

SMILES String Identifications: 

S=P(S)O 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Esters, Monothiophosphates - contains the P(=S)-O- structure (only one sulfur bonded 

to the phosphorus). 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to exclude the Ester class 

when the Esters, Dithiophosphates class is reported. 

Other phosphorus esters classes in ECOSAR include Esters (Phosphates) and Esters 

(Phosphinates). 

Example Esters, Dithiophosphates: 

CAS No. Name SMILES Notation 

000060-51-5 Dimethoate O=C(NC)CSP(OC)(OC)=S 

121-75-5 Malathion CCOC(=O)CC(SP(=S)(OC)OC)C(=O)OCC 

298-04-4 Disulfoton CCOP(=S)(OCC)SCCSCC 

13071-79-9 Terbufos CCOP(=S)(OCC)SCSC(C)(C)C 
ECOSAR Class Definition: Esters, Monothiophosphates

The Esters, Monothiophosphates class is identified by the following structure: 

 

R1 P O

S

R3

R2

R1 and R2 - can be anything except sulfur (additional sulfurs change the “monothio” 

class identification). 

R3 - must be hydrogen, carbon (alkyl, olefinic, acetylenic, aromatic, or carbonyl), 

nitrogen, oxygen, phosphorus, or sulfur. 

In the current ECOSAR program, the Esters, Monothiophosphates class meets the 

criteria as shown in the structures above. 

Notation: Currently, ECOSAR does not identify compounds having a structure such as 

P(=O)S as a possible Monothiophosphate. 

SMILES String Identifications: 

S=P(O) 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Esters, Dithiophosphates - contains the P(=S)-S- structure. 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to exclude the Ester class 

when the Esters, Monothiophosphates class is reported. 

Other phosphorus esters classes in ECOSAR include Esters (Phosphates) and Esters 

(Phosphinates). 

Example Esters, Monothiophosphates: 

CAS No. Name SMILES Notation 

115-90-2 Fensulfothion CCOP(=S)(OCC)Oc1ccc(cc1)S(C)=O 

8000-97-3 Demeton S=P(OCC)(OCC)OCCSCC 

333-41-5 Diazinon O(P(OCC)(Oc(nc(nc1C)C(C)C)c1)=S)CC 

2921-88-2 Chlorpyrifos CCOP(=S)(OCC)Oc1nc(Cl)c(Cl)cc1Cl 

2104-64-5 EPN CCOP(=S)(Oc1ccc(cc1)N(=O)=O)c2ccccc2 
ECOSAR Class Definition: Esters, Phosphates

The Esters, Phosphates class is identified by the following structures: 

 

O P R3

O

R2

R1 S P R3

O

R2

R4

R1 - can be alkyl carbon, olefinic carbon, acetylenic carbon, aromatic carbon, a 

carbonyl, phosphorus, sulfur, oxygen or nitrogen. 

R2 and R3 - can be anything except a hydroxy group (-OH. 

R4 - can be alkyl carbon, olefinic carbon, acetylenic carbon, aromatic carbon, or 

phosphorus. 

In the current ECOSAR program, the Esters, Phosphates class meets the criteria as 

shown in the structures above. 

SMILES String Identifications: 

O=P(O) 

O=P(S) 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to report the Ester class 

whenever the Esters, Phosphates class is reported 

Other phosphorus esters classes in ECOSAR include Esters, Monothiophosphates, 

Esters (Phosphinates) and Esters, Dithiophosphates ... the Esters, Phosphates class 

structure is not identified when these classes are identified. 

Example Esters, Phosphates: 

CAS No. Name SMILES Notation 

512-56-1 Trimethyl phosphate O=P(OC)(OC)OC 

115-96-8 Tris(beta-chloroethyl)phosphate O=P(OCCCl)(OCCCl)OCCCl 

1080-32-6 Diethyl benzylphosphonate O=P(OCC)(OCC)Cc(cccc1)c1 

126-72-7 Tris(2,3-dibromopropyl)phosphate O=P(OCC(Br)CBr)(OCC(Br)CBr)OCC(Br)CBr
ECOSAR Class Definition: Esters (Phosphinates)

The Esters (Phosphinates) class is identified by the following structure: 

 

R1 P O

O

R2

Carbon

R1 - can be anything except oxygen. 

R2 - must be hydrogen, carbon (alkyl, olefinic, acetylenic, aromatic, or carbonyl), 

nitrogen, oxygen, phosphorus, or sulfur. 

Carbon - alkyl, olefinic, acetylenic, or aromatic carbon (not including carbonyl). 

In the current ECOSAR program, the Esters (Phosphinates) class meets the criteria as 

shown in the structure above. 

SMILES String Identifications: 

O=P(O)C 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to exclude the Ester class 

when the Esters (Phosphinates) class is reported. 

Other phosphorus esters classes in ECOSAR include Esters (Phosphates). 

Example Esters (Phosphinates): 

CAS No. Name SMILES Notation 

96-64-0 Soman CC(OP(C)(F)=O)C(C)(C)C 

107-44-8 Sarin CC(C)OP(C)(F)=O 

1224-64-2 Nibufin N(=O)(=O)c1ccc(OP(=O)(CCCC)CCCC)cc1

2511-09-3 Phosphinic acid,phenyl-,ethyl ester O=P(c1ccccc1)OCC 
Haloacetamide: The haloacetamide class is identified by the following structure: 

R1 and R2 - can be anything except a carbonyl group. 

If a carbonyl group is attached at R1 or R2, then ECOSAR will identify the class 

as imides 

In the current ECOSAR program, the haloacetamide structure must meet the following 

criteria: 

The carbonyl group has an aliphatic nitrogen and an alkyl carbon substituent, 

[NC(=O)C] and the alkyl carbon has one or more halogen substituents. 

Notation: Currently, if alkyl carbon has two or more fluorine attachments (and no other 

halogen attachments), the haloacetamide identification is not counted by ECOSAR. 

SMILES String Identifications: 

NC(=O)CBr 

NC(=O)CCl 

NC(=O)CF 

NC(=O)CI 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Example haloacetamide: 

CAS No. Name SMILES Notation 

683-72-7 Acetamide, 2,2-dichloro- O=C(N)C(Cl)Cl 

10222-01-2 Acetamide, 2,2-dibromo-2-cyano- O=C(N)C(C#N)(Br)Br 

15972-60-8 Alachlor CCc1cccc(CC)c1N(COC)C(=O)CCl 
ECOSAR Class Definition: Haloacids

The Haloacid class is identified by the following structures: 

C

C

OH

O

Halogen C

C

OH

O

Halogen

C

C

C

O

O

Halogen { Na, K, Li }

 

In the current ECOSAR program, the Haloacid structure meets the following: 

(1) a carboxylic acid function [-C(=O)-OH] is attached to an alkyl or olefinic carbon 

atom. 

(2) the alkyl or olefinic carbon atom has an attached halogen (bromine, chlorine, 

fluorine or iodine). 

(3) the hydrogen atom in the carboxylic acid function [-C(=O)-OH] can be substituted 

with a sodium, potassium or lithium atom. 

SMILES String Identifications: 

OC(=O)CCl or OC(=O)CBr or OC(=O)CF or OC(=O)CI 

OC(=O)C(Br)=C 

[Na]OC(=O)CBr 

 ... (halogen attachments can be Cl or Br or F or I)

Associated ECOSAR Class(s): 

None specifically. 

Example Haloacids: 

CAS No. Name SMILES Notation 

79-11-8 Monochloroacetic acid O=C(O)CCl 

76-03-9 Trichloroacetic acid O=C(O)C(Cl)(Cl)Cl 

75-99-0 2,2-Dichloropropionic acid O=C(O)C(Cl)(Cl)C 

127-20-9 Dalapon CC(Cl)(Cl)C(O[Na])=O 

 
ECOSAR Class Definition: Halo Alcohols

The Halo Alcohols class is identified by the following example structures: 

 HO

C

{Br,Cl,I} C

HO C

{Br,Cl,I} C

HO C

C {Br,Cl,I}

In the current ECOSAR program, the Halo Alcohols structure meets one of the following 

criteria: 

(1) a single alkyl carbon atom has both an hydroxy attachment (-OH) and a halogen 

attachment. For all criteria here halogens are limited to bromine, chlorine and iodine 

(fluorine is excluded). 

(2) an alkyl carbon is attached to another alkyl carbon (or olefinic carbon). The halogen 

and hydroxy (-OH) are on different carbons. A maximum of three carbon atoms can 

occur between the halogen and hydroxy (-OH). 

SMILES String Identifications: 

OCBr or OCCl or OCI 

OCCBr or OCCCl or OCCI 

OCCCBr or OCCCCl or OCCCI 

 ... initial OC equivalent to: HOC or [H]OC 

Associated ECOSAR Class(s): 

None specifically. 

ECOSAR includes a variety of other classes containing alcohol or halogens, but not in 

combination in the same class. 

Example Halo Alcohols: 

CAS No. Name SMILES Notation 

107-07-3 2-Chloroethanol OCCCl 

627-30-5 1-Propanol, 3-chloro- OCCCCl 

96-13-9 1-Propanol, 2,3-dibromo- OCC(Br)CBr 

115-20-8 Ethanol, 2,2,2-trichloro- OCC(Cl)(Cl)Cl 
Halo Epoxides

The Halo Epoxides class is identified by the occurrence following ring structure(s): 

ECOSAR identifies an Epoxide ring as follows: 

(1) a three member aliphatic ring consisting of one aliphatic oxygen and two aliphatic 

carbons 

(2) the carbon atoms cannot have double or triple bonds (excludes olefinic and 

acetylenic carbons or carbons with bonds such as C=N) 

(3) the Epoxide ring can be part of a fused-ring system 

In addition to one or more epoxide rings, to be classified as Halo Epoxides, a structure 

must contain: a halogen atom (Br, Cl, F, I) attached directly to an epoxide ring or a 

halogen atom (Br, Cl, F, I) attached to an alkyl carbon that is attached directly to an 

epoxide ring. Halogen atoms further removed from the epoxide ring are not currently 

included in the Halo Epoxide identification. 

SMILES String Identifications: 

O1CC1Br or O1CC1Cl or O1CC1F or O1CC1I 

O1CC1CBr or O1CC1CCl or O1CC1CF or O1CC1CI 

Associated ECOSAR Class(s): 

Epoxides, Mono - - if a structure contains one epoxide rings and no acid function, it will 

be classified as Epoxides, Mono. In the current ECOSAR program, a structure 

classified as Halo Epoxides cannot be additionally classified as Epoxides, Mono. 

Epoxides, Mono Acid Substituted - contains one epoxide ring and an acid function. In 

the current ECOSAR program, a structure classified as Halo Epoxides cannot be 

additionally classified as Epoxides, Mono Acid Subsituted. 

Epoxides, Poly - if a structure contains two or more epoxide rings, it will be classified as 

Epoxides. In the current ECOSAR program, a structure can be classified as both Halo 

Epoxides and Epoxides, Poly 

Example Halo Epoxides: 

CAS No. Name SMILES Notation

106‐89‐8 Epichlorohydrin O(C1CCl)C1

3132‐64‐7 Epibromohydrin O(C1CBr)C1
ECOSAR Class Definition: Halo Esters

The Halo Esters class is identified by the following structures: 

 C

C

O

O

Halogen R C

O

O

R

Halogen

R - must be alkyl, oelfinic, acetylenic or aromatic carbon (carbonyl not included). 

Halogen - bromine (Br), chlorine (Cl), fluorine (F) or iodine (I). 

In the current ECOSAR program, the Halo Esters class meets the criteria as shown in 

the structure above and the following: 

(1) the carbon atom (to which the Halogen is attached) must be an alkyl carbon (an 

olefinic carbon not currently allowed). The halogen can be in either the alpha- or betapositions where the alpha-position is direct attachment to the carbonyl. 

(2) Fluorine was previously excluded, but is now included in this class. 

SMILES String Identifications: 

OC(=O)CBr or OC(=O)CCl or OC(=O)CI or OC(=O)F 

OC(=O)Br or OC(=O)Cl or OC(=O)CI or OC(=O)F 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to exclude the Ester class 

when the Halo Esters class is reported. 

Acid Halides - the Acid Halides class includes any structure with C(=O)-Halogen; 

ECOSAR reports both classes when present in a structure. 

Example Halo Esters: 

CAS No. Name SMILES Notation 

14064-10-9 Diethyl chloromalonate O=C(OCC)C(C(=O)OCC)Cl 

105-39-5 Acetic acid, chloro-, ethyl ester O=C(OCC)CCl 

599-99-5 Tribromoacetic acid, ethyl ester BrC(Br)(Br)C(=O)OCC 

356-24-1 Butanoic acid, heptafluoro-, methyl ester O=C(OC)C(F)(F)C(F)(F)C(F)(F)F 

623-48-3 Acetic acid, iodo-, ethyl ester O=C(OCC)CI 
ECOSAR Class Definition: Halo Ethers 

The Halo Ethers class is identified by the following structures: 

 C

O

C

Halogen C

O

C

C

Halogen

The ether function is identified as an aliphatic oxygen attached to two carbons atoms 

(alkyl, olefinic, acetylenic or aromatic carbon). 

Note: The oxygen may not be contained within a 3 member ring. If so, ECOSAR will 

classify that chemical as a halo epoxide 

In the current ECOSAR program, the Halo Ether structure must meet one of the 

following criteria: 

(1) an alkyl carbon of an ether function has a halogen attachment (Br, Cl, F or I). 

(2) an alkyl carbon (that is attached to an alkyl carbon of an ether function) has a 

halogen attachment (Br, Cl, F or I). 

In the current ECOSAR program, the halogen can be in either the alpha- or betaposition. 

SMILES String Identifications: 

COCBr or COCCl or COCF or COCI 

COCCBr or COCCCl or COCCF or COCCI 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

None specifically. 

The ether function also occurs in the Vinyl/Allyl Ether class. 

Example Halo Ethers: 

CAS No. Name SMILES Notation 

3188-13-4 Chloromethyl ethyl ether CCOCCl 

111-44-4 Bis(2-chloroethyl)ether O(CCCl)CCCl 

34723-82-5 (2-Bromomethyl)-tetrahaydropyran BrCC1CCCCO1 

ECOSAR Class Definition: Haloimides

The Haloimides class is identified by the following structure:

 

N

[S or N] O

R

1

R

2

O [S or N]

R

3

R1 or R3 can be anything (no exclusions). 

Please note that in the parent imide class R1 and R3 can not be a nitrogen atom, 

otherwise ECOSAR will identify the class as carbonyl ureas. But for this class 

there are many training set chemicals containing a nitrogen atom with a halogen 

attachment in the R1 or R3 position, and all are much more toxic to fish and 

daphnid than the carbonyl urea estimates. It appears these halogen attachments 

are driving toxicity. Therefore we are not excluding these attachments so that 

the haloimides estimates will be provided displaying more accurate toxicity 

estimates based on analogs. 

R2 - must be a Cl, Br, I or F

Haloimides class does not currently have acute or chronic QSARs for Green Algae. 

However, based on the fact that associated chemicals are used as herbicides, toxicity to 

green algae is expected to be significant.

In the current ECOSAR program, the Haloimides structure must meet the following 

criteria:

Notation: Currently, the halogen must be attached to the nitrogen.

SMILES String Identifications:

Haloimide Group:

 C(=O)N(Cl, Br, or I)C(=O)

 C(=S)N(Cl, Br, or I)C(=S)

 C(=N)N(Cl, Br, or I)C(=N) ... equivalent to: C(=NH)NC(=NH)

 ... (or any combination of the various carbonyl-types)

 ... (attachments as defined above)

Example Haloimides:

CAS No. Name SMILES Notation

77-48-5 2,4-Imidazolidinedione, 1,3-dibromo-5,5-dimethyl- O=C(N(C(C1(=O))(C)C)Br)N1Br

118-52-5 1,3-Dichloro-5,5-dimethylhydantoin O=C(N(C(C1(=O))(C)C)Cl)N1Cl

126-06-7 3-Bromo-1-chloro-5,5-dimethylhydantoin O=C(N(C(C1(=O))(C)C)Cl)N1Br
ECOSAR Class Definition: Halo Ketones (2 Free Hydrogens) 

Halo Ketones (2 Free H) are identified by the following structures: 

 C CH2

Halogen

O

C C

O

CH2 Halogen

To be classified as Halo Ketones (2 Free H) by the current ECOSAR program, the 

structure must meet the following criteria: 

(1) The basic ketone fragment is identified as a carbonyl group attached to carbon 

atoms on both sides where the carbon atoms must be an alkyl, olefinic, acetylenic or 

aromatic carbon. 

To be classified as Halo Ketones (2 Free H), the Halogen atom (bromine, chlorine, 

fluorine or iodine) must be attached at an alpha- or beta-position carbon to the carbonyl. 

In addition, the Halogen must be attached to a CH2 alkyl carbon (two free hydrogens on 

the alkyl carbon). 

SMILES String Identifications: 

CC(=O)CBr or CC(=O)CCl or CC(=O)CF or CC(=O)CI 

CC(=O)CCBr or CC(=O)CCCl or CC(=O)CCF or CC(=O)CCI 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

In addition to the Halo Ketones (2 Free H) class, the ECOSAR program will add any of 

the classes below to the to the program output if identified in a structure. 

Diketones - Diketones have two ketone functions at 1,3-positions. A structure can be 

classified as both Diketones and Benzyl Ketones (e.g. SMILES: 

c1ccccc1CC(=O)CC(=O)CC). 

Vinyl/Allyl Ketones - a ketone with a vinyl (-C=C) or allyl (-C-C=C) attachment to the 

carbonyl 

Benzyl Ketones - a ketone with -C-aromatic ring attachment to the carbonyl 

Example Halo Ketones (2 Free H): 

CAS No. Name SMILES Notation 

1204-21-3 Bromomethyl-2,5-dimethoxyphenyl ketone COc1ccc(OC)c(c1)C(=O)CBr 

78-95-5 2-Propanone, 1-chloro- O=C(CCl)C 
Halo Nitriles

The Halo Nitriles class is identified by the following structures: 

In the current ECOSAR program, the Halo Nitriles structure meets the following criteria: 

(1) A nitrile group (carbon triple-bonded to nitrogen; SMILES of C#N) is attached to an 

alkyl carbon. 

(2) An alkyl carbon in the alpha- or beta-position to the nitrile has one (or more) 

halogen attachments (bromine, chlorine, fluorine or iodine). 

(3) The alkyl carbons (alpha- or beta-position) can have other attachments (no current 

exclusions). 

Notations: Halogens attached to olefinic, acetylenic or aromatic carbons are not

currently included in the class identification. Halogens further removed from a nitrile 

group are not included (further than alpha- or beta-position). 

SMILES String Identifications: 

BrCC#N or ClCC#N or FCC#N or ICC#N 

BrCCC#N or ClCCC#N or FCCC#N or ICCC#N 

Associated ECOSAR Class(s): 

None specifically. 

Other SAR Nitrile classes include: Azonitriles, Nitrile Esters, Nitrile Alpha-OH, 

Phthalonitriles, Vinyl/Allyl Nitriles, and Nitriles, Polyaliphatic. 

Example Halo Nitriles: 

CAS No. Name SMILES Notation 

107-14-2 Acetonitrile, chloro- N#CCCl 

3252-43-5 Acetonitrile, dibromo- N#CC(Br)Br 

375-00-8 Butanenitrile, heptafluoro- N#CC(F)(F)C(F)(F)C(F)(F)F 
Halo Pyridines

The Halo Pyridines class is identified by the following structure: 

In the current ECOSAR program, the Halo Pyridines structure identification meets the 

following criteria: 

(1) The ECOSAR program identifies a six-member aromatic ring containing five carbon 

atoms and one nitrogen atom (a pyridine ring). 

 (2) The aromatic carbon atoms on the pyridine ring have one or more halogen 

attachments (halogens include bromine, chlorine, fluorine or iodine). 

 (3) The pyridine ring can be fused to additional ring(s). 

SMILES String Identifications: 

n1ccccc1Br 

n1ccccc1Cl 

n1ccccc1F 

n1ccccc1I 

 ... (the halogen can be attached to any of the aromatic carbons)

Associated ECOSAR Class(s): 

Other ECOSAR classes specifically containing a Pyridine ring: 

Pyridine-alpha-Acid - a carboxylic acid group (-C(=O)-OH) is attached to the pyridine 

ring in an ortho-position to the nitrogen atom. A structure can be classified as both a 

Pyridine-alpha-Acid and a Halo Pyridine. 

Notation: the Pyridine Thiones class does not contain an aromatic pyridine ring (the 

ring is an aliphatic thione ring with C(=S) as part of the ring). 

Examples Halo Pyridines: 

CAS No. Name SMILES Notation

109‐09‐1 2‐Chloropyridine n1ccccc1Cl

626‐55‐1 3‐Bromopyridine n1cccc(Br)c1

1929‐82‐4 Pyridine, 2‐chloro‐6‐(trichloromethyl)‐  n(c(ccc1)C(Cl)(Cl)Cl)c1Cl

2176‐62‐7 Pyridine, pentachloro‐  n(c(c(c(c1Cl)Cl)Cl)Cl)c1Cl
ECOSAR Class Definition: Hydrazines 

ECOSAR currently identifies several different types of structures as Hydrazines which 

are described separately below. 

Common Hydrazines: 

 

N N

R1

R2 R4

R3

Common hydrazines are identified by two aliphatic nitrogen atoms attached with a 

single-bond. At least one of the R1, R2, R3 or R4 substituents muct be an alkyl, 

olefinic, acetylentic or aromatic carbon. 

Notation: In the current ECOSAR program, the R1, R2, R3 and R4 substituents can be 

anything. 

SMILES String Identifications: 

NN 

 ... (attachments as defined above)

Hydrazones as Hydrazines: 

 C N N C C N N R

The R substituent can be anything. 

SMILES String Identifications: 

C=NN=C 

C=NN 

 ... (attachments as defined above)

Hydrazides, Semicarbazides and Thiosemicarbazides as Hydrazines: 

 C N N R

O

C N N R

S

C N N C

O

The R substituent can be anything. ECOSAR identifies various hydrazides, 

carbazides and carbazones as Hydrazines. 

SMILES String Identifications: 

C(=O)NN 

C(=S)NN 
C(=O)NN=C 

 ... (attachments as defined above) 

Notation: Azo Structures as Hydrazines: 

 R1 N N R2

In ECOSAR versions prior to v1.10, the linear azo structure was identified as a 

Hydrazine. However, this azo structure is no longer identified as an ECOSAR 

Hydrazine. 

Previously Associated ECOSAR Class(s): 

Semicarbazide (Aryl-Ortho), Semicarbazide (Aryl-Meta/Para), Semicarbazide (Akyl) - 

identified by N-N-C(=O)-N-R ... These previously identified classes (but no longer 

identified ECOSAR classes) do not have SAR equations. The Hydrazine class is 

identified and used by ECOSAR. 

Example Hydrazines: 

CAS No. Name SMILES Notation 

302-01-2 Hydrazine NN 

57-14-7 1,1-Dimethylhydrazine NN(C)C 

122-66-7 Hydrazine, 1,2-diphenyl- N(Nc(cccc1)c1)c(cccc2)c2 

79-19-6 Thiosemicarbazide NC(=S)NN 

54-85-3 Isoniazid NNC(=O)c1ccncc1 

537-47-3 4-Phenylsemicarbazide c1ccccc1NC(=O)NN 
ECOSAR Class Definition: Hydroquinones

The Hydroquinones class is identified by the following example structures: 

 OH

OH

In the current ECOSAR program, a hydroquinone is a six-member aromatic ring 

(benzene or any other aromatic ring including hetero-aromatic rings) that has hydroxyl 

groups [-OH] in para-position. The aromatic ring can be fused to another ring. 

SMILES String Identifications: 

Oc1ccc(O)cc1 

Associated ECOSAR Class(s): 

Quinone – Under environmental conditions, a reversible reduction-oxidation (redox) 

change from hydroquinone to semiquinone and to quinone may occur. 

Phenols, Poly - the hydroquinone identification is a more toxic sub-class of the Phenols, 

Poly class. ECOSAR reports both classes. 

Example Hydroquinones: 

CAS No. Name SMILES Notation 

123-31-9 1,4-Hydroquinone Oc1ccc(O)cc1 

58-27-5 2-Methyl-1,4-hydroquinone Oc1cc(C)c(O)cc1 
ECOSAR Class Definition: Imidazoles

The Imidazoles class is identified by the following structure: 

 

N

N

In the current ECOSAR program, the Imidazoles structure must meet the following 

criteria: 

(1) The Imidazole ring is a five-member aromatic ring with nitrogen atoms at the 1- and 

3-positions. The 1-position is [NH] if unsubstituted, but the hydrogen can be replaced 

by another substituent. 

 (2) The imidazole ring can be fused to another ring (e.g. Benzimidazole) 

SMILES String Identifications: 

[nH]1cncc1 

n1cncc1 

c1ncnc1 

c(n1)cnc1 

N1C=NC=C1 

Associated ECOSAR Class(s): 

None specifically. However, ECOSAR includes other “ring structure” classes such as 

Triazines, Benzotriazoles, Triazoles, Triazole Pyrimidines and Thiazole, Benzo. 

Examples Imidazoles: 

CAS No. Name SMILES Notation 

288-32-4 1H-Imidazole N1C=NC=C1 

51-17-2 1H-Benzimidazole n(c(c(n1)ccc2)c2)c1 

58-08-2 Caffeine CN1C(=O)N(C)c2ncn(C)c2C1(=O) 

693-98-1 2-Methylimidazole N(C=CN1)=C1C 

2034-22-2 2,4,5-Tribromoimidazole BrC1=NC(Br)=C(Br)N1 
ECOSAR Class Definition: Imides 

The Imides class is identified by the following example structures: 

 

N

[S or N] O

R1

R2

O [S or N]

R3

R1 and R3 can be anything except a nitrogen atom. 

If R1 or R3 are a nitrogen atoms, ECOSAR will identify the class as carbonyl 

ureas. 

Note that If R1 or R3 are an oxygen atoms, ECOSAR will also identify the 

class as carbamate, esters. At this time substitution of the oxygen atom is 

not being excluded because we do not have supporting evidence 

indicating which class has higher toxicity potential or if any chemicals 

actually contain a hybrid of both functional groups. 

R2 can be anything except a halogen atom or a [C-aromatic] group: 

If R2 is a halogen attachment, ECOSAR will identify the class as haloimides 

If R2 is a [C-aromatic] group, ECOSAR will identify the class as benzyl imides. A 

strict definition of “benzyl” implies the single alkyl carbon is a -CH2- group and 

the aromatic ring is a benzene ring. However, in the current ECOSAR program, 

the single alkyl carbon can be -CH2-, -CH< or >C< and the aromatic ring can be 

any aromatic ring including hetero-aromatic rings. 

The oxygen in the carbonyl(s) could be replaced by sulfur or NH. The structure can 

have any combination of C=O, C=S or C=NH as long as the nitrogen has two such 

attachments. 

SMILES String Identifications: 

Imide Group: 

 C(=O)NC(=O) 

 C(=S)NC(=S) 

 C(=N)NC(=N) ... equivalent to: C(=NH)NC(=NH) 

 ... (or any combination of the various carbonyl-types)

 ... (attachments as defined above)

Example Imides: 

CAS No. Name SMILES Notation 

123-56-8 Succinimide O=C(NC(=O)C1)C1 
ECOSAR Class Definition: Thiazolones (Iso) or Isothiazolones

The Isothiazolone class is identified by the following structures: 

 

N

S

C

O

S

N

C

O

N S

C

O

In the current ECOSAR program, the Isothiazolone structure meets the following 

criteria: 

(1) a five-member ring containing one carbonyl, one aliphatic sulfur, one aliphatic 

nitrogen and two carbon atoms. The two carbon atoms can be aromatic if the 

isothiazolone ring is fused to an aromatic ring. If there are no aromatic carbon atoms in 

the ring, the ring has one double bond. 

(2) the sulfur and nitrogen atoms in the ring are adjacent to each other. 

(3) The atoms in the ring can have other attachments (no exclusions). 

SMILES String Identifications: 

O=C 1NSC=C1 

O=C1SNC=C1 

O-C1C=NSC1 

Associated ECOSAR Class(s): 

None specifically. 

The Thiazolidinone class ring also contains a carbonyl, one sulfur, one nitrogen and two 

carbon atoms, but in a different order. 

Example Isothiazolones: 

CAS No. Name SMILES Notation 

26530-20-1 3(2H)-Isothiazolone, 2-octyl- O=C1C=CSN1CCCCCCCC 

2682-20-4 3(2H)-Isothiazolone, 2-methyl- S1N(C)C(=O)C=C1 
ECOSAR Class Definition: Ketone Alcohols (or a-,b-Ketone Alcohol) 

The Ketone Alcohols class is identified by the following structures: 

 C

C

C

O

OH

C

C

C

O

C

OH

To be classified as Ketone Alcohols by the current ECOSAR program, the structure 

must meet the following criteria: 

(1) The basic ketone fragment is identified as a carbonyl group attached to carbon 

atoms on both sides where the carbon atoms must be an alkyl, olefinic, acetylenic or 

aromatic carbon. 

(2) An hydroxy group (-OH) is attached to an alkyl carbon at an alpha- or beta-position 

to the ketone carbonyl. 

SMILES String Identifications: 

CC(=O)CO ... equivalent to: CC(=O)COH or CC(=O)CO[H] 

CC(=O)CCO ... equivalent to: CC(=O)CCOH or CC(=O)CCO[H] 

Associated ECOSAR Class(s): 

Diketones - Diketones have two ketone functions at 1,3-positions. A structure can be 

classified as both Diketones and Benzyl Ketones (e.g. SMILES: 

c1ccccc1CC(=O)CC(=O)CC). 

Vinyl/Allyl Ketones - a ketone with a vinyl (-C=C) or allyl (-C-C=C) attachment to the 

carbonyl 

Benzyl Ketones - a ketone with -C-aromatic ring attachment to the carbonyl 

Halo Ketones (2 Free H) - a ketone with a -CH2-Halogen attachment to a carbon atom 

at the alpha- or beta-position to the carbonyl 

Example Ketone Alcohols: 

CAS No. Name SMILES Notation 

123-42-2 

2-Pentanone, 4-hydroxy-4-

methyl- O=C(CC(O)(C)C)C 

50-02-2 Dexamethasone 

C1(=O)C=C2CCC3C4CC(C)C(O)(C(=O)CO)C4(C)CC(O)C3(F)

C2(C)C=C1 

50-22-6 Corticosterone CC34CC(O)C1C(CCC2=CC(=O)CCC12C)C3CCC4C(=O)CO 

96-26-4 

2-Propanone, 1,3-

dihydroxy- O=C(CO)CO 
ECOSAR Class Definition: Malonitriles

The Malonitrile class is characterized by the following structure: 

 

C

N

C

C

N

C

N

C

C

N

C

In the current ECOSAR program, the Malonitrile structure must have two or more nitrile 

groups (carbon triple-bonded to nitrogen; SMILES of C#N) attached to a single carbon 

in the structure. The carbon must be either an alkyl or olefinic carbon. 

SMILES String Identifications: 

N#CCC#N 

C=C(C#N)C#N 

Associated ECOSAR Class(s): 

Nitrile, Polyaliphatic - Malonitriles are a more toxic sub-class of the Nitriles, 

Polyaliphatic. In the Polyaliphatic, Nitriles class, the two or more cyano groups do not

need to be attached to the same carbon. ECOSAR reports both classes when 

identified. 

Vinyl/Allyl Nitriles - basically, a vinyl (-C=C) or allyl group (-C-C=C) is attached to one 

or more nitriles groups. When two or more nitrile groups are attached to the same alkyl 

or olefinic carbon, the structure will be classified as a Vinyl/Allyl Nitriles and either a 

Nitriles, Polyaliphatic or a Malonitriles. 

Other SAR Nitrile classes include: Azonitriles, Halo Nitriles, Nitrile Esters, Nitrile AlphaOH, and Phthalonitriles. 

Example Malonitriles: 

CAS No. Name SMILES Notation 

2698-41-1 O-Chlorobenzylidene malononitrile N#CC(C#N)=Cc(c(ccc1)Cl)c1 

109-77-3 Malononitrile C(#N)CC(#N) 
Melamines 

The Melamines class is identified by the following structure: 

R1, R2 and R3 - can be hydrogen or any other single-bonded atom. 

In the current ECOSAR program, the Melamine structure must meet the following 

criteria: 

(1) A six-member aromatic ring with three nitrogen atoms in sym-positions. The three 

carbon atoms have aliphatic nitrogen subsitiuents as either -NH2 or -NH- (the aliphatic 

nitrogen must have at least one hydrogen). 

Associated ECOSAR Class(s): 

Anilines (amino-meta) - this class currently allows hetero-aromatic rings. Amino 

substituents in the meta-position (as Melamines allows) are additionally classified by 

ECOSAR as Anilines (amino-meta). 

Example Melamines: 

CAS No. Name SMILES Notation 

108-78-1 Melamine Nc1nc(N)nc(N)n1 

2827-46-5 2,4,6-Trimethylmelamine n1c(NC)nc(NC)nc1NC 

66215-27-8 Cyromazine n1c(N)nc(N)nc1NC2CC2 
ECOSAR Class Definition: Methacrylates

The Methacrylates class is identified by the following structures: 

 

C

C

{O,S}

O

C R2

CH3

C

C

{O,S}

S

C R2

CH3

R2 - attachment must be either an alkyl carbon, olefinic carbon, acetylenic carbon or 

aromatic carbon. 

{O,S} - can be either oxygen (-O-) or sulfur (-S-) 

Internally, the ECOSAR program initially detects a carbonyl function [C(=O)] or a 

thiocarbonyl function [C(=S)] with one olefinic attachment and one oxygen or sulfur 

attachment. The olefinic carbon attached to the carbonyl (or thiocarbonyl) must have a 

methyl (CH3) attachment (anything other than a methyl group (CH3) changes the 

classification from a Methacrylate to an Acrylate. The oxygen or sulfur must have either 

an alkyl carbon, olefinic carbon, acetylenic carbon or aromatic carbon attachment to be 

classified as either a Methacrylate or Acrylate. 

SMILES String Identifications: 

C=C(C)C(=O)O ... equivalent to: C=C(C(H)(H)H)C(=O)O 

C=C(C)C(=O)S 

C=C(C)C(=S)O 

C=C(C)C(=S)S 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Acrylates - The olefinic carbon attached to the carbonyl (or thiocarbonyl) must have a 

methyl (CH3) attachment (anything other than a methyl group (CH3) changes the 

classification from a Methacrylate to an Acrylate. 

Thiomethacrylates - Thiomethacrylates are methacrylates with having a thiocarbonyl or 

a sulfur attached to the carbonyl function. In the current ECOSAR program, structures 

classified as Thiomethacrylates are also classified as Methacrylates. 

Example Methacrylates: 

CAS No. Name SMILES Notation 

80-62-6 Methyl methacrylate C=C(C)C(=O)OC 

96-05-9 Allyl methacrylate C=C(C)C(=O)OCC=C 

2495-37-6 Benzyl methacrylate C=C(C)C(=O)OCc1ccccc1 
 O-Methyl thiomethacrylate C=C(C)C(=S)OC 

 S-Methyl thiomethacrylate C=C(C)C(=O)SC 

 

 
ECOSAR Class Definition: Neonicotinoids

Neonicotinoids act as agonists of the nicotinic acetylcholine receptor (nAChR) in a 

similar mechanism as nicotinoids; however, the presence of a electronegative nitro or 

cyano group attached to the aliphatic nitrogen in neonicotinoids alters the binding 

potential compared to nicotinoids and results in varied toxicity in mammals and insects 

(Tomizawa & Casida, 2003). Although toxicity of nicotinoids and neonicotinoids in 

aquatic organisms appear to differ based on a few available data points, insufficient 

information and data are available for aquatic organisms to make any firm conclusions. 

Additional uncertainties include the effect a halogen substitution has on the pyridine 

ring. Thus, further research is needed to confirm the separate classification of 

nicotinoids and neonicotinoids for aquatic toxicity. 

Neonicotinoids are identified by the following structures: 

N

N

R

N

N

R

N

N

R

N N

R

R = an electronegative nitro or cyano group (e.g., -C=NC#N or -C=NT). 

In the current ECOSAR program, the Neonicotinoids class meets the criteria as shown 

in the structure above. Substitutions on the pyridine or pyrrole ring are allowed. 

SMILES String Identifications: 

Associated ECOSAR Class(s): 

Nicotinoids: Are neonicotinoids without an electronegative nitro or cyano substitution on 

the aliphatic nitrogen. 

Example Neonicotinoids: 

CAS No. Name SMILES Notation 

138261-41-3 Imidacloprid c1cc(Cl)ncc1CN2CCNC2=NT 

210880-92-5 Clothianidin c1nc(Cl)sc1CNC(=NT)NC 

153719-23-4 Thiamethoxam c1nc(Cl)sc1CN2C(=NT)N(C)COC2 

135410-20-7 Acetamiprid c1cc(Cl)ncc1cn(C)C(C)=NC#N 

111988-49-9 Thiacloprid c1cc(Cl)ncc1CN2C(=NC#N)SCC2 

 

References: 

Tomizawa M., Casida J.E. 2003. Selective toxicity of neonicotinoids attributable to 

specificity of insect and mammalian nicotinic receptors. Annu. Rev. Entomol., 48:339-

64. 
ECOSAR Class Definition: Nereistoxin Analogues

The Nereistoxin Analogues class is identified by the following sub-structure: 

 

N

S S

In the current ECOSAR program, the Nereistoxin Analogues structure meets the 

following criteria: 

(1) The structure as depicted above. The nitrogen cannot be aromatic. 

(2) Attachments to the thiol can be anything including hydrogen, sulfur, or carbons 

(alkyl, olefinic or acetylenic). 

SMILES String Identifications: 

CN(C)C(CS)CS 

 

(attachments as defined above)

Associated ECOSAR Class(s): 

Aliphatic Amines – Nitrogens with aliphatic carbon attachments (alkyl, olefinic or 

acetylenic carbon). 

Thiols & Mercaptans - A thiol-mercaptan function (-SH) attached to an alkyl, olefinic, 

acetylenic or aromatic carbon atom. 

Example Nereistoxin Analogues: 

CAS No. Name SMILES Notation 

15263-53-3 Cartap CN(C)C(CSC(=O)N)CSC(=O)N

31895-21-3 Thiocyclam C1SSSCC1N(C)C 
ECOSAR Class Definition: Neutral Organics

The following types of example classes are represented by the neutral organics class 

which assumes a simple non-polar narcosis mechanism of action for solvents and nonreactive, non-ionizable organic compounds

1. Alcohols

2. Acetals

3. Ketones

4. Ethers

5. Alkyl halides

6. Aryl halides

7. Aromatic hydrocarbons

8. Halogenated aromatic hydrocarbons

9. Halogenated aliphatic hydrocarbons

10. Sulfides and di-sulfides

11. Sulfoxides and sulfones

Please note: If there are no positive identifications of any other associated SAR 

classes for the query chemical, ECOSAR reports the structure as a Neutral Organic 

(regardless of what chemical functions may occur in the structure). When this occurs, 

the user will be promoted with the following flag:

Example Neutral Organics from the SAR Sheet:

CAS No. Name SMILES Notation

112-27-6 Triethylene glycol O(CCOCCO)CCO

67-68-5 Dimethyl sulfoxide CS(=O)C

67-64-1 Acetone O=C(C)C

110-86-1 Pyridine n1ccccc1

60-29-7 Diethyl ether CCOCC

110-00-9 Furan O1C=CC=C1

71-43-2 Benzene c1ccccc1

100-61-8 N-Methylaniline CNc1ccccc1

ECOSAR Class Definition: Nicotinoids

Nicotinoids act as agonists of the nicotinic acetylcholine receptor (nAChR) in a similar 

mechanism as neonicotinoids; however, the absence of a electronegative nitro or cyano 

group attached to the aliphatic nitrogen in nicotinoids alters the binding potential 

compared to neonicotinoids and results in varied toxicity in mammals and insects 

(Tomizawa & Casida, 2003). Although toxicity of nicotinoids and neonicotinoids in 

aquatic organisms appear to differ based on a few available data points, insufficient 

information and data are available for aquatic organisms to make any firm conclusions. 

Additional uncertainties include the affect a halogen substitution has on the pyridine 

ring. Thus, further research is needed to confirm the separate classification of 

nicotinoids and neonicotinoids for aquatic toxicity. 

Nicotines are identified by the following structures: 

N

N

N

N

N

N N N

In the current ECOSAR program, the Nicotinoids class meets the criteria as shown in 

the structure above. Substitutions on the pyridine or pyrrole ring are allowed. 

SMILES String Identifications: 

Associated ECOSAR Class(s): 

Neonicotinoids: A sub-classification of nicotinoids with a substitution of an 

electronegative cyano or nitro group on the aliphatic nitrogen. 

Example Nicotines: 

CAS No. Name SMILES Notation 

140111-52-0 Epibatidine c1cc(Cl)ncc1C2C3NC(CC3)C2 

54-11-5 Nicotine c1ccncc1C2N(C)CCC2 

525-74-6 Dihydronicotyrine c1ccncc1C2=CCCN2C 

494-52-0 Anabasine c1ccncc1C2NCCCC2 

494-97-3 Nornicotine c1ccncc1C2NCCC2 

 

References: 

Tomizawa M., Casida J.E. 2003. Selective toxicity of neonicotinoids attributable to 

specificity of insect and mammalian nicotinic receptors. Annu. Rev. Entomol., 48:339-

64. 
ECOSAR Class Definition: Nitrile Alpha-OH

The Nitrile Alpha-OH class is identified by the following structures: 

 

C

C N

OH

C

C C N

OH

In the current ECOSAR program, the Nitrile Alpha-OH structure meets the following 

criteria: 

(1) A nitrile group (carbon triple-bonded to nitrogen; SMILES of C#N) is attached to an 

alkyl or olefinic carbon. In addition, an hydroxyl group (-OH) is attached to the same 

alkyl or olefinic carbon. 

(2) The alkyl carbon can have other attachments (no current exclusions). 

SMILES String Identifications: 

C(O)C#N ... equivalent to: C(OH)C#N or C(O[H])C#N 

C=C(O)C#N ... equivalent to: C=C(OH)C#N or C=C(O[H])C#N 

 ... (attachment as defined above)

Associated ECOSAR Class(s): 

None specifically. 

Other SAR Nitrile classes include: Azonitriles, Nitrile Esters, Halo Nitriles, 

Phthalonitriles, Vinyl/Allyl Nitriles, and Nitriles, Polyaliphatic. 

Example Nitrile Alpha-OH: 

CAS No. Name SMILES Notation 

78-97-7 Lactonitrile N#CC(O)C 

75-86-5 Acetone Cyanohydrin N#CC(O)(C)C 

513-96-2 3,3,3-Trichlorolactonitrile ClC(Cl)(Cl)C(O)C#N 

532-28-5 Mandelonitrile N#CC(O)c(cccc1)c1 
ECOSAR Class Definition: Nitro Alcohols

The Nitro Alcohols class is identified by the following example structures: 

 

HO

C

NO2 C

HO C

NO2 C

HO C

C

NO2

In the current ECOSAR program, the Nitro Alcohols structure meets one of the following 

criteria: 

(1) a single alkyl carbon atom has both an hydroxy attachment (-OH) and a nitro 

function attachment (NO2). 

(2) an alkyl carbon is attached to another alkyl carbon (or olefinic carbon). The nitro 

function (NO2) and hydroxy (-OH) are on different carbons. A maximum of three carbon 

atoms can occur between the nitro function (NO2) and hydroxy (-OH). 

SMILES String Identifications: 

OCN(=O)(=O) ... equivalent to: HOCN(=O)(=O) or [H]OCN(=O)(=O) 

OCCN(=O)(=O) 

OCCCN(=O)(=O) 

 ... nitro function (NO2) can be either N(=O)(=O) or [N+](=O)([O-]) 

OC[N+](=O)([O-]) or OCC[N+](=O)([O-]) or OCCC[N+](=O)([O-]) 

 ... nitro function (NO2) can entered as T ... this is unique to all EPI Suite programs

OCT or OCCT or OCCCT 

Associated ECOSAR Class(s): 

None specifically. 

ECOSAR includes a variety of other classes containing alcohol or nitro functions, but 

not in combination in the same class. 

Example Nitro Alcohols: 

CAS No. Name SMILES Notation 

52-51-7 1,3-Propanediol, 2-bromo-2-nitro- N(=O)(=O)C(Br)(CO)CO 

760-40-7 3-Nitro-1,1,1-trichloro-2-propanol ClC(Cl)(Cl)C(O)CN(=O)=O 

89167-84-0 2-Propanol, 1,1-dinitro- N(=O)(=O)C(N(=O)(=O))C(O)C 
ECOSAR Class Definition: Nitro-/Nitroso-Benzamides

The Nitro-/Nitroso-Benzamides class is identified by the following structures: 

 

C

O N

R2

R1

NO2

C

O N

R2

R1

N O

R1 and R2 - must be either hydrogen or alkyl, olefinic, acetylenic or aromatic carbon 

(carbonyl not included). 

In the current ECOSAR program, the Nitro-/Nitroso-Benzamide structure meets the 

following criteria: 

(1) A six-member aromatic ring (benzene or any other aromatic ring including heteroaromatic rings) has both an amide-substituent (as noted above in the structure) and 

either a nitro substituent (-NO2) or a nitroso substituent (-N=O). The positioning on the 

ring does not matter. 

(2) The aromatic ring can be fused to another ring. 

SMILES String Identifications: 

Nitrosobenzamide (ortho-isomer only SMILES): 

 O=Nc1ccccc1C(=O)N 

Nitrobenzamide (ortho-isomer only SMILES): 

 N(=O)(=O)c1ccccc1C(=O)N 

 ... nitro function (NO2) can be either N(=O)(=O) or [N+](=O)([O-]) 

 [N+](=O)([O-])c1ccccc1C(=O)N 

 ... nitro function (NO2) can entered as T ... this is unique to all EPI Suite programs

 Tc1ccccc1C(=O)N 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Amides - the ECOSAR Amides class is a general class having a CC(=O)N or 

NC(=O)N group that occurs in other ECOSAR classes. In general, the Amides class is 

reported by ECOSAR in addition to the other classes (as in Nitro-/Nitroso-Benzamides). 

Example Nitro-/Nitroso-Benzamides: 

CAS No. Name SMILES Notation 

619-80-7 4-Nitrobenzamide O=C(N)c(ccc(N(=O)(=O))c1)c1 

144189-66-2 3-Nitrosobenzamide NC(=O)c1cc(N=O)ccc1 

3011-89-0 Aklomide Clc1cc(N(=O)(=O))ccc1C(=O)N 

13160-58-2 Pyridine, 4-(p-nitrobenzamido)- n1ccc(NC(=O)c2ccc(N(=O)=O)cc2)cc1 
ECOSAR Class Definition: Omadines

The Omadines class is identified by the following structures: 

 

N

S

O

N

S

O N

SH

O

In the current ECOSAR program, the Omadine structure identification meets the 

following criteria: 

(1) The ECOSAR program identifies a six-member aliphatic ring containing four olefinic 

carbon atoms (and two double bonds), one nitrogen atom (as N=O) and one 

thiocarbonyl group [C(=S)]. 

(2) Also identified is an aromatic pyridine-N-oxide ring with a thiol [-SH] at an orthoposition. 

(3) The omadine ring can be fused to additional ring(s). 

SMILES String Identifications: 

S=C1C=CN(=O)C=C1 

S=C1N(=O)C=CC=C1 

O=n1c(S)cccc1 

Associated ECOSAR Class(s): 

None specifically related to the whole Omadine ring. 

Vinyl/Allyl Amines - both ring structures above are additionally classified as Vinyl/Allyl 

Amines 

Aliphatic Amines - the first ring structure above (nitrogen para-position to thiocarbonyl) 

is additionally classified as an Aliphatic Amine. 

Example Omadines: 

None specifically. Experimental data is CBI (Confidential Business Information). 
ECOSAR Class Definition: Oxetanes

The Oxetanes class is identified by the following structure: 

 

O

C

C

C

In the current ECOSAR program, the Oxetane structure identification meets the 

following criteria: 

(1) The ECOSAR program identifies a four-member ring containing three alkyl carbon 

atoms and one oxygen atom. 

 (2) The alkyl carbon atoms can have any substituent attachments; the substituent 

attachments are not included in the Oxetane identification. 

(3) The Oxetane ring can be fused to additional ring(s). 

SMILES String Identifications: 

O1CCC1 

C1OCC1 

O(C1)CC1 

Associated ECOSAR Class(s): 

None. 

Examples Oxetanes: 

CAS No. Name SMILES Notation 

503-30-0 Oxetane O1CCC1 

68797-60-4 Oxetane, dibromo- BrC1C(CO1)Br 

425-82-1 Hexafluoro oxetane O1C(F)(F)C(F)(F)C1(F)F 

3047-32-3 3-Oxetanemethanol, 3-ethyl- O(CC1(CC)CO)C1 
ECOSAR Class Definition: Oxyamines

The Oxyamines class is identified by the following structure: 

 R2

N O R3

R1

R1 and R2 - must be hydrogen. 

R3 - attachments must be alkyl, olefinic, acetylenic or aromatic carbon (hydrogen not 

included). 

In the current ECOSAR program, the Oxyamine structure meets the criteria as defined 

above. 

SMILES String Identifications: 

NOC 

NOC=C 

NOC#C 

NOc1ccccc1 

 ... (nitrogen attachments as defined above)

Associated ECOSAR Class(s): 

Aliphatic Amines - under the current identification scheme, ECOSAR commonly 

classifies a structure as both Aliphatic Amines and Oxyamines. ECOSAR reports both 

identifications. 

Example Oxyamines: 

CAS No. Name SMILES Notation 

29812-79-1 o-Decylhydroxylamine NOCCCCCCCCCC 
ECOSAR Class Definition: Peroxy Acids

The Peroxy Acids class is identified by the following structure: 

 

R1 O O R2

R1 and R2 - In the current ECOSAR program, can be anything with one exception. 

The exception is that either R1 or R2 is a carbonyl [C(=O)] and the other is not a 

hydrogen ... This exception identifies the Peroxy Ester class. 

The ECOSAR program initially identifies any -O-O- structure as a Peroxy Acid. 

Whenever a Peroxy Ester class is identified, the previous Peroxy Acid identification is 

negated to give precedence to the more specific Peroxy Ester class. 

SMILES String Identifications: 

OO 

 ... (attachments as defined above) 

Associated ECOSAR Class(s): 

Peroxy Esters - an Ester class identified by C(=O)-O-O-X (where X is anything except 

hydrogen). 

Example Peroxy Acids: 

CAS No. Name SMILES Notation 

79-21-0 Peroxyacetic acid CC(=O)OO 

628-37-5 Diethyl peroxide CCOOCC 

29914-92-9 Dipropyl peroxide CCCOOCCC 
ECOSAR Class Definition: Peroxy Esters

The Peroxy Esters class is identified by the following structure: 

 O O

C R2

R1

O

R1 - can be anything (no exclusions). 

R2 - can be anything except hydrogen (hydrogen would make it a Peroxy Acid). 

The ECOSAR program initially identifies any -O-O- structure as a Peroxy Acid. 

Whenever a Peroxy Ester class is identified, the previous Peroxy Acid identification is 

negated to give precedence to the more specific Peroxy Ester class. 

SMILES String Identifications: 

C(=O)OO 

 ... (attachments as defined above) 

Associated ECOSAR Class(s): 

Peroxy Acids - a peroxy class identified by -O-OExample Peroxy Esters: 

CAS No. Name SMILES Notation 

16066-38-9 Peroxydicarbonic acid, dipropyl ester O=C(OCCC)OOC(=O)OCCC 

3313-92-6 Peroxydicarbonic acid, disodium salt [Na]OC(=O)OOC(=O)O[Na] 

110-22-5 Peroxide, diacetyl O=C(OOC(=O)C)C 
ECOSAR Class Definition: Phenol Amines

The Phenol Amines class is identified by the following structure combination: 

 

OH

+ an Amine

[ Phenol ring can also be Hetero-Aromatic ]

The current ECOSAR program identifies the Phenol Amines class using identifications 

of other ECOSAR classes and the following logic: 

(1) First, the structure must already be classified as (a) Phenols, (b) Dinitrophenols or 

(c) Phenols, Poly. 

(2) If the first criteria is satisfied and the structure is additionally classified as any one of 

the ECOSAR Amine classes, then the structure is additionally classified as Phenol 

Amines. The ECOSAR Amine classes include Aliphatic Amines, Anilines (Aromatic 

Amines), Dinitro Aromatic Amine, Benzyl Amines, Propargyl Amines, Amides, and 

Vinyl/Allyl Ether Amines. 

SMILES String Identifications: 

c(O) or c1O ... full ring: c1ccccc1O ... equivalent to: c1ccccc1OH or c1ccccc1O[H] 

 ... Plus any of the SAR Amine Classes listed above (see the individual definition 

documents) 

Associated ECOSAR Class(s): 

See criteria (1) and (2) above. 

Examples Phenol Amines: 

CAS No. Name SMILES Notation 

119-34-6 4-Amino-2-nitrophenol O=N(=O)c(c(O)ccc1N)c1 

94-67-7 Salicyclaldoxime N(O)=Cc(c(O)ccc1)c1 

133-11-9 Phenyl-4-aminosalicylate Oc1cc(N)ccc1C(=O)Oc2ccccc2 

123-30-8 4-Aminophenol Oc(ccc(N)c1)c1 

103-90-2 Acetamide, N-(4-hydroxyphenyl)- O=C(Nc(ccc(O)c1)c1)C 

591-27-5 3-Aminophenol Oc(cccc1N)c1 
ECOSAR Class Definition: Phenols, Poly

The Phenols, Poly class is identified by the following structures: 

 

OH

OH

X

HO OH

[ Rings can also be Hetero-Aromatics ]

X - can be either a direct connection of two rings or another fragment separating the 

rings 

In the current ECOSAR program, the Phenols, Poly structure must meet the following 

criteria: 

(1) More than one hydroxyl (-OH) group are attached to aromatic rings in the structure. 

The aromatic ring can be either a phenyl ring or any other aromatic ring unit including 

heterocyclic aromatic rings. 

(2) The hydroxyl (-OH) groups attached to aromatic ring(s) can either be on the same 

ring or separate rings. 

SMILES String Identifications: 

c(O) or c1O ... equivalent to: c(OH) or c(OH) or c(O[H]) or c1O[H] 

 ... example complete ring: Oc1ccccc1O ... equivalent to: HOc1ccccc1OH 

Associated ECOSAR Class(s): 

Phenols - Only one hydroxyl group can be attached to aromatic rings in the structure. 

Dinitrophenols - Two or more nitro (-NO2) groups must be attached to the same 

aromatic ring as the hydroxyl (-OH) group. 

Hydroquinone - the hydroquinone identification is a more toxic sub-class of the Phenols, 

Poly class. ECOSAR reports both classes. 

Examples Phenols: 

CAS 

No. Name SMILES Notation 

80-05-7 Bisphenol A Oc(ccc(c1)C(c(ccc(O)c2)c2)(C)C)c1 

97-23-4 Phenol, 2,2'-methylenebis 4-chloro- Oc(c(cc(c1)Cl)Cc(c(O)ccc2Cl)c2)c1 

79-95-8 

Phenol, 4,4'-(1-methylethylidene)bis 2,6-

dichloro- Oc(c(cc(c1)C(c(cc(c(O)c2Cl)Cl)c2)(C)C)Cl)c1Cl 

70-30-4 Phenol, 2,2'-methylenebis 3,4,6-trichloro- Oc(c(c(c(c1)Cl)Cl)Cc(c(c(cc2Cl)Cl)Cl)c2O)c1Cl 
ECOSAR Class Definition: Phenols

The Phenols class is identified by the following structures: 

 

OH

Hetero-Aromatic Ring

OH

In the current ECOSAR program, the Phenols structure must meet the following criteria: 

(1) An hydroxyl (-OH) group is attached to an aromatic ring. The aromatic ring can be 

either a phenyl ring or any other aromatic ring unit including heterocyclic aromatic rings. 

(2) The structure can contain only one hydroxyl (-OH) group attached to an aromatic 

ring. Multiple hydroxyl groups attached to aromatic rings changes the classification to 

Phenols, Poly. 

SMILES String Identifications: 

c(O) or c1O ... equivalent to: c(OH) or c(OH) or c(O[H]) or c1O[H] 

 ... example complete ring: c1ccccc1O ... equivalent to: c1ccccc1OH 

Associated ECOSAR Class(s): 

Phenols, Poly - More than one hydroxyl groups are attached to aromatic rings in the 

structure. 

Dinitrophenols - Two or more nitro (-NO2) groups must be attached to the same 

aromatic ring as the hydroxyl (-OH) group. 

Examples Phenols: 

CAS No. Name SMILES Notation

108‐95‐2 Phenol Oc1ccccc1

150‐76‐5 4‐Methoxyphenol Oc1ccc(OC)cc1

88‐75‐5 2‐Nitrophenol Oc1ccccc1N(=O)=O

95‐48‐7 o‐Cresol Oc1ccccc1C

90‐15‐3 1‐Naphthol Oc(c(c(ccc1)cc2)c1)c2
ECOSAR Class Definition: Phosphine Oxide

The Phosphine Oxide class is identified by the following structure: 

 

P

O

R1 R3

R2

R1, R2 and R3 - must be hydrogen or an alkyl, olefinic, acetylenic or aromatic carbon. 

In the current ECOSAR program, the Phosphine Oxide structure must meet the 

following criteria: 

(1) A P(=O) function is attached to hydrogen atoms or to alkyl, olefinic, acetylenic or 

aromatic carbon atoms. 

SMILES String Identifications: 

O=P or P(=O) 

 ... (attachments attachments as defined above) 

example string: 

 O=P(C)(C) ... equivalent to: O=P(C)(C)H 

Associated ECOSAR Class(s): 

None specifically. 

Example Phosphine Oxides: 

CAS No. Name SMILES Notation 

791-28-6 Triphenylphosphine oxide O=P(c(cccc1)c1)(c(cccc2)c2)c(cccc3)c3

1638-75-1 Phosphine oxide, (chloromethyl)dimethyl- O=P(CCl)(C)C 

14717-29-4 Phosphine oxide, dicyclohexyl- P(=O)(C(CCC1)CC1)C(CCC2)CC2 
ECOSAR Class Definition: Phthalonitriles

The Phthalonitriles class is identified by the following structure: 

 

C

C

N

N

In the current ECOSAR program, the Phthalonitriles structure meets the following 

criteria: 

(1) Two nitrile groups (carbon triple-bonded to nitrogen; SMILES of C#N) are attached 

to an aromatic ring in ortho-positions to each other. 

(2) The aromatic ring must be six-member aromatic ring. The ring can be a benzene 

ring or a hetero-aromatic ring (such as pyridine). 

SMILES String Identifications: 

N#Cc1ccccc1C#N 

c1cc(C#N)c(C#N)cc1 

c(c1C#N)cccc1C#N 

Associated ECOSAR Class(s): 

None specifically. 

Other SAR Nitrile classes include: Azonitriles, Nitrile Esters, Halo Nitriles, Vinyl/Allyl 

Nitriles, Nitriles Alpha-OH, and Nitriles, Polyaliphatic. 

Example Phthalonitriles: 

CAS No. Name SMILES Notation 

91-15-6 1,2-Benzenedicarbonitrile C(#N)c(c(C(#N))ccc1)c1 

712-74-3 Tetracyanobenzene N#Cc1c(C#N)cc(C#N)c(C#N)c1 

1835-65-0 Tetrafluorophthalonitrile Fc(c(F)c(F)c1C#N)c(F)c1C#N 

1953-99-7 Tetrachlorophthalonitrile Clc(c(Cl)c(Cl)c1C#N)c(Cl)c1C#N 
ECOSAR Class Definition: Nitriles, Polyaliphatic

The Nitriles, Polyaliphatic class is characterized by the following structure: 

 

C

N

C

N

Structure

(2 or more cyano groups attached to aliphatic atoms)

In the current ECOSAR program, the Nitriles, Polyaliphatic structure must meet the 

following criteria: 

 (1) Two or more nitrile groups (carbon triple-bonded to nitrogen; SMILES of C#N) are 

attached to aliphatic atoms in the structure. The aliphatic atoms include alkyl carbon, 

olefinic carbon, acetylenic carbon, nitrogen, sulfur and phosphorus. Other aliphatic 

atoms are not currently included (e.g. oxygen). 

SMILES String Identifications: 

CC#N 

C=CC#N 

C#CC#N 

NC#N 

SC#N 

PC#N 

 ... (two or more of these cyano [C#N] attachments required)

Associated ECOSAR Class(s): 

Malonitriles - Malonitriles are a more toxic sub-class of the Nitriles, Polyaliphatic class 

that consist of 2 cyano groups separated by a single carbon. 

Vinyl/Allyl Nitriles - basically, a vinyl (-C=C) or allyl group (-C-C=C) is attached to one 

or more nitriles groups. When two or more nitrile groups are attached to the same alkyl 

or olefinic carbon, the structure will be classified as a Vinyl/Allyl Nitriles and either a 

Nitriles, Polyaliphatic or Malonitriles. 

Other SAR Nitrile classes include: Azonitriles, Halo Nitriles, Nitrile Esters, Nitrile AlphaOH, and Phthalonitriles. 

Example Vinyl/Allyl Nitriles: 

CAS No. Name SMILES Notation 

2698-41-1 O-Chlorobenzylidene malononitrile N#CC(C#N)=Cc(c(ccc1)Cl)c1 

109-77-3 Malononitrile C(#N)CC(#N) 

110-61-2 Butanedinitrile C(#N)CCC(#N) 

111-69-3 Hexanedinitrile C(#N)CCCCC(#N) 
ECOSAR Class Definition: Polynitroanilines (Polynitro Aromatic Amine) 

The Polynitroanilines class is identified by the following structure: 

 

NH2

O2N NO2

In the current ECOSAR program, the Polynitroaniline structure meets the following 

criteria: 

(1) A benzene ring (or any other aromatic ring including hetero-aromatic rings) has one 

(or more) amine substituent (as -NH2) and two (or more) nitro substituents (-NO2). 

(2) The aromatic ring can be fused to another ring. 

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N< 

is not identified as an amine for this class. 

SMILES String Identifications: 

Nc1c(N(=O)(=O))cccc1N(=O)=O 

Nc1c([N+](=O)([O-]))cccc1[N+]([O-])=O 

 ... nitro function (NO2) can be either N(=O)(=O) or [N+](=O)([O-]) 

Nc1cc(T)ccc1T 

 ... nitro function (NO2) can entered as T ... this is unique to all EPI Suite programs

Associated ECOSAR Class(s): 

Anilines (Unhindered) - An aromatic ring has an amine substituent (-NH2) that is not 

hindered by specific ortho-substituents. If the Polynitroanilines class is identified, 

ECOSAR reports both identifications. 

Anilines (Hindered) - An aromatic ring has an amine substituent (-NH2) that is hindered 

by specific ortho-substituents. If the Polynitroanilines class is identified, ECOSAR 

reports both identifications 

Dinitrobenzenes - An aromatic ring has two (or more) -NO2 substituents. If the 

Polynitroanilines class is identified, ECOSAR excludes the Polynitrobenzene 

identification. 

Anilines (amino-ortho), Anilines (amino-meta), Anilines (amino-para) - These classes 

are identified when a six-member aromatic ring has two -NH2 substituents in either an 

ortho-, meta- or para-position. When identified in conjunction with Polynitroanilines, 

they are also reported by ECOSAR. 

Example Polynitroanilines: 

CAS No. Name SMILES Notation 

97-02-9 2,4-Dinitroaniline N(=O)(=O)c(ccc(N)c1N(=O)(=O))c1 

96-91-3 Picramic acid Nc1cc(cc(N(=O)=O)c1O)N(=O)=O 

489-98-5 2,4,6-Trinitroaniline Nc1c(cc(cc1N(=O)=O)N(=O)=O)N(=O)=O 
ECOSAR Class Definition: Polynitrobenzenes 

The Polynitrobenzenes class is identified by the following structures: 

 

NO2

NO2

or ... Hetero-Aromatic Ring

 with two or more -NO2

In the current ECOSAR program, the Polynitrobenzenes structure identification meets 

the following criteria: 

(1) The ECOSAR program looks for an aromatic ring (either a benzene or any heteroaromatic ring) with two or more nitro groups (-NO2) attached to the same ring. The 

position of the NO2 groups on the ring does not matter. 

 (2) The aromatic ring can not additionally have the following attachments: -OH or an 

amine (NH2). The presence of these groups changes the current ECOSAR 

classification to Polynitrophenols or Polynitroanilines. 

 (3) The aromatic ring can be fused to one additional aromatic ring. 

SMILES String Identifications: 

c1c(N(=O)(=O))cccc1N(=O)=O 

c1c([N+](=O)([O-]))cccc1[N+]([O-])=O 

 ... nitro function (NO2) can be either N(=O)(=O) or [N+](=O)([O-]) 

Nc1cc(T)ccc1T 

 ... nitro function (NO2) can entered as T ... this is unique to all EPI Suite programs 

Associated ECOSAR Class(s): 

Polynitroanilines - an aromatic ring containing two or more nitro substituents (NO2) plus 

an amine substituent (e.g. -NH2). In the current ECOSAR program, an aromatic ring 

will not be classified as both Dinitrobenzene and Dinitroaniline (the Amine is given 

precedence). 

Polynitrophenols - an aromatic ring containing two or more nitro substituents (NO2) plus 

an hydroxyl (-OH) substituent. In the current ECOSAR program, an aromatic ring will 

not be classified as both Polynitrobenzenes and Polynitrophenols (the phenol is given 

precedence). 

Example Polynitrobenzenes: 

CAS No. Name SMILES Notation 

100-25-4 1,4-Dinitrobenzene N(=O)(=O)c(ccc(N(=O)(=O))c1)c1 

528-29-0 1,2-Dinitrobenzene O=N(=O)c1ccccc1N(=O)=O 

121-14-2 Benzene, 1-methyl-2,4-dinitro- N(=O)(=O)c(ccc(c1N(=O)(=O))C)c1 

3698-83-7 Benzene, 1,5-dichloro-2,4-dinitro- O=N(=O)c(c(cc(c1N(=O)=O)Cl)Cl)c1 
ECOSAR Class Definition: Polynitrophenols 

The Polynitrophenols class is identified by the following structures: 

 

OH

NO2 O2N

[ Ring can also be Hetero-Aromatic ]

In the current ECOSAR program, the Polynitrophenols structure must meet the following 

criteria: 

(1) One or more hydroxyl (-OH) groups are attached to an aromatic ring. The aromatic 

ring can be either a phenyl ring or any other aromatic ring unit including heterocyclic 

aromatic rings. 

(2) Two or more nitro (-NO2) groups must be attached to the same aromatic ring as the 

hydroxyl (-OH) group. 

SMILES String Identifications: 

Oc1c(N(=O)(=O))cccc1N(=O)=O 

Oc1c([N+](=O)([O-]))cccc1[N+]([O-])=O 

 ... nitro function (NO2) can be either N(=O)(=O) or [N+](=O)([O-]) 

Oc1cc(T)ccc1T 

 ... nitro function (NO2) can entered as T ... this is unique to all EPI Suite programs

Associated ECOSAR Class(s): 

Phenols - Only one hydroxyl group can be attached to aromatic rings in the structure. 

Phenols, Poly - More than one hydroxyl groups are attached to aromatic rings in the 

entire structure. 

Examples Polynitrophenols: 

CAS No. Name SMILES Notation 

51-28-5 2,4-Dinitrophenol N(=O)(=O)c(ccc(O)c1N(=O)(=O))c1 

88-89-1 2,4,6-Trinitrophenol N(=O)(=O)c(cc(N(=O)(=O))c(O)c1N(=O)(=O))c1 

534-52-1 4,6-Dinitro-o-cresol N(=O)(=O)c(cc(N(=O)(=O))c(O)c1C)c1 
Propargyl Alcohols-Hindered

The Propargyl Alcohols-Hindered class is identified by the following structures: 

 

C C C OH

R

R

C C C C OH

R

R R

R

R - is attached to alkyl carbons. These alkyl carbons can have two attachments each; 

the combination R attachments that identify Propargyl Alcohols-Hindered are noted 

below. 

In the current ECOSAR program, the hydroxy group (-OH) can be attached to the 

propargyl function (C#C-C-) at either an alpha- or beta-position. The Propargyl AlcoholHindered structure meets one of the following criteria: 

(1) In the first structure above, the hydroxyl group (-OH) is attached to an alkyl carbon 

that attached directly to an acetylenic carbon (alpha-position) . Neither of the Rsubstituents can be hydrogen (if either R is hydrogen, the structure is identified as a 

Propargyl Alcohol). 

(2) In the second structure above, an hydroxyl group (-OH) is attached at the betaposition. If both R-substituents off the beta-carbon are not hydrogen, then the Propargyl 

Alcohol-Hindered class is identified (regardless of the alpha-carbon substituents). If 

either substituent off the alpha-carbon is not hydrogen, then the Propargyl AlcoholHindered class is identified (regardless of the beta-carbon substituents). 

Notation: The ECOSAR classification changes from Propargyl Alcohols-Hindered to 

Propargyl Alcohols when the basic structure is identified, but the R-substituents do not 

meet the criteria above.. 

SMILES String Identifications: 

C#CCO ... equivalent to: C#CCOH or C#CCO[H] 

C#CCCO ... equivalent to: C#CCCOH or C#CCCO[H] 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Propargyl Alcohols - see notation above. 

Example Propargyl Alcohols-Hindered: 

CAS No. Name SMILES Notation 

115-19-5 3-Butyn-2-ol, 2-methyl- OC(C#C)(C)C 

77-75-8 1-Pentyn-3-ol, 3-methyl- OC(C#C)(CC)C 

127-66-2 2-Phenyl-3-butyn-2-ol OC(C#C)(c(cccc1)c1)C 
Propargyl Alcohols

The Propargyl Alcohols class is identified by the following structures: 

 C C CH OH

R

C C CH2 CH OH

R

R - can be anything (no exclusions) 

In the current ECOSAR program, the Propargyl Alcohol structure is identified as shown 

above. The hydroxy group (-OH) can be attached to the propargyl function (C#C-C-) at 

either an alpha- or beta-position. 

Notation: The Propargyl Alcohols class is distinguished from the Propargyl AlcoholsHindered class in that the hydroxyl (-OH) is attached to a straight-chain alkyl carbon. In 

the first structure above, the -OH is attached to a -CH- (with only one substituent). In 

the second structure (beta-position), the chain must be -CH2-CH- (with only one 

substituent off the second carbon) ... If the alkyl carbons have additional substituents 

replacing the designated hydrogens, then the Propargyl Alcohols-Hindered class will be 

identified. 

SMILES String Identifications: 

C#CCO ... equivalent to: C#CCOH or C#CCO[H] 

C#CCCO ... equivalent to: C#CCCOH or C#CCCO[H] 

C#CC(O)C ... equivalent to: C#CC(OH)C or C#CC(O[H])C 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Propargyl Alcohol-Hindered - see notation above. 

Example Propargyl Alcohols: 

CAS No. Name SMILES Notation 

107-19-7 Propargyl alcohol OCC#C 

110-65-6 2-Butyne-1,4-diol OCC#CCO 

927-74-2 3-Butyn-1-ol OCCC#C 

764-01-2 2-Butyn-1-ol CC#CCO 

4117-14-0 2-Decyn-1-ol OCC#CCCCCCCC 
ECOSAR Class Definition: Propargyl Ethers

The Propargyl Ethers class is identified by the following structure: 

 C C C

O

Carbon

In the current ECOSAR program, the Propargyl Ether structure meets the following 

criteria: 

(1) An ether oxygen is attached to an alkyl carbon that is attached to an acetylenic 

carbon. 

(2) The “Carbon” in the structure above can be alkyl, olefinic, acetylenic or aromatic 

carbon. 

SMILES String Identifications: 

C#CCOC 

C#CCOC=C 

C#CCOC#C 

C#CCOc1ccccc1 

Associated ECOSAR Class(s): 

None specifically. 

Vinyl/Allyl Ethers - the propargyl group (C#C-C-O-C) is replaced by an allyl group 

(C=C-C-O-C) 

Example Propargyl Ethers: 

CAS No. Name SMILES Notation 

6921-27-3 Dipropargyl ether O(CC#C)CC#C 

53135-64-1 1-Propyne, 3-propoxy- CCCOCC#C 
ECOSAR Class Definition: Propargyl Halides

The Propargyl Halides class is identified by the following structures: 

 C C Halogen C C C Halogen

In the current ECOSAR program, the Propargyl Halides structure meets one of the 

following criteria: 

(1) A halogen atom (Br, Cl, F, or I) is attached directly to an acetylenic carbon. 

(2) A halogen atom (Br, Cl, F, or I) is attached to an alkyl carbon that is attached 

directly to an acetylenic carbon. 

Notation: In the current ECOSAR program, the first criteria above overlaps with a 

criteria used by the Vinyl/Ally Halides class. ECOSAR identifies and reports both 

classes for a compound such as bromoacetylene (BrC#C). 

SMILES String Identifications: 

C#CBr or C#CCl or C#CF or C#CI 

C#CCBr or C#CCCl or C#CCF or C#CCI 

Associated ECOSAR Class(s): 

Vinyl/Allyl Halides - the propargyl group (C#C-C-) is replaced by a vinyl group (-C=C) or 

an allyl group (C=C-C-). 

Example Propargyl Halides: 

CAS No. Name SMILES Notation 

624-65-7 Propargyl chloride C(#C)CC 

106-96-7 1-Propyne, 3-bromo- C(#C)CBr 

7572-29-4 Dichloroacetylene ClC#CCl 
Pyrazoles/Pyrroles

The Pyrazoles/Pyrroles class is identified by the following structures: 

 

N

H

N

H

N

In the current ECOSAR program, the Pyrazoles/Pyrroles structure identification meets 

the following criteria: 

(1) The ECOSAR program looks for an aromatic ring with the following characteristics: 

(a) a five-member aromatic ring containing four carbon atoms and one nitrogen atom (a 

pyrrole ring) or (b) a five-member aromatic ring containing three carbon atoms and two 

nitrogen atoms that are adjacent to each other (a pyrazole ring). 

 (2) The [nH] in either the pyrazole ring or pyrrole ring can have the hydrogen atom 

attachment replaced by another atom. 

 (3) Either ring can be fused to one additional aromatic ring. 

SMILES String Identifications: 

Pyrrole: 

 n1cccc1 

 Hn1cccc1 

 [nH]1cccc1 

 N1C=CC=C1 

Pyrazole: 

 n1nccc1 

 Hn1nccc1 

 [nH]1nccc1 

 N1N=CC=C1 

Associated ECOSAR Class(s): 

None specifically. However, ECOSAR includes other “ring structure” classes such as 

Triazines, Imidazoles, Triazoles (Non-Fused), Triazole Pyrimidines and Thiazole, 

Benzo. 

Example Pyrazoles/Pyrroles: 

CAS No. Name SMILES Notation 

288-13-1 1H-Pyrazole N1N=CC=C1 

109-97-7 1H-Pyrrole C1=CC=CN1 

122453-73-0 Chlorfenapyr N#Cc1c(Br)c(C(F)(F)F)n(COCC)c1c2ccc(Cl)cc2 

71561-11-0 Pyrazoxyfen Clc1cc(Cl)ccc1C(=O)c2c(C)nn(C)c2OCC(=O)c3ccccc3 

82692-44-2 Benzofenap c1cc(C)ccc1C(=O)COc2n(C)nc(C)c2C(=O)c3ccc(Cl)c(C)c3Cl
ECOSAR Class Definition: Pyrethroids

The Pyrethroids class is identified by the following base structures: 

 

H3C CH3

C

O

C C

C

O

Aromatic/Aliphatic Ring

O

O

C

N

CH3 O

H3C

Attachments can be anything (no exclusions) 

In the current ECOSAR program, the Pyrethroid structure must meet either of the 

structures depicted above. 

Notation: The structures are explicit for Pyrethroid identification. For example, the 

CH3 groups must be CH3 groups and the vinyl group on the first structure (C=C) must 

be a vinyl group. 

Associated ECOSAR Class(s): 

None specifically. 

Example Pyrethroids: 

CAS No. Name SMILES Notation 

70124-77-5 Flucythrinate CC(C)C(C(=O)OC(C#N)c2cccc(Oc1ccccc1)c2)c3ccc(OC(F)F)cc3

10453-86-8 Resmethrin CC(C)=CC3C(C(=O)OCc2coc(Cc1ccccc1)c2)C3(C)C 

52918-63-5 Deltamethrin CC1(C)C(C=C(Br)Br)C1C(=O)OC(C#N)c3cccc(Oc2ccccc2)c3 

52315-07-8 Cypermethrin ClC(Cl)=CC1C(C)(C)C1C(=O)OC(C#N)c2cccc(Oc3ccccc3)c2 
ECOSAR Class Definition: Pyridine-alpha-Acid

The Pyridine-alpha-Acid class is identified by the following structure: 

 

N

OH

O

In the current ECOSAR program, the Pyridine-alpha-Acid structure identification meets 

the following criteria: 

(1) The ECOSAR program identifies a six-member aromatic ring containing five carbon 

atoms and one nitrogen atom (a pyridine ring). 

 (2) A carboxylic acid group (-C(=O)-OH) is attached to the pyridine ring in an orthoposition to the nitrogen atom. 

 (3) The pyridine ring can be fused to additional ring(s). 

SMILES String Identifications: 

n1ccccc1C(=O)O ... equivalent to: n1ccccc1C(=O)OH or n1ccccc1C(=O)O[H] 

N1=CC=CC=C1C(=O)O 

Associated ECOSAR Class(s): 

Other ECOSAR classes specifically containing a Pyridine ring: 

Halo Pyridines - one or more halogen atoms are attached to a pyridine ring. A 

structure can be classified as both a Pyridine-alpha-Acid and a Halo Pyridine. 

Notation: the Pyridine Thiones class does not contain an aromatic pyridine ring (the 

ring is an aliphatic thione ring with C(=S) as part of the ring). 

Examples Pyridine-alpha-Acid: 

CAS No. Name SMILES Notation 

98-98-6 2-Pyridinecarboxylic acid O=C(O)c(nccc1)c1 

10469-09-7 2-Pyridinecarboxylic acid, 3,4,5,6-tetrachloro- O=C(O)c(nc(c(c1Cl)Cl)Cl)c1Cl

499-83-2 2,6-Pyridinedicarboxylic acid O=C(O)c(nc(cc1)C(=O)O)c1 
ECOSAR Class Definition: Quinones

The Quinones/Hydroquinones class is identified by the following example structures: 

 

C

C

O

O

C

C

O

O

C

C

O

O

In the current ECOSAR program, the Quinones structure meets one of the following 

criteria: 

(1) A six-member aliphatic ring with two carbonyls [C(=O)] at para-positions. The other 

four ring members (that are not carbonyl) must be either (a) four olefinic carbons with 

two double-bonds, (b) two olefinic carbons with a double-bond and two aromatic 

carbons as part of a fused ring, or (c) four aromatic carbons as part of a fused ring. 

SMILES String Identifications: 

O=C1C=CC(=O)C=C1 

O=C1C=CC(=O)c2ccccc2c1 

c1ccc2C(=O)c3ccccc3C(=O)c2c1 

Associated ECOSAR Class(s): 

Vinyl/Allyl Ketones - a Quinone ring (with olefinic carbons) also fits the identification of 

the Vinyl/Allyl Ketone class ... However, ECOSAR currently excludes the ketone 

identification when a Quinone ring is identified. 

Example Quinones: 

CAS No. Name SMILES Notation 

106-51-4 1,4-Benzoquinone C1(=O)C=CC(=O)C=C1 

58-27-5 1,4-Naphthalenedione, 2-methyl- c1cc2C(=O)C=C(C)C(=O)c2cc1 

84-65-1 Anthraquinone O=C(c(c(C(=O)c1cccc2)ccc3)c3)c12 

 
ECOSAR Class Definition: Rosins

The Rosins class is identified by the following example structures: 

 

O

OH

O

OH

O

OH

Abietic Acid Pimaric Acid

The primary constituents of rosin are resins acids of the abietic and pimaric types 

having a phenanthrene-shaped ring nucleus. 

In the current ECOSAR program, the Rosin structure meets the following criteria: 

(1) the structure contains a fused three-ring unit comprised of three six-member rings 

having all carbon atoms. The rings are positioned in a phenanthrene-shaped 

configuration. 

(2) At least two of the rings must be primarily aliphatic in nature (comprised mostly of 

aliphatic carbons) ... only one ring can be aromatic (a benzene ring). 

(3) The structure must contain one (or more) carboxylic acid groups [-C(=O)OH]. The 

carboxylic acid group can be located anywhere in the structure. 

SMILES String Identifications: 

Abietic acid ring unit: C1CCC2CC=C3C=CCCC3C2C1 

Pimaric acid ring unit: C1CCC2CCC3=CCCCC3C2C1 

Ring unit with one aromatic ring: C1CCC2CCc3ccccc3C2C1 

Plus a Carboxylic Acid: C(=O)O ... equivalent to: C(=O)OH or C(=O)O[H] 

Associated ECOSAR Class(s): 

None specifically. 

Example Rosins: 

CAS No. Name SMILES Notation 

1740-19-8 Dehydroabietic acid O=C(O)C(C(C(c(c(cc(c1)C(C)C)C2)c1)(CC3)C)C2)(C3)C 

514-10-3 Abietic acid O=C(O)C(C(C(C(C(=C1)C=C(C2)C(C)C)C2)(CC3)C)C1)(C3)C

5835-26-7 Isopimaric acid CC3(CCC1C(=CCC2C1(C)CCCC2(C)C(=O)(O))C3)C=C 

471-77-2 Neoabietic acid C(C(CC1)=C(C)C)=C(CCC2C(C3)(C(=O)O)C)C1C2(CC3)C 
ECOSAR Class Definition: Schiff Bases-Azomethine

The Schiff Bases class is identified by the following structure: 

 

C N R3

R2

R1

R1 and R2 - must be hydrogen or alkyl, olefinic, acetylenic or aromatic carbon atoms 

(no other atoms allowed). 

R3 - cannot be hydrogen 

In the current ECOSAR program, the Schiff Base structure meets the following criteria: 

(1) The structure as depicted above. The C=N fragment cannot be part of a ring 

structure. 

SMILES String Identifications: 

C=N 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

None specifically. 

Example Schiff Bases: 

CAS No. Name SMILES Notation 

64611-40-1 

Methanamine, Nethylidene-, (Z)- CC=NC 

104-71-2 

1,2-Ethanediamine, N,N'-

bis(phenylmethylene)- N(CCN=Cc(cccc1)c1)=Cc(cccc2)c2 

92-29-5 Hydrobenzamide c1ccccc1C=NC(c2ccccc2)N=Cc3ccccc3 
ECOSAR Class Definition: Substituted Ureas 

The Substituted Ureas class is identified by the following structure: 

 

N

O

R N 1

R2

R4

R3

In the current ECOSAR program, the Substituted Ureas structure must meet the 

following criteria: 

R1 and R2 can be either a hydrogen or oxygen atom or alkyl, olefinic, acetylenic or 

aromatic carbon atoms, but at least one attachment must be to a carbon atom. 

R3 and R4 can be anything except a carbonyl group. 

If R3 or R4 contain a carbonyl group, then ECOSAR will identify the class as 

carbonyl ureas. 

SMILES String Identifications: 

NC(=O)N 

 ... (attachments as defined above)

Example Substituted Ureas: 

CAS No. Name SMILES Notation 

330-54-1 Diuron O=C(N(C)C)Nc(ccc(c1Cl)Cl)c1 

18691-97-9 Methabenzthiazuron CNC(=O)N(C)c2nc1ccccc1s2 
Sulfonyl Ureas

The Sulfonyl Ureas class is identified by the following structure: 

R1 and R2 - can be anything (no exclusions) 

In the current ECOSAR program, the Sulfonyl Urea structure must meet the following 

criteria: 

(1) A sulfone group [S(=O)(=O)] is attached to the nitrogen atom of a urea function 

[NC(=O)N]. 

 (2) The urea nitrogens or the sulfone group can have other attachments (no 

exclusions). 

SMILES String Identifications: 

NC(=O)NS(=O)(=O) 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Amides - the ECOSAR Amides class is a general class having a CC(=O)N, NC(=O)N 

or S(=O)N group that occurs in other ECOSAR classes. In general, the Amides class is 

reported by ECOSAR in addition to the other classes (such as Sulfonyl Ureas). 

The Vinyl/Allyl Sulfones class contains the -S(=O)(=O)- function which is the only other 

ECOSAR class containing the sulfone group. 

Example Sulfonyl Ureas: 

CAS No. Name SMILES Notation 

82097-50-5 Triasulfuron ClCCOc1ccccc1S(=O)(=O)NC(=O)Nc2nc(OC)nc(C)n2 

74223-64-6 Metsulfuron-methyl COC(=O)c1ccccc1S(=O)(=O)NC(=O)Nc2nc(OC)nc(C)n2 

64902-72-3 Chlorsulfuron n1c(OC)nc(C)nc1NC(=O)NS(=O)(=O)c2ccccc2Cl 

122931-48-0 Rimsulfuron CCS(=O)(=O)c1cccnc1S(=O)(=O)NC(=O)Nc2nc(OC)cc(OC)n2
ECOSAR Class Definition: Thiazolidinones / Benzothiazolidinones

The Thiazolidinone class is identified by the following structures: 

 

N S

C

O

N S

C

S

N S

C

O

N S

C

S

In the current ECOSAR program, the Thiazolidinone structure meets the following 

criteria: 

(1) a five-member ring containing one carbonyl (or thiocarbonyl) attached to one 

aliphatic sulfur and one aliphatic nitrogen. The two carbon atoms in the ring can be 

either alkyl carbons or two aromatic carbons of a fused-ring. 

(2) The atoms in the thiazolidinone ring can have other attachments (no exclusions). 

Notations: Currently, the thiazolidinone ring cannot contain two olefinic carbons with a 

double bond in place of the aromatic carbons or alkyl carbons. 

SMILES String Identifications: 

O=C1SCCN1 

S=C1SCCN1 

 In conjunction with a fused aromatic ring: 

O=C1Sc2ccccc2N1 

S=C1Sc2ccccc2N1 

Associated ECOSAR Class(s): 

Thiocarbamates & Dithiocarbamates - the order of the carbonyl (or thiocarbonyl) with 

attached sulfur and nitrogen is additionally classified by ECOSAR as one of these 

classes. 

The Isothiazolone class ring also contains a carbonyl, one sulfur, one nitrogen and two 

carbon atoms, but in a different order. 

Example Thiazolidinones / Benzothiazolidinones: 

CAS No. Name SMILES Notation 

25059-80-7 Benazolin-ethyl CCOC(=O)CN1C(=O)Sc2cccc(Cl)c12 

96-53-7 2-Thiazolidinethione N(C(=S)SC1)C1 

1908-87-8 2-Thiazolidinethione, 3-methyl- N(C(SC1)=S)(C1)C 

2682-49-7 2-Thiazolidinone N1CCSC1=O 
ECOSAR Class Definition: Thiazolidinones - Acids

The Thiazolidinones-Acid class is identified by the following structures: 

 

N S

C

O

N S

C

S

N S

C

O

N S

C

S

+ Acid Group

This class is identical to the Thiazolidinone-Benzothiazolidinone class with the addition 

of an acid function. 

In the current ECOSAR program, the Thiazolidinone-Acid structure meets the following 

criteria: 

(1) a five-member ring containing one carbonyl (or thiocarbonyl) attached to one 

aliphatic sulfur and one aliphatic nitrogen. The two carbon atoms in the ring can be 

either alkyl carbons or two aromatic carbons of a fused-ring. 

(2) an Acid group (carboxylic acid, sulfonic acid, phosphonic acid) exists anywhere in 

the structure. 

(3) The atoms in the thiazolidinone ring can have other attachments (no exclusions). 

Notations: Currently, the thiazolidinone ring cannot contain two olefinic carbons with a 

double bond in place of the aromatic carbons or alkyl carbons. 

SMILES String Identifications: 

O=C1SCCN1 

S=C1SCCN1 

 In conjunction with a fused aromatic ring: 

O=C1Sc2ccccc2N1 

S=C1Sc2ccccc2N1 

 Plus - an Acid group: 

Carboxylic Acid: C(=O)O ... equivalent to: C(=O)OH or C(=O)O[H] 

Phosphoric Acid: P(=O)(O) ... equivalent to: P(=O)(OH)OH 

Sulfonic Acid: S(=O)(=O)O ... equivalent to: S(=O)(=O)OH 

Associated ECOSAR Class(s): 

Thiocarbamates & Dithiocarbamates - the order of the carbonyl (or thiocarbonyl) with 

attached sulfur and nitrogen is additionally classified by ECOSAR as one of these 

classes. 

Example Thiazolidinones / Benzothiazolidinones: 

CAS No. Name SMILES Notation 

3813-05-6 Benazalox (Metizolin) OC(=O)CN1C(=O)Sc2cccc(Cl)c12 

ECOSAR Class Definition: Thiocarbamate,Di (Free Acid)

The Thiocarbamate,Di (Free Acid) class is identified by the following structures: 

 H2N

C

S

S

R

N

C

SH

S

R

H2N

C

SH

S

R - can be anything (no exclusions) 

In the current ECOSAR program, the Thiocarbamate,Di (Free Acid) class meets the 

following criteria: 

(1) the core dithiocarbamate structure [N-C(=S)-S] occurs in the structure. 

(2) either (or both) the nitrogen or sulfur exists as free acid in the form of -NH2 or -SH. 

SMILES String Identifications: 

NC(=S)S ... equivalent to: [NH2]C(=S)S or N(H)(H)C(=S)S 

NC(=S)S ... equivalent to: NC(=S)SH or NC(=S)S[H] 

NC(=S)S ... equivalent to: [NH2]C(=S)SH or N(H)(H)C(=S)SH 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Thiocarbamate, Di (Substituted) - both of the free acids are substituted. 

Example Thiocarbamate,Di (Free Acid): 

CAS No. Name SMILES Notation 

29596-83-6 Acetic acid, [(aminothioxomethyl)thio]- S=C(SCC(=O)O)N 

99-00-3 Picadex N1CCN(C(=S)S)CC1 

12656-69-8 Dithane SC(=S)NCCNC(S)=S 
ECOSAR Class Definition: Thiocarbamate,Di (Substituted)

The Thiocarbamate,Di (Substituted) class is identified by the following structures: 

 N

C

S

S

R R

R - can be anything except hydrogen attached to the sulfur or two hydrogens (H2) 

attached the nitrogen. 

In the current ECOSAR program, the Thiocarbamate,Di (Substituted) class meets the 

following criteria: 

(1) the core dithiocarbamate structure [N-C(=S)-S] occurs in the structure. 

(2) both the nitrogen or sulfur have a hydrogen substitution (excluding both as free 

acids). 

SMILES String Identifications: 

NC(=S)S 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Thiocarbamate, Di (Free Acids) - either (or both) the nitrogen or sulfur exists as free 

acid in the form of -NH2 or -SH. 

Example Thiocarbamate,Di (Substituted): 

CAS No. Name SMILES Notation 

137-26-8 Thioperoxydicarbonic diamide,tetramethyl- N(C(=S)SSC(N(C)C)=S)(C)C 

95-06-7 Sulfallate CCN(CC)C(=S)SCC(Cl)=C 

96-53-7 2-Thiazolidinethione N(C(=S)SC1)C1 

533-74-4 Dazomet N(CSC(N1C)=S)(C1)C 
ECOSAR Class Definition: Thiocarbamates, Mono

The Thiocarbamates, Mono class is identified by the following structures: 

 N

C

S

O

R1 R2

N

C

O

S

R1 R3

R1 - can be anything except H2 (two hydrogens off the nitrogen). 

R2 - can be anything (including hydrogen). 

R3 - can be anything except hydrogen 

In the current ECOSAR program, the Thiocarbamates, Mono class meets the criteria as 

shown in the structure above. 

SMILES String Identifications: 

NC(=O)S 

NC(=S)O 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Vinyl/Allyl Thiocarbamates - if the R3 substituent is vinyl (-C=C) or allyl (-CC=C) group, 

ECOSAR will identify the structure as both Thiocarbamates, Mono and Vinyl/Allyl 

Thiocarbamates and report both classes. 

ECOSAR includes a variety of Di-Thiocarbamate ester classes. 

Example Thiocarbamates, Mono: 

CAS No. Name SMILES Notation 

759-94-4 Eptam (EPTC) O=C(N(CCC)CCC)SCC 

1114-71-2 Pebulate CCCCN(CC)C(=O)SCCC 

2303-16-4 Diallate CC(C)N(C(C)C)C(=O)SCC(Cl)=CCl 

42116-76-7 Carnidazole Cc1ncc(N(=O)(=O))n1CCNC(=S)OC 

88678-67-5 Pyributicarb n1c(OC)cccc1N(C)C(=S)Oc2cc(C(C)(C)C)ccc2 
ECOSAR Class Definition: Thiocyanates/Isothiocyanates

The Thiocyanates/Isothiocyanates class is identified by the following structure: 

 R - N = C = S 

R S

C N

R - can be aliphatic, alicyclic, aromatic, or hetercyclic, but not hydrogen. 

SMILES String Identifications: 

N=C=S 

N#CS 

Associated ECOSAR Class(s): 

Isocyanates - the thiocyanate sulfur is replaced by an oxygen (R-N=C=O) 

Example Thiocyanates/Isothiocyanates: 

CAS No. Name SMILES Notation 

57-06-7 Allyl isothiocyanate C=CCN=C=S 

556-61-6 Methyl isothiocyanate CN=C=S 

103-72-0 Phenyl isothiocyanate c1ccccc1N=C=S 

6317-18-6 Methylene bis(thiocyanate) N#CSCSC#N 
ECOSAR Class Definition: Thiols and Mercaptans

The Thiols and Mercaptans class is identified by the following structure: 

 

Aliphatic Carbon

SH

Aromatic Carbon

SH

SH

SH (example)

(example)

In the current ECOSAR program, the Thiol-Mercaptan structure must meet the following 

criteria: 

(1) A thiol-mercaptan function (-SH) is attached to an alkyl, olefinic, acetylenic or 

aromatic carbon atom. 

SMILES String Identifications: 

SC ... equivalent to: HSC or [H]SC 

SC=C ... equivalent to: HSC=C or [H]SC=C 

SC#C ... equivalent to: HSC#C or [H]SC#C 

Sc1ccccc1 ... equivalent to: HSc1ccccc1 or [H]Sc1ccccc1 

Associated ECOSAR Class(s): 

None specifically. 

Example Thiols and Mercaptans: 

CAS No. Name SMILES Notation 

74-93-1 Methanethiol SC 

111-31-9 1-Hexanethiol SCCCCCC 

68-11-1 Mercapto acetic acid O=C(O)CS 

1455-21-6 1-Nonanethiol SCCCCCCCCC 

5331-91-9 Chloro-2-mercaptobenzothiazole S(C(S)=N1)c(ccc2Cl)c1c2 

 
ECOSAR Class Definition: Thiomethacrylates

The Thiomethacrylates class is identified by the following structures: 

 

C

C

S

O

C R1

CH3

C

C

{O,S}

S

C R1

CH3

R1 - attachment must be either an alkyl carbon, olefinic carbon, acetylenic carbon or 

aromatic carbon. 

{O,S} - can be either oxygen (-O-) or sulfur (-S-) 

Internally, the ECOSAR program initially detects a carbonyl function [C(=O)] or a 

thiocarbonyl function [C(=S)] with one olefinic attachment and one oxygen or sulfur 

attachment. The olefinic carbon attached to the carbonyl (or thiocarbonyl) must have a 

methyl (CH3) attachment (anything other than a methyl group (CH3) changes the 

classification from a possible Thiomethacrylate to a possible Acrylate. The oxygen or 

sulfur must have either an alkyl carbon, olefinic carbon, acetylenic carbon or aromatic 

carbon attachment to be classified as either a Thiomethacrylate or Acrylate. 

SMILES String Identifications: 

C=C(C)C(=O)S ... equivalent to: C=C(C(H)(H)H)C(=O)S or C=C([CH3])C(=S)S 

 .... Note: ECOSAR converts a SMILES entry of [CH3] to C(H)(H)(H), then C only 

C=C(C)C(=S)O 

C=C(C)C(=S)S 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Methacrylates are a class separate from either Thiomethacrylates or Acrylates. 

Structures classified as Thiomethacrylates are also classified as Methacrylates. In 

addition, ECOSAR will classify Thiomethacrylates having the thiocarbonyl function 

[C(=S)] as Esters. 

Example Thiomethacrylates: 

CAS No. Name SMILES Notation 

 O-Methyl thiomethacrylate C=C(C)C(=S)OC 

 S-Methyl thiomethacrylate C=C(C)C(=O)SC 

 Methyl dithiomethacrylate C=C(C)C(=S)SC 

 
Thiophenes

The Thiophenes class is identified by the occurrence following ring structure: 

 

S

ECOSAR identifies a Thiophene ring as follows: 

(1) a five-atom-member ring consisting of one sulfur atom and four carbon atoms 

(2) the ring is an aromatic ring; the SMILES designation for an unsubstituted ring is 

s1cccc1 ... if the SMILES entry into ECOSAR is S1C=CC=C1, it will be converted into 

s1cccc1 ... ECOSAR identifies the aromatic ring as a Thiophene 

(3) the Thiophene ring cannot be part of an aromatic fused-ring system (such as 

benzothiophene) ... the Thiophene ring can be fused to an aliphatic ring. 

SMILES String Identifications: 

s1cccc1 

S1C=CC=C1 

Associated ECOSAR Class(s): None 

Example Thiophenes: 

CAS No. Name SMILES Notation

110‐02‐1 Thiophene S1C=CC=C1   [or]   s1cccc1

872‐31‐1 3‐Bromothiophene C1=CC(Br)=CS1

554‐14‐3 2‐Methythiophene C1=C(C)SC=C1

 
ECOSAR Class Definition: Thiophthalimides 

The Thiophthalimides class is identified by the following structure: 

 

Substitutions can be anything (no exclusions). 

In the current ECOSAR program, the thiophthalimides structure contains a benzene ring 

bound to a 5-membered ring containing an aliphatic nitrogen bound to a sulfur atom and 

surround by two carbonyl [C(=O)] groups (as depicted above). 

SMILES String Identifications: 

Thiophthalimides Group: 

C1cccc2c1C(=O)N(SC)C2=O 

Associated ECOSAR Class(s): 

Imides - identified by C(=O)-N-C(=O). 

Example Thiophthalimides: 

CAS No. Name SMILES Notation 

133-06-2 Captan O=C(N(SC(Cl)(Cl)Cl)C(=O)C1CC=CC2)C

12 

133-07-3 Folpet 

O=C(N(SC(Cl)(Cl)Cl)C(=O)c1cccc2)c12 

2939-80-2 Captafol O=C1N(C(=O)C2C1CC=CC2)SC(C(Cl)Cl)

(Cl)Cl 
ECOSAR Class Definition: Thiotetrazoles

The Thiotetrazoles class is identified by the following structures: 

 

N

H

N N

N S

R

S

N

N N

N

R - attachment to the sulfur can be anything in current ECOSAR program. 

In the current ECOSAR program, the Thiotetrazole structure identification meets the 

following criteria: 

(1) The ECOSAR program looks for two aromatic rings with the following 

characteristics: (a) a five-member aromatic ring containing one carbon atom (with an 

aliphatic sulfur attachment) and four nitrogen atoms (a tetrazole ring) or (b) a fivemember aromatic ring containing one sulfur atom and four nitrogen atoms. 

 (2) The [nH] in the tetrazole ring can have the hydrogen atom attachment replaced by 

another atom. 

 (3) The tetrazole or thiotetrazole ring can be fused to additional aromatic ring(s). 

SMILES String Identifications: 

Sc1nnnn1 

Sc1nnn[nH]1 

SC1=NN=NN1 

s1nnnn1 

S1N=NN=N1 

Associated ECOSAR Class(s): 

None specifically. However, ECOSAR includes other “ring structure” classes such as 

Triazines, Imidazoles, Triazoles (Non-Fused), Triazole Pyrimidines and Thiazole, 

Benzo. 

Examples Thiotetrazoles: 

CAS No. Name SMILES Notation 

56610-79-8 

1H-Tetrazole, 1-methyl-5-

[(phenylmethyl)thio]- c1ccccc1CSC2=NN=NN2C 

133088-69-4 

1H-Tetrazole, 5-(hexylsulfinyl)-1-(4-

nitrophenyl)- CCCCCCS(=O)C1=NN=NN1c2ccc(N(=O)=O)cc2 
ECOSAR Class Definition: Thioureas

The Thioureas class is identified by the following structure: 

 

C

S

R1 N N R2

R1 and R2 - can be anything (no exclusions) 

In the current ECOSAR program, the Thiourea structure must meet the following 

criteria: 

(1) A thiocarbonyl function [-C(=S)-] is attached to two aliphatic nitrogen atoms. If the 

thiocarbonyl is attached an aromatic nitrogen (such as a nitrogen in a pyrrole ring), the 

structure will not be classified as a Thiourea. 

(2) The nitrogen atoms can have other attachments (no exclusions). 

SMILES String Identifications: 

NC(=S)N 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

None specifically. 

Other urea classes (e.g. Substituted Ureas or Sufonyl Ureas) pertain to a carbonyl 

[C(=O)] urea as compared to the thiocarbonyl [C(=S)] urea of this class. 

Example Thioureas: 

62-56-6 Thiourea NC(=S)N 

534-13-4 Thiourea, N,N'-dimethyl- N(C(=S)NC)C 

5217-47-0 1,3-Diethyl-thiobarbituric acid O=C(N(C(N(C1=O)CC)=S)CC)C1 
ECOSAR Class Definition: Triazines, Aliphatic 

The Triazines, Aliphatic class is identified by the following example structures: 

N N

N

 

In the current ECOSAR program, the Triazine, Aliphatic structure is a six-member ring 

containing three aliphatic carbon atoms (carbonyls are not included) and three aliphatic 

nitrogen atoms in the sim position . 

SMILES String Identifications: 

N1CNCNC1 

Associated ECOSAR Class(s): 

Triazines, Aromatic- a six-member aromatic ring containing three aromatic nitrogen 

atoms and three aromatic carbon atoms or one aromatic carbon with two carbonyls or 

two aromatic carbons with one carbonyl 

Aliphatic Amines – defined in ECOSAR as any primary, secondary or tertiary aliphatic 

amine group. Since the Aliphatic Triazine class does not take precedence over aliphatic 

amines, both classes are reported in ECOSAR for these chemicals – though aliphatic 

triazines yield higher toxicity profiles. 

Example Triazines: 

CAS No. Name SMILES Notation 

100-97-0 Hexamethylenetetramine N(CN(CN1CN23)C3)(C1)C2 

7779-27-3 

1,3,5-Triazine, 1,3,5-

triethylhexahydro- N(CN(CN1CC)CC)(C1)CC 

 
ECOSAR Class Definition: Triazines, Aromatic 

The Triazines, Aromatic class is identified by the following example structures: 

 Structure 1 Structure 2 Structure 3 Structure 4 

 

N

N

N

R

R

R

N

NN

O

R

R

N

NNO

R

O

N N

O N O

O

Triazine, aromatics consists of a six-member aromatic ring containing three aromatic 

nitrogen atoms in the sim-position in addition to either; 

1) Three aromatic carbon atoms, 2) two aromatic carbons with one carbonyl; 3) one 

aromatic carbon with two carbonyls; or 4) three carbonyl groups (as shown 

above). 

R can be anything except three primary or secondary nitrogen atoms. 

If all R groups are primary or secondary nitrogen atoms, ECOSAR will identify 

the class as Melamine 

In structure 3 and 4 represented above containing at least 2 carbonyls, if there is a 

chlorine atom attached to the nitrogen between two carbonyls, the class will be 

identified at haloimides [(C(=O)NC(=O)] which presents higher toxicity concern 

presumably due to the presence of the halogen based on analysis of similar chemicals. 

SMILES String Identifications: 

n1cnc(=O)nc1=O 

n1cncnc1 

n1cnc(=O)nc1 

n1c(=O)nc(=O)nc1=O 

Example Triazines, Aromatic: 

CAS No. Name SMILES Notation 

101-05-3 Anilazine Clc2nc(Cl)nc(Nc1ccccc1Cl)n2 

122-34-9 Simazine n(c(nc(n1)NCC)NCC)c1Cl 

1912-24-9 Atrazine n(c(nc(n1)NC(C)C)NCC)c1Cl 

 
ECOSAR Class Definition: Triazole Pyrimidines Sulfonamides 

Formerly refered to as the Triazole Pyrimidines class, the Triazole Pyrimidine 

Sulfonamides class is entirely composed of chemicals with the following identifying 

structures: 

 

N N N

N

S N

O

O

The class was updated to include the CNS(=O)(=O) fragment since the entire training 

set for the class (which is a class of pesticides) included this as part of the base 

fragment. 

Searches for toxicity patterns for the former base fragment (c1nn2c(n1)ccnc2) yielded 

no results on toxicity profiles. It is suspected that due to the aromatic nature of the 

backbone this fragment alone would present minimal toxicity, unless substituted with 

reactive functional groups. 

In the current ECOSAR program, the Triazole Pyrimidines Sulfonamide is a sulfonamide 

bound to two fused aromatic rings (as depicted above) with the following characteristics: 

(a) a five-member aromatic ring containing two carbon atoms and three nitrogen atoms 

(a triazole ring), (b) a six-member aromatic ring containing four carbon atoms and two 

nitrogen atoms, and (c) both rings contain one or more fused carbon atoms (meaning 

each ring is fused to another aromatic ring). 

ALERT: Chemicals containing the large molecular fragment for triazole pyrimidine 

sulfonamides are likely designed to act as herbicides. If the query compound contains 

this structural fragment, it is likely to be most closely related to the training set 

chemicals in the triazole pyrimidine sulfonamides class – irrespective of the other 

classes reported. 

SMILES String Identifications: 

CNS(=O)(=O)c1nn2c(n1)ccnc2 

Associated ECOSAR Class(s): 

Other ECOSAR classes containing a fused triazole ring: 

Benzotriazoles - a 1,2,3-triazole ring fused to another aromatic ring 

ECOSAR classes containing a non-fused triazole ring: 

Triazoles (Non-Fused) - a structure containing either a 1,2,4-triazole, 1,2,3-triazole or 

1,3,4-triazole ring that is not fused to another aromatic ring. 

Examples Triazole Pyrimidines: 

CAS No. Name SMILES Notation 

145701-21-9 Diclosulam 

c1(n2c(cc(n1)F)nc(n2)S(=O)(=O)Nc1c(cccc1Cl)Cl)O

CC 

 98967-40-9 Flumetsulam Fc1cccc(F)c1NS(=O)(=O)c2nc3nc(C)ccn3n2 
ECOSAR Class Definition: Triazoles (Non-Fused)

The Triazoles (Non-Fused) class is identified by the following structures: 

 

N

N

N

N

N

N

N

N N

In the current ECOSAR program, the Triazoles (Non-Fused) structure identification 

meets the following criteria: 

(1) The ECOSAR program identifies a five-member aromatic ring containing two carbon 

atoms and three nitrogen atoms (a triazole ring). 

 (2) The position of the nitrogen atoms in the ring does not matter. The ring can be 

either 1,2,4-triazole, 1,2,3-triazole or 1,3,4-triazole. 

 (3) The triazole ring cannot be fused to additional aromatic ring(s). 

SMILES String Identifications: 

n1cncn1 ... equivalent to: [nH]1cncn1 

n1ccnn1 ... equivalent to: [nH]1ccnn1 

n1cnnc1 ... equivalent to: [nH]1cnnc1 

N1C=NC=N1 

N1C=CN=N1 

N1C=NN=C1 

Associated ECOSAR Class(s): 

None specific to a non-fused triazole ring. Other ECOSAR classes containing a fused 

triazole ring: 

Benzotriazoles - a 1,2,3-triazole ring fused to another aromatic ring 

Triazole Pyrimidines - a triazole-pyrimidine fused ring structure 

Examples Triazoles (Non-Fused): 

CAS No. Name SMILES Notation 

288-88-0 1H-1,2,4-Triazole n1ncnc1 

76674-21-0 Flutriafol n1cncn1CC(O)(c2ccc(F)cc2)c3ccccc3F 

43121-43-3 Triadimefon CC(C)(C)C(=O)C(Oc1ccc(Cl)cc1)n2cncn2 

83657-22-1 Uniconazole c1ncnn1C(C(O)C(C)(C)C)=Cc2ccc(Cl)cc2 

79983-71-4 Hexaconazole Clc2c(ccc(c2)Cl)C(Cn1ncnc1)(O)CCCC 

85509-19-9 Flusilazole c1cc(F)ccc1[Si](C)(c2ccc(F)cc2)Cn3ncnc3
ECOSAR Class Definition: Vinyl/Allyl Alcohols

The Vinyl/Allyl Alcohols class is identified by the following structures: 

 C

C

OH C

C

C

OH

In the current ECOSAR program, the Vinyl/Allyl Alcohols structure meets the following 

criteria: 

(1) A hydroxy group (-OH) is attached to a vinyl group (-C=C) or allyl group (-C-C=C). 

The single-bonded carbon on the allyl group is an alkyl carbon. 

SMILES String Identifications: 

C=CO ... equivalent to: C=COH or C=CO[H] 

C=CCO ... equivalent to: C=CCOH or C=CCO[H] 

Associated ECOSAR Class(s): 

None specifically. 

ECOSAR includes a variety of alcohol classes (such as Propargyl Alcohols, Benzyl 

Alcohols, Nitro Alcohols) and Vinyl/Allyl classes. 

Example Vinyl/Allyl Alcohols: 

CAS No. Name SMILES Notation 

107-18-6 Allyl alcohol C=CCO 

924-41-4 1,5-Hexadien-3-ol OC(CC=C)C=C 

4798-44-1 1-Hexen-3-ol OC(C=C)CCC 

66-76-2 Dicumarol O=C1Oc2ccccc2C(O)=C1CC3=C(O)c4ccccc4OC3=O

50-81-7 L-Ascorbic acid O1C(=O)C(O)=C(O)C1C(O)CO 

557-75-5 Vinyl alcohol C=CO 
ECOSAR Class Definition: Vinyl/Allyl Aldehydes

The Vinyl/Allyl Aldehydes class is identified by the following structures: 

 H

C

C

O

C

H

C

C

O

C

C H

C

C

O

C

The Vinyl/Allyl Aldehyde class is identified when an aldehyde group (HC(=O)-) is 

attached to a vinyl (C=C), allyl (-C-C=C) or acetylenic (-C#C) group. 

In the current ECOSAR program, if a structure contains more than one Vinyl/Allyll 

Aldehyde group (or one Vinyl/Allyl Aldehyde group plus additional Aldehyde functional 

groups), the structure will be classified as both Vinyl/Allyl Aldehydes and Aldehydes 

(Poly). Structures classified as Vinyl/Allyl Aldehydes are not classified as Aldehydes 

(Mono). 

SMILES String Identifications: 

O=CC=C ... equivalent to: O=C(H)C=C 

O=CCC=C ... equivalent to: O=C(H)CC=C 

O=CC#C ... equivalent to: O=C(H)C#C 

Associated ECOSAR Class(s): 

Aldehydes (Mono) - If the attachment to the aldehyde group (HC(=O)-) is an alkyl 

carbon, aromatic carbon, carbonyl or hydrogen, the structure will be classified as an 

Aldehyde (Mono) 

Aldehydes (Poly) - the structure must contain two or more aldehyde functional groups. 

In the current ECOSAR program, a structure can be classified as both Aldehydes (Poly) 

and Vinyl/Allyl Aldehydes. 

Example Vinyl/Allyl Aldehydes: 

CAS No. Name SMILES Notation 

107-02-8 Acrolein [or 2-Propenal] O=CC=C 

5392-40-5 2,6-Octadienal, 3,7-dimethyl- O=CC=C(CCC=C(C)C)C 

6203-18-5 4-Dimethylaminocinnamaldehyde O=CC=Cc(ccc(N(C)C)c1)c1 

7319-38-2 3-Butenal O=CCC=C 

 
ECOSAR Class Definition: Vinyl/Allyl Esters

The Vinyl/Allyl Esters class is identified by the following structures: 

C

C

O

O

Vinyl or Allyl

C

C

S

O

Vinyl or Allyl

C

C

O

S

Vinyl or Allyl

C

C

S

S

Vinyl or Allyl

O

C

O

O

Vinyl or Allyl

S

C

S

S

Vinyl or Allyl

Vinyl/Allyl - Vinyl (-C=C) and Allyl (-C-C=C) 

In the current ECOSAR program, the Vinyl/Allyl Esters class meets the criteria as 

shown in the structure above and the following: 

(1) the carbon atom (to which the carbonyl or thiocarbonyl is attached) must be an alkyl, 

olefinic, acetylenic or aromatic carbon. 

(2) carbonate and thiocarbonate esters can also be identified as Vinyl/Allyl Esters. 

SMILES String Identifications: 

CC(=O)OC=C CC(=O)OCC=C 

CC(=S)OC=C CC(=S)OCC=C 

CC(=O)SC=C CC(=O)SCC=C 

CC(=S)SC=C CC(=S)SCC=C 

COC(=O)OC=C COC(=O)OCC=C 

Associated ECOSAR Class(s): 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to include the Ester class when 

the Vinyl/Allyl Esters class is reported. 

Example Vinyl/Allyl Esters: 

CAS No. Name SMILES Notation 

105-38-4 Vinyl propionate O=C(OC=C)CC 

123-20-6 Vinyl butyrate CCCC(=O)OC=C 

123-68-2 Allyl caproate O=C(OCC=C)CCCCC 
ECOSAR Class Definition: Vinyl/Allyl Ethers

The Vinyl/Allyl Ethers class is identified by the following structures: 

 

C

O

C

C C

O

C

C

C

The ether function is identified as an aliphatic oxygen attached to two carbons atoms 

(alkyl, olefinic, acetylenic or aromatic carbon). 

In the current ECOSAR program, the Vinyl/Allyl Ether structure meets the following 

criteria: 

(1) one (or both) sides of the ether function is a vinyl (-C=C) or allyl (-C-C=C) group. 

SMILES String Identifications: 

COC=C 

COCC=C 

C=COC=C 

C=COCC=C 

C#COC=C 

C#COCC=C 

c1ccccc1OC=C 

c1ccccc1OCC=C 

Associated ECOSAR Class(s): 

None specifically. 

The ether function also occurs in the Halo Ether class. 

Example Vinyl/Allyl Ethers: 

CAS No. Name SMILES Notation 

107-25-5 Methyl vinyl ether COC=C 

557-40-4 Allyl ether O(CC=C)CC=C 

83-79-4 Rotenone COc5cc4OCC3Oc2c1CC(Oc1ccc2C(=O)C3c4cc5OC)C(C)=C 

57-24-9 Strychnidin-10-one O=C(N(c(c(C1(C(N(C2)CC(C3C4C5OC6)=C6)C3)C2)ccc7)c7)C14)C5
ECOSAR Class Definition: Vinyl/Allyl Halides

The Vinyl/Allyl Halides class is identified by the following structures: 

 C

C

{Br,Cl,I} C

C

C {Br,Cl,I} C

C

{Br,Cl,I}

In the current ECOSAR program, the Vinyl/Allyl Halides structure must meet the 

following criteria: 

(1) A halogen atom (bromine, chlorine or iodine; fluorine excluded) is attached to a vinyl 

group (-C=C), allyl group (-C-C=C) or acetylenic group (-C#C). The single-bonded 

carbon on the allyl group is an alkyl carbon. 

Notation: Fluorine has been excluded from this class. In addition, the acetylenic group 

(which was included in the original program code) is still included. 

SMILES String Identifications: 

C=CBr or C=CCl or C=CI 

C=CCBr or C=CCCl or C=CCI 

C#CBr or C#CCl or C#CI 

Associated ECOSAR Class(s): 

Propargyl Halides - Vinyl/Allyl Halides identified with the acetylenic group (-C#C) are 

additionally classified as Propargyl Halides by ECOSAR. 

ECOSAR includes a variety of Vinyl/Allyl classes and Halo-Halide classes. 

Example Vinyl/Allyl Halides: 

CAS No. Name SMILES Notation 

107-05-1 Allyl Chloride C=CCCl 

79-01-6 Trichloroethylene C(=CCl)(Cl)Cl 

591-97-9 2-Butene, 1-chloro- C(=CC)CCl 

78-88-6 1-Propene, 2,3-dichloro- C(=C)(CCl)Cl 

127-18-4 Tetrachloroethylene C(=C(Cl)Cl)(Cl)Cl 
ECOSAR Class Definition: Vinyl/Allyl Ketones

Vinyl/Allyl Ketones are identified by the following structures: 

 C C

C

O

C C

O

C

To be classified as Vinyl/Allyl Ketones by the current ECOSAR program, the structure 

must meet the following criteria: 

(1) The basic ketone fragment is identified as carbonyl group attached to carbon atoms 

on both sides where the carbon atoms must be an alkyl, olefinic, acetylenic or aromatic 

carbon. To be classified as Vinyl/Allyl, one or both attachments to the carbonyl must be 

a vinyl group (-C=C) or an allyl group (-C-C=C). 

(2) The vinyl/allyl ketone fragment can be either cyclic or acyclic. 

SMILES String Identifications: 

CC(=O)C=C 

CC(=O)CC=C 

C=CC(=O)C=C 

C=CC(=O)CC=C 

C#CC(=O)C=C 

C#CC(=O)CC=C 

c1ccccc1C(=O)C=C 

c1ccccc1C(=O)CC=C 

Associated ECOSAR Class(s): 

In addition to the Vinyl/Allyl Ketones class, the ECOSAR program will add any of the 

classes below to the to the program output if identified in a structure. 

Diketones - Diketones have two ketone functions at 1,3-positions. A structure can be 

classified as both Diketones and Vinyl/Allyl Ketones (e.g. SMILES: 

C=CC(=O)CC(=O)C). 

Benzyl Ketones - a ketone with -C-aromatic ring attachment to the carbonyl 

Halo Ketones (2 Free H) - a ketone with a -CH2-Halogen attachment to a carbon atom 

at the alpha- or beta-position to the carbonyl 

Halo Ketones (0-1 Free H) - a ketone with a -CH-Halogen (or -C-Halogen) attachment 

to a carbon atom at the alpha- or beta-position to the carbonyl 

Example Vinyl/Allyl Ketones: 

CAS No. Name SMILES Notation 

78-94-4 Vinyl methyl ketone C=CC(=O)C 

78-59-1 Isophorone O=C(C=C(CC1(C)C)C)C1 

141-79-7 Mesityl oxide O=C(C=C(C)C)C 
ECOSAR Class Definition: Vinyl/Allyl Nitriles

The Vinyl/Allyl Nitriles class is identified by the following structures: 

 C

N

C

N

In the current ECOSAR program, the Vinyl/Allyl Nitrile structure must meet one of the 

following criteria: 

(1) A nitrile group (carbon triple-bonded to nitrogen; SMILES of C#N) is attached to a 

vinyl group (-C=C) or an allyl group (-C-C=C). 

(2) Two or more nitrile groups attached to the same alkyl carbon. 

SMILES String Identifications: 

C=CC#N 

C=CCC#N 

Associated ECOSAR Class(s): 

Nitriles, Polyaliphatic - Two or more nitrile groups are attached to aliphatic atoms in the 

whole structure. When two or more nitrile groups are attached to the same alkyl or 

olefinic carbon, the structure will be classified as both Vinyl/Allyl Nitriles and Nitriles, 

Polyaliphatic. 

Other SAR Nitrile classes include: Azonitriles, Halo Nitriles, Nitrile Esters, Nitrile AlphaOH, and Phthalonitriles. 

Example Vinyl/Allyl Nitriles: 

CAS No. Name SMILES Notation 

109-75-1 Allyl cyanide N#CCC=C 

107-13-1 2-Propenenitrile N#CC=C 
Vinyl/Allyl Pyrazoles/Pyrroles

The Vinyl/Allyl Pyrazoles/Pyrroles class is identified by the following structures: 

 

N

R

N

N

R

R = -C=C (vinyl) or –CC=C (allyl) 

In the current ECOSAR program, the Vinyl/Allyl Pyrazoles/Pyrroles structure 

identification meets the following criteria: 

(1) The ECOSAR program looks for an aromatic ring with the following characteristics: 

(a) a five-member aromatic ring containing four carbon atoms and one nitrogen atom (a 

pyrrole ring) or (b) a five-member aromatic ring containing three carbon atoms and two 

nitrogen atoms that are adjacent to each other (a pyrazole ring). 

 (2) The [nH] in either the pyrazole ring or pyrrole ring can have the hydrogen atom 

attachment replaced by another atom. 

 (3) Either ring can be fused to additional aromatic rings. 

SMILES String Identifications: 

Pyrrole: 

 C=Cn1cccc1 

 C=CCn1cccc1 

Pyrazole: 

 C=Cn1nccc1 

 C=CCn1nccc1 

Associated ECOSAR Class(s): 

Pyrazoles/Pyrroles – A five-membered aromatic ring containing either one or two 

nitrogens. 

Example Vinyl/Allyl Pyrazoles/Pyrroles: 

CAS No. Name SMILES Notation 

288-13-1 1H-Pyrazole N1N=CC=C1 

109-97-7 1H-Pyrrole C1=CC=CN1 

122453-73-0 Chlorfenapyr N#Cc1c(Br)c(C(F)(F)F)n(COCC)c1c2ccc(Cl)cc2 

71561-11-0 Pyrazoxyfen Clc1cc(Cl)ccc1C(=O)c2c(C)nn(C)c2OCC(=O)c3ccccc3 

82692-44-2 Benzofenap c1cc(C)ccc1C(=O)COc2n(C)nc(C)c2C(=O)c3ccc(Cl)c(C)c3Cl
ECOSAR Class Definition: Vinyl/Allyl Sulfones

The Vinyl/Allyl Sulfones class is identified by the following structures: 

 C S C

O

C

C S C

O

C

O

C S C

O

C

O

C

C S C

O

C C

In the current ECOSAR program, the Vinyl/Allyl Sulfones structure must meet one of the 

following criteria: 

(1) A sulfone group [S(=O)(=O)] is attached to an alkyl, olefinic, acetylenic or aromatic 

carbon atom and the sulfone group is attached to a vinyl (-C=C) or allyl (-C-C=C) 

group. 

 (2) A sulfoxide group [-S(=O)-] is attached to an alkyl, olefinic, acetylenic or aromatic 

carbon atom and the sulfoxide group is attached to a vinyl (-C=C) or allyl (-C-C=C) 

group. 

SMILES String Identifications: 

C=CS(=O)C

C=CCS(=O)C

C=CS(=O)(=O)C

C=CCS(=O)(=O)C

 ... (bolded C (carbon atom) can be alkyl (C), olefinic (C=C), acetylenic (C#C) or 

aromatic (c))

Associated ECOSAR Class(s): 

None specifically. 

The Sulfonyl Ureas class contains the -N-C(=O)-N-S(=O)(=O)- function which is the only 

other ECOSAR class containing the sulfone group. 

The Amides class contains a sulfoxide group as in: -N-S(=O)- 

Example Vinyl/Allyl Sulfones: 

CAS No. Name SMILES Notation 

3680-02-2 Methyl vinyl sufone CS(=O)(=O)C=C 

16212-05-8 Allyl phenyl sulfone S(=O)(=O)(c1ccccc1)CC=C 

77-79-2 Thiophene, 2,5-dihydro-, 1,1-dioxide O=S(=O)(CC=C1)C1 
ECOSAR Class Definition: Diazoniums, Aromatic

The Diazoniums, Aromatic class is identified by the following structure: 

 Aromatic Ring [N+] N

An aromatic ring is attached to a charged nitrogen that is triple bonded to another 

nitrogen. The SMILES notation representing a diazonium function required by 

ECOSAR is either of the following: 

(1) [N+]#N ... as in c1ccccc1[N+]#N 

(2) N#N ... as in c1ccccc1N#N 

SMILES String Identifications: 

N#N 

[N+]#N 

 ... (requires aromatic attachment) 

Associated ECOSAR Class(s): 

Diazoniums - the Aromatic Ring attachment to the charged nitrogen atom is replaced by 

an aliphatic atom attachment. 

Azides - the Aromatic Ring attachment is replaced by a nitrogen double bonded to the 

charged nitrogen (which will no longer be charged). 

Example Diazoniums, Aromatic: 

CAS No. Name SMILES Notation 

6087-56-5 Benzenediazonium,4-(dimethylamino)- c1cc(N(C)C)ccc1[N+]#N 

52572-38-0 4-Diazo-2-methylpyrrolidinobenzene ZnCl N1(c2c(C)cc([N+]#N)cc2)CCCC1 
Diketones

The Diketones class is identified by the following structure: 

To be classified as Diketones by the current ECOSAR program, the structure must meet 

the following criteria: 

(1) The diketone fragment must be a 1,3-diketone. The two carbonyl groups must be 

separated by one carbon atom; this carbon atom must be an alkyl or olefinic carbon. 

The carbon atoms on the ends of the diketone fragment must be alkyl, olefinic, 

acetylenic or aromatic carbons. 

(2) The diketone fragment must be acyclic. The carbon atom in the middle cannot 

occur in a ring. 

SMILES String Identifications: 

CC(=O)CC(=O)C 

CC(=O)CC(=O)C=C 

CC(=O)CC(=O)C#C 

CC(=O)CC(=O)c ... (aromatic attachment) ... full ring: CC(=O)CC(=O)c1ccccc1 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

In addition to the Diketones class, the ECOSAR program will add any of the classes 

below to the to the program output if identified in a structure. 

Vinyl/Allyl Ketones - a ketone with a vinyl (-C=C) or allyl (-C-C=C) attachment to the 

carbonyl 

Benzyl Ketones - a ketone with -C-aromatic ring attachment to the carbonyl 

Halo Ketones (2 Free H) - a ketone with a -CH2-Halogen attachment to a carbon atom 

at the alpha- or beta-position to the carbonyl 

Halo Ketones (0-1 Free H) - a ketone with a -CH-Halogen (or -C-Halogen) attachment 

to a carbon atom at the alpha- or beta-position to the carbonyl 

Example Diketones: 

CAS No. Name SMILES Notation

123‐54‐6 2,4‐Pentanedione CC(=O)CC(=O)C

3002‐24‐2 2,4‐Hexanedione CC(=O)CC(=O)CC

69725‐37‐7 3,5‐Octanedione, 2,2,7‐trimethyl‐  O=C(C(C)(C)C)CC(=O)CC(C)C
ECOSAR Class Definition: Epoxides, Mono

The Epoxides, Mono class is identified by the following ring structure: 

 

O

ECOSAR identifies an Epoxide ring as follows: 

(1) a three member aliphatic ring consisting of one aliphatic oxygen and two aliphatic 

carbons 

(2) the carbon atoms cannot have double or triple bonds (excludes olefinic and 

acetylenic carbons or carbons with bonds such as C=N) 

(3) the Epoxide ring can be part of a fused-ring system 

To be classified as Epoxides, Mono, a structure must contain only one epoxide ring. 

SMILES String Identifications: 

O1CC1 ... equivalent to: C1OC1 or C(O1)C1 

Associated ECOSAR Class(s): 

Epoxides, Poly - if a structure contains two or more epoxide rings, it will be classified as 

Epoxides, Poly instead of Epoxides, Mono 

Epoxides, Mono Acid Substituted - contains one epoxide ring plus an acid function. 

Structures classified as Epoxides, Mono Acid Substituted are not additionally classified 

as Epoxides, Mono 

Halo Epoxides - structures containing an epoxide ring and a halogen attached directly to 

the ring or on an alkyl carbon attached to the ring). In the current ECOSAR program, 

structures identified as Halo Epoxides are not additionally classified as Epoxides, Mono. 

Example Epoxides, Mono: 

CAS No. Name SMILES Notation 

75-21-8 Ethylene oxide O1CC1 

3266-23-7 Oxirane, 2,3-dimethyl- O(C1C)C1C 

122-60-1 Phenyl glycidyl ether O1CC1COc2ccccc2 

72-20-8 Endrin ClC4=C(Cl)C5(Cl)C3C1CC(C2OC12)C3C4(Cl)C5(Cl)Cl 

 
ECOSAR Class Definition: Epoxides, Poly

The Epoxides, Poly class is identified by more than one occurence the following ring 

structure: 

 

O

ECOSAR identifies an Epoxide ring as follows: 

(1) a three member aliphatic ring consisting of one aliphatic oxygen and two aliphatic 

carbons 

(2) the carbon atoms cannot have double or triple bonds (excludes olefinic and 

acetylenic carbons or carbons with bonds such as C=N) 

(3) the Epoxide ring can be part of a fused-ring system 

To be classified as Epoxides, Poly, a structure must contain two or more epoxide rings. 

SMILES String Identifications: 

O1CC1 ... equivalent to: C1OC1 or C(O1)C1 

Associated ECOSAR Class(s): 

Epoxides, Mono - if a structure contains only one epoxide ring, it will be classified as 

Epoxides, Mono instead of Epoxides, Poly 

Epoxides, Mono Acid Substituted - contains one epoxide ring and an acid function 

Halo Epoxides - structures containing an epoxide ring and a halogen attached directly to 

the ring or on an alkyl carbon attached to the ring). In the current ECOSAR program, 

structures can be classified as both Halo Epoxides and Epoxides, Poly. 

Example Epoxides, Poly: 

CAS No. Name SMILES Notation 

3568-29-4 Glycerin, 1,3-diglycidyl ether O(C1COCC(O)COCC(O2)C2)C1 

54208-63-8 Bisphenol, diglycidyl ether O(C1COc(c(ccc2)Cc(c(OCC(O3)C3)ccc4)c4)c2)C1 

 
ECOSAR Class Definition: Esters

ECOSAR includes a variety of structures identified in the Esters class. The various 

structures identified as Esters are listed below. 

Esters (as Formic Acid Esters)

Formic acid and thioformic acid esters are identified by the following structures 

 H

C

O

O

C H

C

S

O

C

The carbon must be alkyl, olefinic, acetylenic or aromatic carbon. 

SMILES String Identifications: 

O=COC ... equivalent to: O=C(H)OC or O=C([H])OC 

O=CSC ... equivalent to: O=C(H)SC or O=C([H])SC 

 ... (the carbon must be alkyl, olefinic, acetylenic or aromatic): 

O=COC=C 

O=COC#C 

O=COc 

Esters (as Carboxylic Acid Esters)

Carboxylic acid esters and thiocarboxylic acid esters [-C(=O)-S-] are identified by the 

following structures: 

 R1

C

O

O

R2 R1

C

S

O

R2

R1 - must be alkyl, acetylenic, or aromatic carbon or a carbonyl;. 

R2 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included); 

silicon allowed if attached to oxygen. 

Notation: If R1 is olefinic (-C=C), ECOSAR will classify the structure as an Acrylate (or 

Methacrylate), and the Esters class will be excluded from the ECOSAR report. 

SMILES String Identifications: 

C(=O)O or C(=O)S 

 ... (attachments as defined above) 

Esters (as Carbonates and Thiocarbonates)

Carbonic acid esters are identified by the following structures: 
 O

C

O

O

R R S

C

S

O

R R

O

C

S

O

R R

R - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included); silicon 

allowed if attached to oxygen. 

SMILES String Identifications: 

OC(=O)O or SC(=O)S or OC(=O)S 

 ... (attachments as defined above)

Esters (as Carbamic Acid Esters)

Carbamic acid esters are identified by the following structures: 

 N

C

O

O

R R1

N

C

S

O

R R1

R1 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included); 

silicon allowed if attached to oxygen. 

R - attachments to the nitrogen can be anything 

Notation: ECOSAR will classify the structure as a Carbamate Ester or Thiocarbamate. 

SMILES String Identifications: 

NC(=O)O or NC(=O)S {equivalent to: N(H)(H)C(=O)O or N(H)(H)C(=O)S 

 ... (attachments as defined above) 

Esters (as Carbamimidic Acid Esters)

Carbamimidic acid esters are identified by the following structures: 

 N

C

O

NH

R1 R2

N

C

O

N

R2

R3

R1

R1 and R3 - can be anything (no exclusions). 

R2 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). 

SMILES String Identifications: 

NC(=N)O 

 ... (attachments as defined above) 
Esters (as Thioformic Acid Esters)

 H

C

O

S

R H

C

S

S

R

R - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). 

SMILES String Identifications: 

S=CO or S=CS {equivalent to: S=C(H)O or S=C(H)S 

 ... (attachments as defined above) 

Esters (as Thiocarboxylic Acid Esters)

 R1

C

O

S

R2 R1

C

S

S

R2

R1 - must be alkyl, acetylenic, or aromatic carbon or a carbonyl. 

R2 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). 

Notation: If R1 is olefinic (-C=C), ECOSAR will classify the structure as an Acrylate (or 

Methacrylate) in addition to the Esters class ... Note: this differs from the Carboxylic 

acid esters which are excluded from the ECOSAR report when Acrylates (or 

Methacrylates) are identified. 

SMILES String Identifications: 

C(=S)O or C(=S)S 

 ... (attachments as defined above) 

Esters (as Thiocarbamic Acid Esters)

Thiocarbamic acid esters are identified by the following structures: 

 H2N

C

O

S

R

H2N

C

S

S

R

R - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). 

Notation: the amine (-NH2) must be -NH2 ... if a hydrogen is substituted by a carbon, 

ECOSAR will classify the structure as a Thiocarbamate or Dithiocarbamate, and the 

Esters class will be excluded from the ECOSAR report. 

SMILES String Identifications: 

NC(=S)O or NC(=S)S {equivalent to: N(H)(H)C(=S)O or N(H)(H)C(=S)S 

 ... (attachments as defined above) 
Esters (as Thiocarbonates [C(=S)] )

Thiocarbonate acid esters are identified by the following structures: 

 O

C

O

S

R R S

C

S

S

R R

O

C

S

S

R R

R - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). In 

addition, R can be an aromatic nitrogen. 

Notation: the carbonate and thiocarbonate Esters (where the carbonyl is C(=O) instead 

of C(=S)), do not allow the R attachment to be an aromatic nitrogen. 

SMILES String Identifications: 

OC(=S)O or SC(=S)S or OC(=S)S 

 ... (attachments as defined above) 

Esters (as Phosphate-type)

Phosphate esters are identified by the following structures: 

 

O P R3

O

R2

R1 S P R3

O

R2

R4

R1 - can be alkyl carbon, olefinic carbon, acetylenic carbon, aromatic carbon, a 

carbonyl, phosphorus, sulfur, oxygen or nitrogen. 

R2 and R3 - can be anything except a hydroxy group (-OH). 

R4 - can be alkyl carbon, olefinic carbon, acetylenic carbon, aromatic carbon, or 

phosphorus 

Notation: Esters (Phosphates) are a separate ECOSAR class. When identified, 

ECOSAR reports both Esters and Esters (Phosphates). 

SMILES String Identifications: 

P(=O)O or P(=O)S 

 ... (attachments as defined above) 

Esters (as Thiophosphate-type)

Thiophosphate esters are identified by the following structure: 

 

S P R3

S

R2

R1
R1 - can be alkyl carbon, olefinic carbon, acetylenic carbon, aromatic carbon, or 

phosphorus. 

R2 and R3 - can be anything except oxygen. 

Notation: Esters, Monothiophosphates and Esters, Dithiophosphates are separate 

ECOSAR classes from Esters. When either of the two separate classes are identified 

ECOSAR excludes the Esters identification. 

SMILES String Identifications: 

P(=S)S 

 ... (attachments as defined above) 

Esters (as Sulfuric Acid or Sulfonate Esters)

Sulfonate and sulfuric acid esters are identified by the following structures: 

 

O S O

O

O

R1 R1 R2 S O

O

O

R1

R1 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). In 

addition, R1 can be silicon. 

R2 - must be alkyl, olefinic, acetylenic or aromatic carbon (carbonyl not included). 

SMILES String Identifications: 

OS(=O)(=O)O or S(=O)(=O)O 

 ... (attachments as defined above) 

Associated ECOSAR Class(s): 

Other ester classes reported in conjunction with the Esters class by ECOSAR: 

Esters (Phosphates) 

Vinyl/Allyl Esters 

Ester classes that explicitly exclude the Esters class or ECOSAR generally does not 

report both if both are identified: 

 Carbamate Esters 

 Oxime Carbamate Esters 

 Thiocarbamates ... (includes a variety of Thiocarbamate classes ... depending 

on structure, ECOSAR may report both). 

 Beta-Halo Esters 

 Propargyl Carbamates 

 Acrylates 

 Methacrylates 

 Esters (imidic) 

 Esters, Monothiophosphates 

 Esters, (Phosphinates) 

 Esters, Dithiophosphates 
 

Example Esters: 

CAS No. Name SMILES Notation 

 Formates 

107-31-3 Methyl formate O=COC 

 Carboxylates 

141-78-6 Ethyl acetate CC(=O)OCC 

138-22-7 Butyl lactate O=C(OCCCC)C(O)C 

131-11-3 Dimethyl phthalate O=C(OC)c(c(ccc1)C(=O)OC)c1 

 Carbonates 

105-58-8 Diethyl carbonate O=C(OCC)OCC 

 Carbamic Acid Esters 

51-79-6 Carbamic acid, ethyl ester O=C(OCC)N 

 Carbamimidic Acid Esters 

64037-23-6 Benzoxazoline, 5-chloro-2-imino-3-methyl- c12N(C)C(=N)Oc1ccc(Cl)c2 

 Thioformic Acid Esters 

 O-Methyl thioformate S=COC 

 Thiocarboxylic Acid Esters 

2168-84-5 Methyl dithioacetate CC(=S)SC 

 Thiocarbonates 

822-38-8 1,3-Dithiolane-2-thione S(C(SC1)=S)C1 

 Phosphates 

78-40-0 Triethyl phosphate O=P(OCC)(OCC)OCC 

62-73-7 Dichlorvos O=P(OC)(OC)OC=C(Cl)Cl 

 Thiophosphates 

996-05-4 Phosphonotrithioic acid, methyl-,dipropyl CCCSP(=S)(C)SCCC 

 Sulfonates & Sulfuric acid esters 

62-50-0 Methanesulfonic acid, ethyl ester O=S(=O)(OCC)C 

515-46-8 Ethylbenzene sulfonate S(=O)(=O)(OCC)c(ccc1)cc1 

64-67-5 Sulfuric acid, diethyl ester O=S(=O)(OCC)OCC 
ECOSAR Class Definition: Esters, Dithiophosphates

The Esters, Dithiophosphates class is identified by the following structure: 

 

R1 P O

S

R3

S

R2

R1 - can be anything except sulfur (additional sulfurs change the “dithio” class 

identification). 

R2 - must be hydrogen, carbon (alkyl, olefinic, acetylenic, aromatic, or carbonyl) or 

phosphorus. 

R3 - must be hydrogen, carbon (alkyl, olefinic, acetylenic, aromatic, or carbonyl), 

nitrogen, oxygen, phosphorus, or sulfur. 

In the current ECOSAR program, the Esters, Dithiophosphates class meets the criteria 

as shown in the structures above. 

Notation: Currently, ECOSAR does not identify compounds having a structure such as 

P(=O)(S)(S) as a possible Dithiophosphate. 

SMILES String Identifications: 

S=P(S)O 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Esters, Monothiophosphates - contains the P(=S)-O- structure (only one sulfur bonded 

to the phosphorus). 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to exclude the Ester class 

when the Esters, Dithiophosphates class is reported. 

Other phosphorus esters classes in ECOSAR include Esters (Phosphates) and Esters 

(Phosphinates). 

Example Esters, Dithiophosphates: 

CAS No. Name SMILES Notation 

000060-51-5 Dimethoate O=C(NC)CSP(OC)(OC)=S 

121-75-5 Malathion CCOC(=O)CC(SP(=S)(OC)OC)C(=O)OCC 

298-04-4 Disulfoton CCOP(=S)(OCC)SCCSCC 

13071-79-9 Terbufos CCOP(=S)(OCC)SCSC(C)(C)C 
ECOSAR Class Definition: Esters, Monothiophosphates

The Esters, Monothiophosphates class is identified by the following structure: 

 

R1 P O

S

R3

R2

R1 and R2 - can be anything except sulfur (additional sulfurs change the “monothio” 

class identification). 

R3 - must be hydrogen, carbon (alkyl, olefinic, acetylenic, aromatic, or carbonyl), 

nitrogen, oxygen, phosphorus, or sulfur. 

In the current ECOSAR program, the Esters, Monothiophosphates class meets the 

criteria as shown in the structures above. 

Notation: Currently, ECOSAR does not identify compounds having a structure such as 

P(=O)S as a possible Monothiophosphate. 

SMILES String Identifications: 

S=P(O) 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Esters, Dithiophosphates - contains the P(=S)-S- structure. 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to exclude the Ester class 

when the Esters, Monothiophosphates class is reported. 

Other phosphorus esters classes in ECOSAR include Esters (Phosphates) and Esters 

(Phosphinates). 

Example Esters, Monothiophosphates: 

CAS No. Name SMILES Notation 

115-90-2 Fensulfothion CCOP(=S)(OCC)Oc1ccc(cc1)S(C)=O 

8000-97-3 Demeton S=P(OCC)(OCC)OCCSCC 

333-41-5 Diazinon O(P(OCC)(Oc(nc(nc1C)C(C)C)c1)=S)CC 

2921-88-2 Chlorpyrifos CCOP(=S)(OCC)Oc1nc(Cl)c(Cl)cc1Cl 

2104-64-5 EPN CCOP(=S)(Oc1ccc(cc1)N(=O)=O)c2ccccc2 
ECOSAR Class Definition: Esters, Phosphates

The Esters, Phosphates class is identified by the following structures: 

 

O P R3

O

R2

R1 S P R3

O

R2

R4

R1 - can be alkyl carbon, olefinic carbon, acetylenic carbon, aromatic carbon, a 

carbonyl, phosphorus, sulfur, oxygen or nitrogen. 

R2 and R3 - can be anything except a hydroxy group (-OH. 

R4 - can be alkyl carbon, olefinic carbon, acetylenic carbon, aromatic carbon, or 

phosphorus. 

In the current ECOSAR program, the Esters, Phosphates class meets the criteria as 

shown in the structures above. 

SMILES String Identifications: 

O=P(O) 

O=P(S) 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to report the Ester class 

whenever the Esters, Phosphates class is reported 

Other phosphorus esters classes in ECOSAR include Esters, Monothiophosphates, 

Esters (Phosphinates) and Esters, Dithiophosphates ... the Esters, Phosphates class 

structure is not identified when these classes are identified. 

Example Esters, Phosphates: 

CAS No. Name SMILES Notation 

512-56-1 Trimethyl phosphate O=P(OC)(OC)OC 

115-96-8 Tris(beta-chloroethyl)phosphate O=P(OCCCl)(OCCCl)OCCCl 

1080-32-6 Diethyl benzylphosphonate O=P(OCC)(OCC)Cc(cccc1)c1 

126-72-7 Tris(2,3-dibromopropyl)phosphate O=P(OCC(Br)CBr)(OCC(Br)CBr)OCC(Br)CBr
ECOSAR Class Definition: Esters (Phosphinates)

The Esters (Phosphinates) class is identified by the following structure: 

 

R1 P O

O

R2

Carbon

R1 - can be anything except oxygen. 

R2 - must be hydrogen, carbon (alkyl, olefinic, acetylenic, aromatic, or carbonyl), 

nitrogen, oxygen, phosphorus, or sulfur. 

Carbon - alkyl, olefinic, acetylenic, or aromatic carbon (not including carbonyl). 

In the current ECOSAR program, the Esters (Phosphinates) class meets the criteria as 

shown in the structure above. 

SMILES String Identifications: 

O=P(O)C 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to exclude the Ester class 

when the Esters (Phosphinates) class is reported. 

Other phosphorus esters classes in ECOSAR include Esters (Phosphates). 

Example Esters (Phosphinates): 

CAS No. Name SMILES Notation 

96-64-0 Soman CC(OP(C)(F)=O)C(C)(C)C 

107-44-8 Sarin CC(C)OP(C)(F)=O 

1224-64-2 Nibufin N(=O)(=O)c1ccc(OP(=O)(CCCC)CCCC)cc1

2511-09-3 Phosphinic acid,phenyl-,ethyl ester O=P(c1ccccc1)OCC 
Haloacetamide: The haloacetamide class is identified by the following structure: 

R1 and R2 - can be anything except a carbonyl group. 

If a carbonyl group is attached at R1 or R2, then ECOSAR will identify the class 

as imides 

In the current ECOSAR program, the haloacetamide structure must meet the following 

criteria: 

The carbonyl group has an aliphatic nitrogen and an alkyl carbon substituent, 

[NC(=O)C] and the alkyl carbon has one or more halogen substituents. 

Notation: Currently, if alkyl carbon has two or more fluorine attachments (and no other 

halogen attachments), the haloacetamide identification is not counted by ECOSAR. 

SMILES String Identifications: 

NC(=O)CBr 

NC(=O)CCl 

NC(=O)CF 

NC(=O)CI 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Example haloacetamide: 

CAS No. Name SMILES Notation 

683-72-7 Acetamide, 2,2-dichloro- O=C(N)C(Cl)Cl 

10222-01-2 Acetamide, 2,2-dibromo-2-cyano- O=C(N)C(C#N)(Br)Br 

15972-60-8 Alachlor CCc1cccc(CC)c1N(COC)C(=O)CCl 
ECOSAR Class Definition: Haloacids

The Haloacid class is identified by the following structures: 

C

C

OH

O

Halogen C

C

OH

O

Halogen

C

C

C

O

O

Halogen { Na, K, Li }

 

In the current ECOSAR program, the Haloacid structure meets the following: 

(1) a carboxylic acid function [-C(=O)-OH] is attached to an alkyl or olefinic carbon 

atom. 

(2) the alkyl or olefinic carbon atom has an attached halogen (bromine, chlorine, 

fluorine or iodine). 

(3) the hydrogen atom in the carboxylic acid function [-C(=O)-OH] can be substituted 

with a sodium, potassium or lithium atom. 

SMILES String Identifications: 

OC(=O)CCl or OC(=O)CBr or OC(=O)CF or OC(=O)CI 

OC(=O)C(Br)=C 

[Na]OC(=O)CBr 

 ... (halogen attachments can be Cl or Br or F or I)

Associated ECOSAR Class(s): 

None specifically. 

Example Haloacids: 

CAS No. Name SMILES Notation 

79-11-8 Monochloroacetic acid O=C(O)CCl 

76-03-9 Trichloroacetic acid O=C(O)C(Cl)(Cl)Cl 

75-99-0 2,2-Dichloropropionic acid O=C(O)C(Cl)(Cl)C 

127-20-9 Dalapon CC(Cl)(Cl)C(O[Na])=O 

 
ECOSAR Class Definition: Halo Alcohols

The Halo Alcohols class is identified by the following example structures: 

 HO

C

{Br,Cl,I} C

HO C

{Br,Cl,I} C

HO C

C {Br,Cl,I}

In the current ECOSAR program, the Halo Alcohols structure meets one of the following 

criteria: 

(1) a single alkyl carbon atom has both an hydroxy attachment (-OH) and a halogen 

attachment. For all criteria here halogens are limited to bromine, chlorine and iodine 

(fluorine is excluded). 

(2) an alkyl carbon is attached to another alkyl carbon (or olefinic carbon). The halogen 

and hydroxy (-OH) are on different carbons. A maximum of three carbon atoms can 

occur between the halogen and hydroxy (-OH). 

SMILES String Identifications: 

OCBr or OCCl or OCI 

OCCBr or OCCCl or OCCI 

OCCCBr or OCCCCl or OCCCI 

 ... initial OC equivalent to: HOC or [H]OC 

Associated ECOSAR Class(s): 

None specifically. 

ECOSAR includes a variety of other classes containing alcohol or halogens, but not in 

combination in the same class. 

Example Halo Alcohols: 

CAS No. Name SMILES Notation 

107-07-3 2-Chloroethanol OCCCl 

627-30-5 1-Propanol, 3-chloro- OCCCCl 

96-13-9 1-Propanol, 2,3-dibromo- OCC(Br)CBr 

115-20-8 Ethanol, 2,2,2-trichloro- OCC(Cl)(Cl)Cl 
Halo Epoxides

The Halo Epoxides class is identified by the occurrence following ring structure(s): 

ECOSAR identifies an Epoxide ring as follows: 

(1) a three member aliphatic ring consisting of one aliphatic oxygen and two aliphatic 

carbons 

(2) the carbon atoms cannot have double or triple bonds (excludes olefinic and 

acetylenic carbons or carbons with bonds such as C=N) 

(3) the Epoxide ring can be part of a fused-ring system 

In addition to one or more epoxide rings, to be classified as Halo Epoxides, a structure 

must contain: a halogen atom (Br, Cl, F, I) attached directly to an epoxide ring or a 

halogen atom (Br, Cl, F, I) attached to an alkyl carbon that is attached directly to an 

epoxide ring. Halogen atoms further removed from the epoxide ring are not currently 

included in the Halo Epoxide identification. 

SMILES String Identifications: 

O1CC1Br or O1CC1Cl or O1CC1F or O1CC1I 

O1CC1CBr or O1CC1CCl or O1CC1CF or O1CC1CI 

Associated ECOSAR Class(s): 

Epoxides, Mono - - if a structure contains one epoxide rings and no acid function, it will 

be classified as Epoxides, Mono. In the current ECOSAR program, a structure 

classified as Halo Epoxides cannot be additionally classified as Epoxides, Mono. 

Epoxides, Mono Acid Substituted - contains one epoxide ring and an acid function. In 

the current ECOSAR program, a structure classified as Halo Epoxides cannot be 

additionally classified as Epoxides, Mono Acid Subsituted. 

Epoxides, Poly - if a structure contains two or more epoxide rings, it will be classified as 

Epoxides. In the current ECOSAR program, a structure can be classified as both Halo 

Epoxides and Epoxides, Poly 

Example Halo Epoxides: 

CAS No. Name SMILES Notation

106‐89‐8 Epichlorohydrin O(C1CCl)C1

3132‐64‐7 Epibromohydrin O(C1CBr)C1
ECOSAR Class Definition: Halo Esters

The Halo Esters class is identified by the following structures: 

 C

C

O

O

Halogen R C

O

O

R

Halogen

R - must be alkyl, oelfinic, acetylenic or aromatic carbon (carbonyl not included). 

Halogen - bromine (Br), chlorine (Cl), fluorine (F) or iodine (I). 

In the current ECOSAR program, the Halo Esters class meets the criteria as shown in 

the structure above and the following: 

(1) the carbon atom (to which the Halogen is attached) must be an alkyl carbon (an 

olefinic carbon not currently allowed). The halogen can be in either the alpha- or betapositions where the alpha-position is direct attachment to the carbonyl. 

(2) Fluorine was previously excluded, but is now included in this class. 

SMILES String Identifications: 

OC(=O)CBr or OC(=O)CCl or OC(=O)CI or OC(=O)F 

OC(=O)Br or OC(=O)Cl or OC(=O)CI or OC(=O)F 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to exclude the Ester class 

when the Halo Esters class is reported. 

Acid Halides - the Acid Halides class includes any structure with C(=O)-Halogen; 

ECOSAR reports both classes when present in a structure. 

Example Halo Esters: 

CAS No. Name SMILES Notation 

14064-10-9 Diethyl chloromalonate O=C(OCC)C(C(=O)OCC)Cl 

105-39-5 Acetic acid, chloro-, ethyl ester O=C(OCC)CCl 

599-99-5 Tribromoacetic acid, ethyl ester BrC(Br)(Br)C(=O)OCC 

356-24-1 Butanoic acid, heptafluoro-, methyl ester O=C(OC)C(F)(F)C(F)(F)C(F)(F)F 

623-48-3 Acetic acid, iodo-, ethyl ester O=C(OCC)CI 
ECOSAR Class Definition: Halo Ethers 

The Halo Ethers class is identified by the following structures: 

 C

O

C

Halogen C

O

C

C

Halogen

The ether function is identified as an aliphatic oxygen attached to two carbons atoms 

(alkyl, olefinic, acetylenic or aromatic carbon). 

Note: The oxygen may not be contained within a 3 member ring. If so, ECOSAR will 

classify that chemical as a halo epoxide 

In the current ECOSAR program, the Halo Ether structure must meet one of the 

following criteria: 

(1) an alkyl carbon of an ether function has a halogen attachment (Br, Cl, F or I). 

(2) an alkyl carbon (that is attached to an alkyl carbon of an ether function) has a 

halogen attachment (Br, Cl, F or I). 

In the current ECOSAR program, the halogen can be in either the alpha- or betaposition. 

SMILES String Identifications: 

COCBr or COCCl or COCF or COCI 

COCCBr or COCCCl or COCCF or COCCI 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

None specifically. 

The ether function also occurs in the Vinyl/Allyl Ether class. 

Example Halo Ethers: 

CAS No. Name SMILES Notation 

3188-13-4 Chloromethyl ethyl ether CCOCCl 

111-44-4 Bis(2-chloroethyl)ether O(CCCl)CCCl 

34723-82-5 (2-Bromomethyl)-tetrahaydropyran BrCC1CCCCO1 

ECOSAR Class Definition: Haloimides

The Haloimides class is identified by the following structure:

 

N

[S or N] O

R

1

R

2

O [S or N]

R

3

R1 or R3 can be anything (no exclusions). 

Please note that in the parent imide class R1 and R3 can not be a nitrogen atom, 

otherwise ECOSAR will identify the class as carbonyl ureas. But for this class 

there are many training set chemicals containing a nitrogen atom with a halogen 

attachment in the R1 or R3 position, and all are much more toxic to fish and 

daphnid than the carbonyl urea estimates. It appears these halogen attachments 

are driving toxicity. Therefore we are not excluding these attachments so that 

the haloimides estimates will be provided displaying more accurate toxicity 

estimates based on analogs. 

R2 - must be a Cl, Br, I or F

Haloimides class does not currently have acute or chronic QSARs for Green Algae. 

However, based on the fact that associated chemicals are used as herbicides, toxicity to 

green algae is expected to be significant.

In the current ECOSAR program, the Haloimides structure must meet the following 

criteria:

Notation: Currently, the halogen must be attached to the nitrogen.

SMILES String Identifications:

Haloimide Group:

 C(=O)N(Cl, Br, or I)C(=O)

 C(=S)N(Cl, Br, or I)C(=S)

 C(=N)N(Cl, Br, or I)C(=N) ... equivalent to: C(=NH)NC(=NH)

 ... (or any combination of the various carbonyl-types)

 ... (attachments as defined above)

Example Haloimides:

CAS No. Name SMILES Notation

77-48-5 2,4-Imidazolidinedione, 1,3-dibromo-5,5-dimethyl- O=C(N(C(C1(=O))(C)C)Br)N1Br

118-52-5 1,3-Dichloro-5,5-dimethylhydantoin O=C(N(C(C1(=O))(C)C)Cl)N1Cl

126-06-7 3-Bromo-1-chloro-5,5-dimethylhydantoin O=C(N(C(C1(=O))(C)C)Cl)N1Br
ECOSAR Class Definition: Halo Ketones (2 Free Hydrogens) 

Halo Ketones (2 Free H) are identified by the following structures: 

 C CH2

Halogen

O

C C

O

CH2 Halogen

To be classified as Halo Ketones (2 Free H) by the current ECOSAR program, the 

structure must meet the following criteria: 

(1) The basic ketone fragment is identified as a carbonyl group attached to carbon 

atoms on both sides where the carbon atoms must be an alkyl, olefinic, acetylenic or 

aromatic carbon. 

To be classified as Halo Ketones (2 Free H), the Halogen atom (bromine, chlorine, 

fluorine or iodine) must be attached at an alpha- or beta-position carbon to the carbonyl. 

In addition, the Halogen must be attached to a CH2 alkyl carbon (two free hydrogens on 

the alkyl carbon). 

SMILES String Identifications: 

CC(=O)CBr or CC(=O)CCl or CC(=O)CF or CC(=O)CI 

CC(=O)CCBr or CC(=O)CCCl or CC(=O)CCF or CC(=O)CCI 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

In addition to the Halo Ketones (2 Free H) class, the ECOSAR program will add any of 

the classes below to the to the program output if identified in a structure. 

Diketones - Diketones have two ketone functions at 1,3-positions. A structure can be 

classified as both Diketones and Benzyl Ketones (e.g. SMILES: 

c1ccccc1CC(=O)CC(=O)CC). 

Vinyl/Allyl Ketones - a ketone with a vinyl (-C=C) or allyl (-C-C=C) attachment to the 

carbonyl 

Benzyl Ketones - a ketone with -C-aromatic ring attachment to the carbonyl 

Example Halo Ketones (2 Free H): 

CAS No. Name SMILES Notation 

1204-21-3 Bromomethyl-2,5-dimethoxyphenyl ketone COc1ccc(OC)c(c1)C(=O)CBr 

78-95-5 2-Propanone, 1-chloro- O=C(CCl)C 
Halo Nitriles

The Halo Nitriles class is identified by the following structures: 

In the current ECOSAR program, the Halo Nitriles structure meets the following criteria: 

(1) A nitrile group (carbon triple-bonded to nitrogen; SMILES of C#N) is attached to an 

alkyl carbon. 

(2) An alkyl carbon in the alpha- or beta-position to the nitrile has one (or more) 

halogen attachments (bromine, chlorine, fluorine or iodine). 

(3) The alkyl carbons (alpha- or beta-position) can have other attachments (no current 

exclusions). 

Notations: Halogens attached to olefinic, acetylenic or aromatic carbons are not

currently included in the class identification. Halogens further removed from a nitrile 

group are not included (further than alpha- or beta-position). 

SMILES String Identifications: 

BrCC#N or ClCC#N or FCC#N or ICC#N 

BrCCC#N or ClCCC#N or FCCC#N or ICCC#N 

Associated ECOSAR Class(s): 

None specifically. 

Other SAR Nitrile classes include: Azonitriles, Nitrile Esters, Nitrile Alpha-OH, 

Phthalonitriles, Vinyl/Allyl Nitriles, and Nitriles, Polyaliphatic. 

Example Halo Nitriles: 

CAS No. Name SMILES Notation 

107-14-2 Acetonitrile, chloro- N#CCCl 

3252-43-5 Acetonitrile, dibromo- N#CC(Br)Br 

375-00-8 Butanenitrile, heptafluoro- N#CC(F)(F)C(F)(F)C(F)(F)F 
Halo Pyridines

The Halo Pyridines class is identified by the following structure: 

In the current ECOSAR program, the Halo Pyridines structure identification meets the 

following criteria: 

(1) The ECOSAR program identifies a six-member aromatic ring containing five carbon 

atoms and one nitrogen atom (a pyridine ring). 

 (2) The aromatic carbon atoms on the pyridine ring have one or more halogen 

attachments (halogens include bromine, chlorine, fluorine or iodine). 

 (3) The pyridine ring can be fused to additional ring(s). 

SMILES String Identifications: 

n1ccccc1Br 

n1ccccc1Cl 

n1ccccc1F 

n1ccccc1I 

 ... (the halogen can be attached to any of the aromatic carbons)

Associated ECOSAR Class(s): 

Other ECOSAR classes specifically containing a Pyridine ring: 

Pyridine-alpha-Acid - a carboxylic acid group (-C(=O)-OH) is attached to the pyridine 

ring in an ortho-position to the nitrogen atom. A structure can be classified as both a 

Pyridine-alpha-Acid and a Halo Pyridine. 

Notation: the Pyridine Thiones class does not contain an aromatic pyridine ring (the 

ring is an aliphatic thione ring with C(=S) as part of the ring). 

Examples Halo Pyridines: 

CAS No. Name SMILES Notation

109‐09‐1 2‐Chloropyridine n1ccccc1Cl

626‐55‐1 3‐Bromopyridine n1cccc(Br)c1

1929‐82‐4 Pyridine, 2‐chloro‐6‐(trichloromethyl)‐  n(c(ccc1)C(Cl)(Cl)Cl)c1Cl

2176‐62‐7 Pyridine, pentachloro‐  n(c(c(c(c1Cl)Cl)Cl)Cl)c1Cl
ECOSAR Class Definition: Hydrazines 

ECOSAR currently identifies several different types of structures as Hydrazines which 

are described separately below. 

Common Hydrazines: 

 

N N

R1

R2 R4

R3

Common hydrazines are identified by two aliphatic nitrogen atoms attached with a 

single-bond. At least one of the R1, R2, R3 or R4 substituents muct be an alkyl, 

olefinic, acetylentic or aromatic carbon. 

Notation: In the current ECOSAR program, the R1, R2, R3 and R4 substituents can be 

anything. 

SMILES String Identifications: 

NN 

 ... (attachments as defined above)

Hydrazones as Hydrazines: 

 C N N C C N N R

The R substituent can be anything. 

SMILES String Identifications: 

C=NN=C 

C=NN 

 ... (attachments as defined above)

Hydrazides, Semicarbazides and Thiosemicarbazides as Hydrazines: 

 C N N R

O

C N N R

S

C N N C

O

The R substituent can be anything. ECOSAR identifies various hydrazides, 

carbazides and carbazones as Hydrazines. 

SMILES String Identifications: 

C(=O)NN 

C(=S)NN 
C(=O)NN=C 

 ... (attachments as defined above) 

Notation: Azo Structures as Hydrazines: 

 R1 N N R2

In ECOSAR versions prior to v1.10, the linear azo structure was identified as a 

Hydrazine. However, this azo structure is no longer identified as an ECOSAR 

Hydrazine. 

Previously Associated ECOSAR Class(s): 

Semicarbazide (Aryl-Ortho), Semicarbazide (Aryl-Meta/Para), Semicarbazide (Akyl) - 

identified by N-N-C(=O)-N-R ... These previously identified classes (but no longer 

identified ECOSAR classes) do not have SAR equations. The Hydrazine class is 

identified and used by ECOSAR. 

Example Hydrazines: 

CAS No. Name SMILES Notation 

302-01-2 Hydrazine NN 

57-14-7 1,1-Dimethylhydrazine NN(C)C 

122-66-7 Hydrazine, 1,2-diphenyl- N(Nc(cccc1)c1)c(cccc2)c2 

79-19-6 Thiosemicarbazide NC(=S)NN 

54-85-3 Isoniazid NNC(=O)c1ccncc1 

537-47-3 4-Phenylsemicarbazide c1ccccc1NC(=O)NN 
ECOSAR Class Definition: Hydroquinones

The Hydroquinones class is identified by the following example structures: 

 OH

OH

In the current ECOSAR program, a hydroquinone is a six-member aromatic ring 

(benzene or any other aromatic ring including hetero-aromatic rings) that has hydroxyl 

groups [-OH] in para-position. The aromatic ring can be fused to another ring. 

SMILES String Identifications: 

Oc1ccc(O)cc1 

Associated ECOSAR Class(s): 

Quinone – Under environmental conditions, a reversible reduction-oxidation (redox) 

change from hydroquinone to semiquinone and to quinone may occur. 

Phenols, Poly - the hydroquinone identification is a more toxic sub-class of the Phenols, 

Poly class. ECOSAR reports both classes. 

Example Hydroquinones: 

CAS No. Name SMILES Notation 

123-31-9 1,4-Hydroquinone Oc1ccc(O)cc1 

58-27-5 2-Methyl-1,4-hydroquinone Oc1cc(C)c(O)cc1 
ECOSAR Class Definition: Imidazoles

The Imidazoles class is identified by the following structure: 

 

N

N

In the current ECOSAR program, the Imidazoles structure must meet the following 

criteria: 

(1) The Imidazole ring is a five-member aromatic ring with nitrogen atoms at the 1- and 

3-positions. The 1-position is [NH] if unsubstituted, but the hydrogen can be replaced 

by another substituent. 

 (2) The imidazole ring can be fused to another ring (e.g. Benzimidazole) 

SMILES String Identifications: 

[nH]1cncc1 

n1cncc1 

c1ncnc1 

c(n1)cnc1 

N1C=NC=C1 

Associated ECOSAR Class(s): 

None specifically. However, ECOSAR includes other “ring structure” classes such as 

Triazines, Benzotriazoles, Triazoles, Triazole Pyrimidines and Thiazole, Benzo. 

Examples Imidazoles: 

CAS No. Name SMILES Notation 

288-32-4 1H-Imidazole N1C=NC=C1 

51-17-2 1H-Benzimidazole n(c(c(n1)ccc2)c2)c1 

58-08-2 Caffeine CN1C(=O)N(C)c2ncn(C)c2C1(=O) 

693-98-1 2-Methylimidazole N(C=CN1)=C1C 

2034-22-2 2,4,5-Tribromoimidazole BrC1=NC(Br)=C(Br)N1 
ECOSAR Class Definition: Imides 

The Imides class is identified by the following example structures: 

 

N

[S or N] O

R1

R2

O [S or N]

R3

R1 and R3 can be anything except a nitrogen atom. 

If R1 or R3 are a nitrogen atoms, ECOSAR will identify the class as carbonyl 

ureas. 

Note that If R1 or R3 are an oxygen atoms, ECOSAR will also identify the 

class as carbamate, esters. At this time substitution of the oxygen atom is 

not being excluded because we do not have supporting evidence 

indicating which class has higher toxicity potential or if any chemicals 

actually contain a hybrid of both functional groups. 

R2 can be anything except a halogen atom or a [C-aromatic] group: 

If R2 is a halogen attachment, ECOSAR will identify the class as haloimides 

If R2 is a [C-aromatic] group, ECOSAR will identify the class as benzyl imides. A 

strict definition of “benzyl” implies the single alkyl carbon is a -CH2- group and 

the aromatic ring is a benzene ring. However, in the current ECOSAR program, 

the single alkyl carbon can be -CH2-, -CH< or >C< and the aromatic ring can be 

any aromatic ring including hetero-aromatic rings. 

The oxygen in the carbonyl(s) could be replaced by sulfur or NH. The structure can 

have any combination of C=O, C=S or C=NH as long as the nitrogen has two such 

attachments. 

SMILES String Identifications: 

Imide Group: 

 C(=O)NC(=O) 

 C(=S)NC(=S) 

 C(=N)NC(=N) ... equivalent to: C(=NH)NC(=NH) 

 ... (or any combination of the various carbonyl-types)

 ... (attachments as defined above)

Example Imides: 

CAS No. Name SMILES Notation 

123-56-8 Succinimide O=C(NC(=O)C1)C1 
ECOSAR Class Definition: Thiazolones (Iso) or Isothiazolones

The Isothiazolone class is identified by the following structures: 

 

N

S

C

O

S

N

C

O

N S

C

O

In the current ECOSAR program, the Isothiazolone structure meets the following 

criteria: 

(1) a five-member ring containing one carbonyl, one aliphatic sulfur, one aliphatic 

nitrogen and two carbon atoms. The two carbon atoms can be aromatic if the 

isothiazolone ring is fused to an aromatic ring. If there are no aromatic carbon atoms in 

the ring, the ring has one double bond. 

(2) the sulfur and nitrogen atoms in the ring are adjacent to each other. 

(3) The atoms in the ring can have other attachments (no exclusions). 

SMILES String Identifications: 

O=C 1NSC=C1 

O=C1SNC=C1 

O-C1C=NSC1 

Associated ECOSAR Class(s): 

None specifically. 

The Thiazolidinone class ring also contains a carbonyl, one sulfur, one nitrogen and two 

carbon atoms, but in a different order. 

Example Isothiazolones: 

CAS No. Name SMILES Notation 

26530-20-1 3(2H)-Isothiazolone, 2-octyl- O=C1C=CSN1CCCCCCCC 

2682-20-4 3(2H)-Isothiazolone, 2-methyl- S1N(C)C(=O)C=C1 
ECOSAR Class Definition: Ketone Alcohols (or a-,b-Ketone Alcohol) 

The Ketone Alcohols class is identified by the following structures: 

 C

C

C

O

OH

C

C

C

O

C

OH

To be classified as Ketone Alcohols by the current ECOSAR program, the structure 

must meet the following criteria: 

(1) The basic ketone fragment is identified as a carbonyl group attached to carbon 

atoms on both sides where the carbon atoms must be an alkyl, olefinic, acetylenic or 

aromatic carbon. 

(2) An hydroxy group (-OH) is attached to an alkyl carbon at an alpha- or beta-position 

to the ketone carbonyl. 

SMILES String Identifications: 

CC(=O)CO ... equivalent to: CC(=O)COH or CC(=O)CO[H] 

CC(=O)CCO ... equivalent to: CC(=O)CCOH or CC(=O)CCO[H] 

Associated ECOSAR Class(s): 

Diketones - Diketones have two ketone functions at 1,3-positions. A structure can be 

classified as both Diketones and Benzyl Ketones (e.g. SMILES: 

c1ccccc1CC(=O)CC(=O)CC). 

Vinyl/Allyl Ketones - a ketone with a vinyl (-C=C) or allyl (-C-C=C) attachment to the 

carbonyl 

Benzyl Ketones - a ketone with -C-aromatic ring attachment to the carbonyl 

Halo Ketones (2 Free H) - a ketone with a -CH2-Halogen attachment to a carbon atom 

at the alpha- or beta-position to the carbonyl 

Example Ketone Alcohols: 

CAS No. Name SMILES Notation 

123-42-2 

2-Pentanone, 4-hydroxy-4-

methyl- O=C(CC(O)(C)C)C 

50-02-2 Dexamethasone 

C1(=O)C=C2CCC3C4CC(C)C(O)(C(=O)CO)C4(C)CC(O)C3(F)

C2(C)C=C1 

50-22-6 Corticosterone CC34CC(O)C1C(CCC2=CC(=O)CCC12C)C3CCC4C(=O)CO 

96-26-4 

2-Propanone, 1,3-

dihydroxy- O=C(CO)CO 
ECOSAR Class Definition: Malonitriles

The Malonitrile class is characterized by the following structure: 

 

C

N

C

C

N

C

N

C

C

N

C

In the current ECOSAR program, the Malonitrile structure must have two or more nitrile 

groups (carbon triple-bonded to nitrogen; SMILES of C#N) attached to a single carbon 

in the structure. The carbon must be either an alkyl or olefinic carbon. 

SMILES String Identifications: 

N#CCC#N 

C=C(C#N)C#N 

Associated ECOSAR Class(s): 

Nitrile, Polyaliphatic - Malonitriles are a more toxic sub-class of the Nitriles, 

Polyaliphatic. In the Polyaliphatic, Nitriles class, the two or more cyano groups do not

need to be attached to the same carbon. ECOSAR reports both classes when 

identified. 

Vinyl/Allyl Nitriles - basically, a vinyl (-C=C) or allyl group (-C-C=C) is attached to one 

or more nitriles groups. When two or more nitrile groups are attached to the same alkyl 

or olefinic carbon, the structure will be classified as a Vinyl/Allyl Nitriles and either a 

Nitriles, Polyaliphatic or a Malonitriles. 

Other SAR Nitrile classes include: Azonitriles, Halo Nitriles, Nitrile Esters, Nitrile AlphaOH, and Phthalonitriles. 

Example Malonitriles: 

CAS No. Name SMILES Notation 

2698-41-1 O-Chlorobenzylidene malononitrile N#CC(C#N)=Cc(c(ccc1)Cl)c1 

109-77-3 Malononitrile C(#N)CC(#N) 
Melamines 

The Melamines class is identified by the following structure: 

R1, R2 and R3 - can be hydrogen or any other single-bonded atom. 

In the current ECOSAR program, the Melamine structure must meet the following 

criteria: 

(1) A six-member aromatic ring with three nitrogen atoms in sym-positions. The three 

carbon atoms have aliphatic nitrogen subsitiuents as either -NH2 or -NH- (the aliphatic 

nitrogen must have at least one hydrogen). 

Associated ECOSAR Class(s): 

Anilines (amino-meta) - this class currently allows hetero-aromatic rings. Amino 

substituents in the meta-position (as Melamines allows) are additionally classified by 

ECOSAR as Anilines (amino-meta). 

Example Melamines: 

CAS No. Name SMILES Notation 

108-78-1 Melamine Nc1nc(N)nc(N)n1 

2827-46-5 2,4,6-Trimethylmelamine n1c(NC)nc(NC)nc1NC 

66215-27-8 Cyromazine n1c(N)nc(N)nc1NC2CC2 
ECOSAR Class Definition: Methacrylates

The Methacrylates class is identified by the following structures: 

 

C

C

{O,S}

O

C R2

CH3

C

C

{O,S}

S

C R2

CH3

R2 - attachment must be either an alkyl carbon, olefinic carbon, acetylenic carbon or 

aromatic carbon. 

{O,S} - can be either oxygen (-O-) or sulfur (-S-) 

Internally, the ECOSAR program initially detects a carbonyl function [C(=O)] or a 

thiocarbonyl function [C(=S)] with one olefinic attachment and one oxygen or sulfur 

attachment. The olefinic carbon attached to the carbonyl (or thiocarbonyl) must have a 

methyl (CH3) attachment (anything other than a methyl group (CH3) changes the 

classification from a Methacrylate to an Acrylate. The oxygen or sulfur must have either 

an alkyl carbon, olefinic carbon, acetylenic carbon or aromatic carbon attachment to be 

classified as either a Methacrylate or Acrylate. 

SMILES String Identifications: 

C=C(C)C(=O)O ... equivalent to: C=C(C(H)(H)H)C(=O)O 

C=C(C)C(=O)S 

C=C(C)C(=S)O 

C=C(C)C(=S)S 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Acrylates - The olefinic carbon attached to the carbonyl (or thiocarbonyl) must have a 

methyl (CH3) attachment (anything other than a methyl group (CH3) changes the 

classification from a Methacrylate to an Acrylate. 

Thiomethacrylates - Thiomethacrylates are methacrylates with having a thiocarbonyl or 

a sulfur attached to the carbonyl function. In the current ECOSAR program, structures 

classified as Thiomethacrylates are also classified as Methacrylates. 

Example Methacrylates: 

CAS No. Name SMILES Notation 

80-62-6 Methyl methacrylate C=C(C)C(=O)OC 

96-05-9 Allyl methacrylate C=C(C)C(=O)OCC=C 

2495-37-6 Benzyl methacrylate C=C(C)C(=O)OCc1ccccc1 
 O-Methyl thiomethacrylate C=C(C)C(=S)OC 

 S-Methyl thiomethacrylate C=C(C)C(=O)SC 

 

 
ECOSAR Class Definition: Neonicotinoids

Neonicotinoids act as agonists of the nicotinic acetylcholine receptor (nAChR) in a 

similar mechanism as nicotinoids; however, the presence of a electronegative nitro or 

cyano group attached to the aliphatic nitrogen in neonicotinoids alters the binding 

potential compared to nicotinoids and results in varied toxicity in mammals and insects 

(Tomizawa & Casida, 2003). Although toxicity of nicotinoids and neonicotinoids in 

aquatic organisms appear to differ based on a few available data points, insufficient 

information and data are available for aquatic organisms to make any firm conclusions. 

Additional uncertainties include the effect a halogen substitution has on the pyridine 

ring. Thus, further research is needed to confirm the separate classification of 

nicotinoids and neonicotinoids for aquatic toxicity. 

Neonicotinoids are identified by the following structures: 

N

N

R

N

N

R

N

N

R

N N

R

R = an electronegative nitro or cyano group (e.g., -C=NC#N or -C=NT). 

In the current ECOSAR program, the Neonicotinoids class meets the criteria as shown 

in the structure above. Substitutions on the pyridine or pyrrole ring are allowed. 

SMILES String Identifications: 

Associated ECOSAR Class(s): 

Nicotinoids: Are neonicotinoids without an electronegative nitro or cyano substitution on 

the aliphatic nitrogen. 

Example Neonicotinoids: 

CAS No. Name SMILES Notation 

138261-41-3 Imidacloprid c1cc(Cl)ncc1CN2CCNC2=NT 

210880-92-5 Clothianidin c1nc(Cl)sc1CNC(=NT)NC 

153719-23-4 Thiamethoxam c1nc(Cl)sc1CN2C(=NT)N(C)COC2 

135410-20-7 Acetamiprid c1cc(Cl)ncc1cn(C)C(C)=NC#N 

111988-49-9 Thiacloprid c1cc(Cl)ncc1CN2C(=NC#N)SCC2 

 

References: 

Tomizawa M., Casida J.E. 2003. Selective toxicity of neonicotinoids attributable to 

specificity of insect and mammalian nicotinic receptors. Annu. Rev. Entomol., 48:339-

64. 
ECOSAR Class Definition: Nereistoxin Analogues

The Nereistoxin Analogues class is identified by the following sub-structure: 

 

N

S S

In the current ECOSAR program, the Nereistoxin Analogues structure meets the 

following criteria: 

(1) The structure as depicted above. The nitrogen cannot be aromatic. 

(2) Attachments to the thiol can be anything including hydrogen, sulfur, or carbons 

(alkyl, olefinic or acetylenic). 

SMILES String Identifications: 

CN(C)C(CS)CS 

 

(attachments as defined above)

Associated ECOSAR Class(s): 

Aliphatic Amines – Nitrogens with aliphatic carbon attachments (alkyl, olefinic or 

acetylenic carbon). 

Thiols & Mercaptans - A thiol-mercaptan function (-SH) attached to an alkyl, olefinic, 

acetylenic or aromatic carbon atom. 

Example Nereistoxin Analogues: 

CAS No. Name SMILES Notation 

15263-53-3 Cartap CN(C)C(CSC(=O)N)CSC(=O)N

31895-21-3 Thiocyclam C1SSSCC1N(C)C 
ECOSAR Class Definition: Neutral Organics

The following types of example classes are represented by the neutral organics class 

which assumes a simple non-polar narcosis mechanism of action for solvents and nonreactive, non-ionizable organic compounds

1. Alcohols

2. Acetals

3. Ketones

4. Ethers

5. Alkyl halides

6. Aryl halides

7. Aromatic hydrocarbons

8. Halogenated aromatic hydrocarbons

9. Halogenated aliphatic hydrocarbons

10. Sulfides and di-sulfides

11. Sulfoxides and sulfones

Please note: If there are no positive identifications of any other associated SAR 

classes for the query chemical, ECOSAR reports the structure as a Neutral Organic 

(regardless of what chemical functions may occur in the structure). When this occurs, 

the user will be promoted with the following flag:

Example Neutral Organics from the SAR Sheet:

CAS No. Name SMILES Notation

112-27-6 Triethylene glycol O(CCOCCO)CCO

67-68-5 Dimethyl sulfoxide CS(=O)C

67-64-1 Acetone O=C(C)C

110-86-1 Pyridine n1ccccc1

60-29-7 Diethyl ether CCOCC

110-00-9 Furan O1C=CC=C1

71-43-2 Benzene c1ccccc1

100-61-8 N-Methylaniline CNc1ccccc1

ECOSAR Class Definition: Nicotinoids

Nicotinoids act as agonists of the nicotinic acetylcholine receptor (nAChR) in a similar 

mechanism as neonicotinoids; however, the absence of a electronegative nitro or cyano 

group attached to the aliphatic nitrogen in nicotinoids alters the binding potential 

compared to neonicotinoids and results in varied toxicity in mammals and insects 

(Tomizawa & Casida, 2003). Although toxicity of nicotinoids and neonicotinoids in 

aquatic organisms appear to differ based on a few available data points, insufficient 

information and data are available for aquatic organisms to make any firm conclusions. 

Additional uncertainties include the affect a halogen substitution has on the pyridine 

ring. Thus, further research is needed to confirm the separate classification of 

nicotinoids and neonicotinoids for aquatic toxicity. 

Nicotines are identified by the following structures: 

N

N

N

N

N

N N N

In the current ECOSAR program, the Nicotinoids class meets the criteria as shown in 

the structure above. Substitutions on the pyridine or pyrrole ring are allowed. 

SMILES String Identifications: 

Associated ECOSAR Class(s): 

Neonicotinoids: A sub-classification of nicotinoids with a substitution of an 

electronegative cyano or nitro group on the aliphatic nitrogen. 

Example Nicotines: 

CAS No. Name SMILES Notation 

140111-52-0 Epibatidine c1cc(Cl)ncc1C2C3NC(CC3)C2 

54-11-5 Nicotine c1ccncc1C2N(C)CCC2 

525-74-6 Dihydronicotyrine c1ccncc1C2=CCCN2C 

494-52-0 Anabasine c1ccncc1C2NCCCC2 

494-97-3 Nornicotine c1ccncc1C2NCCC2 

 

References: 

Tomizawa M., Casida J.E. 2003. Selective toxicity of neonicotinoids attributable to 

specificity of insect and mammalian nicotinic receptors. Annu. Rev. Entomol., 48:339-

64. 
ECOSAR Class Definition: Nitrile Alpha-OH

The Nitrile Alpha-OH class is identified by the following structures: 

 

C

C N

OH

C

C C N

OH

In the current ECOSAR program, the Nitrile Alpha-OH structure meets the following 

criteria: 

(1) A nitrile group (carbon triple-bonded to nitrogen; SMILES of C#N) is attached to an 

alkyl or olefinic carbon. In addition, an hydroxyl group (-OH) is attached to the same 

alkyl or olefinic carbon. 

(2) The alkyl carbon can have other attachments (no current exclusions). 

SMILES String Identifications: 

C(O)C#N ... equivalent to: C(OH)C#N or C(O[H])C#N 

C=C(O)C#N ... equivalent to: C=C(OH)C#N or C=C(O[H])C#N 

 ... (attachment as defined above)

Associated ECOSAR Class(s): 

None specifically. 

Other SAR Nitrile classes include: Azonitriles, Nitrile Esters, Halo Nitriles, 

Phthalonitriles, Vinyl/Allyl Nitriles, and Nitriles, Polyaliphatic. 

Example Nitrile Alpha-OH: 

CAS No. Name SMILES Notation 

78-97-7 Lactonitrile N#CC(O)C 

75-86-5 Acetone Cyanohydrin N#CC(O)(C)C 

513-96-2 3,3,3-Trichlorolactonitrile ClC(Cl)(Cl)C(O)C#N 

532-28-5 Mandelonitrile N#CC(O)c(cccc1)c1 
ECOSAR Class Definition: Nitro Alcohols

The Nitro Alcohols class is identified by the following example structures: 

 

HO

C

NO2 C

HO C

NO2 C

HO C

C

NO2

In the current ECOSAR program, the Nitro Alcohols structure meets one of the following 

criteria: 

(1) a single alkyl carbon atom has both an hydroxy attachment (-OH) and a nitro 

function attachment (NO2). 

(2) an alkyl carbon is attached to another alkyl carbon (or olefinic carbon). The nitro 

function (NO2) and hydroxy (-OH) are on different carbons. A maximum of three carbon 

atoms can occur between the nitro function (NO2) and hydroxy (-OH). 

SMILES String Identifications: 

OCN(=O)(=O) ... equivalent to: HOCN(=O)(=O) or [H]OCN(=O)(=O) 

OCCN(=O)(=O) 

OCCCN(=O)(=O) 

 ... nitro function (NO2) can be either N(=O)(=O) or [N+](=O)([O-]) 

OC[N+](=O)([O-]) or OCC[N+](=O)([O-]) or OCCC[N+](=O)([O-]) 

 ... nitro function (NO2) can entered as T ... this is unique to all EPI Suite programs

OCT or OCCT or OCCCT 

Associated ECOSAR Class(s): 

None specifically. 

ECOSAR includes a variety of other classes containing alcohol or nitro functions, but 

not in combination in the same class. 

Example Nitro Alcohols: 

CAS No. Name SMILES Notation 

52-51-7 1,3-Propanediol, 2-bromo-2-nitro- N(=O)(=O)C(Br)(CO)CO 

760-40-7 3-Nitro-1,1,1-trichloro-2-propanol ClC(Cl)(Cl)C(O)CN(=O)=O 

89167-84-0 2-Propanol, 1,1-dinitro- N(=O)(=O)C(N(=O)(=O))C(O)C 
ECOSAR Class Definition: Nitro-/Nitroso-Benzamides

The Nitro-/Nitroso-Benzamides class is identified by the following structures: 

 

C

O N

R2

R1

NO2

C

O N

R2

R1

N O

R1 and R2 - must be either hydrogen or alkyl, olefinic, acetylenic or aromatic carbon 

(carbonyl not included). 

In the current ECOSAR program, the Nitro-/Nitroso-Benzamide structure meets the 

following criteria: 

(1) A six-member aromatic ring (benzene or any other aromatic ring including heteroaromatic rings) has both an amide-substituent (as noted above in the structure) and 

either a nitro substituent (-NO2) or a nitroso substituent (-N=O). The positioning on the 

ring does not matter. 

(2) The aromatic ring can be fused to another ring. 

SMILES String Identifications: 

Nitrosobenzamide (ortho-isomer only SMILES): 

 O=Nc1ccccc1C(=O)N 

Nitrobenzamide (ortho-isomer only SMILES): 

 N(=O)(=O)c1ccccc1C(=O)N 

 ... nitro function (NO2) can be either N(=O)(=O) or [N+](=O)([O-]) 

 [N+](=O)([O-])c1ccccc1C(=O)N 

 ... nitro function (NO2) can entered as T ... this is unique to all EPI Suite programs

 Tc1ccccc1C(=O)N 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Amides - the ECOSAR Amides class is a general class having a CC(=O)N or 

NC(=O)N group that occurs in other ECOSAR classes. In general, the Amides class is 

reported by ECOSAR in addition to the other classes (as in Nitro-/Nitroso-Benzamides). 

Example Nitro-/Nitroso-Benzamides: 

CAS No. Name SMILES Notation 

619-80-7 4-Nitrobenzamide O=C(N)c(ccc(N(=O)(=O))c1)c1 

144189-66-2 3-Nitrosobenzamide NC(=O)c1cc(N=O)ccc1 

3011-89-0 Aklomide Clc1cc(N(=O)(=O))ccc1C(=O)N 

13160-58-2 Pyridine, 4-(p-nitrobenzamido)- n1ccc(NC(=O)c2ccc(N(=O)=O)cc2)cc1 
ECOSAR Class Definition: Omadines

The Omadines class is identified by the following structures: 

 

N

S

O

N

S

O N

SH

O

In the current ECOSAR program, the Omadine structure identification meets the 

following criteria: 

(1) The ECOSAR program identifies a six-member aliphatic ring containing four olefinic 

carbon atoms (and two double bonds), one nitrogen atom (as N=O) and one 

thiocarbonyl group [C(=S)]. 

(2) Also identified is an aromatic pyridine-N-oxide ring with a thiol [-SH] at an orthoposition. 

(3) The omadine ring can be fused to additional ring(s). 

SMILES String Identifications: 

S=C1C=CN(=O)C=C1 

S=C1N(=O)C=CC=C1 

O=n1c(S)cccc1 

Associated ECOSAR Class(s): 

None specifically related to the whole Omadine ring. 

Vinyl/Allyl Amines - both ring structures above are additionally classified as Vinyl/Allyl 

Amines 

Aliphatic Amines - the first ring structure above (nitrogen para-position to thiocarbonyl) 

is additionally classified as an Aliphatic Amine. 

Example Omadines: 

None specifically. Experimental data is CBI (Confidential Business Information). 
ECOSAR Class Definition: Oxetanes

The Oxetanes class is identified by the following structure: 

 

O

C

C

C

In the current ECOSAR program, the Oxetane structure identification meets the 

following criteria: 

(1) The ECOSAR program identifies a four-member ring containing three alkyl carbon 

atoms and one oxygen atom. 

 (2) The alkyl carbon atoms can have any substituent attachments; the substituent 

attachments are not included in the Oxetane identification. 

(3) The Oxetane ring can be fused to additional ring(s). 

SMILES String Identifications: 

O1CCC1 

C1OCC1 

O(C1)CC1 

Associated ECOSAR Class(s): 

None. 

Examples Oxetanes: 

CAS No. Name SMILES Notation 

503-30-0 Oxetane O1CCC1 

68797-60-4 Oxetane, dibromo- BrC1C(CO1)Br 

425-82-1 Hexafluoro oxetane O1C(F)(F)C(F)(F)C1(F)F 

3047-32-3 3-Oxetanemethanol, 3-ethyl- O(CC1(CC)CO)C1 
ECOSAR Class Definition: Oxyamines

The Oxyamines class is identified by the following structure: 

 R2

N O R3

R1

R1 and R2 - must be hydrogen. 

R3 - attachments must be alkyl, olefinic, acetylenic or aromatic carbon (hydrogen not 

included). 

In the current ECOSAR program, the Oxyamine structure meets the criteria as defined 

above. 

SMILES String Identifications: 

NOC 

NOC=C 

NOC#C 

NOc1ccccc1 

 ... (nitrogen attachments as defined above)

Associated ECOSAR Class(s): 

Aliphatic Amines - under the current identification scheme, ECOSAR commonly 

classifies a structure as both Aliphatic Amines and Oxyamines. ECOSAR reports both 

identifications. 

Example Oxyamines: 

CAS No. Name SMILES Notation 

29812-79-1 o-Decylhydroxylamine NOCCCCCCCCCC 
ECOSAR Class Definition: Peroxy Acids

The Peroxy Acids class is identified by the following structure: 

 

R1 O O R2

R1 and R2 - In the current ECOSAR program, can be anything with one exception. 

The exception is that either R1 or R2 is a carbonyl [C(=O)] and the other is not a 

hydrogen ... This exception identifies the Peroxy Ester class. 

The ECOSAR program initially identifies any -O-O- structure as a Peroxy Acid. 

Whenever a Peroxy Ester class is identified, the previous Peroxy Acid identification is 

negated to give precedence to the more specific Peroxy Ester class. 

SMILES String Identifications: 

OO 

 ... (attachments as defined above) 

Associated ECOSAR Class(s): 

Peroxy Esters - an Ester class identified by C(=O)-O-O-X (where X is anything except 

hydrogen). 

Example Peroxy Acids: 

CAS No. Name SMILES Notation 

79-21-0 Peroxyacetic acid CC(=O)OO 

628-37-5 Diethyl peroxide CCOOCC 

29914-92-9 Dipropyl peroxide CCCOOCCC 
ECOSAR Class Definition: Peroxy Esters

The Peroxy Esters class is identified by the following structure: 

 O O

C R2

R1

O

R1 - can be anything (no exclusions). 

R2 - can be anything except hydrogen (hydrogen would make it a Peroxy Acid). 

The ECOSAR program initially identifies any -O-O- structure as a Peroxy Acid. 

Whenever a Peroxy Ester class is identified, the previous Peroxy Acid identification is 

negated to give precedence to the more specific Peroxy Ester class. 

SMILES String Identifications: 

C(=O)OO 

 ... (attachments as defined above) 

Associated ECOSAR Class(s): 

Peroxy Acids - a peroxy class identified by -O-OExample Peroxy Esters: 

CAS No. Name SMILES Notation 

16066-38-9 Peroxydicarbonic acid, dipropyl ester O=C(OCCC)OOC(=O)OCCC 

3313-92-6 Peroxydicarbonic acid, disodium salt [Na]OC(=O)OOC(=O)O[Na] 

110-22-5 Peroxide, diacetyl O=C(OOC(=O)C)C 
ECOSAR Class Definition: Phenol Amines

The Phenol Amines class is identified by the following structure combination: 

 

OH

+ an Amine

[ Phenol ring can also be Hetero-Aromatic ]

The current ECOSAR program identifies the Phenol Amines class using identifications 

of other ECOSAR classes and the following logic: 

(1) First, the structure must already be classified as (a) Phenols, (b) Dinitrophenols or 

(c) Phenols, Poly. 

(2) If the first criteria is satisfied and the structure is additionally classified as any one of 

the ECOSAR Amine classes, then the structure is additionally classified as Phenol 

Amines. The ECOSAR Amine classes include Aliphatic Amines, Anilines (Aromatic 

Amines), Dinitro Aromatic Amine, Benzyl Amines, Propargyl Amines, Amides, and 

Vinyl/Allyl Ether Amines. 

SMILES String Identifications: 

c(O) or c1O ... full ring: c1ccccc1O ... equivalent to: c1ccccc1OH or c1ccccc1O[H] 

 ... Plus any of the SAR Amine Classes listed above (see the individual definition 

documents) 

Associated ECOSAR Class(s): 

See criteria (1) and (2) above. 

Examples Phenol Amines: 

CAS No. Name SMILES Notation 

119-34-6 4-Amino-2-nitrophenol O=N(=O)c(c(O)ccc1N)c1 

94-67-7 Salicyclaldoxime N(O)=Cc(c(O)ccc1)c1 

133-11-9 Phenyl-4-aminosalicylate Oc1cc(N)ccc1C(=O)Oc2ccccc2 

123-30-8 4-Aminophenol Oc(ccc(N)c1)c1 

103-90-2 Acetamide, N-(4-hydroxyphenyl)- O=C(Nc(ccc(O)c1)c1)C 

591-27-5 3-Aminophenol Oc(cccc1N)c1 
ECOSAR Class Definition: Phenols, Poly

The Phenols, Poly class is identified by the following structures: 

 

OH

OH

X

HO OH

[ Rings can also be Hetero-Aromatics ]

X - can be either a direct connection of two rings or another fragment separating the 

rings 

In the current ECOSAR program, the Phenols, Poly structure must meet the following 

criteria: 

(1) More than one hydroxyl (-OH) group are attached to aromatic rings in the structure. 

The aromatic ring can be either a phenyl ring or any other aromatic ring unit including 

heterocyclic aromatic rings. 

(2) The hydroxyl (-OH) groups attached to aromatic ring(s) can either be on the same 

ring or separate rings. 

SMILES String Identifications: 

c(O) or c1O ... equivalent to: c(OH) or c(OH) or c(O[H]) or c1O[H] 

 ... example complete ring: Oc1ccccc1O ... equivalent to: HOc1ccccc1OH 

Associated ECOSAR Class(s): 

Phenols - Only one hydroxyl group can be attached to aromatic rings in the structure. 

Dinitrophenols - Two or more nitro (-NO2) groups must be attached to the same 

aromatic ring as the hydroxyl (-OH) group. 

Hydroquinone - the hydroquinone identification is a more toxic sub-class of the Phenols, 

Poly class. ECOSAR reports both classes. 

Examples Phenols: 

CAS 

No. Name SMILES Notation 

80-05-7 Bisphenol A Oc(ccc(c1)C(c(ccc(O)c2)c2)(C)C)c1 

97-23-4 Phenol, 2,2'-methylenebis 4-chloro- Oc(c(cc(c1)Cl)Cc(c(O)ccc2Cl)c2)c1 

79-95-8 

Phenol, 4,4'-(1-methylethylidene)bis 2,6-

dichloro- Oc(c(cc(c1)C(c(cc(c(O)c2Cl)Cl)c2)(C)C)Cl)c1Cl 

70-30-4 Phenol, 2,2'-methylenebis 3,4,6-trichloro- Oc(c(c(c(c1)Cl)Cl)Cc(c(c(cc2Cl)Cl)Cl)c2O)c1Cl 
ECOSAR Class Definition: Phenols

The Phenols class is identified by the following structures: 

 

OH

Hetero-Aromatic Ring

OH

In the current ECOSAR program, the Phenols structure must meet the following criteria: 

(1) An hydroxyl (-OH) group is attached to an aromatic ring. The aromatic ring can be 

either a phenyl ring or any other aromatic ring unit including heterocyclic aromatic rings. 

(2) The structure can contain only one hydroxyl (-OH) group attached to an aromatic 

ring. Multiple hydroxyl groups attached to aromatic rings changes the classification to 

Phenols, Poly. 

SMILES String Identifications: 

c(O) or c1O ... equivalent to: c(OH) or c(OH) or c(O[H]) or c1O[H] 

 ... example complete ring: c1ccccc1O ... equivalent to: c1ccccc1OH 

Associated ECOSAR Class(s): 

Phenols, Poly - More than one hydroxyl groups are attached to aromatic rings in the 

structure. 

Dinitrophenols - Two or more nitro (-NO2) groups must be attached to the same 

aromatic ring as the hydroxyl (-OH) group. 

Examples Phenols: 

CAS No. Name SMILES Notation

108‐95‐2 Phenol Oc1ccccc1

150‐76‐5 4‐Methoxyphenol Oc1ccc(OC)cc1

88‐75‐5 2‐Nitrophenol Oc1ccccc1N(=O)=O

95‐48‐7 o‐Cresol Oc1ccccc1C

90‐15‐3 1‐Naphthol Oc(c(c(ccc1)cc2)c1)c2
ECOSAR Class Definition: Phosphine Oxide

The Phosphine Oxide class is identified by the following structure: 

 

P

O

R1 R3

R2

R1, R2 and R3 - must be hydrogen or an alkyl, olefinic, acetylenic or aromatic carbon. 

In the current ECOSAR program, the Phosphine Oxide structure must meet the 

following criteria: 

(1) A P(=O) function is attached to hydrogen atoms or to alkyl, olefinic, acetylenic or 

aromatic carbon atoms. 

SMILES String Identifications: 

O=P or P(=O) 

 ... (attachments attachments as defined above) 

example string: 

 O=P(C)(C) ... equivalent to: O=P(C)(C)H 

Associated ECOSAR Class(s): 

None specifically. 

Example Phosphine Oxides: 

CAS No. Name SMILES Notation 

791-28-6 Triphenylphosphine oxide O=P(c(cccc1)c1)(c(cccc2)c2)c(cccc3)c3

1638-75-1 Phosphine oxide, (chloromethyl)dimethyl- O=P(CCl)(C)C 

14717-29-4 Phosphine oxide, dicyclohexyl- P(=O)(C(CCC1)CC1)C(CCC2)CC2 
ECOSAR Class Definition: Phthalonitriles

The Phthalonitriles class is identified by the following structure: 

 

C

C

N

N

In the current ECOSAR program, the Phthalonitriles structure meets the following 

criteria: 

(1) Two nitrile groups (carbon triple-bonded to nitrogen; SMILES of C#N) are attached 

to an aromatic ring in ortho-positions to each other. 

(2) The aromatic ring must be six-member aromatic ring. The ring can be a benzene 

ring or a hetero-aromatic ring (such as pyridine). 

SMILES String Identifications: 

N#Cc1ccccc1C#N 

c1cc(C#N)c(C#N)cc1 

c(c1C#N)cccc1C#N 

Associated ECOSAR Class(s): 

None specifically. 

Other SAR Nitrile classes include: Azonitriles, Nitrile Esters, Halo Nitriles, Vinyl/Allyl 

Nitriles, Nitriles Alpha-OH, and Nitriles, Polyaliphatic. 

Example Phthalonitriles: 

CAS No. Name SMILES Notation 

91-15-6 1,2-Benzenedicarbonitrile C(#N)c(c(C(#N))ccc1)c1 

712-74-3 Tetracyanobenzene N#Cc1c(C#N)cc(C#N)c(C#N)c1 

1835-65-0 Tetrafluorophthalonitrile Fc(c(F)c(F)c1C#N)c(F)c1C#N 

1953-99-7 Tetrachlorophthalonitrile Clc(c(Cl)c(Cl)c1C#N)c(Cl)c1C#N 
ECOSAR Class Definition: Nitriles, Polyaliphatic

The Nitriles, Polyaliphatic class is characterized by the following structure: 

 

C

N

C

N

Structure

(2 or more cyano groups attached to aliphatic atoms)

In the current ECOSAR program, the Nitriles, Polyaliphatic structure must meet the 

following criteria: 

 (1) Two or more nitrile groups (carbon triple-bonded to nitrogen; SMILES of C#N) are 

attached to aliphatic atoms in the structure. The aliphatic atoms include alkyl carbon, 

olefinic carbon, acetylenic carbon, nitrogen, sulfur and phosphorus. Other aliphatic 

atoms are not currently included (e.g. oxygen). 

SMILES String Identifications: 

CC#N 

C=CC#N 

C#CC#N 

NC#N 

SC#N 

PC#N 

 ... (two or more of these cyano [C#N] attachments required)

Associated ECOSAR Class(s): 

Malonitriles - Malonitriles are a more toxic sub-class of the Nitriles, Polyaliphatic class 

that consist of 2 cyano groups separated by a single carbon. 

Vinyl/Allyl Nitriles - basically, a vinyl (-C=C) or allyl group (-C-C=C) is attached to one 

or more nitriles groups. When two or more nitrile groups are attached to the same alkyl 

or olefinic carbon, the structure will be classified as a Vinyl/Allyl Nitriles and either a 

Nitriles, Polyaliphatic or Malonitriles. 

Other SAR Nitrile classes include: Azonitriles, Halo Nitriles, Nitrile Esters, Nitrile AlphaOH, and Phthalonitriles. 

Example Vinyl/Allyl Nitriles: 

CAS No. Name SMILES Notation 

2698-41-1 O-Chlorobenzylidene malononitrile N#CC(C#N)=Cc(c(ccc1)Cl)c1 

109-77-3 Malononitrile C(#N)CC(#N) 

110-61-2 Butanedinitrile C(#N)CCC(#N) 

111-69-3 Hexanedinitrile C(#N)CCCCC(#N) 
ECOSAR Class Definition: Polynitroanilines (Polynitro Aromatic Amine) 

The Polynitroanilines class is identified by the following structure: 

 

NH2

O2N NO2

In the current ECOSAR program, the Polynitroaniline structure meets the following 

criteria: 

(1) A benzene ring (or any other aromatic ring including hetero-aromatic rings) has one 

(or more) amine substituent (as -NH2) and two (or more) nitro substituents (-NO2). 

(2) The aromatic ring can be fused to another ring. 

Notation: the amine substituent must be -NH2 ... an amine substituent as -NH- or -N< 

is not identified as an amine for this class. 

SMILES String Identifications: 

Nc1c(N(=O)(=O))cccc1N(=O)=O 

Nc1c([N+](=O)([O-]))cccc1[N+]([O-])=O 

 ... nitro function (NO2) can be either N(=O)(=O) or [N+](=O)([O-]) 

Nc1cc(T)ccc1T 

 ... nitro function (NO2) can entered as T ... this is unique to all EPI Suite programs

Associated ECOSAR Class(s): 

Anilines (Unhindered) - An aromatic ring has an amine substituent (-NH2) that is not 

hindered by specific ortho-substituents. If the Polynitroanilines class is identified, 

ECOSAR reports both identifications. 

Anilines (Hindered) - An aromatic ring has an amine substituent (-NH2) that is hindered 

by specific ortho-substituents. If the Polynitroanilines class is identified, ECOSAR 

reports both identifications 

Dinitrobenzenes - An aromatic ring has two (or more) -NO2 substituents. If the 

Polynitroanilines class is identified, ECOSAR excludes the Polynitrobenzene 

identification. 

Anilines (amino-ortho), Anilines (amino-meta), Anilines (amino-para) - These classes 

are identified when a six-member aromatic ring has two -NH2 substituents in either an 

ortho-, meta- or para-position. When identified in conjunction with Polynitroanilines, 

they are also reported by ECOSAR. 

Example Polynitroanilines: 

CAS No. Name SMILES Notation 

97-02-9 2,4-Dinitroaniline N(=O)(=O)c(ccc(N)c1N(=O)(=O))c1 

96-91-3 Picramic acid Nc1cc(cc(N(=O)=O)c1O)N(=O)=O 

489-98-5 2,4,6-Trinitroaniline Nc1c(cc(cc1N(=O)=O)N(=O)=O)N(=O)=O 
ECOSAR Class Definition: Polynitrobenzenes 

The Polynitrobenzenes class is identified by the following structures: 

 

NO2

NO2

or ... Hetero-Aromatic Ring

 with two or more -NO2

In the current ECOSAR program, the Polynitrobenzenes structure identification meets 

the following criteria: 

(1) The ECOSAR program looks for an aromatic ring (either a benzene or any heteroaromatic ring) with two or more nitro groups (-NO2) attached to the same ring. The 

position of the NO2 groups on the ring does not matter. 

 (2) The aromatic ring can not additionally have the following attachments: -OH or an 

amine (NH2). The presence of these groups changes the current ECOSAR 

classification to Polynitrophenols or Polynitroanilines. 

 (3) The aromatic ring can be fused to one additional aromatic ring. 

SMILES String Identifications: 

c1c(N(=O)(=O))cccc1N(=O)=O 

c1c([N+](=O)([O-]))cccc1[N+]([O-])=O 

 ... nitro function (NO2) can be either N(=O)(=O) or [N+](=O)([O-]) 

Nc1cc(T)ccc1T 

 ... nitro function (NO2) can entered as T ... this is unique to all EPI Suite programs 

Associated ECOSAR Class(s): 

Polynitroanilines - an aromatic ring containing two or more nitro substituents (NO2) plus 

an amine substituent (e.g. -NH2). In the current ECOSAR program, an aromatic ring 

will not be classified as both Dinitrobenzene and Dinitroaniline (the Amine is given 

precedence). 

Polynitrophenols - an aromatic ring containing two or more nitro substituents (NO2) plus 

an hydroxyl (-OH) substituent. In the current ECOSAR program, an aromatic ring will 

not be classified as both Polynitrobenzenes and Polynitrophenols (the phenol is given 

precedence). 

Example Polynitrobenzenes: 

CAS No. Name SMILES Notation 

100-25-4 1,4-Dinitrobenzene N(=O)(=O)c(ccc(N(=O)(=O))c1)c1 

528-29-0 1,2-Dinitrobenzene O=N(=O)c1ccccc1N(=O)=O 

121-14-2 Benzene, 1-methyl-2,4-dinitro- N(=O)(=O)c(ccc(c1N(=O)(=O))C)c1 

3698-83-7 Benzene, 1,5-dichloro-2,4-dinitro- O=N(=O)c(c(cc(c1N(=O)=O)Cl)Cl)c1 
ECOSAR Class Definition: Polynitrophenols 

The Polynitrophenols class is identified by the following structures: 

 

OH

NO2 O2N

[ Ring can also be Hetero-Aromatic ]

In the current ECOSAR program, the Polynitrophenols structure must meet the following 

criteria: 

(1) One or more hydroxyl (-OH) groups are attached to an aromatic ring. The aromatic 

ring can be either a phenyl ring or any other aromatic ring unit including heterocyclic 

aromatic rings. 

(2) Two or more nitro (-NO2) groups must be attached to the same aromatic ring as the 

hydroxyl (-OH) group. 

SMILES String Identifications: 

Oc1c(N(=O)(=O))cccc1N(=O)=O 

Oc1c([N+](=O)([O-]))cccc1[N+]([O-])=O 

 ... nitro function (NO2) can be either N(=O)(=O) or [N+](=O)([O-]) 

Oc1cc(T)ccc1T 

 ... nitro function (NO2) can entered as T ... this is unique to all EPI Suite programs

Associated ECOSAR Class(s): 

Phenols - Only one hydroxyl group can be attached to aromatic rings in the structure. 

Phenols, Poly - More than one hydroxyl groups are attached to aromatic rings in the 

entire structure. 

Examples Polynitrophenols: 

CAS No. Name SMILES Notation 

51-28-5 2,4-Dinitrophenol N(=O)(=O)c(ccc(O)c1N(=O)(=O))c1 

88-89-1 2,4,6-Trinitrophenol N(=O)(=O)c(cc(N(=O)(=O))c(O)c1N(=O)(=O))c1 

534-52-1 4,6-Dinitro-o-cresol N(=O)(=O)c(cc(N(=O)(=O))c(O)c1C)c1 
Propargyl Alcohols-Hindered

The Propargyl Alcohols-Hindered class is identified by the following structures: 

 

C C C OH

R

R

C C C C OH

R

R R

R

R - is attached to alkyl carbons. These alkyl carbons can have two attachments each; 

the combination R attachments that identify Propargyl Alcohols-Hindered are noted 

below. 

In the current ECOSAR program, the hydroxy group (-OH) can be attached to the 

propargyl function (C#C-C-) at either an alpha- or beta-position. The Propargyl AlcoholHindered structure meets one of the following criteria: 

(1) In the first structure above, the hydroxyl group (-OH) is attached to an alkyl carbon 

that attached directly to an acetylenic carbon (alpha-position) . Neither of the Rsubstituents can be hydrogen (if either R is hydrogen, the structure is identified as a 

Propargyl Alcohol). 

(2) In the second structure above, an hydroxyl group (-OH) is attached at the betaposition. If both R-substituents off the beta-carbon are not hydrogen, then the Propargyl 

Alcohol-Hindered class is identified (regardless of the alpha-carbon substituents). If 

either substituent off the alpha-carbon is not hydrogen, then the Propargyl AlcoholHindered class is identified (regardless of the beta-carbon substituents). 

Notation: The ECOSAR classification changes from Propargyl Alcohols-Hindered to 

Propargyl Alcohols when the basic structure is identified, but the R-substituents do not 

meet the criteria above.. 

SMILES String Identifications: 

C#CCO ... equivalent to: C#CCOH or C#CCO[H] 

C#CCCO ... equivalent to: C#CCCOH or C#CCCO[H] 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Propargyl Alcohols - see notation above. 

Example Propargyl Alcohols-Hindered: 

CAS No. Name SMILES Notation 

115-19-5 3-Butyn-2-ol, 2-methyl- OC(C#C)(C)C 

77-75-8 1-Pentyn-3-ol, 3-methyl- OC(C#C)(CC)C 

127-66-2 2-Phenyl-3-butyn-2-ol OC(C#C)(c(cccc1)c1)C 
Propargyl Alcohols

The Propargyl Alcohols class is identified by the following structures: 

 C C CH OH

R

C C CH2 CH OH

R

R - can be anything (no exclusions) 

In the current ECOSAR program, the Propargyl Alcohol structure is identified as shown 

above. The hydroxy group (-OH) can be attached to the propargyl function (C#C-C-) at 

either an alpha- or beta-position. 

Notation: The Propargyl Alcohols class is distinguished from the Propargyl AlcoholsHindered class in that the hydroxyl (-OH) is attached to a straight-chain alkyl carbon. In 

the first structure above, the -OH is attached to a -CH- (with only one substituent). In 

the second structure (beta-position), the chain must be -CH2-CH- (with only one 

substituent off the second carbon) ... If the alkyl carbons have additional substituents 

replacing the designated hydrogens, then the Propargyl Alcohols-Hindered class will be 

identified. 

SMILES String Identifications: 

C#CCO ... equivalent to: C#CCOH or C#CCO[H] 

C#CCCO ... equivalent to: C#CCCOH or C#CCCO[H] 

C#CC(O)C ... equivalent to: C#CC(OH)C or C#CC(O[H])C 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Propargyl Alcohol-Hindered - see notation above. 

Example Propargyl Alcohols: 

CAS No. Name SMILES Notation 

107-19-7 Propargyl alcohol OCC#C 

110-65-6 2-Butyne-1,4-diol OCC#CCO 

927-74-2 3-Butyn-1-ol OCCC#C 

764-01-2 2-Butyn-1-ol CC#CCO 

4117-14-0 2-Decyn-1-ol OCC#CCCCCCCC 
ECOSAR Class Definition: Propargyl Ethers

The Propargyl Ethers class is identified by the following structure: 

 C C C

O

Carbon

In the current ECOSAR program, the Propargyl Ether structure meets the following 

criteria: 

(1) An ether oxygen is attached to an alkyl carbon that is attached to an acetylenic 

carbon. 

(2) The “Carbon” in the structure above can be alkyl, olefinic, acetylenic or aromatic 

carbon. 

SMILES String Identifications: 

C#CCOC 

C#CCOC=C 

C#CCOC#C 

C#CCOc1ccccc1 

Associated ECOSAR Class(s): 

None specifically. 

Vinyl/Allyl Ethers - the propargyl group (C#C-C-O-C) is replaced by an allyl group 

(C=C-C-O-C) 

Example Propargyl Ethers: 

CAS No. Name SMILES Notation 

6921-27-3 Dipropargyl ether O(CC#C)CC#C 

53135-64-1 1-Propyne, 3-propoxy- CCCOCC#C 
ECOSAR Class Definition: Propargyl Halides

The Propargyl Halides class is identified by the following structures: 

 C C Halogen C C C Halogen

In the current ECOSAR program, the Propargyl Halides structure meets one of the 

following criteria: 

(1) A halogen atom (Br, Cl, F, or I) is attached directly to an acetylenic carbon. 

(2) A halogen atom (Br, Cl, F, or I) is attached to an alkyl carbon that is attached 

directly to an acetylenic carbon. 

Notation: In the current ECOSAR program, the first criteria above overlaps with a 

criteria used by the Vinyl/Ally Halides class. ECOSAR identifies and reports both 

classes for a compound such as bromoacetylene (BrC#C). 

SMILES String Identifications: 

C#CBr or C#CCl or C#CF or C#CI 

C#CCBr or C#CCCl or C#CCF or C#CCI 

Associated ECOSAR Class(s): 

Vinyl/Allyl Halides - the propargyl group (C#C-C-) is replaced by a vinyl group (-C=C) or 

an allyl group (C=C-C-). 

Example Propargyl Halides: 

CAS No. Name SMILES Notation 

624-65-7 Propargyl chloride C(#C)CC 

106-96-7 1-Propyne, 3-bromo- C(#C)CBr 

7572-29-4 Dichloroacetylene ClC#CCl 
Pyrazoles/Pyrroles

The Pyrazoles/Pyrroles class is identified by the following structures: 

 

N

H

N

H

N

In the current ECOSAR program, the Pyrazoles/Pyrroles structure identification meets 

the following criteria: 

(1) The ECOSAR program looks for an aromatic ring with the following characteristics: 

(a) a five-member aromatic ring containing four carbon atoms and one nitrogen atom (a 

pyrrole ring) or (b) a five-member aromatic ring containing three carbon atoms and two 

nitrogen atoms that are adjacent to each other (a pyrazole ring). 

 (2) The [nH] in either the pyrazole ring or pyrrole ring can have the hydrogen atom 

attachment replaced by another atom. 

 (3) Either ring can be fused to one additional aromatic ring. 

SMILES String Identifications: 

Pyrrole: 

 n1cccc1 

 Hn1cccc1 

 [nH]1cccc1 

 N1C=CC=C1 

Pyrazole: 

 n1nccc1 

 Hn1nccc1 

 [nH]1nccc1 

 N1N=CC=C1 

Associated ECOSAR Class(s): 

None specifically. However, ECOSAR includes other “ring structure” classes such as 

Triazines, Imidazoles, Triazoles (Non-Fused), Triazole Pyrimidines and Thiazole, 

Benzo. 

Example Pyrazoles/Pyrroles: 

CAS No. Name SMILES Notation 

288-13-1 1H-Pyrazole N1N=CC=C1 

109-97-7 1H-Pyrrole C1=CC=CN1 

122453-73-0 Chlorfenapyr N#Cc1c(Br)c(C(F)(F)F)n(COCC)c1c2ccc(Cl)cc2 

71561-11-0 Pyrazoxyfen Clc1cc(Cl)ccc1C(=O)c2c(C)nn(C)c2OCC(=O)c3ccccc3 

82692-44-2 Benzofenap c1cc(C)ccc1C(=O)COc2n(C)nc(C)c2C(=O)c3ccc(Cl)c(C)c3Cl
ECOSAR Class Definition: Pyrethroids

The Pyrethroids class is identified by the following base structures: 

 

H3C CH3

C

O

C C

C

O

Aromatic/Aliphatic Ring

O

O

C

N

CH3 O

H3C

Attachments can be anything (no exclusions) 

In the current ECOSAR program, the Pyrethroid structure must meet either of the 

structures depicted above. 

Notation: The structures are explicit for Pyrethroid identification. For example, the 

CH3 groups must be CH3 groups and the vinyl group on the first structure (C=C) must 

be a vinyl group. 

Associated ECOSAR Class(s): 

None specifically. 

Example Pyrethroids: 

CAS No. Name SMILES Notation 

70124-77-5 Flucythrinate CC(C)C(C(=O)OC(C#N)c2cccc(Oc1ccccc1)c2)c3ccc(OC(F)F)cc3

10453-86-8 Resmethrin CC(C)=CC3C(C(=O)OCc2coc(Cc1ccccc1)c2)C3(C)C 

52918-63-5 Deltamethrin CC1(C)C(C=C(Br)Br)C1C(=O)OC(C#N)c3cccc(Oc2ccccc2)c3 

52315-07-8 Cypermethrin ClC(Cl)=CC1C(C)(C)C1C(=O)OC(C#N)c2cccc(Oc3ccccc3)c2 
ECOSAR Class Definition: Pyridine-alpha-Acid

The Pyridine-alpha-Acid class is identified by the following structure: 

 

N

OH

O

In the current ECOSAR program, the Pyridine-alpha-Acid structure identification meets 

the following criteria: 

(1) The ECOSAR program identifies a six-member aromatic ring containing five carbon 

atoms and one nitrogen atom (a pyridine ring). 

 (2) A carboxylic acid group (-C(=O)-OH) is attached to the pyridine ring in an orthoposition to the nitrogen atom. 

 (3) The pyridine ring can be fused to additional ring(s). 

SMILES String Identifications: 

n1ccccc1C(=O)O ... equivalent to: n1ccccc1C(=O)OH or n1ccccc1C(=O)O[H] 

N1=CC=CC=C1C(=O)O 

Associated ECOSAR Class(s): 

Other ECOSAR classes specifically containing a Pyridine ring: 

Halo Pyridines - one or more halogen atoms are attached to a pyridine ring. A 

structure can be classified as both a Pyridine-alpha-Acid and a Halo Pyridine. 

Notation: the Pyridine Thiones class does not contain an aromatic pyridine ring (the 

ring is an aliphatic thione ring with C(=S) as part of the ring). 

Examples Pyridine-alpha-Acid: 

CAS No. Name SMILES Notation 

98-98-6 2-Pyridinecarboxylic acid O=C(O)c(nccc1)c1 

10469-09-7 2-Pyridinecarboxylic acid, 3,4,5,6-tetrachloro- O=C(O)c(nc(c(c1Cl)Cl)Cl)c1Cl

499-83-2 2,6-Pyridinedicarboxylic acid O=C(O)c(nc(cc1)C(=O)O)c1 
ECOSAR Class Definition: Quinones

The Quinones/Hydroquinones class is identified by the following example structures: 

 

C

C

O

O

C

C

O

O

C

C

O

O

In the current ECOSAR program, the Quinones structure meets one of the following 

criteria: 

(1) A six-member aliphatic ring with two carbonyls [C(=O)] at para-positions. The other 

four ring members (that are not carbonyl) must be either (a) four olefinic carbons with 

two double-bonds, (b) two olefinic carbons with a double-bond and two aromatic 

carbons as part of a fused ring, or (c) four aromatic carbons as part of a fused ring. 

SMILES String Identifications: 

O=C1C=CC(=O)C=C1 

O=C1C=CC(=O)c2ccccc2c1 

c1ccc2C(=O)c3ccccc3C(=O)c2c1 

Associated ECOSAR Class(s): 

Vinyl/Allyl Ketones - a Quinone ring (with olefinic carbons) also fits the identification of 

the Vinyl/Allyl Ketone class ... However, ECOSAR currently excludes the ketone 

identification when a Quinone ring is identified. 

Example Quinones: 

CAS No. Name SMILES Notation 

106-51-4 1,4-Benzoquinone C1(=O)C=CC(=O)C=C1 

58-27-5 1,4-Naphthalenedione, 2-methyl- c1cc2C(=O)C=C(C)C(=O)c2cc1 

84-65-1 Anthraquinone O=C(c(c(C(=O)c1cccc2)ccc3)c3)c12 

 
ECOSAR Class Definition: Rosins

The Rosins class is identified by the following example structures: 

 

O

OH

O

OH

O

OH

Abietic Acid Pimaric Acid

The primary constituents of rosin are resins acids of the abietic and pimaric types 

having a phenanthrene-shaped ring nucleus. 

In the current ECOSAR program, the Rosin structure meets the following criteria: 

(1) the structure contains a fused three-ring unit comprised of three six-member rings 

having all carbon atoms. The rings are positioned in a phenanthrene-shaped 

configuration. 

(2) At least two of the rings must be primarily aliphatic in nature (comprised mostly of 

aliphatic carbons) ... only one ring can be aromatic (a benzene ring). 

(3) The structure must contain one (or more) carboxylic acid groups [-C(=O)OH]. The 

carboxylic acid group can be located anywhere in the structure. 

SMILES String Identifications: 

Abietic acid ring unit: C1CCC2CC=C3C=CCCC3C2C1 

Pimaric acid ring unit: C1CCC2CCC3=CCCCC3C2C1 

Ring unit with one aromatic ring: C1CCC2CCc3ccccc3C2C1 

Plus a Carboxylic Acid: C(=O)O ... equivalent to: C(=O)OH or C(=O)O[H] 

Associated ECOSAR Class(s): 

None specifically. 

Example Rosins: 

CAS No. Name SMILES Notation 

1740-19-8 Dehydroabietic acid O=C(O)C(C(C(c(c(cc(c1)C(C)C)C2)c1)(CC3)C)C2)(C3)C 

514-10-3 Abietic acid O=C(O)C(C(C(C(C(=C1)C=C(C2)C(C)C)C2)(CC3)C)C1)(C3)C

5835-26-7 Isopimaric acid CC3(CCC1C(=CCC2C1(C)CCCC2(C)C(=O)(O))C3)C=C 

471-77-2 Neoabietic acid C(C(CC1)=C(C)C)=C(CCC2C(C3)(C(=O)O)C)C1C2(CC3)C 
ECOSAR Class Definition: Schiff Bases-Azomethine

The Schiff Bases class is identified by the following structure: 

 

C N R3

R2

R1

R1 and R2 - must be hydrogen or alkyl, olefinic, acetylenic or aromatic carbon atoms 

(no other atoms allowed). 

R3 - cannot be hydrogen 

In the current ECOSAR program, the Schiff Base structure meets the following criteria: 

(1) The structure as depicted above. The C=N fragment cannot be part of a ring 

structure. 

SMILES String Identifications: 

C=N 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

None specifically. 

Example Schiff Bases: 

CAS No. Name SMILES Notation 

64611-40-1 

Methanamine, Nethylidene-, (Z)- CC=NC 

104-71-2 

1,2-Ethanediamine, N,N'-

bis(phenylmethylene)- N(CCN=Cc(cccc1)c1)=Cc(cccc2)c2 

92-29-5 Hydrobenzamide c1ccccc1C=NC(c2ccccc2)N=Cc3ccccc3 
ECOSAR Class Definition: Substituted Ureas 

The Substituted Ureas class is identified by the following structure: 

 

N

O

R N 1

R2

R4

R3

In the current ECOSAR program, the Substituted Ureas structure must meet the 

following criteria: 

R1 and R2 can be either a hydrogen or oxygen atom or alkyl, olefinic, acetylenic or 

aromatic carbon atoms, but at least one attachment must be to a carbon atom. 

R3 and R4 can be anything except a carbonyl group. 

If R3 or R4 contain a carbonyl group, then ECOSAR will identify the class as 

carbonyl ureas. 

SMILES String Identifications: 

NC(=O)N 

 ... (attachments as defined above)

Example Substituted Ureas: 

CAS No. Name SMILES Notation 

330-54-1 Diuron O=C(N(C)C)Nc(ccc(c1Cl)Cl)c1 

18691-97-9 Methabenzthiazuron CNC(=O)N(C)c2nc1ccccc1s2 
Sulfonyl Ureas

The Sulfonyl Ureas class is identified by the following structure: 

R1 and R2 - can be anything (no exclusions) 

In the current ECOSAR program, the Sulfonyl Urea structure must meet the following 

criteria: 

(1) A sulfone group [S(=O)(=O)] is attached to the nitrogen atom of a urea function 

[NC(=O)N]. 

 (2) The urea nitrogens or the sulfone group can have other attachments (no 

exclusions). 

SMILES String Identifications: 

NC(=O)NS(=O)(=O) 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Amides - the ECOSAR Amides class is a general class having a CC(=O)N, NC(=O)N 

or S(=O)N group that occurs in other ECOSAR classes. In general, the Amides class is 

reported by ECOSAR in addition to the other classes (such as Sulfonyl Ureas). 

The Vinyl/Allyl Sulfones class contains the -S(=O)(=O)- function which is the only other 

ECOSAR class containing the sulfone group. 

Example Sulfonyl Ureas: 

CAS No. Name SMILES Notation 

82097-50-5 Triasulfuron ClCCOc1ccccc1S(=O)(=O)NC(=O)Nc2nc(OC)nc(C)n2 

74223-64-6 Metsulfuron-methyl COC(=O)c1ccccc1S(=O)(=O)NC(=O)Nc2nc(OC)nc(C)n2 

64902-72-3 Chlorsulfuron n1c(OC)nc(C)nc1NC(=O)NS(=O)(=O)c2ccccc2Cl 

122931-48-0 Rimsulfuron CCS(=O)(=O)c1cccnc1S(=O)(=O)NC(=O)Nc2nc(OC)cc(OC)n2
ECOSAR Class Definition: Thiazolidinones / Benzothiazolidinones

The Thiazolidinone class is identified by the following structures: 

 

N S

C

O

N S

C

S

N S

C

O

N S

C

S

In the current ECOSAR program, the Thiazolidinone structure meets the following 

criteria: 

(1) a five-member ring containing one carbonyl (or thiocarbonyl) attached to one 

aliphatic sulfur and one aliphatic nitrogen. The two carbon atoms in the ring can be 

either alkyl carbons or two aromatic carbons of a fused-ring. 

(2) The atoms in the thiazolidinone ring can have other attachments (no exclusions). 

Notations: Currently, the thiazolidinone ring cannot contain two olefinic carbons with a 

double bond in place of the aromatic carbons or alkyl carbons. 

SMILES String Identifications: 

O=C1SCCN1 

S=C1SCCN1 

 In conjunction with a fused aromatic ring: 

O=C1Sc2ccccc2N1 

S=C1Sc2ccccc2N1 

Associated ECOSAR Class(s): 

Thiocarbamates & Dithiocarbamates - the order of the carbonyl (or thiocarbonyl) with 

attached sulfur and nitrogen is additionally classified by ECOSAR as one of these 

classes. 

The Isothiazolone class ring also contains a carbonyl, one sulfur, one nitrogen and two 

carbon atoms, but in a different order. 

Example Thiazolidinones / Benzothiazolidinones: 

CAS No. Name SMILES Notation 

25059-80-7 Benazolin-ethyl CCOC(=O)CN1C(=O)Sc2cccc(Cl)c12 

96-53-7 2-Thiazolidinethione N(C(=S)SC1)C1 

1908-87-8 2-Thiazolidinethione, 3-methyl- N(C(SC1)=S)(C1)C 

2682-49-7 2-Thiazolidinone N1CCSC1=O 
ECOSAR Class Definition: Thiazolidinones - Acids

The Thiazolidinones-Acid class is identified by the following structures: 

 

N S

C

O

N S

C

S

N S

C

O

N S

C

S

+ Acid Group

This class is identical to the Thiazolidinone-Benzothiazolidinone class with the addition 

of an acid function. 

In the current ECOSAR program, the Thiazolidinone-Acid structure meets the following 

criteria: 

(1) a five-member ring containing one carbonyl (or thiocarbonyl) attached to one 

aliphatic sulfur and one aliphatic nitrogen. The two carbon atoms in the ring can be 

either alkyl carbons or two aromatic carbons of a fused-ring. 

(2) an Acid group (carboxylic acid, sulfonic acid, phosphonic acid) exists anywhere in 

the structure. 

(3) The atoms in the thiazolidinone ring can have other attachments (no exclusions). 

Notations: Currently, the thiazolidinone ring cannot contain two olefinic carbons with a 

double bond in place of the aromatic carbons or alkyl carbons. 

SMILES String Identifications: 

O=C1SCCN1 

S=C1SCCN1 

 In conjunction with a fused aromatic ring: 

O=C1Sc2ccccc2N1 

S=C1Sc2ccccc2N1 

 Plus - an Acid group: 

Carboxylic Acid: C(=O)O ... equivalent to: C(=O)OH or C(=O)O[H] 

Phosphoric Acid: P(=O)(O) ... equivalent to: P(=O)(OH)OH 

Sulfonic Acid: S(=O)(=O)O ... equivalent to: S(=O)(=O)OH 

Associated ECOSAR Class(s): 

Thiocarbamates & Dithiocarbamates - the order of the carbonyl (or thiocarbonyl) with 

attached sulfur and nitrogen is additionally classified by ECOSAR as one of these 

classes. 

Example Thiazolidinones / Benzothiazolidinones: 

CAS No. Name SMILES Notation 

3813-05-6 Benazalox (Metizolin) OC(=O)CN1C(=O)Sc2cccc(Cl)c12 

ECOSAR Class Definition: Thiocarbamate,Di (Free Acid)

The Thiocarbamate,Di (Free Acid) class is identified by the following structures: 

 H2N

C

S

S

R

N

C

SH

S

R

H2N

C

SH

S

R - can be anything (no exclusions) 

In the current ECOSAR program, the Thiocarbamate,Di (Free Acid) class meets the 

following criteria: 

(1) the core dithiocarbamate structure [N-C(=S)-S] occurs in the structure. 

(2) either (or both) the nitrogen or sulfur exists as free acid in the form of -NH2 or -SH. 

SMILES String Identifications: 

NC(=S)S ... equivalent to: [NH2]C(=S)S or N(H)(H)C(=S)S 

NC(=S)S ... equivalent to: NC(=S)SH or NC(=S)S[H] 

NC(=S)S ... equivalent to: [NH2]C(=S)SH or N(H)(H)C(=S)SH 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Thiocarbamate, Di (Substituted) - both of the free acids are substituted. 

Example Thiocarbamate,Di (Free Acid): 

CAS No. Name SMILES Notation 

29596-83-6 Acetic acid, [(aminothioxomethyl)thio]- S=C(SCC(=O)O)N 

99-00-3 Picadex N1CCN(C(=S)S)CC1 

12656-69-8 Dithane SC(=S)NCCNC(S)=S 
ECOSAR Class Definition: Thiocarbamate,Di (Substituted)

The Thiocarbamate,Di (Substituted) class is identified by the following structures: 

 N

C

S

S

R R

R - can be anything except hydrogen attached to the sulfur or two hydrogens (H2) 

attached the nitrogen. 

In the current ECOSAR program, the Thiocarbamate,Di (Substituted) class meets the 

following criteria: 

(1) the core dithiocarbamate structure [N-C(=S)-S] occurs in the structure. 

(2) both the nitrogen or sulfur have a hydrogen substitution (excluding both as free 

acids). 

SMILES String Identifications: 

NC(=S)S 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Thiocarbamate, Di (Free Acids) - either (or both) the nitrogen or sulfur exists as free 

acid in the form of -NH2 or -SH. 

Example Thiocarbamate,Di (Substituted): 

CAS No. Name SMILES Notation 

137-26-8 Thioperoxydicarbonic diamide,tetramethyl- N(C(=S)SSC(N(C)C)=S)(C)C 

95-06-7 Sulfallate CCN(CC)C(=S)SCC(Cl)=C 

96-53-7 2-Thiazolidinethione N(C(=S)SC1)C1 

533-74-4 Dazomet N(CSC(N1C)=S)(C1)C 
ECOSAR Class Definition: Thiocarbamates, Mono

The Thiocarbamates, Mono class is identified by the following structures: 

 N

C

S

O

R1 R2

N

C

O

S

R1 R3

R1 - can be anything except H2 (two hydrogens off the nitrogen). 

R2 - can be anything (including hydrogen). 

R3 - can be anything except hydrogen 

In the current ECOSAR program, the Thiocarbamates, Mono class meets the criteria as 

shown in the structure above. 

SMILES String Identifications: 

NC(=O)S 

NC(=S)O 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Vinyl/Allyl Thiocarbamates - if the R3 substituent is vinyl (-C=C) or allyl (-CC=C) group, 

ECOSAR will identify the structure as both Thiocarbamates, Mono and Vinyl/Allyl 

Thiocarbamates and report both classes. 

ECOSAR includes a variety of Di-Thiocarbamate ester classes. 

Example Thiocarbamates, Mono: 

CAS No. Name SMILES Notation 

759-94-4 Eptam (EPTC) O=C(N(CCC)CCC)SCC 

1114-71-2 Pebulate CCCCN(CC)C(=O)SCCC 

2303-16-4 Diallate CC(C)N(C(C)C)C(=O)SCC(Cl)=CCl 

42116-76-7 Carnidazole Cc1ncc(N(=O)(=O))n1CCNC(=S)OC 

88678-67-5 Pyributicarb n1c(OC)cccc1N(C)C(=S)Oc2cc(C(C)(C)C)ccc2 
ECOSAR Class Definition: Thiocyanates/Isothiocyanates

The Thiocyanates/Isothiocyanates class is identified by the following structure: 

 R - N = C = S 

R S

C N

R - can be aliphatic, alicyclic, aromatic, or hetercyclic, but not hydrogen. 

SMILES String Identifications: 

N=C=S 

N#CS 

Associated ECOSAR Class(s): 

Isocyanates - the thiocyanate sulfur is replaced by an oxygen (R-N=C=O) 

Example Thiocyanates/Isothiocyanates: 

CAS No. Name SMILES Notation 

57-06-7 Allyl isothiocyanate C=CCN=C=S 

556-61-6 Methyl isothiocyanate CN=C=S 

103-72-0 Phenyl isothiocyanate c1ccccc1N=C=S 

6317-18-6 Methylene bis(thiocyanate) N#CSCSC#N 
ECOSAR Class Definition: Thiols and Mercaptans

The Thiols and Mercaptans class is identified by the following structure: 

 

Aliphatic Carbon

SH

Aromatic Carbon

SH

SH

SH (example)

(example)

In the current ECOSAR program, the Thiol-Mercaptan structure must meet the following 

criteria: 

(1) A thiol-mercaptan function (-SH) is attached to an alkyl, olefinic, acetylenic or 

aromatic carbon atom. 

SMILES String Identifications: 

SC ... equivalent to: HSC or [H]SC 

SC=C ... equivalent to: HSC=C or [H]SC=C 

SC#C ... equivalent to: HSC#C or [H]SC#C 

Sc1ccccc1 ... equivalent to: HSc1ccccc1 or [H]Sc1ccccc1 

Associated ECOSAR Class(s): 

None specifically. 

Example Thiols and Mercaptans: 

CAS No. Name SMILES Notation 

74-93-1 Methanethiol SC 

111-31-9 1-Hexanethiol SCCCCCC 

68-11-1 Mercapto acetic acid O=C(O)CS 

1455-21-6 1-Nonanethiol SCCCCCCCCC 

5331-91-9 Chloro-2-mercaptobenzothiazole S(C(S)=N1)c(ccc2Cl)c1c2 

 
ECOSAR Class Definition: Thiomethacrylates

The Thiomethacrylates class is identified by the following structures: 

 

C

C

S

O

C R1

CH3

C

C

{O,S}

S

C R1

CH3

R1 - attachment must be either an alkyl carbon, olefinic carbon, acetylenic carbon or 

aromatic carbon. 

{O,S} - can be either oxygen (-O-) or sulfur (-S-) 

Internally, the ECOSAR program initially detects a carbonyl function [C(=O)] or a 

thiocarbonyl function [C(=S)] with one olefinic attachment and one oxygen or sulfur 

attachment. The olefinic carbon attached to the carbonyl (or thiocarbonyl) must have a 

methyl (CH3) attachment (anything other than a methyl group (CH3) changes the 

classification from a possible Thiomethacrylate to a possible Acrylate. The oxygen or 

sulfur must have either an alkyl carbon, olefinic carbon, acetylenic carbon or aromatic 

carbon attachment to be classified as either a Thiomethacrylate or Acrylate. 

SMILES String Identifications: 

C=C(C)C(=O)S ... equivalent to: C=C(C(H)(H)H)C(=O)S or C=C([CH3])C(=S)S 

 .... Note: ECOSAR converts a SMILES entry of [CH3] to C(H)(H)(H), then C only 

C=C(C)C(=S)O 

C=C(C)C(=S)S 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

Methacrylates are a class separate from either Thiomethacrylates or Acrylates. 

Structures classified as Thiomethacrylates are also classified as Methacrylates. In 

addition, ECOSAR will classify Thiomethacrylates having the thiocarbonyl function 

[C(=S)] as Esters. 

Example Thiomethacrylates: 

CAS No. Name SMILES Notation 

 O-Methyl thiomethacrylate C=C(C)C(=S)OC 

 S-Methyl thiomethacrylate C=C(C)C(=O)SC 

 Methyl dithiomethacrylate C=C(C)C(=S)SC 

 
Thiophenes

The Thiophenes class is identified by the occurrence following ring structure: 

 

S

ECOSAR identifies a Thiophene ring as follows: 

(1) a five-atom-member ring consisting of one sulfur atom and four carbon atoms 

(2) the ring is an aromatic ring; the SMILES designation for an unsubstituted ring is 

s1cccc1 ... if the SMILES entry into ECOSAR is S1C=CC=C1, it will be converted into 

s1cccc1 ... ECOSAR identifies the aromatic ring as a Thiophene 

(3) the Thiophene ring cannot be part of an aromatic fused-ring system (such as 

benzothiophene) ... the Thiophene ring can be fused to an aliphatic ring. 

SMILES String Identifications: 

s1cccc1 

S1C=CC=C1 

Associated ECOSAR Class(s): None 

Example Thiophenes: 

CAS No. Name SMILES Notation

110‐02‐1 Thiophene S1C=CC=C1   [or]   s1cccc1

872‐31‐1 3‐Bromothiophene C1=CC(Br)=CS1

554‐14‐3 2‐Methythiophene C1=C(C)SC=C1

 
ECOSAR Class Definition: Thiophthalimides 

The Thiophthalimides class is identified by the following structure: 

 

Substitutions can be anything (no exclusions). 

In the current ECOSAR program, the thiophthalimides structure contains a benzene ring 

bound to a 5-membered ring containing an aliphatic nitrogen bound to a sulfur atom and 

surround by two carbonyl [C(=O)] groups (as depicted above). 

SMILES String Identifications: 

Thiophthalimides Group: 

C1cccc2c1C(=O)N(SC)C2=O 

Associated ECOSAR Class(s): 

Imides - identified by C(=O)-N-C(=O). 

Example Thiophthalimides: 

CAS No. Name SMILES Notation 

133-06-2 Captan O=C(N(SC(Cl)(Cl)Cl)C(=O)C1CC=CC2)C

12 

133-07-3 Folpet 

O=C(N(SC(Cl)(Cl)Cl)C(=O)c1cccc2)c12 

2939-80-2 Captafol O=C1N(C(=O)C2C1CC=CC2)SC(C(Cl)Cl)

(Cl)Cl 
ECOSAR Class Definition: Thiotetrazoles

The Thiotetrazoles class is identified by the following structures: 

 

N

H

N N

N S

R

S

N

N N

N

R - attachment to the sulfur can be anything in current ECOSAR program. 

In the current ECOSAR program, the Thiotetrazole structure identification meets the 

following criteria: 

(1) The ECOSAR program looks for two aromatic rings with the following 

characteristics: (a) a five-member aromatic ring containing one carbon atom (with an 

aliphatic sulfur attachment) and four nitrogen atoms (a tetrazole ring) or (b) a fivemember aromatic ring containing one sulfur atom and four nitrogen atoms. 

 (2) The [nH] in the tetrazole ring can have the hydrogen atom attachment replaced by 

another atom. 

 (3) The tetrazole or thiotetrazole ring can be fused to additional aromatic ring(s). 

SMILES String Identifications: 

Sc1nnnn1 

Sc1nnn[nH]1 

SC1=NN=NN1 

s1nnnn1 

S1N=NN=N1 

Associated ECOSAR Class(s): 

None specifically. However, ECOSAR includes other “ring structure” classes such as 

Triazines, Imidazoles, Triazoles (Non-Fused), Triazole Pyrimidines and Thiazole, 

Benzo. 

Examples Thiotetrazoles: 

CAS No. Name SMILES Notation 

56610-79-8 

1H-Tetrazole, 1-methyl-5-

[(phenylmethyl)thio]- c1ccccc1CSC2=NN=NN2C 

133088-69-4 

1H-Tetrazole, 5-(hexylsulfinyl)-1-(4-

nitrophenyl)- CCCCCCS(=O)C1=NN=NN1c2ccc(N(=O)=O)cc2 
ECOSAR Class Definition: Thioureas

The Thioureas class is identified by the following structure: 

 

C

S

R1 N N R2

R1 and R2 - can be anything (no exclusions) 

In the current ECOSAR program, the Thiourea structure must meet the following 

criteria: 

(1) A thiocarbonyl function [-C(=S)-] is attached to two aliphatic nitrogen atoms. If the 

thiocarbonyl is attached an aromatic nitrogen (such as a nitrogen in a pyrrole ring), the 

structure will not be classified as a Thiourea. 

(2) The nitrogen atoms can have other attachments (no exclusions). 

SMILES String Identifications: 

NC(=S)N 

 ... (attachments as defined above)

Associated ECOSAR Class(s): 

None specifically. 

Other urea classes (e.g. Substituted Ureas or Sufonyl Ureas) pertain to a carbonyl 

[C(=O)] urea as compared to the thiocarbonyl [C(=S)] urea of this class. 

Example Thioureas: 

62-56-6 Thiourea NC(=S)N 

534-13-4 Thiourea, N,N'-dimethyl- N(C(=S)NC)C 

5217-47-0 1,3-Diethyl-thiobarbituric acid O=C(N(C(N(C1=O)CC)=S)CC)C1 
ECOSAR Class Definition: Triazines, Aliphatic 

The Triazines, Aliphatic class is identified by the following example structures: 

N N

N

 

In the current ECOSAR program, the Triazine, Aliphatic structure is a six-member ring 

containing three aliphatic carbon atoms (carbonyls are not included) and three aliphatic 

nitrogen atoms in the sim position . 

SMILES String Identifications: 

N1CNCNC1 

Associated ECOSAR Class(s): 

Triazines, Aromatic- a six-member aromatic ring containing three aromatic nitrogen 

atoms and three aromatic carbon atoms or one aromatic carbon with two carbonyls or 

two aromatic carbons with one carbonyl 

Aliphatic Amines – defined in ECOSAR as any primary, secondary or tertiary aliphatic 

amine group. Since the Aliphatic Triazine class does not take precedence over aliphatic 

amines, both classes are reported in ECOSAR for these chemicals – though aliphatic 

triazines yield higher toxicity profiles. 

Example Triazines: 

CAS No. Name SMILES Notation 

100-97-0 Hexamethylenetetramine N(CN(CN1CN23)C3)(C1)C2 

7779-27-3 

1,3,5-Triazine, 1,3,5-

triethylhexahydro- N(CN(CN1CC)CC)(C1)CC 

 
ECOSAR Class Definition: Triazines, Aromatic 

The Triazines, Aromatic class is identified by the following example structures: 

 Structure 1 Structure 2 Structure 3 Structure 4 

 

N

N

N

R

R

R

N

NN

O

R

R

N

NNO

R

O

N N

O N O

O

Triazine, aromatics consists of a six-member aromatic ring containing three aromatic 

nitrogen atoms in the sim-position in addition to either; 

1) Three aromatic carbon atoms, 2) two aromatic carbons with one carbonyl; 3) one 

aromatic carbon with two carbonyls; or 4) three carbonyl groups (as shown 

above). 

R can be anything except three primary or secondary nitrogen atoms. 

If all R groups are primary or secondary nitrogen atoms, ECOSAR will identify 

the class as Melamine 

In structure 3 and 4 represented above containing at least 2 carbonyls, if there is a 

chlorine atom attached to the nitrogen between two carbonyls, the class will be 

identified at haloimides [(C(=O)NC(=O)] which presents higher toxicity concern 

presumably due to the presence of the halogen based on analysis of similar chemicals. 

SMILES String Identifications: 

n1cnc(=O)nc1=O 

n1cncnc1 

n1cnc(=O)nc1 

n1c(=O)nc(=O)nc1=O 

Example Triazines, Aromatic: 

CAS No. Name SMILES Notation 

101-05-3 Anilazine Clc2nc(Cl)nc(Nc1ccccc1Cl)n2 

122-34-9 Simazine n(c(nc(n1)NCC)NCC)c1Cl 

1912-24-9 Atrazine n(c(nc(n1)NC(C)C)NCC)c1Cl 

 
ECOSAR Class Definition: Triazole Pyrimidines Sulfonamides 

Formerly refered to as the Triazole Pyrimidines class, the Triazole Pyrimidine 

Sulfonamides class is entirely composed of chemicals with the following identifying 

structures: 

 

N N N

N

S N

O

O

The class was updated to include the CNS(=O)(=O) fragment since the entire training 

set for the class (which is a class of pesticides) included this as part of the base 

fragment. 

Searches for toxicity patterns for the former base fragment (c1nn2c(n1)ccnc2) yielded 

no results on toxicity profiles. It is suspected that due to the aromatic nature of the 

backbone this fragment alone would present minimal toxicity, unless substituted with 

reactive functional groups. 

In the current ECOSAR program, the Triazole Pyrimidines Sulfonamide is a sulfonamide 

bound to two fused aromatic rings (as depicted above) with the following characteristics: 

(a) a five-member aromatic ring containing two carbon atoms and three nitrogen atoms 

(a triazole ring), (b) a six-member aromatic ring containing four carbon atoms and two 

nitrogen atoms, and (c) both rings contain one or more fused carbon atoms (meaning 

each ring is fused to another aromatic ring). 

ALERT: Chemicals containing the large molecular fragment for triazole pyrimidine 

sulfonamides are likely designed to act as herbicides. If the query compound contains 

this structural fragment, it is likely to be most closely related to the training set 

chemicals in the triazole pyrimidine sulfonamides class – irrespective of the other 

classes reported. 

SMILES String Identifications: 

CNS(=O)(=O)c1nn2c(n1)ccnc2 

Associated ECOSAR Class(s): 

Other ECOSAR classes containing a fused triazole ring: 

Benzotriazoles - a 1,2,3-triazole ring fused to another aromatic ring 

ECOSAR classes containing a non-fused triazole ring: 

Triazoles (Non-Fused) - a structure containing either a 1,2,4-triazole, 1,2,3-triazole or 

1,3,4-triazole ring that is not fused to another aromatic ring. 

Examples Triazole Pyrimidines: 

CAS No. Name SMILES Notation 

145701-21-9 Diclosulam 

c1(n2c(cc(n1)F)nc(n2)S(=O)(=O)Nc1c(cccc1Cl)Cl)O

CC 

 98967-40-9 Flumetsulam Fc1cccc(F)c1NS(=O)(=O)c2nc3nc(C)ccn3n2 
ECOSAR Class Definition: Triazoles (Non-Fused)

The Triazoles (Non-Fused) class is identified by the following structures: 

 

N

N

N

N

N

N

N

N N

In the current ECOSAR program, the Triazoles (Non-Fused) structure identification 

meets the following criteria: 

(1) The ECOSAR program identifies a five-member aromatic ring containing two carbon 

atoms and three nitrogen atoms (a triazole ring). 

 (2) The position of the nitrogen atoms in the ring does not matter. The ring can be 

either 1,2,4-triazole, 1,2,3-triazole or 1,3,4-triazole. 

 (3) The triazole ring cannot be fused to additional aromatic ring(s). 

SMILES String Identifications: 

n1cncn1 ... equivalent to: [nH]1cncn1 

n1ccnn1 ... equivalent to: [nH]1ccnn1 

n1cnnc1 ... equivalent to: [nH]1cnnc1 

N1C=NC=N1 

N1C=CN=N1 

N1C=NN=C1 

Associated ECOSAR Class(s): 

None specific to a non-fused triazole ring. Other ECOSAR classes containing a fused 

triazole ring: 

Benzotriazoles - a 1,2,3-triazole ring fused to another aromatic ring 

Triazole Pyrimidines - a triazole-pyrimidine fused ring structure 

Examples Triazoles (Non-Fused): 

CAS No. Name SMILES Notation 

288-88-0 1H-1,2,4-Triazole n1ncnc1 

76674-21-0 Flutriafol n1cncn1CC(O)(c2ccc(F)cc2)c3ccccc3F 

43121-43-3 Triadimefon CC(C)(C)C(=O)C(Oc1ccc(Cl)cc1)n2cncn2 

83657-22-1 Uniconazole c1ncnn1C(C(O)C(C)(C)C)=Cc2ccc(Cl)cc2 

79983-71-4 Hexaconazole Clc2c(ccc(c2)Cl)C(Cn1ncnc1)(O)CCCC 

85509-19-9 Flusilazole c1cc(F)ccc1[Si](C)(c2ccc(F)cc2)Cn3ncnc3
ECOSAR Class Definition: Vinyl/Allyl Alcohols

The Vinyl/Allyl Alcohols class is identified by the following structures: 

 C

C

OH C

C

C

OH

In the current ECOSAR program, the Vinyl/Allyl Alcohols structure meets the following 

criteria: 

(1) A hydroxy group (-OH) is attached to a vinyl group (-C=C) or allyl group (-C-C=C). 

The single-bonded carbon on the allyl group is an alkyl carbon. 

SMILES String Identifications: 

C=CO ... equivalent to: C=COH or C=CO[H] 

C=CCO ... equivalent to: C=CCOH or C=CCO[H] 

Associated ECOSAR Class(s): 

None specifically. 

ECOSAR includes a variety of alcohol classes (such as Propargyl Alcohols, Benzyl 

Alcohols, Nitro Alcohols) and Vinyl/Allyl classes. 

Example Vinyl/Allyl Alcohols: 

CAS No. Name SMILES Notation 

107-18-6 Allyl alcohol C=CCO 

924-41-4 1,5-Hexadien-3-ol OC(CC=C)C=C 

4798-44-1 1-Hexen-3-ol OC(C=C)CCC 

66-76-2 Dicumarol O=C1Oc2ccccc2C(O)=C1CC3=C(O)c4ccccc4OC3=O

50-81-7 L-Ascorbic acid O1C(=O)C(O)=C(O)C1C(O)CO 

557-75-5 Vinyl alcohol C=CO 
ECOSAR Class Definition: Vinyl/Allyl Aldehydes

The Vinyl/Allyl Aldehydes class is identified by the following structures: 

 H

C

C

O

C

H

C

C

O

C

C H

C

C

O

C

The Vinyl/Allyl Aldehyde class is identified when an aldehyde group (HC(=O)-) is 

attached to a vinyl (C=C), allyl (-C-C=C) or acetylenic (-C#C) group. 

In the current ECOSAR program, if a structure contains more than one Vinyl/Allyll 

Aldehyde group (or one Vinyl/Allyl Aldehyde group plus additional Aldehyde functional 

groups), the structure will be classified as both Vinyl/Allyl Aldehydes and Aldehydes 

(Poly). Structures classified as Vinyl/Allyl Aldehydes are not classified as Aldehydes 

(Mono). 

SMILES String Identifications: 

O=CC=C ... equivalent to: O=C(H)C=C 

O=CCC=C ... equivalent to: O=C(H)CC=C 

O=CC#C ... equivalent to: O=C(H)C#C 

Associated ECOSAR Class(s): 

Aldehydes (Mono) - If the attachment to the aldehyde group (HC(=O)-) is an alkyl 

carbon, aromatic carbon, carbonyl or hydrogen, the structure will be classified as an 

Aldehyde (Mono) 

Aldehydes (Poly) - the structure must contain two or more aldehyde functional groups. 

In the current ECOSAR program, a structure can be classified as both Aldehydes (Poly) 

and Vinyl/Allyl Aldehydes. 

Example Vinyl/Allyl Aldehydes: 

CAS No. Name SMILES Notation 

107-02-8 Acrolein [or 2-Propenal] O=CC=C 

5392-40-5 2,6-Octadienal, 3,7-dimethyl- O=CC=C(CCC=C(C)C)C 

6203-18-5 4-Dimethylaminocinnamaldehyde O=CC=Cc(ccc(N(C)C)c1)c1 

7319-38-2 3-Butenal O=CCC=C 

 
ECOSAR Class Definition: Vinyl/Allyl Esters

The Vinyl/Allyl Esters class is identified by the following structures: 

C

C

O

O

Vinyl or Allyl

C

C

S

O

Vinyl or Allyl

C

C

O

S

Vinyl or Allyl

C

C

S

S

Vinyl or Allyl

O

C

O

O

Vinyl or Allyl

S

C

S

S

Vinyl or Allyl

Vinyl/Allyl - Vinyl (-C=C) and Allyl (-C-C=C) 

In the current ECOSAR program, the Vinyl/Allyl Esters class meets the criteria as 

shown in the structure above and the following: 

(1) the carbon atom (to which the carbonyl or thiocarbonyl is attached) must be an alkyl, 

olefinic, acetylenic or aromatic carbon. 

(2) carbonate and thiocarbonate esters can also be identified as Vinyl/Allyl Esters. 

SMILES String Identifications: 

CC(=O)OC=C CC(=O)OCC=C 

CC(=S)OC=C CC(=S)OCC=C 

CC(=O)SC=C CC(=O)SCC=C 

CC(=S)SC=C CC(=S)SCC=C 

COC(=O)OC=C COC(=O)OCC=C 

Associated ECOSAR Class(s): 

Esters - the Esters class includes a wide variety of organic ester types including various 

phosphorus esters. Currently, ECOSAR is programmed to include the Ester class when 

the Vinyl/Allyl Esters class is reported. 

Example Vinyl/Allyl Esters: 

CAS No. Name SMILES Notation 

105-38-4 Vinyl propionate O=C(OC=C)CC 

123-20-6 Vinyl butyrate CCCC(=O)OC=C 

123-68-2 Allyl caproate O=C(OCC=C)CCCCC 
ECOSAR Class Definition: Vinyl/Allyl Ethers

The Vinyl/Allyl Ethers class is identified by the following structures: 

 

C

O

C

C C

O

C

C

C

The ether function is identified as an aliphatic oxygen attached to two carbons atoms 

(alkyl, olefinic, acetylenic or aromatic carbon). 

In the current ECOSAR program, the Vinyl/Allyl Ether structure meets the following 

criteria: 

(1) one (or both) sides of the ether function is a vinyl (-C=C) or allyl (-C-C=C) group. 

SMILES String Identifications: 

COC=C 

COCC=C 

C=COC=C 

C=COCC=C 

C#COC=C 

C#COCC=C 

c1ccccc1OC=C 

c1ccccc1OCC=C 

Associated ECOSAR Class(s): 

None specifically. 

The ether function also occurs in the Halo Ether class. 

Example Vinyl/Allyl Ethers: 

CAS No. Name SMILES Notation 

107-25-5 Methyl vinyl ether COC=C 

557-40-4 Allyl ether O(CC=C)CC=C 

83-79-4 Rotenone COc5cc4OCC3Oc2c1CC(Oc1ccc2C(=O)C3c4cc5OC)C(C)=C 

57-24-9 Strychnidin-10-one O=C(N(c(c(C1(C(N(C2)CC(C3C4C5OC6)=C6)C3)C2)ccc7)c7)C14)C5
ECOSAR Class Definition: Vinyl/Allyl Halides

The Vinyl/Allyl Halides class is identified by the following structures: 

 C

C

{Br,Cl,I} C

C

C {Br,Cl,I} C

C

{Br,Cl,I}

In the current ECOSAR program, the Vinyl/Allyl Halides structure must meet the 

following criteria: 

(1) A halogen atom (bromine, chlorine or iodine; fluorine excluded) is attached to a vinyl 

group (-C=C), allyl group (-C-C=C) or acetylenic group (-C#C). The single-bonded 

carbon on the allyl group is an alkyl carbon. 

Notation: Fluorine has been excluded from this class. In addition, the acetylenic group 

(which was included in the original program code) is still included. 

SMILES String Identifications: 

C=CBr or C=CCl or C=CI 

C=CCBr or C=CCCl or C=CCI 

C#CBr or C#CCl or C#CI 

Associated ECOSAR Class(s): 

Propargyl Halides - Vinyl/Allyl Halides identified with the acetylenic group (-C#C) are 

additionally classified as Propargyl Halides by ECOSAR. 

ECOSAR includes a variety of Vinyl/Allyl classes and Halo-Halide classes. 

Example Vinyl/Allyl Halides: 

CAS No. Name SMILES Notation 

107-05-1 Allyl Chloride C=CCCl 

79-01-6 Trichloroethylene C(=CCl)(Cl)Cl 

591-97-9 2-Butene, 1-chloro- C(=CC)CCl 

78-88-6 1-Propene, 2,3-dichloro- C(=C)(CCl)Cl 

127-18-4 Tetrachloroethylene C(=C(Cl)Cl)(Cl)Cl 
ECOSAR Class Definition: Vinyl/Allyl Ketones

Vinyl/Allyl Ketones are identified by the following structures: 

 C C

C

O

C C

O

C

To be classified as Vinyl/Allyl Ketones by the current ECOSAR program, the structure 

must meet the following criteria: 

(1) The basic ketone fragment is identified as carbonyl group attached to carbon atoms 

on both sides where the carbon atoms must be an alkyl, olefinic, acetylenic or aromatic 

carbon. To be classified as Vinyl/Allyl, one or both attachments to the carbonyl must be 

a vinyl group (-C=C) or an allyl group (-C-C=C). 

(2) The vinyl/allyl ketone fragment can be either cyclic or acyclic. 

SMILES String Identifications: 

CC(=O)C=C 

CC(=O)CC=C 

C=CC(=O)C=C 

C=CC(=O)CC=C 

C#CC(=O)C=C 

C#CC(=O)CC=C 

c1ccccc1C(=O)C=C 

c1ccccc1C(=O)CC=C 

Associated ECOSAR Class(s): 

In addition to the Vinyl/Allyl Ketones class, the ECOSAR program will add any of the 

classes below to the to the program output if identified in a structure. 

Diketones - Diketones have two ketone functions at 1,3-positions. A structure can be 

classified as both Diketones and Vinyl/Allyl Ketones (e.g. SMILES: 

C=CC(=O)CC(=O)C). 

Benzyl Ketones - a ketone with -C-aromatic ring attachment to the carbonyl 

Halo Ketones (2 Free H) - a ketone with a -CH2-Halogen attachment to a carbon atom 

at the alpha- or beta-position to the carbonyl 

Halo Ketones (0-1 Free H) - a ketone with a -CH-Halogen (or -C-Halogen) attachment 

to a carbon atom at the alpha- or beta-position to the carbonyl 

Example Vinyl/Allyl Ketones: 

CAS No. Name SMILES Notation 

78-94-4 Vinyl methyl ketone C=CC(=O)C 

78-59-1 Isophorone O=C(C=C(CC1(C)C)C)C1 

141-79-7 Mesityl oxide O=C(C=C(C)C)C 
ECOSAR Class Definition: Vinyl/Allyl Nitriles

The Vinyl/Allyl Nitriles class is identified by the following structures: 

 C

N

C

N

In the current ECOSAR program, the Vinyl/Allyl Nitrile structure must meet one of the 

following criteria: 

(1) A nitrile group (carbon triple-bonded to nitrogen; SMILES of C#N) is attached to a 

vinyl group (-C=C) or an allyl group (-C-C=C). 

(2) Two or more nitrile groups attached to the same alkyl carbon. 

SMILES String Identifications: 

C=CC#N 

C=CCC#N 

Associated ECOSAR Class(s): 

Nitriles, Polyaliphatic - Two or more nitrile groups are attached to aliphatic atoms in the 

whole structure. When two or more nitrile groups are attached to the same alkyl or 

olefinic carbon, the structure will be classified as both Vinyl/Allyl Nitriles and Nitriles, 

Polyaliphatic. 

Other SAR Nitrile classes include: Azonitriles, Halo Nitriles, Nitrile Esters, Nitrile AlphaOH, and Phthalonitriles. 

Example Vinyl/Allyl Nitriles: 

CAS No. Name SMILES Notation 

109-75-1 Allyl cyanide N#CCC=C 

107-13-1 2-Propenenitrile N#CC=C 
Vinyl/Allyl Pyrazoles/Pyrroles

The Vinyl/Allyl Pyrazoles/Pyrroles class is identified by the following structures: 

 

N

R

N

N

R

R = -C=C (vinyl) or –CC=C (allyl) 

In the current ECOSAR program, the Vinyl/Allyl Pyrazoles/Pyrroles structure 

identification meets the following criteria: 

(1) The ECOSAR program looks for an aromatic ring with the following characteristics: 

(a) a five-member aromatic ring containing four carbon atoms and one nitrogen atom (a 

pyrrole ring) or (b) a five-member aromatic ring containing three carbon atoms and two 

nitrogen atoms that are adjacent to each other (a pyrazole ring). 

 (2) The [nH] in either the pyrazole ring or pyrrole ring can have the hydrogen atom 

attachment replaced by another atom. 

 (3) Either ring can be fused to additional aromatic rings. 

SMILES String Identifications: 

Pyrrole: 

 C=Cn1cccc1 

 C=CCn1cccc1 

Pyrazole: 

 C=Cn1nccc1 

 C=CCn1nccc1 

Associated ECOSAR Class(s): 

Pyrazoles/Pyrroles – A five-membered aromatic ring containing either one or two 

nitrogens. 

Example Vinyl/Allyl Pyrazoles/Pyrroles: 

CAS No. Name SMILES Notation 

288-13-1 1H-Pyrazole N1N=CC=C1 

109-97-7 1H-Pyrrole C1=CC=CN1 

122453-73-0 Chlorfenapyr N#Cc1c(Br)c(C(F)(F)F)n(COCC)c1c2ccc(Cl)cc2 

71561-11-0 Pyrazoxyfen Clc1cc(Cl)ccc1C(=O)c2c(C)nn(C)c2OCC(=O)c3ccccc3 

82692-44-2 Benzofenap c1cc(C)ccc1C(=O)COc2n(C)nc(C)c2C(=O)c3ccc(Cl)c(C)c3Cl
ECOSAR Class Definition: Vinyl/Allyl Sulfones

The Vinyl/Allyl Sulfones class is identified by the following structures: 

 C S C

O

C

C S C

O

C

O

C S C

O

C

O

C

C S C

O

C C

In the current ECOSAR program, the Vinyl/Allyl Sulfones structure must meet one of the 

following criteria: 

(1) A sulfone group [S(=O)(=O)] is attached to an alkyl, olefinic, acetylenic or aromatic 

carbon atom and the sulfone group is attached to a vinyl (-C=C) or allyl (-C-C=C) 

group. 

 (2) A sulfoxide group [-S(=O)-] is attached to an alkyl, olefinic, acetylenic or aromatic 

carbon atom and the sulfoxide group is attached to a vinyl (-C=C) or allyl (-C-C=C) 

group. 

SMILES String Identifications: 

C=CS(=O)C

C=CCS(=O)C

C=CS(=O)(=O)C

C=CCS(=O)(=O)C

 ... (bolded C (carbon atom) can be alkyl (C), olefinic (C=C), acetylenic (C#C) or 

aromatic (c))

Associated ECOSAR Class(s): 

None specifically. 

The Sulfonyl Ureas class contains the -N-C(=O)-N-S(=O)(=O)- function which is the only 

other ECOSAR class containing the sulfone group. 

The Amides class contains a sulfoxide group as in: -N-S(=O)- 

Example Vinyl/Allyl Sulfones: 

CAS No. Name SMILES Notation 

3680-02-2 Methyl vinyl sufone CS(=O)(=O)C=C 

16212-05-8 Allyl phenyl sulfone S(=O)(=O)(c1ccccc1)CC=C 

77-79-2 Thiophene, 2,5-dihydro-, 1,1-dioxide O=S(=O)(CC=C1)C1