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Compound Groups

Compound groups are groups of chemicals that share structural or chemical features. In most cases, hazard lists will assign hazards to individual substances. Compound groups are useful because in some cases, lists will instead identify a group of structurally similar compounds (such as lead compounds) as all having the same hazard. The Pharos staff is in the process of establishing and populating compound groups, and associating warnings from the hazard lists with them. The table below indicates how each compound group is populated, and what is the status of its population.
Compound Groups
COMPOUND GROUP NAME POPULATION STATUS DATE POPULATED DESCRIPTION PROFILE TYPE # MEMBERS # HAZARDS
Cresol isomers complete This compound group has not yet been assigned a structural definition. other 4 1
Crude and refined coal tars complete 04/01/21

This compound group was populated from existing compound groups for the Cradle to Cradle (C2C) RSL.

48 1
CYANIDE COMPOUNDS complete

This compound group includes both commercially relevant compounds such as Hydrogen Cyanide, Sodium Cyanide, Potassium Cyanide, and Calcium Cyanide, as well as cyanide salts that are less common. 

structure 39 8
Cyclocyloxanes - Biomonitoring CA complete

This group is populated from the list at https://biomonitoring.ca.gov/chemicals

fixed list 4 1
Di- and triether of alkanediols and -triols (C3-C8, linear and branched) with epichlorohydrin (content of free epichlorohydrin < 20 ppm, not characterized as H351 or H350) complete 06/17/19 fixed list 16 0
Di-isodecyl phthalate and metabolite complete This compound group has not yet been assigned a structural definition. other 7 0
Di-n-Octyl Phthalate and metabolites complete This compound group has not yet been assigned a structural definition. other 2 0
Dibutyl phthalate and metabolites complete This compound group has not yet been assigned a structural definition. other 2 0
Dichlorobenzenes complete This compound group has not yet been assigned a structural definition. other 5 6
Dichloroethylenes complete This compound group has not yet been assigned a structural definition. other 6 0
dichloropropanes complete This compound group has not yet been assigned a structural definition. other 17 0
Dicyclohexyl phthalate and metabolite complete This compound group has not yet been assigned a structural definition. other 3 0
Diethyl hexyl phthalate and metabolites complete This compound group has not yet been assigned a structural definition. other 12 0
Dimethylarsenic acids complete

This compound group is defined by the SMILES string '[CH3][As](=O)([CH3])O'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 18 39
Dimethyltin derivatives complete 07/26/18

This compound group is defined by the SMILES string '[CH3][Sn]([CH3])', then subtracting compounds with 3+ methyl ligands. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 276 17
Dinoterb salts and esters complete

This compound group is defined by a substructure search of PubChem the SMILES/SMARTS string "[CH3]C([CH3])([CH3])C1=[CH1]C(=[CH1]C(=C1[OD1])[N+](=O)[O-])[N+](=O)[O-] plus [CH3]C([CH3])([CH3])C1=[CH1]C(=[CH1]C(=C1OC(=O)C)[N+](=O)[O-])[N+](=O)[O-]". The setting "Remove any explicit hydrogens before searching" was deselected from each substructure search. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 7 9
Dioctyltin dilaurate, stannane, dioctyl-, bis(coco acyloxy) derivs., and any other stannane, dioctyl-, bis(fatty acyloxy) derivs. wherein C12 is the predominant carbon number of the fatty acyloxy moiety complete 02/27/23

ECHA chemical group parent

3 5
dioctyltin dilaurate; stannane, dioctyl-, bis(coco acyloxy) derivs. (ECHA defined) complete 02/27/23

ECHA chemical group parent

2 5
Diphenyltin derivatives complete 07/26/18

This compound group is defined by the SMILES string '[CH]1=[CH][CH]=C([CH]=[CH]1)[Sn](C2=[CH][CH]=[CH][CH]=[CH]2)'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 153 19
Endocrine Disruptors - Apple RSL complete

This compound group is populated from Apple's Regulated Substances Specification

fixed list 13 1
Endosulfan Isomers complete This compound group was populated from the Stockholm POPs Convention decision http://chm.pops.int/TheConvention/ThePOPs/TheNewPOPs/tabid/2511/Default.aspx fixed list 2 3
Fatty alcohols, saturated, with even-numbered C-chain, number of C-atoms >=16, with terminating OH-group complete 39 0
Formaldehyde compounds and polymers complete 09/11/18

This compound group was populated by searching ChemIDplus for all compounds whose name contained "formaldehyde". Additionally, it contains the compounds in its subgroups. 

other 1164 2
Formaldehyde Donors complete 05/29/20

This compound group is populated from a list of chemicals in an ECHA Investigation Report - Formaldehyde and Formaldehyde Releasers as well as manual searches. Report downloaded from https://echa.europa.eu/documents/10162/13641/annex_xv_report_formaldehyde_en.pdf/58be2f0a-7ca7-264d-a594-da5051a1c74b

149-44-0 (Sodium formaldehyde sulfoxylate) was added based on suggestion by GreenSeal, citing https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-hydroxymethanesulfinate and https://www.fishersci.com/store/msds?partNumber=AC149190250&productDescription=SODIUM+FORMALDEHYDESULFO+25KG&vendorId=VN00032119&countryCode=US&language=en 

functional use 187 1
Germanium Compounds complete 08/09/18

This compound group is defined by the SMILES string '[Ge]'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

element 1206 1
Gold salts complete 04/01/21

This compound group was populated using a substructure search of PubChem using the SMILES string [Au].

element 495 1
halogenated monomethyldiphenylmethanes - UN Transport of Dangerous Goods complete 04/28/23 3 1
Halogenated Solvents complete 08/17/23

This compound group is populated by selecting halogenated solvents (excluding salts) from GSPI's Six Classes of Problematic Chemicals - Some Solvents List.

fixed list 973 5
Halogenated Solvents - City of Portland, OR complete 05/17/17

Includes chemicals from https://www.portlandoregon.gov/water/article/28482

1-Chlorobutane (CAS 109-69-3) added by suggestion of GreenSeal citing https://pubchem.ncbi.nlm.nih.gov/compound/1-Chlorobutane#section=Use-Classification

functional use 88 5
HBCDD / HBCD isomers complete

This compound group is defined by the SMILES/SMARTS string "C1CC(C(CCC(C(CCC(C1Br)Br)Br)Br)Br)Br" and populated from a substructure search of PubChem. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

 

 

structure 32 11
Hexabromocyclododecane (HBCDD) complete 02/27/23

Hexabromocyclododecane (HBCDD) and all major diastereoisomers identified

7 17
Hydrofluorocarbons (HFCs) in Google's MRSL complete 02/12/21

This compound group was populated from the Google Manufacturing Restricted Substances Specification (v1.0) (TTD_3549)

 

fixed list 19 1
Inorganic Ammonium Salts complete 08/01/18

This compound group is defined by the SMILES string '[NH4] subtracting [NH4].C'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

other 275 3
Inorganic cyanide compounds complete 03/12/20

This compound group was manually populated with inorganic cyanide compounds. It is based on an entry in Korea's GHS.

other 22 13
Ioxynil salts complete 07/30/18

This compound group has not yet been assigned a structural definition.

other 11 0
Iron Oxides (MAK list of 4) complete

This compound group is populated from the MAK list.

fixed list 6 1
ISOCYANATES complete 07/19/17

This compound group is defined by the SMARTS string "[NX2:2]=[C:1]=[OX1:3]". For more information on SMARTS, see https://en.wikipedia.org/wiki/Smiles_arbitrary_target_specification.

structure 2936 2
Manganese Compounds complete 08/09/18

This compound group is defined by the SMILES string '[Mn]'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

element 614 5
Medium-chain chlorinated paraffins (MCCP) complete 02/27/23

UVCB substances consisting of more than or equal to 80% linear chloroalkanes with carbon chain lengths within the range from C14 to C17

ECHA chemical group parent

4 13
Mercury, organic compounds (MAK) complete

MAK provides the following criteria for the organic mercury compounds it flags as hazardous. This compound group is defined by the SMILES/SMARTS string "C[Hg]" and populated from a substructure search of PubChem.

"Organomercury compounds are characterized chemically by the covalent binding of one or two alkyl or aryl groups and covalent or ionic binding of a group such as halide,hydroxide, acetate, nitrate or phosphate to the mercury atom."

https://onlinelibrary.wiley.com/doi/10.1002/3527600418.mb743997orge0015

structure 965 46
Metal salts of 2-ethylhexanoic acid complete 05/22/23

ECHA defined chemical group

fixed list 9 4
Methylarsenic compounds complete

This compound group is defined by a substructure search of PubChem the SMILES/SMARTS string "[As][CH3]". The setting "Remove any explicit hydrogens before searching" was deselected from the substructure search.

structure 398 39
Molybdenum Compounds complete 08/09/18

This compound group is defined by the SMILES string '[Mo]'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

element 391 4
Monohalomethanes complete

This compound group is composed of four chemicals so no substructure search is needed to populate it

other 4 2
Monometharsonic acids complete

This compound group is defined by A PubChem Substructure search of the SMILES/SMARTS string "[CH3][As](=O)(O)O". The setting "Remove any explicit hydrogens before searching" was deselected from the substructure search. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

 

 

structure 34 39
Monomethyltin derivatives complete 07/26/18

This compound group is defined by the SMILES string '[Sn][CH3]' subtracting compounds with 2+ methyl ligands. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 95 17
Monophenyltin derivatives complete 07/26/18

This compound group is defined by the SMILES string '[CH]1=[CH][CH]=C([CH]=[CH]1)[Sn]', then subtracting compounds matching diphenyltin. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 70 19
National Health and Nutrition Examination Survey (NHANES) Chemical List complete 07/27/20

This list was copied from https://comptox.epa.gov/dashboard/chemical_lists/NHANES2019

fixed list 516 0
Nickel compounds, inorganic complete

This compound group is defined by the SMILES/SMARTS string "[Ni] subtract [Ni].C" and populated from a substructure search of PubChem. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 507 1
Nickel compounds, oxidic complete

This compound group is defined by the SMILES/SMARTS string "O=[Ni]" and populated from a substructure search of PubChem. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

"including nickel oxide, nickel-copper oxide, nickel silicate oxides, and complex oxides"

https://www.canada.ca/en/health-canada/services/environmental-workplace-health/reports-publications/environmental-contaminants/canadian-environmental-protection-act-priority-substances-list-assessment-report-nickel-compounds.html

structure 29 28
Nickel Compounds, Soluble (MAK list) complete

This compound group has been populated using subgroups listed by MAK Commission of Germany.

fixed list 11 29
Nonadecafluorodecanoic acid (PFDA) and its sodium and ammonium salts complete 02/27/23

ECHA chemical group parent

3 4
Organohalogen Flame Retardants - NAS OFR expanded set complete 02/12/24

This compound group is populated from "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants" by National Academies of Sciences, Engineering, and Medicine. The committee identified a set of 1073 analogue compounds as "expanded set" based on combined functional, structural, and predicted bioactivity information.

The subclasses from the seed list used to expand this list are also in Pharos:

fixed list 1084 1
ORGANOPHOSPHOROUS COMPOUNDS complete 09/13/18

This compound group is defined by the SMILES string 'POC'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 3174 1
Orthoboric acid, sodium salt (group) complete 02/27/23

ECHA chemical group parent

6 4
Ozone Depleting Chemicals - Apple RSS complete

This compound group is populated from Apple's Regulated Substances Specification

fixed list 84 0
Ozone Depleting Chemicals (ODCs) in Google's MRSL complete 02/12/21

This compound group was populated from the Google Manufacturing Restricted Substances Specification (v1.0) (TTD_3549)

fixed list 209 3
Ozone Depleting Chemicals, Hydrochlorofluorocarbons - Apple RSL complete

This compound group is populated from Apple's Regulated Substances Specification

fixed list 115 0
Pentachlorophenol salts and esters complete

This compound group is defined by a substructure search of PubChem the SMILES/SMARTS string "C1(=C(C(=C(C(=C1Cl)Cl)Cl)Cl)Cl)[OD1] plus C1(=C(C(=C(C(=C1Cl)Cl)Cl)Cl)Cl)[O]C(C)=O". The setting "Remove any explicit hydrogens before searching" was deselected from each substructure search. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 118 12
Pentanol isomers (MAK list) complete

This compound group has not yet been assigned a structural definition.

fixed list 11 4
Perfluorocarbons (PFCs) in Google's MRSL complete 02/12/21

This compound group was populated from the Google Manufacturing Restricted Substances Specification (v1.0) (TTD_3549)

fixed list 9 1
Perfluorohexanesulfonic acid and its salts (PFHxS) complete 02/27/23

ECHA chemical group parent

37 22
Perfluorooctane sulfonates (PFOS) complete

This compound group is defined by the SMILES/SMARTS string "C(C(C(C(C(F)(F)S(=O)(=O)O)(F)F)(F)F)(F)F)(C(C(C(F)(F)F)(F)F)(F)F)(F)F" and populated from a substructure search of PubChem. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 41 32
Perfluorooctane Sulfonates (PFOS) and PFOS salts in Google's MRSL complete 02/12/21

This compound group was populated from the Google Manufacturing Restricted Substances Specification (v1.0) (TTD_3549)

fixed list 28 2
Petroleum Process Streams complete 03/10/23

EPA's Partially Exempt Petroleum Process Streams list

from EPA's Chemical Data Reporting: https://www.epa.gov/chemical-data-reporting/partially-exempt-petroleum-process-streams

fixed list 636 0
PFAS - OECD Comprehensive Global Database of PFASs (2018) complete

OECD's Comprehensive Global Database of PFASs

4747 13
PFAS soluable in DMSO - EPAPFASIV complete 08/14/23

This compound group is populated from EPAPFASIV's list. EPA filtered several publicly available PFAS lists to exclude most high (>500) and low (<50) molecular weight compounds, aromatic compounds, metal-containing compounds, and chemicals with a low ratio of fluorine to carbon. The PFAS chemicals in this list are in the current inventory found to be soluble in DMSO.

fixed list 437 14
PFNA, Perfluorononan-1-oic-acid and its sodium and ammonium salts complete 02/27/23

ECHA chemical group parent

other 3 5
Phenol, alkylation products (mainly in para position) with C12-rich branched alkyl chains from oligomerisation, covering any individual isomers and/ or combinations thereof (PDDP) complete 02/27/23

full name: Phenol, alkylation products (mainly in para position) with C12-rich branched alkyl chains from oligomerisation, covering any individual isomers and/ or combinations thereof (PDDP)

ECHA chemical group parent

7 8
Phenol, isopropylated, phosphate (3:1) - EPA PBT complete 07/12/23

EPA's background information about PBT define this compound group as a family of structures in which each of the three aryl groups have at least one isopropyl group: Tris(3-isopropylphenyl) phosphate, Tri(isopropylphenyl) phosphate, Tri(4-isopropylphenyl) phosphate

fixed list 3 1
Phthalates - Apple RSS complete

This compound group is populated from Apple's Regulated Substances Specification

fixed list 51 1
PHTHALATES (orthophthalates) complete

This compound group is defined by a substructure search of PubChem using the SMILES string 'COC(=O)c1[cH][cH][cH][cH]c1C(=O)OC'. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 639 12
Pigments containing or manufactured with chlorine complete 07/19/23

This compound group is populated with ChemForward's inadvertent PCB (iPCB) Pigment Resources - pigments with "Yes" for "Contains Chlorine?" or a "Yes" for "Manufactured using chlorine solvent?".

fixed list 177 0
POLYBROMINATED BIPHENYLS (PBBs) complete

This compound group was populated from the 2016 GADSL list at http://www.gadsl.org/

other 56 45
Polybrominated Diphenyl Ethers (PBDEs) - Apple RSL complete

This compound group is populated from Apple's Regulated Substances Specification

fixed list 23 1
POLYCYCLIC AROMATIC COMPOUNDS (OSHA EXCLUSIONS) complete This compound group is defined by a list in the US EPA's Toxics Release Inventory (TRI) Basis of OSHA Carcinogens document, available at https://www.epa.gov/toxics-release-inventory-tri-program/tri-basis-osha-carcinogens. fixed list 24 6
POLYCYCLIC AROMATIC HYDROCARBONS (PAHs) complete

This list is drawn from:

other 95 19
Polycyclic Aromatic Hydrocarbons (PAHs) - Apple RSL complete

This compound group is populated from Apple's Regulated Substances Specification

fixed list 38 1
Polyhalogenated alicycles (NAS OFR subclass) complete

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

20 12
Polyhalogenated aliphatic carboxylate (NAS OFR subclass) complete

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

6 12
Polyhalogenated aliphatic chains (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 42 12
Polyhalogenated benzene alicycles (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 4 12
Polyhalogenated benzene aliphatics and functionalized (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 22 12
Polyhalogenated benzenes (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 20 12
Polyhalogenated bisphenol aliphatics and functionalized (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 42 12
Polyhalogenated carbocycles (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 40 12
Polyhalogenated diphenyl ethers (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 19 12
Polyhalogenated organophosphates (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 38 12
Polyhalogenated phenol derivatives (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 10 12
Polyhalogenated phenol-aliphatic ethers (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 14 12
Polyhalogenated phthalates/benzoates/imides (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 21 12
Polyhalogenated triazines (NAS OFR subclass) complete 05/21/19

This compound group is populated from a National Academies of Science report "A Class Approach to Hazard Assessment of Organohalogen Flame Retardants (2019)" available at https://www.nap.edu/catalog/25412/a-class-approach-to-hazard-assessment-of-organohalogen-flame-retardants

fixed list 7 12
POLYISOCYANATE COMPOUNDS complete 07/24/17

This compound group is defined by the SMARTS string ([NX2:2]=[C:1]=[OX1:3].[NX2:2]=[C:1]=[OX1:3]), subtracting any compounds whose name contains "polymer". This SMARTS search unfortunately captures polymers made from isocyanates, because their structures are often represented by individual monomers. For more information on SMARTS, see https://en.wikipedia.org/wiki/Smiles_arbitrary_target_specification.

structure 575 3
QUATERNARY AMMONIUM COMPOUNDS complete 07/09/19

This compound group was populated from a manual search of the Pharos database. 

other 120 1
QUINOLINE STRONG ACID SALTS complete 07/09/19

Strong acid salts are listed at https://comptox.epa.gov/dashboard/dsstoxdb/mixture_search?cid=1798

fixed list 6 4
Reaction products of 1,3,4-thiadiazolidine-2,5-dithione, formaldehyde and 4-heptylphenol, branched and linear (RP-HP) complete 02/27/23

with ≥0.1% w/w 4-heptylphenol, branched and linear (4-HPbl)

ECHA chemical group parent

2 5
salts and esters of dinoterb - ECHA complete 05/26/23

ECHA defined chemical group

fixed list 1 13
Salts of 3,3'-dichlorobenzidine complete

This compound group is defined by the SMILES string '[CH1]1=[CH1]C(=C([CH1]=C1C2=[CH1]C(=C([CH1]=[CH1]2)[ND1])[ClD1])[ClD1])[ND1]'. The setting "Remove any explicit hydrogens before searching" was deselected from the substructure search. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 9 11
Salts of 3,3'-dimethoxybenzidine complete

This compound group is defined by a substructure search of PubChem the SMILES/SMARTS string "[CH1]1=[CH1]C(=C([CH1]=C1C2=[CH1]C(=C([CH1]=[CH1]2)[ND1])O[CH3])O[CH3])[ND1]". The setting "Remove any explicit hydrogens before searching" was deselected from the substructure search. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 5 8
Salts of 4-aminobiphenyl complete

This compound group is defined by the SMILES string '[CH1]1=[CH1][CH1]=C([CH1]=[CH1]1)C2=[CH1][CH1]=C([CH1]=[CH1]2)[ND1]'. The setting "Remove any explicit hydrogens before searching" was deselected from the substructure search. For more information on SMILES, see https://en.wikipedia.org/wiki/Simplified_molecular-input_line-entry_system.

structure 6 11