Most Common Functional Groups
In Order of Priority for the Principal Name


Class Formula Substituent Prefix Principal Name Suffix

Carboxylic acid -COOH Carboxy -carboxylic acid
-(C)OOH - -oic acid

Acid anhydrides -CO-O-COR - R...carboxylic anhydride
-(C)O-O-COR - R...oic anhydride
Esters -COOR R-oxycarbonyl R...carboxylate
-(C)OOR - R...oate

Acid halides -CO-Halogen Haloformil -carbonyl halide
-(C)O-Halogen - -oyl halide

Amides -CO-NH2 Carbamoyl -carboxamide
-(C)O-NH2 - -amide

Nitriles -CN Cyano -carbonitrile
-(C)N - -nitrile

Aldehydes -CHO Formyl -carbaldehyde
-(C)HO Oxo -al

Ketones >(C)=O Oxo -one

Alcohols and Phenols -OH Hydroxy -ol

Amines -NH2 Amino amine

Ethers -OR R-oxy ether (non-IUPAC)

Alkyl Halide -F, -Cl, -Br, -I fluoro-, chloro-, bromo-, iodo- fluoride, chloride, bromide, iodide (non-IUPAC)


Others: cations, anions (or salts of anions), sulfur containing compds., peroxides (-O-O-), =N2, -N3, -NO, -NO2, -ClO, -ClO2, -ClO3, -IO, -IO2, or ring systems.


"(C)" represents the naming as part of a longer carbon chain.

Adapted from Sections A, B and C of IUPAC "Blue Book," Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F, and H, Pergamon Press, Oxford, 1979. Copyright 1979 IUPAC.

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