Functional Group Priorities
for Principal Name


Class Formula Substituent Prefix Principal Name Suffix

Cations -onio -onium
-onia -onium

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

Sulfonic acid -SO3H Sulfo -sulfonic acid

Salts of -COOM - Metal...carboxylate
carboxylic acids -(C)OOR - Metal...oate

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

Amidines -C(=NH)-NH2 Amidino -carboxamidine
-(C)(=NH)-NH2 - -amidine

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

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

Ketones >(C)=O Oxo -one

Alcohols -OH Hydroxy -ol

Phenols -OH Hydroxy -ol

Thiols -SH Mercapto -thiol

Hydroperoxides -O-OH Hydroperoxy -

Amines -NH2 Amino amine

Imines =NH Imino -imine

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

Peroxides -O-OR R-dioxy peroxide (non-IUPAC)

Sulfone -SO2-R R-sulfonyl sulfone (non-IUPAC)

Sulfoxide -SO-R R-sulfinyl sulfoxide (non-IUPAC)

Sulfide -SR R-thio sulfide (non-IUPAC)

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

Azide -N3 Azido -azide (non-IUPAC)



"(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.