-COOH
Carboxylic acid; -oic acid
-COOR
Ester; -oate
-SO3H
Sulfonic acid; -sulfonic acid
-COCl
Acid chloride; -oyl chloride
-CONH2(R)2
Amide; -amide
-CO-
Ketone; -one
-CHO
Aldehyde; -al
-CN
Nitrile; -nitrile
-O-
Ether
-SH
Thiol; -thiol
-NH2
Amine; -amine
-S-
Sulfide
-S2-
Disulfide
-SO-
Sulfoxide
-NO2
Nitro