Summary of Functional Groups
Carboxylic acids are the highest-priority functional group because they contain three bonds to
oxygen: one from a hydroxyl group and two from a carbonyl group.
Carboxylic acids are always terminal, although their derivatives may occur within a molecule.
Carboxylic acids are named with the suffix –oic acid. They are very rarely named as a prefix.
Common names for carboxylic acids follow the trend for aldehydes. Formic acid is methanoic
acid, acetic acid is ethanoic acid, and propionic acid is propanoic acid.
Esters are carboxylic acid derivatives where –OH is replaced with –OR, an alkoxy group.
Esters use the suffix –oate or the prefix alkoxycarbonyl–.
Common names for esters are derived from the alcohol and the carboxylic acid used during
synthesis.
Amides replace the hydroxyl group of a carboxylic acid with an amino group that may or may not
be substituted.
Amides use the suffix –amide or the prefix carbamoyl– or amido–. Substituents attached to
the amide nitrogen are designated with a capital N–.
Anhydrides are formed from two carboxylic acids by dehydration. They may be symmetric (two
of the same acid), asymmetric (two different acids), or cyclic (intramolecular reaction of a
dicarboxylic acid)
Anhydrides are named using the suffix anhydride in place of acid. If the anhydride is formed
from more than one carboxylic acid, both are named in alphabetical order in the name before
the word anhydride.
Functional groups are arranged in order of priority as follows: Carboxylic acid > anhydride > ester
> amide > aldehyde > ketone > alcohol > alkene or alkyne > alkane
