89 Properties
89.1 Nomenclature.
The systematic IUPAC nomenclature for carboxylic acids requires the longest carbon chain
of the molecule to be identified and the -e of alkane name to be replaced with -oic acid.
The traditional names of many carboxylic acids are still in common use.
Nomenclature of carboxylic acids
formula IUPAC name traditional name
HCOOH methanoic acid formic acid
CH 3 -COOH ethanoic acid acetic acid
CH 3 CH 2 -COOH propanoic acid propionic acid
CH 2 =CH-COOH propenoic acid acrylic acid
CF 3 -COOH trifluoroethanoic acidThe systematic approach for naming dicarboxylic acids (alkanes with carboxylic acids on
either end) is the same as for carboxylic acids, except that the suffix is -dioic acid. Common
name Nomenclature of dicarboxylic acids is aided by the acronym OMSGAP (Om’s Gap),
where each letter stands for the first letter of the first seven names for each dicarboxylic
acid, starting from the simplest.
Nomenclature of dicarboxylic acids
formula IUPAC name traditional name
HOOCCOOH Ethanedioic acid Oxalic acid
HOOCCH 2 -COOH propanedioic acid Malonic acid
HOOCCH 2 CH 2 -COOH butanedioic acid Succinic acid
HOOCCH 2 CH 2 CH 2 -COOH pentanedioic acid Glutaric acid
HOOCCH 2 CH 2 CH 2 CH 2 -COOH hexanedioic acid Adipic acid
HOOCCH 2 CH 2 CH 2 CH 2 CH 2 -COOH heptanedioic acid Pimelic acid89.2 Acidity
Most carboxylic acids are weak acids. To quantify the acidities we need to know the pKa
values: The pH above which the acids start showing mostly acidic behaviour: Ethanoic
acid: 4.8 Phenol: 10.0 Ethanol: 15.9 Water: 15.7
Acidity of carboxylic acids in water
acid formula pKa
methanoic acid H-COOH 3.75