Nomenclature of carboxylic acid
Carboxylic acids are named according to following systems:
1. Common System: Common name of carboxylic acids are given on the basic of the source from which they are obtained. For example, the name formic acid was given since it was first obtained by the distillation of red ants (Latin: Formica = ants). Similarly, the name valeric acid is given since it is naturally found in valerian plant, which is a perennial flowering plant and so on.
The positions of the substituents are indicated by the Greek letters- α, β, γ, δ, etc. The α– carbon is the one bearing the —COOH group, the next one as β and so on as:
2. Derived system: According to this system, some monocarboxylic acids are named as alkyl derivatives of acetic acid.
3. IUPAC system
a. Monocarboxylic acids: The longest chain of carbon atoms including –COOH in monocarboxylic acid is considered the parent chain, and is named by replacing the –e of the corresponding parent alkane with –oic acid and hence IUPAC name of monocarboxylic acid is Alkanoic acid.Carbon is always given as C-1, in numbering the carbon atom in the parent chain as:
b. Dicarboxylic acids: IUPAC name of dicarboxylic acid is Alkanedioic acid. The suffix –dioic acid is added to the name of parent alkane containing the same number of carbon atoms.
c. Tricarboxylic acids:
If more than two carboxyl groups are bonded to unbranched longest carbon chain, carbon atoms of the carboxyl groups are not included in the parent chain.