IUPAC Nomenclature of Carboxylic Acids

Identify the longest carbon chain containing the –COOH group as the parent chain. Replace the terminal -e of the corresponding alkane with the suffix -oic acid. Number the chain starting from the –COOH carbon, identify substituents and their positions, then assemble the complete name with stereochemistry if needed.

For dicarboxylic acids, select the parent chain including both –COOH carbons and number to give substituents the lowest locants. Retain the terminal -e of the parent hydrocarbon and add the suffix -dioic acid, unlike monocarboxylic acids where the terminal -e is replaced with -oic acid.

Unsaturated carboxylic acids derive their parent name from the corresponding alkene or alkyne. The position of the double or triple bond is indicated by a locant prefixed to the parent name. Stereochemistry around double bonds is shown using cis/trans or E/Z notation prefixed to the parent name.

The –COOH group has the highest priority among functional groups. All other groups like –CHO, –CO–, –OH, –OR, –NH2, and halogens are treated as substituents when a carboxylic acid is present and are named as prefixes to the parent name.

When a –COOH group is bonded directly to a cycloalkane or aromatic ring, the suffix -carboxylic acid is added to the parent ring name. The ring carbon bearing the –COOH group is numbered as carbon-1, unlike acyclic carboxylic acids where numbering starts from the carboxylic acid carbon.

Compounds with multiple –COOH groups use prefixes di- or tri- to indicate the number of carboxylic acid groups. Sometimes one carboxylic acid is treated as the main functional group while others are named as substituents using prefixes like carboxymethyl- to the parent name.

When naming dicarboxylic acids, the parent chain must be numbered from the end that gives substituents the lowest locant values. This ensures the most systematic and unambiguous name, following IUPAC rules for locant assignment and maintaining consistency in nomenclature across all carboxylic acid structures.