In the IUPAC system, aliphatic carboxylic acids are named by replacing the ending –e in the name of the corresponding alkane with –oic acid. In numbering the carbon chain, the carboxylic carbon is numbered one. For naming compounds containing more than one carboxyl group, the alkyl chain leaving carboxyl groups is numbered and the number of carboxyl groups is indicated by adding the multiplicative prefix, dicarboxylic acid, tricarboxylic acid, etc. to the name of parent alkyl chain. The position of –COOH groups are indicated by the arabic numeral before the multiplicative prefix.

What is the IUPAC name of terephthalic acid?

Benzene-1,4-dicarboxylic acid

The correct answer is option 4. Benzene-1,4-dicarboxylic acid.

Terephthalic acid is an aromatic dicarboxylic acid with the two carboxyl groups on the opposite ends (para position) of a benzene ring. So the IUPAC name of the compound will be Benzene-1,4-dicarboxylic acid.