Match List-I with List-II.
| List-I | List-II |
| Acid | IUPAC name |
| (a) Phthalic acid | (i) Hexane-1,6-dioic acid |
| (b) Oxalic acid | (ii) Benzene-1,2-dicarboxylic acid |
| (c) Succinic acid | (iii) Butane-1,4-dioic acid |
| (d) Adipic acid | (iv) Ethane-1,2-dioic acid |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)
In the IUPAC system an aliphatic acid is named from the alkane with the same number of carbon atoms, counting the carboxyl carbons, and the ending –e becomes –oic acid. With two carboxyl groups the ending is –dioic acid, and the numbers in front give their positions.
When the –COOH groups are attached to a ring, the ring carbons carry them, and the name ends in –dicarboxylic acid.
(a) Phthalic acid — This matches (ii) Benzene-1,2-dicarboxylic acid. Phthalic acid, \( \ce{C6H4(COOH)2} \), is a benzene ring with two –COOH groups on adjacent ring carbons (positions 1 and 2).
(b) Oxalic acid — This matches (iv) Ethane-1,2-dioic acid. Oxalic acid, \( \ce{HOOC-COOH} \), has only the two carboxyl carbons: a 2-carbon chain, so the parent is ethane.
(c) Succinic acid — This matches (iii) Butane-1,4-dioic acid. Succinic acid, \( \ce{HOOC-(CH2)2-COOH} \), has 2 + 2 = 4 carbons, with the carboxyl groups on C-1 and C-4.
(d) Adipic acid — This matches (i) Hexane-1,6-dioic acid. Adipic acid, \( \ce{HOOC-(CH2)4-COOH} \), has 4 + 2 = 6 carbons, with the carboxyl groups on C-1 and C-6.
These names are also written without the locants: ethanedioic, butanedioic and hexanedioic acid are the same as ethane-1,2-dioic, butane-1,4-dioic and hexane-1,6-dioic acid.
NCERT (2026-27 edition):
Nomenclature
