Consider the following statements about carboxylic acids and their nomenclature.
(A) The carboxyl group consists of a carbonyl group attached to a hydroxyl group.
(B) In the IUPAC system, aliphatic carboxylic acids are named by replacing the ending –e in the name of the corresponding alkane with –oic acid.
(C) In numbering the carbon chain of an aliphatic carboxylic acid, the carbon atom next to the carboxylic carbon is numbered one.
(D) In naming compounds with more than one carboxyl group, the positions of the –COOH groups are indicated by Greek letters before the multiplicative prefix.
(E) Carboxylic acids serve as starting material for anhydrides, esters, acid chlorides and amides.
Which of the statements given above are incorrect? Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (C) and (D) only
In the IUPAC names of carboxylic acids, the carboxylic carbon is carbon 1 of the chain, and the positions of –COOH groups are given by numbers, as in propane-1,2,3-tricarboxylic acid and benzene-1,2-dicarboxylic acid.
(A) The carboxyl group consists of a carbonyl group attached to a hydroxyl group. — Correct statement. Carbonyl plus hydroxyl gives the name carboxyl.
(B) In the IUPAC system, aliphatic carboxylic acids are named by replacing the ending –e in the name of the corresponding alkane with –oic acid. — Correct statement. For example, ethane gives ethanoic acid.
(C) In numbering the carbon chain of an aliphatic carboxylic acid, the carbon atom next to the carboxylic carbon is numbered one. — Incorrect statement. The carboxylic carbon itself is numbered one; the carbon next to it is carbon 2, as in 2-methylpropanoic acid, \( \ce{(CH3)2CHCOOH} \).
(D) In naming compounds with more than one carboxyl group, the positions of the –COOH groups are indicated by Greek letters before the multiplicative prefix. — Incorrect statement. The positions are shown by arabic numerals, not Greek letters.
(E) Carboxylic acids serve as starting material for anhydrides, esters, acid chlorides and amides. — Correct statement. These acid derivatives are all made from carboxylic acids.
NCERT (2026-27 edition):
Carboxylic Acids – “…The carboxyl group, consists of a carbonyl group attached to a hydroxyl group, hence its name carboxyl. … Carboxylic acids serve as starting material for several other important organic compounds such as anhydrides, esters, acid chlorides, amides, etc.”
8.6.1 Nomenclature – “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. … The position of –COOH groups are indicated by the arabic numeral before the multiplicative prefix.”