Q24 / 180 · COMEDK 2023 (Evening Shift) · Chemistry
Choose the incorrect statement.
- A$\mathrm{m}$ - Cresol is a weaker acid than Phenol.
- BAcetylation of Salicylic acid produces 2-Acetoxybenzoic acid.
- Correct answerCPhenol on heating with Conc. $\mathrm{H}_2 \mathrm{SO}_4$ yields sulphanilic acid.
- DAcidic nature of Phenol is due to -I effect of oxygen of the hydroxyl group.
Solution
(1) Correct: m-Cresol has a $-CH_3$ group ($+I$ effect) which destabilizes the phenoxide ion $\to$ weaker acid than phenol.
(2) Correct: Acetylation of salicylic acid (2-hydroxybenzoic acid) with acetic anhydride gives 2-acetoxybenzoic acid (aspirin).
(3) Incorrect: Phenol on heating with conc. $H_2SO_4$ undergoes sulfonation to give phenol-2-sulfonic acid or phenol-4-sulfonic acid (depending on temperature), not sulphanilic acid. Sulphanilic acid is obtained by heating aniline with conc. $H_2SO_4$.
(4) Correct: The acidic nature of phenol is due to resonance stabilization of the phenoxide ion (the $-I$ effect of oxygen also contributes).
Incorrect statement: (3)
(2) Correct: Acetylation of salicylic acid (2-hydroxybenzoic acid) with acetic anhydride gives 2-acetoxybenzoic acid (aspirin).
(3) Incorrect: Phenol on heating with conc. $H_2SO_4$ undergoes sulfonation to give phenol-2-sulfonic acid or phenol-4-sulfonic acid (depending on temperature), not sulphanilic acid. Sulphanilic acid is obtained by heating aniline with conc. $H_2SO_4$.
(4) Correct: The acidic nature of phenol is due to resonance stabilization of the phenoxide ion (the $-I$ effect of oxygen also contributes).
Incorrect statement: (3)
Hence, the correct answer is option: 'C'.