See image — Alcohols Phenols and Ethers Chemistry Question

💡 Solution & Explanation

Concept: The isocyanide (carbylamine) test is positive when a primary amine (RNH2) reacts with chloroform and KOH to give an isocyanide (foul-smelling). Only primary amines give a positive isocyanide test. Step 1: Identify the product of each reaction. (a) Benzamide (Ph-CO-NH2) + LiAlH4: LiAlH4 is a strong reducing agent that reduces amides to amines. Ph-CO-NH2 is reduced to Ph-CH2-NH2 (benzylamine), which is a PRIMARY amine. This gives a positive isocyanide test. (b) Benzamide (Ph-CO-NH2) + NaBH4: NaBH4 is a mild reducing agent and does NOT reduce amides. No amine product is formed; the amide remains unreacted. No positive isocyanide test. (c) N-methylacetanilide / Ph-NH-CO-CH3 (a secondary amide) + LiAlH4: LiAlH4 reduces this secondary amide to Ph-NH-CH2-CH3 (N-ethylaniline), which is a SECONDARY amine. Secondary amines do NOT give a positive isocyanide test. (d) Ph-NH-CO-CH3 + NaBH4: NaBH4 does not reduce amides, so no reaction occurs to give an amine. No positive isocyanide test. Step 2: Determine which reaction yields a primary amine. Only reaction (a) produces a primary amine (benzylamine, Ph-CH2-NH2) via LiAlH4 reduction of a primary amide. Step 3: Why other options fail. - (b) fails because NaBH4 cannot reduce amides. - (c) fails because the product is a secondary amine. - (d) fails because NaBH4 cannot reduce amides. Therefore, the correct answer is A.