JEE Chemistry 2025 Question with Solution

Given: The compounds A, B, C, D and E are to be checked for reaction with Hinsberg's reagent, i.e. benzenesulfonyl chloride, $C_6H_5SO_2Cl$.

Find: Which of the given compounds react with Hinsberg's reagent.

Hinsberg's reagent is used to distinguish primary and secondary amines from tertiary amines. Tertiary amines do not react because they do not have a replaceable hydrogen atom on nitrogen required for sulfonamide formation.

From the given structures:

1. A = aniline, $C_6H_5NH_2$, a primary amine 1 reacts.
2. B = N,N-dimethylaniline, $C_6H_5N(CH_3)_2$, a tertiary amine 1 does not react.
3. C = methylamine, $CH_3NH_2$, a primary amine 1 reacts.
4. D = trimethylamine, $N(CH_3)_3$, a tertiary amine 1 does not react.
5. E = diphenylamine, $(C_6H_5)_2NH$, a secondary amine 1 reacts.

Therefore, the compounds that react with Hinsberg's reagent are A, C and E only.

The correct option is D.

Given: Hinsberg's reagent is benzenesulfonyl chloride.

Find: Identify which listed amines react with it.

Reaction rule:

• Primary amines react to form sulfonamides.
• Secondary amines also react to form sulfonamides.
• Tertiary amines do not react because nitrogen has no hydrogen atom attached to it.

Applying this rule to each compound:

• A: aniline, $C_6H_5NH_2$ 1 primary amine, so it reacts.
• B: N,N-dimethylaniline, $C_6H_5N(CH_3)_2$ 1 tertiary amine, so it does not react.
• C: methylamine, $CH_3NH_2$ 1 primary amine, so it reacts.
• D: trimethylamine, $N(CH_3)_3$ 1 tertiary amine, so it does not react.
• E: diphenylamine, $(C_6H_5)_2NH$ 1 secondary amine, so it reacts.

Hence the reacting compounds are A, C and E only.

Note: The solution contains one inconsistent line stating "The Correct Option is D" and elsewhere also states "Correct Answer: A, C, and E only." These are consistent because option D corresponds to A, C and E only.