Question

Which of the following amines does not react with Hinsberg Reagent?
(A) $C{{H}_{3}}C{{H}_{2}}-N{{H}_{2}}$
(B) $C{{H}_{3}}-NH-C{{H}_{3}}$
(C) ${{(C{{H}_{3}}C{{H}_{2}})}_{3}}N$
(D) none of these

Answer 1

Hint: Hinsberg reagent is the name of Benzene sulfonyl chloride. In this test, amines act as nucleophiles and attack the electrophile (sulfonyl chloride). This test is based on the difference in the solubility of the sulfonamide product in alkali.

Complete step by step answer: Hinsberg reagent is an alternative name of Benzene sulfonyl chloride, and it is used for detection of Primary, secondary and tertiary amines. Hinsberg reaction is a test for detection of primary , secondary and tertiary amines. In this test, The amine is shaken well with Hinsberg reagent in the presence of aqueous alkali. Hinsberg reagent contains an aqueous sodium hydroxide solution and benzenesulfonyl chloride is added to a substrate. Tertiary amine do not undergo reaction with hinsberg reagent, therefore, do not give hinsberg reaction.
To know which of these options undergo reaction with Hinsberg reagent, we will consider each option one by one.
Considering option (A), $C{{H}_{3}}C{{H}_{2}}-N{{H}_{2}}$. Given compound is a primary amine, with an amine group attached to one primary carbon atom. Therefore, it will give a hinsberg reaction.
Considering option (B), $C{{H}_{3}}-NH-C{{H}_{3}}$. Given compound is a secondary amine, with an amine group attached to two carbon atoms.Therefore, it will give a hinsberg reaction.

Considering option (C), ${{(C{{H}_{3}}C{{H}_{2}})}_{3}}N$. Given compound is a tertiary amine. It has an amine group attached to three carbon atoms, therefore it will not give a hinsberg reaction.


Note: In the hinsberg test, the amines act as nucleophiles and attack the electrophile (sulphonyl chloride). This leads to the displacement of the chloride and the generation of the sulphonamides. When primary and secondary amines form sulfonamides, this sulfonamide product is not soluble and precipitates from the solution as a solid.