Question

An amine on reaction with benzenesulfonyl chloride produces a compound insoluble in alkaline solution. This amine can be prepared by ammonolysis of ethyl chloride. The correct structure of amine is:

• A. ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2{\mathrm{NHCH}}_2{\mathrm{CH}}_3$
• B. ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2{\mathrm{NHCH}}_3$
• C.

  

• D. ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{NH}}_2$

Answer 1

The correct option is A

${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2{\mathrm{NHCH}}_2{\mathrm{CH}}_3$

Explanation for correct option:

A) ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{NHCH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{3}}$

• The reaction of amines with benzene sulphonyl chloride is used to distinguish primary, secondary and tertiary amines, it is known as Heisenberg's test.
• The compound in this option is a secondary amine.
• When secondary amines react with benzene sulphonyl chloride, they form an insoluble salt in an alkaline medium.
• Also, it has an ethyl group so it will form ethyl chloride on ammonolysis.

Explanation for incorrect options:

B) ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{NHCH}}_{\mathbf{3}}$

• The compound in this option is also a secondary amine.
• But, it does not bear ethyl group hence it will not form ethyl chloride on ammonolysis.

C)

• The compound in this option is also a secondary amine.
• But, it does not bear ethyl group hence it will not form ethyl chloride on ammonolysis.

D) ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{CH}}_{\mathbf{2}}{\mathbf{NH}}_{\mathbf{2}}$

• The compound in this option is a primary amine.
• Primary amines react with benzene sulphonyl chloride to form a soluble salt acidic in nature.

Hence option A is correct.