Question

Hinsberg’s reagent is –

• A. Benzene sulphonic acid
• B. Benzene sulphonyl chloride
• C. Benzene sulphonamide
• D. Phenyl isocyanide

Hint:

Hinsberg’s reagent (C$_6$H$_5$SO$_2$Cl) is used for distinguishing primary, secondary, and tertiary amines.

Answer 1

The Correct Option is B

Step 1: Recall Hinsberg’s reagent.
Hinsberg’s reagent is benzene sulphonyl chloride (C$_6$H$_5$SO$_2$Cl). It is used to distinguish between primary, secondary, and tertiary amines.

Step 2: Reasoning.
- Primary amines react with Hinsberg’s reagent to form soluble sulphonamides.
- Secondary amines form insoluble sulphonamides.
- Tertiary amines do not react.

Step 3: Analyzing options.
- (A) Benzene sulphonic acid: Incorrect.
- (B) Benzene sulphonyl chloride: Correct.
- (C) Benzene sulphonamide: This is a product, not the reagent.
- (D) Phenyl isocyanide: Related to carbylamine test, not Hinsberg’s reagent.

Step 4: Conclusion.
Hence, Hinsberg’s reagent is benzene sulphonyl chloride.

Final Answer: \[ \boxed{\text{(B) Benzene sulphonyl chloride}} \]