Question

Hinsberg’s reagent is

• A. $HCl/ZnCl_2$
• B. $Sn/HCl$
• C. ammoniacal $AgNO_3$
• D. $FeBr_3$
• E. benzenesulphonyl chloride

Hint:

Remember the solubilities for the Hinsberg test: $1^\circ \to$ Soluble in base; $2^\circ \to$ Insoluble in base; $3^\circ \to$ No reaction.

Answer 1

Answer: (E)

Step 1: Understanding the Concept:
Hinsberg's test is a chemical method used to distinguish between primary ($1^\circ$), secondary ($2^\circ$), and tertiary ($3^\circ$) amines.

Step 2: Detailed Explanation:
1. Hinsberg's Reagent: The specific chemical used is benzenesulphonyl chloride ($C_6H_5SO_2Cl$).
2. Mechanism:
- $1^\circ$ Amines: React to form a sulfonamide that is soluble in alkali (NaOH) due to an acidic hydrogen.
- $2^\circ$ Amines: React to form a sulfonamide that is insoluble in alkali (no acidic hydrogen).
- $3^\circ$ Amines: Do not react with the reagent under standard conditions.
3. Other Reagents:
- $HCl/ZnCl_2$ is Lucas reagent (for alcohols).
- Ammoniacal $AgNO_3$ is Tollen's reagent (for aldehydes).

Step 3: Final Answer:
Hinsberg's reagent is benzenesulphonyl chloride.