Hinsberg reagent is benzenesulfonyl chloride. In aqueous KOH this reacts with primary amine `(RNH_(2))` to give a clear solution which on acidification gives a white precipitate, which is due to the formation of

Options

A. `R-NHSO_(2)C_(6)H_(5)`
B. `C_(6)H_(5)SO_(2)NH_(2)`
C. `R-N-SO_(2)C_(6)H_(5)K^(+)`
D. `R-overset(N)overset(|)underset(H)underset(|)(N^(+))-SO_(2)C_(6)H_(5)OH^(-)`

Answer

To solve the question regarding the reaction of Hinsberg reagent (benzenesulfonyl chloride) with a primary amine (RNH₂) in aqueous KOH, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- The Hinsberg reagent is benzenesulfonyl chloride (C₆H₅SO₂Cl).
- The primary amine is represented as RNH₂.

2. **Reaction with Aqueous KOH**:
- When benzenesulfonyl chloride reacts with a primary amine in the presence of aqueous KOH, the amine acts as a nucleophile. The nitrogen atom in the amine has a lone pair of electrons that can attack the electrophilic sulfur atom in the sulfonyl chloride.

3. **Formation of the Sulfonamide**:
- The nucleophilic attack leads to the formation of a sulfonamide intermediate. The chlorine atom is displaced as a good leaving group (Cl⁻), resulting in the formation of RNH-SO₂-C₆H₅ (the sulfonamide).

4. **Formation of a Clear Solution**:
- The reaction produces a clear solution due to the formation of the sulfonamide, which is soluble in the aqueous medium.

5. **Acidification**:
- Upon acidification (adding H⁺ ions), the sulfonamide can protonate the nitrogen atom, leading to the formation of a positively charged sulfonamide complex.

6. **Precipitation of the Sulfonamide**:
- The protonation of the sulfonamide results in decreased solubility, leading to the formation of a white precipitate. This precipitate is the sulfonamide RNH-SO₂-C₆H₅.

7. **Conclusion**:
- The white precipitate formed upon acidification is due to the formation of the sulfonamide, which can be represented as RNH-SO₂-C₆H₅.

### Final Answer:
The white precipitate formed upon acidification is due to the formation of **RNH-SO₂-C₆H₅ (sulfonamide)**.

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