What is Hinsberg's reagent ?

Explanation

**Step-by-Step Solution:**

1. **Definition of Hinsberg's Reagent**: Hinsberg's reagent is a chemical reagent used primarily to distinguish between primary, secondary, and tertiary amines.

2. **Chemical Structure**: The chemical structure of Hinsberg's reagent is benzene sulfonyl chloride. This compound consists of a benzene ring attached to a sulfonyl group (–SO2) and a chlorine atom (–Cl).

3. **Formation of Hinsberg's Reagent**: Hinsberg's reagent is synthesized through the reaction of benzene with chlorosulfonic acid (HSO3Cl). This reaction introduces the sulfonyl chloride group to the benzene ring, resulting in the formation of benzene sulfonyl chloride.

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