Hinsberg's reagent is a chemical reagent used to distinguish between primary, secondary, and tertiary amines. It is benzenesulfonyl chloride, with the chemical formula $C_{6} H_{5} {SO}_{2} Cl$ .

How it works:

Step 1: The amine is treated with Hinsberg's reagent (benzenesulfonyl chloride) in the presence of aqueous alkali (e.g., NaOH).

Step 2: Different types of amines react differently:

Primary amines form a N-alkylbenzenesulfonamide that is soluble in alkali. This is because the hydrogen attached to nitrogen is acidic and can be removed by base, forming a soluble salt.
Secondary amines form a N,N-dialkylbenzenesulfonamide that is insoluble in alkali. There is no acidic hydrogen, so it doesn't form a salt.
Tertiary amines do not react with Hinsberg's reagent. They remain unchanged and do not form a sulfonamide.

Related Topics:

Classification of Amines: Amines are classified based on the number of alkyl or aryl groups attached to the nitrogen atom: primary (1°), secondary (2°), and tertiary (3°). This classification is crucial for predicting their reactivity.

Reactions of Amines: Amines undergo various characteristic reactions like acylation, alkylation, and reaction with sulfonyl chlorides, which are used for their identification and separation.

Important Formulae:

The general reaction for a primary amine (RNH₂) with Hinsberg's reagent is: $C_{6} H_{5} {SO}_{2} Cl + R {NH}_{2} \to C_{6} H_{5} {SO}_{2} N H R + HCl$ The product (RNH-SO₂C₆H₅) dissolves in NaOH due to salt formation: $C_{6} H_{5} {SO}_{2} N H R + NaOH \to C_{6} H_{5} {SO}_{2} N^{-} R {Na}^{+} + H_{2} O$

Final Answer: Based on the options provided, Hinsberg's reagent is $C_{6} H_{5} {SO}_{2} Cl$ (Benzenesulfonyl chloride).