CBSE · Class 12 · Chemistry · Aminesहिंसबर्ग परीक्षण (बेंजीन सल्फोनिल क्लोराइड परीक्षण) का उपयोग करके प्राथमिक, द्वितीयक और तृतीयक ऐमीनों के बीच अंतर कीजिए। रासायनिक समीकरण लिखिए और शामिल अभिक्रियाओं को विस्तार से समझाइए।

Introduction\nHinsberg's reagent, which is benzene sulphonyl chloride ($C_6H_5SO_2Cl$), is widely used in laboratory chemistry to distinguish between primary, secondary, and tertiary aliphatic or aromatic amines. The test relies on the varying acidity of the sulphonamides formed when these amines react with the reagent.

1. Reaction with Primary Amines ($1^\circ$ Amines)\nWhen a primary amine reacts with benzene sulphonyl chloride, it undergoes a nucleophilic substitution reaction where the amine nitrogen displaces the chloride ion, yielding an N-alkylbenzenesulphonamide.

• Reaction Equation: $C_6H_5SO_2Cl + H_2N-R \rightarrow C_6H_5SO_2-NH-R + HCl$
• Solubility Feature: The resulting N-alkylbenzenesulphonamide contains a strongly acidic hydrogen atom attached to the nitrogen atom, which is electron-withdrawing due to the adjacent strong sulphonyl group. Consequently, this sulphonamide is readily soluble in aqueous alkali ($NaOH$) solution, forming a clear, soluble sodium salt ($C_6H_5SO_2-N^-Na^+-R$).

2. Reaction with Secondary Amines ($2^\circ$ Amines)\nWhen a secondary amine reacts with benzene sulphonyl chloride, it forms an N,N-dialkylbenzenesulphonamide.

• Reaction Equation: $C_6H_5SO_2Cl + HN(R)_2 \rightarrow C_6H_5SO_2-N(R)_2 + HCl$
• Solubility Feature: The resulting N,N-dialkylbenzenesulphonamide lacks any hydrogen atom attached to the nitrogen atom because both valencies are satisfied by alkyl groups. Therefore, it is devoid of acidic hydrogen and is completely insoluble in aqueous alkali ($NaOH$) solution, remaining as an insoluble residue or second layer.

3. Reaction with Tertiary Amines ($3^\circ$ Amines)\nTertiary amines do not possess any replaceable hydrogen atoms attached to the nitrogen atom. Therefore, they do not react with benzene sulphonyl chloride to form sulphonamides.

• Reaction Equation: $C_6H_5SO_2Cl + N(R)_3 \rightarrow \text{No Reaction}$ (or sometimes salt formation)
• Solubility Feature: Since no reaction occurs, the tertiary amine remains insoluble in the reagent mixture, but it dissolves readily upon the addition of dilute hydrochloric acid due to the formation of a water-soluble quaternary ammonium salt.

Summary of Hinsberg Test

• $1^\circ$ Amine: Forms sulphonamide $\rightarrow$ Soluble in $NaOH$.
• $2^\circ$ Amine: Forms sulphonamide $\rightarrow$ Insoluble in $NaOH$.
• $3^\circ$ Amine: No reaction with Hinsberg reagent $\rightarrow$ Insoluble in alkali, soluble in dilute acid.