Important Reactions and Tests of Amines

Identify the amine class. Select the reagent: acyl chloride for acylation, alkyl halide for alkylation, CHCl3/KOH for carbylamine, Hinsberg reagent for distinction, or nitrous acid for class-specific products. Then write the product and observation if asked.

A decision table for primary, secondary, and tertiary amines with carbylamine and Hinsberg tests is useful.

Writing an isocyanide product for a secondary amine in carbylamine reaction is wrong because the reaction requires an N-H pattern of a primary amine.

Amines undergo reactions based on the nucleophilic lone pair of nitrogen, including acylation, alkylation, carbylamine reaction, Hinsberg test, and reaction with nitrous acid.

Amines undergo reactions based on the nucleophilic lone pair of nitrogen, including acylation, alkylation, carbylamine reaction, Hinsberg test, and reaction with nitrous acid. Key patterns: RNH2 + RCOCl gives substituted amide; primary amine + CHCl₃ + alcoholic KOH gives isocyanide; Hinsberg reagent distinguishes amine classes through sulphonamide formation and solubility behaviour. Aniline reacts with benzoyl chloride in the presence of base to form N-phenylbenzamide. Methylamine gives a positive carbylamine test, but dimethylamine does not.

Primary and secondary amines react with acyl chlorides or acid anhydrides to form substituted amides. Alkylation can give higher amines and eventually quaternary ammonium salts. Primary amines give the carbylamine reaction with chloroform and alcoholic KOH, forming isocyanides with an unpleasant odour, while secondary and tertiary amines do not give this test. Hinsberg reagent helps distinguish primary, secondary, and tertiary amines by their sulphonamide behaviour. Nitrous acid reactions differ for aliphatic and aromatic amines and for amine class. Key patterns: RNH2 + RCOCl gives substituted amide; primary amine + CHCl₃ + alcoholic KOH gives isocyanide; Hinsberg reagent distinguishes amine classes through sulphonamide formation and solubility behaviour. Distinguish ethylamine and diethylamine. Use carbylamine test: ethylamine is primary and gives isocyanide formation, while diethylamine is secondary and does not give the test. Questions ask for product prediction, distinguishing tests, named reagent use, completion of reactions, and explanations for selective reactions of primary amines. Writing an isocyanide product for a secondary amine in carbylamine reaction is wrong because the reaction requires an N-H pattern of a primary amine.