MHTCET 18 Apr 2026 Shift 1 Paper

Concept:The carbylamine reaction is a test specific to primary amines.Only primary amines react with chloroform and alcoholic KOH to form alkyl isocyanides.Explanation:The general reaction is:$$\mathrm{RNH}_2 + \mathrm{CHCl}_3 + 3\mathrm{KOH} \rightarrow \mathrm{RNC} + 3\mathrm{KCl} + 3\mathrm{H}_2\mathrm{O}$$Methanamine is $\mathrm{CH}_3\mathrm{NH}_2$, a primary amine, so it forms methyl isocyanide.Propan-2-amine is $(\mathrm{CH}_3)_2\mathrm{CHNH}_2$, also a primary amine, so it reacts.Ethanamine is $\mathrm{C}_2\mathrm{H}_5\mathrm{NH}_2$, a primary amine, so it reacts too.N,N-Diethylethanamine is $\mathrm{N}(\mathrm{C}_2\mathrm{H}_5)_3$, a tertiary amine.Tertiary amines lack an $-\mathrm{NH}_2$ group, so they do not undergo the carbylamine reaction.Hence, this amine does not produce an alkyl isocyanide.Answer:Option C: N,N-Diethylethanamine.