Question: The major product of carbylamine reaction is:

Step 1 (Governing Reaction Equation): [0.5 Mark]

The carbylamine reaction (also known as the Hofmann isocyanide test) is a diagnostic test for primary amines. When an aliphatic or aromatic primary amine is heated with chloroform ($CHCl_3$) and an alcoholic base (like $KOH$), it produces an isocyanide (carbylamine).

The general chemical equation is:

$$R-NH_2 + CHCl_3 + 3KOH_{(alc)} \xrightarrow{\Delta} R-NC + 3KCl + 3H_2O$$

Step 2 (Step-by-Step Deduction): [0.25 Mark]

• The reactant is a primary amine ($R-NH_2$).
• The reagents are $CHCl_3$ and $KOH$.
• The reaction mechanism involves the formation of a highly reactive dichlorocarbene ($:CCl_2$) intermediate.
• The nitrogen atom of the amine attacks the carbene, leading to the elimination of $HCl$ and the formation of the isocyanide functional group ($-NC$).

Step 3 (Final Concluded Answer): [0.25 Mark]

Based on the reaction product $R-NC$, the correct option is (D) Isocyanide.

💡 EL10 Concept Insight: Think of the carbylamine reaction as a "stinky test" for primary amines; when you mix them with chloroform and base, the nitrogen gets "locked" into a carbon atom, turning it into an isocyanide, which is famous for having a very foul, unmistakable smell.