Benzyl isocyanide can be obtained from which of the following reactions?

This question is based on the preparation of isocyanides (isonitriles). Isocyanides are organic compounds containing the functional group:

R–NC

One of the most important methods for preparing isocyanides is the Carbylamine Reaction.

In this reaction, a primary amine reacts with chloroform in the presence of alcoholic potassium hydroxide or aqueous sodium hydroxide to form an isocyanide.

General reaction:

RNH₂ + CHCl₃ + 3KOH → RNC + 3KCl + 3H₂O

The reaction is specific to primary amines and is widely used as a qualitative test for primary amines.

To prepare benzyl isocyanide, the starting compound must be benzylamine:

C₆H₅CH₂NH₂

When benzylamine reacts with chloroform and aqueous NaOH, it forms:

C₆H₅CH₂NC

which is benzyl isocyanide.

The other options involve benzyl bromide reacting with KCN or AgCN. These reactions generally produce nitriles or related products rather than isocyanides.

A useful rule to remember is:

• KCN generally gives nitriles (R–CN).
• Carbylamine reaction of primary amines gives isocyanides (R–NC).

Since option (b) contains benzylamine reacting with CHCl₃ and aqueous NaOH, it correctly produces benzyl isocyanide.

Correct Answer: Option (b)