JEE Main 2025 Jan 24 Shift 2, Chemistry Q18: Preparation of Alkyl Halides (Halo Alkanes) & Aryl Halides (Halo Arenes)

Silver cyanide ($AgCN$) is a classical reagent in which the silver-bound cyanide is largely covalent. As a result the more available, less hindered lone pair sits on nitrogen, so $AgCN$ attacks alkyl halides through the nitrogen end (an $S_{N}1$-leaning, ion-pair pathway promoted by the formation of insoluble $AgX$).

The aryl halides (-I and -Br on the ring) are unreactive under these conditions because they cannot undergo nucleophilic substitution. Only the benzylic $-C{H}_{2}Cl$ reacts.

Outcome: the benzylic chloride is converted to a benzylic isocyanide ($-C{H}_{2}NC$), with -I and -Br untouched.

Correct option: (2)