Question

Account for the following: (i) Allyl chloride is hydrolyzed more readily than n-propyl chloride.
(ii) Isocyanides are formed when alkyl halides are treated with silver cyanide.
(iii) Methyl chloride reacts faster with OH$^-$ ion in $S_N2$ reaction than t-butyl chloride.

Hint:

In $S_N2$ reactions, the reaction rate depends on the size and accessibility of the group attached to the carbon undergoing substitution.

Answer 1

(i) Allyl chloride undergoes hydrolysis more readily than n-propyl chloride because the allyl group (C$=$C) stabilizes the transition state in the $S_N2$ mechanism through resonance, making the nucleophilic substitution faster.
(ii) Isocyanides are formed when alkyl halides react with silver cyanide because silver cyanide is a strong nucleophile that replaces the halide ion, leading to the formation of isocyanides (RNC).
(iii) Methyl chloride reacts faster with OH$^-$ because the methyl group is small and does not hinder the nucleophile's approach, unlike t-butyl chloride, where the bulky tert-butyl group sterically hinders the attack.