Question

C6H6CH2Cl or C6H5CH2Cl which one undergo SN1 reaction faster and why

Answer 1

In SN¹ ,reaction proceeds in two steps.First step involves slow separation of halogen to form carbonium ion. Second step involves attack of nucleophile on carbonium ion from both sides to form alcohol.

Any species which is capable of forming stable carbonium ion would prefer to undergo nucleophilic substitution by SN¹. Benzyl cation is very well stabilised by resonance than ethyl cation.Hence benzyl chloride follow SN¹ most readily.