question_answer

Which of the following undergoes nucleophilic substitution exclusively by \[{{S}_{N}}1\] mechanism?

A) Ethyl chloride    

B) Isopropyl chloride

C) Chlorobenzene   

D) Benzyl chloride

Correct Answer: D

Solution :

\[{{S}_{N}}1\] reactions involve the formation of carbocation, more is stability of carbocation, higher will be the probability of alkyl halide to undergo \[{{S}_{N}}1\]mechanism. Thus decreasing order of \[{{S}_{N}}1\]mechanisms follows order Benzyl \[>\] allyl \[>\] tertiary alkyl halide\[>\] secondary alkyl halide \[>\]primary alkyl halides Obtained from \[{{S}_{N}}1\] path. This molecule is resonance stabilised.