Structure V reacts fastest with trimethylamine in SN2 reaction. Owing to less steric crowding in the transition state and ease of cleavage of the R - I bond
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SN2 reaction is a type of nucleophilic reaction in which the nucleophile attacks the substrate from the reverse side. This is a synchronous reaction because the leaving group departs as the entering group attacks simultaneously in a hypervalent transition state.
SN2 reaction is favored by structure V owing to less steric crowding in the transition state and the easy of cleavage of the R - I bond. Hence, structure V reacts fastest with trimethylamine in SN2 reaction.
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