Computational studies and reactivity of nucleophiles in benzylation reactions

The nucleophilic substitution reactions of benzyl bromide using 2-mercapto benzimidazole, 2-mercaptobenzoxazole and 2-mercaptobenzothiazole as nucleophiles have been studied in methanol and acetone media. The higher reactivity of 2-mercaptobenzimidazole is attributed to the presence of two nitrogen atoms holding a pair of electrons on either side of the >C=S group. The heat of formation, ΔH f , computed from AM1 studies indicates that the reactivity of the nucleophiles is related to ΔH f , and HOMO-LUMO gap of the nucleophile.