The mechanism of alkylation reactions. Part 1. The effect of substituents on the reaction of phenacyl bromide with pyridine in methanol

Abstract

Rate constants have been determined for the solvolysis of phenacyl bromide in 50–100% aqueous methanol, for the reactions in methanol of six m- and p-substituted phenacyl bromides with pyridine and for phenacyl bromide with five 3- and 4-substituted pyridines, aniline, imidazole, and benzimidazole. The results have been discussed in terms of linear free energy relationships. Evidence is presented for a reaction in which a special combination of field and conjugative effects contribute to the enhanced reactivity of phenacyl halides.