Kinetics, stoicheiometry, and mechanism in the bromination of aromatic heterocycles. Part 5. Aqueous bromination of benzimidazole, 1-methylbenzimidazole, and 2-methylbenzimidazole

Abstract

The method of halogenation by instalments with coulo-chrono-potentiometric monitoring has been used to obtain reactivity profiles for reactions of benzimidazoles with bromine (aqueous solution, 298 K). Values of bimolecular rate constants for attack by Br₂ on molecular substrates, calculated using literature values of acidity constants, were: [graphic omitted]. Reactivities of azoles and benzazoles are correlated with site charge densities calculated by VESCF/BJ, CNDO/2, and CNDO/S molecular orbital methods.