Kinetic and mechanistic investigations on the oxidative reactions of aromatic aldehydes with 1-bromobenzimidazole in aqueous acetic acid medium

B. Ramkumara, V. Santhosh Kuma

Abstract

The oxidation kinetics of aromatic aldehydes by 1-bromobenzimidazole (BBI) has been studied in 80% (v/v) acetic acid – water mixture in presence of mercuric acetate. The reaction exhibits first order dependence each in [BBI], [Aldehyde] and [H+] ions. Increase in acetic acid content of the solvent medium increases the rate of reaction. The rate of reaction is not influenced by the addition of electrolyte like sodium perchlorate. Thermodynamic parameters have been calculated. Electron donating groups increase the rate while electron-withdrawing groups decrease the rate while electron-withdrawing groups decrease the rate. (H2OBr)+ has been postulated as the reactive oxidizing species. Suitable mechanism consistent with the observed kinetic data is proposed.