Effect of Substituents on the Kinetics of the Oxidation of Benzyl Chloride Using Acid-Dichromate

Abstract

Kinetics of the oxidation of benzyl chloride and some of its para-substituted derivatives by acid-dichromate have been investigated in acetic acid-water mixture. The reaction shows first order dependence on the concentrations of the oxidant as well as the substrate. The reaction is acid catalyzed and shows fractional order with respect to sulphuric acid concentration. The product of oxidation is the corresponding benzaldehyde. Electron releasing substituents accelerate the reaction, whereas electron withdrawing groups retard the rate. The rate data obey the Hammett's relationship. The reaction constant ρ is negative. Isosbestic point was found at 297 nm. The reaction does not induce polymerization of acrylonitrile. The effect of solvent composition shows that the rate increases with an increase in the polarity of the solvent. Activation parameters have been evaluated and a mechanism consistent with the kinetic results has been proposed.