Cooxidation of Dibenzalacetone with Oxalic Acid by Pyrazinium Chlorochromate

Abstract

Oxidation of dibenzalacetone with pyrazinium chlorochromate in presence of oxalic acid has been studied at 313 K. Various reaction parameters such as effect of varying oxidant, substrate, Hydrogen ion concentration, catalyst, solvent composition, ionic strength, effect of Mn2+, effect of Al3+ and effect of temperature were studied to determine the kinetics of the reaction. Our study revealed that the reaction followed first order dependence with respect to oxidant and catalyst. The reaction followed fractional order kinetics with respect to substrate and H+. Increase in ionic strength was found to have no effect on the reaction rate and decrease in the dielectric constant of the medium decreases the reaction rate. Increase in the concentration of manganous sulphate retarded the reaction rate which confirmed the two-electron transfer involved in the mechanism. There was no possibility of free radical mechanism, which was confirmed by the addition of acrylonitrile shows no significant effect on the reaction rate indicating the non-involvement of free radical reaction.. Based on the experimental observations a mechanism and rate law has been derived. Moreover, the oxidation product was found to be chalcone epoxide, which was characterized by IR spectrum.