Relative Kinetic Study of Oxidation of Ethanol by Potassium Dichromate and Potassium Permanganate in Aqueous Acidic Media

Ravindra Shimpi

Abstract: The kinetics of the oxidation reaction of ethanol with acid dichromate and permanganate was studied. The reactions were found to be first order with respect to substrate concentration and oxidant concentration in both the cases. Pseudo-first-order kinetics was found to be perfectly applicable with ethanol. The pseudo-first-order rate constants were found to be independent of concentration of the dichromate. The rate constant increased with the increase of H+ ion concentration in both cases. Negative salt effect was observed with addition of KCl to the reaction mixture in case of dichromate as an oxidant. Addition of KCl to the reaction mixture has no effect on the reaction mixture in case of permanganate as an oxidant. There is formation of an intermediate complex i.e. chromate ester in case of dichromate. It is suggested that in case of permanganate the reacting species of manganese is Mn (III) and the reactants pass through a transition state involving the ethanol and Mn(III). A suitable mechanism for the reaction were suggested which agrees with the experimental findings.

Keywords: Oxidation, permanganate, dichromate, ethanol, acetaldehyde, pseudo-first-order, intermediate complex