Mechanism of Rhoduim(III) Catalyzed Oxidation of Ethylene Glycol by Bromate in Acidic Medium.

Abstract

Kinetic investigation in Rh(III) catalyzed oxidation of ethylene glycol in an acidified solution of potassium bromate in the presence of Hg(OAc)2 as a scavenger, have been studied in the temperature range of 300- 450 C. The reaction exhibits first order kinetics with respect to KBrO3 and catalyst Rh(III) while zero order kinetics with respect to substrate and HClO4. The influence of Hg(OAc)2, ionic strength and Cl- ion on the rate was found to be insignificant. Mercuric acetate is used in the reaction mixture as a scavenger for Br- ion to prevent parallel oxidation by bromine. A suitable mechanism in conformity with the kinetic observations has been proposed and the rate law is derived on the basis of obtained data. The various activation parameters such as energy of activation (∆E*), Arrhenius factor (A), entropy of activation (∆S*) were calculated from the rate measurements at 300, 350,400 and 450C. The rate law has been derived on the basis of obtained data.