Mechanistic Study of Ruthenium(III) Catalyzed Oxidation of Cyclohexanone by Acidic Bromate

Abstract

In this work, kinetics and mechanism of Ru(III) catalyzed oxidation of cyclohexanone by acidified solution of potassium bromate has been studied. Present study employ mercuric acetate Hg (OAc) 2 as a scavenger for Br − ion to prevent parallel oxidation by bromine. The kinetics and mechanism have also been studied in the temperature range of 30˚C-45˚C. The reaction exhibits first order kinetics with respect to Ru (III), while zero order kinetics with respect to KBrO 3 and HClO 4. The influence of Hg(OAc) 2 and ionic strength on the rate of reaction was found to be insignificant. Positive effect in the reaction mixture was also observed upon addition of chloride ion; while as the negative effect was revealed with acetic acid. 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 (ΔE*), Arrhenius factor (A), entropy of activation (ΔS*) were calculated from the rate measurements at 30˚C, 35˚C-40˚C and 45˚C.