Thermodynamics of homogeneous oxidations: Part II. Kinetics and thermodynamics of homogeneous oxidation of cyclohexanol to cis-1 ,3-cyclohexanediol by ruthenium(iii) analogue of the model peroxidase system: Ru(III)-EDTA-ascorbate-H₂O₂

Abstract

Kinetics and thermodynamics of the homogeneous oxidation of cyclohexanol to cis-1,3-cyclohexanediol by Ru(III) analogue of the model peroxidase system, Ru(III)-EDTA-ascorbate-H₂O₂, have been investigated in the wide temperature range 288-313 K at μ=0.1 M KNO₃. The dependence of the rate of oxidation of cyclohexanol on factors such as temperature and concentration of the reactants, viz. Ru(III)-EDTA, ascorbic acid, hydrogen peroxide, cyclohexanol and hydrogen ion, are studied in detail. First-order dependence of the oxidation reaction was observed with respect to the concentrations of Ru(III)-EDTA, ascorbic acid, H₂O₂ and cyclohexanol. The rate of oxidation is inverse first-order with respect to hydrogen ion concentration. The rate and equilibrium constants of the complicated reaction were resolved by potentiometric and spectrophotometric techniques and by kinetic rate data analysis, using the appropriate mathematical solution of the rate expressions. Temperature dependence parameters corresponding to rate and equilibrium constants were computed and the mechanistic implication of the oxidation reaction is discussed from the kinetic and thermodynamic point of view.