Comparative Study of Kinetics of Catalyzed Oxidation of D (+)galactose and lactose by Ruthenium (III) in Alkaline Medium

Kinetic investigation in Ru(III) catalyzed oxidation of D(+)-galactose and lactose in an alkaline solution of potassium bromate in the presence of mercuric acetate as a scavenger for Br – ion has been carried out in the temperature range 30-45°C. The rate shows first order dependence with respect to the bromate and zeroth order with respect to the substrate (sugars). The reaction exhibits first order dependence on the catalyst ruthenium(III) and there is inverse order on the rate of reaction. Potassium chloride and acetic acid have a positive effect on the rate. Negligible effect of change in Hg(OAc)2, ionic strength of the medium and D2O. [RuCl3(H2O)OH] -1 and BrO3 are the most reactive species Ru(III) chloride and bromated, respectively. Galactonic acid and lactobionic acid have been identified as the main oxidation products of the reaction. Various activation parameters have bee calculated and recorded. On the basis of experimental findings, a suitable mechanism consistent with the observed kinetics was proposed and the rate law has been derived on the basis of obtained data.