Kinetics of the oxidative degradation of rac-serine by aqueous alkaline permanganate

The kinetics of the oxidation of mc-serine by permanganate in aqueous alkal ine medium was studied spectrophotometrically. The reaction showed first or der kinetics in permanganate ion concentration and an order less than unity in mc-serine and alkali concentration. Increasing ionic strength and decre asing dielectric constant of the medium increase the rate. The oxidation re action proceeds via an alkali-permanganate species which forms a complex wi th rac-serine. The latter decomposes slowly, followed by a fast reaction be tween a free radical of rac-serine and another molecule of permanganate to give the products. There is a good agreement between the observed and the c alculated rate constants under different experimental conditions. Investiga tions at different temperatures allowed the determination of the activation parameters with respect to the slow step of the proposed mechanism.