Kinetics and mechanism of the oxidation of polyhydric alcohols by dihydroxyditelluratoargentate(III) in alkaline medium

The kinetics of oxidation of 1,2-propanediol and 1,2,3-propanetriol by dihydroxyditelluratoargentate(III) (DDA) were studied spectrophotometrically between 298.2 K and 313.2 K in alkaline medium. The reaction rate showed first order dependence on DDA and 1 < nap < 2 order on the reductant. It was found that the pseudo-first order rate constant kobs increased with increasing concentration of OH- and decreasing concentration of TeO42-. There is a negative salt effect and no free radicals were detected. In view of this, the dihydroxymonotelluratoargentate(III) species is assumed to be the active species. A plausible mechanism involving a two-electron transfer is proposed and the rate equations derived from the mechanism can explain all the experimental results. The activation parameters, as well as the rate constants of the rate-determining step were calculated