Mechanism of Oxidation of Xylitol by a New Oxidant, Diperiodatoargentate (III), in Aqueous Alkaline Medium

The oxidation of xylitol (XYL) by Ag (III) periodate complex (DPA) in aqueous alkaline medium at 298 K and a constant ionic strength of 0.06 mol dm(-3) was studied spectrophotometrically. The reaction between xylitol and DPA in alkaline medium exhibits 1:2 stoichiometry in the reaction. The order of the reaction with respect to [DPA] was unity while the apparent order with respect to [XYL] was less than unity over the concentration range studied. The rate of the reaction increased with increase in [OH-] whereas the rate decreased with increase in [IO-4]. The main products were identified by FT-IR and LC-MS spectral studies. The probable mechanism was proposed. The activation parameters with respect to slow step of the mechanism were computed and are discussed. Thermodynamic quantities were also calculated. Kinetic studies suggest that [Ag (H2IO6) (H2O) 2] is the reactive species of Ag (III).