Abstract
The kinetics of oxidation of methyl cellulose polysaccharide by acidic permanganate at a constant ionic strength of 2.0 mol dm(-3) has been investigated, spectrophotometrically. Pseudo-first-order plots showed two distinct stages. The first stage was found to be relatively slow which corresponded to the formation of the substrate radical and Mn3+ or Mn4+ species as initial oxidation products, followed by an increase in the reaction rate at longer time periods. The reaction kinetics showed first-order dependence in permanganate and fractional second-order kinetics with respect to methyl cellulose concentration. The hydrogen ion dependence of the reaction rates indicated that the oxidation process is acid catalyzed. The induced polymerization of acrylonitrile indicated the intervention of free-radical mechanism. A kinetic evidence for the formation of 1:2 intermediate complex between the oxidant and the reductant, respectively, was revealed. The activation parameters have been evaluated, and a tentative reaction mechanism consistent with the kinetic results obtained is discussed.