Oxidation of DL-tartaric acid by water soluble colloidal MnO2 in the absence and presence of surfactants

Conventional spectrophotometry has been employed to study the oxidation of DL-tartaric acid by water soluble colloidal MnO2 in the absence and presence of surfactants. Anionic sodium dodecyl sulfate has no effect, non-ionic Triton X-100 catalyzed the reaction and experiments were not possible in presence of cationic cetyltrimethylammonium bromide due to the precipitation of MnO2. The reaction is autocatalytic and follows first-order kinetics in [tartaric acid] in both the media. The reaction has acid-dependent and acid-independent paths and, in the former case, the order is fractional in [H+]. The effect of externally added manganese(II) is complex. Due to its involvement in a series of reactions, it is not possible to predict exact dependence of rate constants on [Mn(II)]. On the basis of observed kinetic results, a probable mechanism for the reaction has been proposed and discussed. The catalytic effect.. of TX-100 has been explained in terms of the mathematical model proposed by Tuncay, et al.