Kinetic and Mechanistic Study of the Influence of Micelles on the Oxidation of Acetone by N-Bromophthalimide in Aqueous Acetic Acid Medium

The effect of cationic micelles of Cetyltrimethylammonium bromide (CTAB) and anionic micelles of Sodium dodecyl Sulphate (SDS) on the kinetics of oxidation of acetone by N-Bromophthalimide (NBP) was studied iodometrically at 308 K. in addition to kinetic experiments, conductivity measurements have also been done to obtain critical micelle concentration and other thermodynamic properties. The kinetic observations indicate fractional order and first order dependence, with respect to [Acetone] and [NBP] respectively. Cationic surfactant (CTAB) strongly catalysed the oxidation of acetone in aqueous acetic acid medium and typical k(obs) and [CTAB] profile was observed i.e. with the progressive increase in [CTAB], the reaction rate increased, at higher concentration constancy in k(obs) was observed, whereas anionic surfactant (SDS) was found to show no considerable effect on reaction rate. Mercuric acetate and phthalimide exhibited nil effect on the reaction rate. The presence of inorganic salts (KCI, KBr) exhibits positive effect in the reaction rate. The various activation parameters in presence of CTAB and SDS have been also evaluated. A suitable mechanism consistent with the experimental findings has been proposed. The binding constant with surfactants has been evaluated.