Kinetics and Mechanism of meso-Tetraphenylporphyrin Iron(III) Chloride Catalysed Oxidation of Indole-3-Acetic Acid by Peroxomonosulphate

Mechanistic study on meso-tetraphenylporphyrin iron(III) chloride (TPP) catalysed oxidation of indole-3-acetic acid by peroxomonosulphate (oxone) in aqueous acetonitrile medium has been carried out. The reaction follows a first order with respect to both substrate and oxidant. The order with respect to catalyst was found to be fractional. The order of reaction with respect to catalyst varies with a concentration of catalyst. Increase in percentage of acetonitrile decreased the rate. The reaction fails to initiate polymerization, and a radical mechanism is ruled out. Activation and thermodynamic parameters have been computed. A suitable kinetic scheme based on these observations is proposed. Significant catalytic activity is observed for the reaction system in the presence of TPP.