Oxidation of aniline and its derivatives by tert-butylhydroperoxide using meso-tetraphenylporphyriniron(iii) chloride as catalyst in aqueous acetic acid medium: Degradation kinetics

摘要

Highly selective oxidation reactions are supported by Heme-enzymes such as cytochromes P450. meso-tetraphenylporphyriniron(III) chloride is a mimic compounds for cytochrome P450. To understand the mechanism a study was carried out on oxidation of anilines by tert-butylhydroperoxide catalyzed by meso-tetraphenylironporphyrin(III) chloride in acidic medium. The reaction is second order with respect to the aniline and first order with respect to the meso-tetraphenylironporphyrin(III) chloride and tert-butylhydroperoxide. Degradation of the catalyst is found while varying the concentration of the catalyst. The Product obtained was azobenzene. The increase in hydrogen ion concentration delays the oxidation reaction rate. Kinetic studies were carried out by varying the temperatures with meta- and para- substituted anilines. The thermodynamic parameters were determined and discussed. The tert-butylhydroperoxide catalysed oxidation rate with aniline substituted compounds justifies the Exner correlation as well as the isokinetic relationship. It was also found that there is no correlation in linear free energy. The acetic acid, which acts as a solvent is also a character in leading the oxidation reaction. A suitable mechanism is proposed based on the oxidation reaction.