KINETIC-STUDY OF THE RUTHENIUM-CATALYZED OXIDATION OF STYRENE AND SUBSTITUTED STYRENES

The kinetics of ruthenium catalysed oxidation of styrene and substitut ed styrenes by sodium hypochlorite solution was investigated using gas chromatography. The substituted styrenes used were p-methoxystyrene, p-methylstyrene, p-bromostyrene and m-nitrostyrene. It was found that the reaction rates increased from p-methoxystyrene to m-nitrostyrene. The rate constants showed that an electron donating group slowed the r ate of reaction while an electron withdrawing group increased the rate of the reaction. The rate constants did not give a good linear relati onship with the Hammett substituent constants when correlation with th e Hammett equation was attempted. On the other hand, this trend was co nsistent with the results of analysis by the frontier molecular orbita l theory, in which the activation energy of a reaction was correlated with the energy difference between the HOMO of the substituted styrene s and the LUMO of ruthenium tetroxide.