Investigation On Selective Oxidation Of Phenol Catalyzed By Metalloporphyrins And Their Electron Spin Resonance

Environmental and economic pressures are forcing industry urgently to develop new catalytic routes to produce catechol and hydroxyquinone that have high additional value, using phenol and cheap, clean oxidants such as 62. It has been found that metalloporphyrins, analogous complexes simulating the behavior of cytochrome P-450, can catalyze dioxygen to oxidate phenol to be benzenediol under ambient conditions. The reaction mechanism and effects of different reaction conditions on the conversion ratio of phenol and the selectivities of benzenediol are the focus of recent studies.The selective oxidation of phenol catalyzed by metalloporphyrins without consumption of co-reductant was investigated in attempting to develop a new process for production of catechol and hydroxyquinone. The Electron Spin Resonance (ESR) measurements had been performed on the catalysts, as well as.In this dissertation, the effects of reactive conditions, such as reactive time, reactive temperature, amount of catalysts and initial phenol concentration, on the hydroxylation of phenol were studied. The optimal process parameters derived from experiments were M=lmol/L, R=0.6%, TR=60℃, tR = 6h. On this condition, we investigated the activities of various catalysts, the results showed that the metalloporphyrins we used had notable catalytic activity. And generally, the catalytic activity of cobalt porphyrins was better than that of other metalloporphyrins. The activities of these catalysts were tetra-(o-nitrophenyl) metalloporphyrins > tetra-(p-nitrophenyl) metalloporphyrins > tetra-(o-chlorophenyl) metalloporphyrins > tetra- (p-chlorophenyl) metalloporphyrins, we also found that the catalytic activity of chloridized metalloporphyrins was better than that of metalloporphrins which werenot coordinated by chloride in axis. The most active catalyst was tetra-(o-nitrophenyl) cobalt porphyrins, and the phenol conversion was up to 22.46%, the selectivity of CA was 82.53%, which was good. The results showed above provided reliable experimental data for investigating the relationship between structure and catalytic activity of metal porphyrins.In addition, the ESR spectrums for cobalt porphyrins were studied. The results showed the all cobalt ion in porphyrins we studied was +2 valence whatever they were coordinated by chloride in axis or not, or whatever they had which kind of substituent. The result was not found in other else literatures.