The Investigation On Aerobic Selective Oxidation Of Hydrocarbons Catalyzed By Metalloporphyrins

This paper aims to develop and establish a cleaning, effective and mild catalytic selective oxidation method for replacing traditional hydrocarbon oxidation process. We proposed a simple metalloporphyrin-air catalytic system in which the cheaper and easily available: catalysts-the first genaration metalloporphyrins could catalytically oxidize cyclohexane., methylcycohexane, toluene, and p-xylene to alchol or carbonly compounds without any solvent and coreductants.An improved synthetic method for large-scale synthesis of μ-oxo-bisiron(III)-porphyrin compounds from meso-tetraarylporphyrins and ferrous salts in one-step reaction was firstly developed in this paper. The uniform design and partial least square (PLS) have been utilized to optimize the reaction conditions for preparation of (Tp-ClPPFe)2O, such as meso-tetraarylporphyrins concentration, ferrous chloride loading, NaOH loading, and reaction time. It is observed that about 90% yield of μ-oxo-bisiron(III)porphyrin compounds can be obtained under the optimum reaction conditions.The simple metalloporphyrin-air catalytic system is expanded into catalytic oxidation of cyclohexane to KA oil and adipic acid, that of oxidation of methycylohexane to methylcylohexanol and methylcylohexanone, that of oxidation of toluene to benzaldehyde and benzyl alcohol, and that of oxidation p-xylene to p-tolualdehyde and p- methylbenzyl alcohol. The influencing factors, such as reaction temperature, air pressure, and catalyst loading has been systematically investigated. A conversion of cyclohexane as high as 10.18 %, with a 88.68 % selectivity to KA oil and a 42164 turnover number of catalyst was obtained under a optimized condition, in which the TPPCoCl is 5 mg(calculated as 350mL cyclohexane), the reaction temperature is 145 ℃, the air pressure is 0.8 MPa, the air flow is 0.08 m3/h, and the reaction time is 60 min. This method would provide a promising approach to cyclohexane oxidation with air in industrial scale. Recently, our group has cooperated with the Balin Company of SINOPEC to develop and establish the first industrial process of "biomimetic areobic oxidation of cyclohexane to cyclohexanone" in the world. It brings a new technologic revolution to selective hydrocarbon oxidation process.The kinetics of simple metalloporphyrins catalytic oxidation of hydrocarbons has been investigated primarily, and the activation energies of different C-H bonds in hydrocarbon oxidation were obtained. It is shown that the activation energy is correlated with the C-Hbond strength.The subsituent effects of monometalloporphyrins and μ-oxo-bisiron(III)porphyrin have been studied systematically in the aerobic cyclohexane oxidation. The Hammett equations of three series catalysts investigated in this study show that the reaction constant p is not quite different.Methylcyclohexane, with one tertiary C-H bond, 12 equivalent secondary C-H bons and 3 equivalent C-H bonds, has been used as a mechanism probe to gain valuable regioselectivity information about the process of C-H bond activation. A 3°/2° value of 2-4.5 is founded in the aerobic oxidation methylcyclohexane catalyzed by various substituented manganese (III) porphyrins.At the end of this dissertation, a possible mechanism of aerobic oxidation hydrocarbon catalyzed by simple metalloporphyrins is proposed according the results of some mechanistic studies and related literatures.