Synchronous Synthesis And Immobilization Of Pyridyl Porphyrins On Cps Microspheres And Catalytic Oxidation Property Of Immobilized Cationic Co-porphyrins

As models of cytochrome P-450, Cationic metalloporphyrins have been used to oxidate hydrocarbons with molecular oxygen under mild conditions.A novel preparation method of Cationic metalloporphyrins catalyst has been designed in this thesis, Pyridylaldehyde (PyAL) groups were bound onto the surfaces of crosslinked polystyrene (CPS) microspheres via quaternization,subsequently, pyridylporphyrin on CPS microspheres were successfully realized via the Adler reaction between solid-liquid phases, further,PyP was transformed to N-methyl pyridyl porphyrin (MPyP) iodide by reacting with methyl iodide,at last cationic cobalt porphyrin was prepared through the coordination reaction between CoMPyP-CPS microspheres and cobalt salt.The polymer-supported catalyst was used in the catalytic oxidation of ethyl benzene with molecular oxygen as oxidant, and some valuable research results for the field of heterogeneous biomimetic catalyst were found.First of all,Crosslinked polystyrene microspheres (CPS) were chloromethylated with 1,4-bis(chloromethoxy)butane (BCMB) as the chloromethylation reagent, resulting in the chloromethylated crosslinked polystyrene (CMCPS) microspheres. Subsequently, the quaternization reaction between CMCPS microspheres and 4-pyridylaldehyde was carried out, and 4-pyridylaldehyde (PyAL) was allowed to be bond on the surfaces of CPS microspheres, forming the modified microspheres PyAL-CPS. The effects of main factors such as reaction temperature and solvent variety on the modification reaction were investigated emphatically. The experimental results show that the modification reaction of CMCPS microspheres, i.e. the quaternization reaction, can effectively carried out under suitable conditions such as with fine solvent (CCl4) in which CMCPS microspheres can sufficiently swelled and at higher temperature (60℃). Quaternization degree can get to 62%.Subsequently,Alder reaction was performed at the interface of solid/solution by using microspheres PyAL-CPS, 4-pyridylaldehyde and pyrrole in solution as co-reactants, so that the synchronistic synthesis and immobilization of pyridyl porphyrin (PyP) on the crosslinked microspheres CPS was realized.In this investigation, the effects of the main factors on the process of synchronistic synthesis and immobilization of porphyrins were studied. The experimental results show that the acidity of the catalysts, the polarity of the solvents and reaction temperature affect the reaction greatly.As the temperature is 110℃, the stronger polarity solvent DMSO and catalyst with a pKa value in the region of 3.0-3.9 is used, the porphyrin microspheres with a higher immobilization amount of 25mmol/100g will be obtained.further, the microspheres PyP-CPS were allowed to react with methyl iodide, and PyP was transformed to N-methyl pyridyl porphyrin (MPyP) iodide, leading to the formation of MPyP-CPS microspheres, on which cationic porphyrin was immobilized;MPyP-CPS; cobalt porphyrin was immobilized, was prepared through the coordination reaction between CoMPyP-CPS microspheres and cobalt salt.The cobalt content of solid catalyst was determined by the atomic absorption spectrometry. The catalytic activities of the solid catalysts were tested in the catalytic oxidation reaction of ethyl benzene by dioxygen, and the main factors on the catalytic activity were researched. Besides, the catalytic character of the composite catalyst CPW, which is prepared by association of CoMPyP-CPS (C) and phospho-tungstic(PW)heteropoly acid, was also investigated The experimental results show that The immobilized cationic metalloporphyrin catalyst CoMPyP-CPS has excellent catalytic activity and fine selectivity in the oxidation of ethylbenzene by molecular oxygen, The yield of acetophenone at ordinary pressure of oxygen and 110℃in 12h can get up to 21%. As the biomimetic catalyst, excess addition will inhibit the catalyst activity; and the catalyst has a good reuse performance. and the composite catalyst CPW possesses much higher catalytic activity. The yield of acetophenone can get up to 30%.