Study On Epoxidation Of Methallyl Chloride Catalyzed By Phosphotungstateperoxide

The epoxidation of olefins with hydrogen peroxide by heteropolyacid associated with quaternary ammonium salt has distinct advantages, such as moderate conditions, highly yield of epoxides and no pollution. The type of heteropolyacid、solvent、 cocatalyst and other reaction conditions have obvious significance for the process. Here we studied the epoxidation of methallyl chloride for β-methyl epichlorohydrin by hydrogen peroxide with quaternaryammonium of heteropolyacid as PTC(phase transfer catalyst), and also studied the catalytic effect of the TPC(triphase catalyst, namely, chloromethlated polystyrene grafted quaternaryammonium immobilizing phosphotungsticperoxide) for recycling and reusing of the catalyst。Furthermore, the chloromethlated polystyrene grafted double quaternaryammonium was synthesized for immobilizing more quantity of phosphotungsticperoxide and improving the catalytic efficiency in epoxidation.In the catalytic epoxidation of methallyl chloride, the phosphotungsticperoxide show more efficiency than others (phosphotungsticacid、phosphomolybdicacid and phosphomolybdicperoxide). Then the synthesis of phosphotungsticperoxide was simplified and optimized for reducing cost and industrially producting conveniently. The effect of single factors on the epoxidaiton was investigated and concluded the optimum technological conditions:H2O2(30%) O.lmol, methallyl chloride0.3mol, catalyst0.5g(0.250mmol), cocatalyst(Na2HPO4)0.04g(0.283mmol),60℃and3.5h. In the conditions, the conversion of H2O2was approaching100%, yield and selectivity of β-methyl epichlorohydrin is96.36%and96.80%respectively.For recycling catalyst convienently, the chloromethlated polystyrene grafted quaternaryammonium was synthesised for immobiling the phosphotungsticperoxide as TPC(triphase catalyst). The optimum technological conditions of epoxidaion showed that the conversion of H2O2was approaching100%, while the yield of β-methyl epichlorohydrin is a little more half of its theoretical yield.For improving the efficiency of the TPC, the chloromethlated polystyrene grafted double quaternaryammonium was designed and synthesized in order to increase the quantity of N+for increasing the quantity of phosphotungsticperoxide. The new TPC’s structure has been characterized by FT-IR and NMR spectrum, and was used in epoxidation successfully. The conversion of H2O2is about100%, yield and selectivity of β-methyl epichlorohydrin is92.3%and93.5%respectively under optimum technological conditions that is H2O2(30%) O.lmol, methallyl chloride0.3mol, catalyst1.5g(2.74mmol), cocatalyst(Na2HPO4)0.05g(0.283mmol),60℃and3.5h. The recovery rate of catalyst is about95%and could be reused with on degeneration of catalytic efficiency in five times.