双功能Mn基催化剂在二氧化碳和环氧化物环加成反应中的应用OA北大核心

The cycloaddition reaction of carbon dioxide(CO2)and epoxides is an effective method to synthesize cyclic carbonates.Catalysts are important for the activation of CO2 and epoxides in the reaction.A series of bifunctional Mn-based catalysts LnMn(CO)3Br(n=1～6)were prepared by 2,2'-bipyridine with its derivatives as the ligands,Mn(CO)5Br as the metal source and ethyl ether as the solvent.The chemical structures,molecular weights and chemical groups of LnMn(CO)3Br were characterized by 1H NMR,13C NMR,HR-MS and FT-IR,etc.The catalytic performances of LnMn(CO)3Br in the cycloaddition reaction of CO2 and epichlorohydrin and the adaptability of L1Mn(CO)3Br to a series of epoxide substrates were studied.The results show that the electron donating properties of electron donating groups(methoxy group,tertiary butyl and methyl group)in LnMn(CO)3Br and the positions of methyl group on the pyridine ring have influences on their catalytic performances.For the cycloaddition reaction of CO2 and epiglorohydrin,under the conditions of L1Mn(CO)3Br dosage(mole fraction)of 0.05％,reaction temperature of 125 ℃ and reaction pressure of 3.0 MPa for 1 h,the epiglorohydrin conversion rate and catalyst turnover frequency of L1Mn(CO)3Br are 42％and 840 h-1,respectively.L1Mn(CO)3Br has adaptability to the cycloaddition reaction of several epoxides.And the steric hindrance effects of the substrates have great influences on catalytic performance of L1Mn(CO3)Br.