双金属氰化络合物及其催化的聚合反应

Double Metal Cyanide Complex Catalyst and Its Catalysis for Epoxides-Involved Polymerization

本文综述了双金属氰化络合物及其催化的环氧化物参与的聚合反应研究。双金属氰化络合物是由其内界金属MⅡ通过氰基与外界金属MⅠ连接形成的含MⅡ—C≡N—MⅠ桥键的三维网络状无机高分子(MⅠ一般为Zn2+、Fe2+、Co2+和Ni2+等二价金属离子,MⅡ一般为Fe2+、Fe3+、Co2+、Co3+和Ni2+等过渡金属离子)。外界金属MⅠ一般被认为是催化反应的活性中心金属。该类催化剂早期被用于催化环氧化物开环聚合,并逐步发展成为合成中高分子量、低不饱和度聚醚多元醇的极高效催化剂。近年来该类催化剂被用来催化环氧化物/环状酸酐共聚、环氧化物/CX2(X=O,S)共聚和环氧化物/环状酸酐/CO2三元共聚反应合成聚酯、聚碳酸酯、聚(醚-碳酸酯)、聚硫代碳酸酯和聚(碳酸酯-酯)等具有生物降解性的聚合物。尤其对氧化环己烯(CHO)与CO2(或酸酐)共聚,锌-钴双金属氰化络合物表现出了极高的催化活性和选择性。结合本研究组十多年的研究结果,本文讨论了双金属氰化络合物催化活性中心的可能结构和催化机理,提出了双金属氰化络合物催化聚合的共性难题和解决这些问题的方向。

This its catalysis for epo review focuses on the recent advances in double metal cyanide complex （DMCC） catalyst and xides-involved polymerizations. DMCC is an inorganic coordinated polymer with three- dimensional network, in which the inner metal M I is linked with the external metal Ml by several cyano-bridges （ MⅡ-C≡N-MⅠ , generally, MI = divalent metal ions such as Zn2＋ , Fe2＋ , Co2＋ , Ni2＋ , et al. , M II = transition metal ions such as Fe2＋ , Fe3＋ , Co2＋ , Co3＋ , Ni2＋ , et al）. The external metal M1 on the surface of the catalyst is generally considered to be the active site for the polymerizations due to its unsaturated coordinated structure. DMCC catalyst was initially applied to the catalysis of the ring-opening polymerization （ROP） of epoxides, and then modified and used as a highly active catalyst for making polyether-polyols with both moderate or high molecular weights and low unsaturation degrees. Later, this catalyst was utilized to catalyze the alternating copolymerization of epoxides and CO2 for producing aliphatic polycarbonates. The productivity of DMCC-catalyzedepoxides/CO2 copolymerization is clearly higher than those of other heterogeneous catalysts, while the polycarbonate selectivity of this catalyst is unsatisfied, e. g. ： for propylene oxide （PO）/CO2 copolymerization, the maximum alternating degree of the resultant copolymer was up to -74%. That is, the copolymer is a poly （ether-carbonate） with random chain structure. However, Zn-Co2 DMCC exhibits high activity （TOF： 3 815h-1） for cyclohexene oxide （CHO）/CO2 copolymerization with high alternating degree of 〉 90%. Furthermore, this catalyst can also be applied to catalyze epoxide/cyclic anhydrides for producing polyesters, epoxide/CS2 copolymerization for producing polythiocarbonates, as well as epoxide/cyclic anhydride/CO2 terpolymerization for producing poly （carbonate- ester） s with high productivity. Based on the research work of our group in recent ten years, this review will discuss the possible structure of the active sites of DMCC and related catalytic mechanism, as well as some common problems for DMCC and DMCC catalyzed polymerizations and possible solutions.