高分子钴和铁络合物对环氧丙烷与二氧化碳反应生成环丙烯碳酸酯的催化作用

SYNTHESIS OF PROPYLENE CARBONATE FROM PROPYLENE OXIDE AND CARBON DIOXIDE BY POLYMERIC CATALYSTS

环丙烯碳酸酯(PC)是一种高极性的溶剂,可用作许多有机反应及多种聚合物的溶剂,近来,由于它具有非常高的介电常数,也作为高压Li_2O-MnO_2电池的介电质使用.由环氧丙烷(PO)与二氧化碳作用生成环丙烯碳酸酯的反应(1),W.J.Pepple已研究过用四配位的胺盐催化,但是,反应条件比较苛刻,而且反应产物带有颜色;Nomura等用有机锡和有机锑化合物催化,反应可以在相对温和的条件下进行.但以上均属于均相催化,从产物中分离和回收催化剂比较困难.为了克服这些缺点,我们研究了几种高分子金属络合物对该反应的催化作用,有的活性较高.

The catalysis of polymer metal (Co2+or Fe3+) complexes [silicapoly-γ-diphenylphos-phinopropylsiloxane (Si-P), silica-poly-γ-aminopropylsiloxane (Si-N), silica-poiy-γ-mercaptopropylsiloxane (Si-S) and silica-styrene maleic acid copolymer (Si-PMS) and cobalt chloride or ferric chloride complexes] in the reaction between propylene oxide (PO) and carbon dioxide has been investigated. It was shown that some of the polymer catalysts tested not only catalyze this reaction very effectively like small molecular organic metallic complexes, but also can be resued because of their high stability and operated easily. (Si-P)(4), (Si-N)(5), (Si-S)(6), (Si-PMS) (7)were prepared and used, which contain coordination atom, P, N, S and O respectively. Co2+and Fe3+complexes of (Si-P), (Si-N), (Si-S) and (Si-PMS) were prepared by refluxing and stirring the mixture of (Si-P) , (Si-N), (Si-S) or (Si-PMS) and CoCl2 ?6H2O or FeCl3 ?6H2O and ethanol until the solid particies were colored and the liquid became colorless and transparent. The mixture was filtered, and the solid particles were dried to obtained the complex. The carboxylation of proplyene oxide by carbon dioxide was carried out in an autoclvae at 160-170℃ and 5MPa Co2for 24 hours.The results showed that the catalytic activities of Si-P-Co2+and Si-P-Fe3+are the highest in these catalysts, when 0.1 mol% of Fe3+ or Co2+ complex of Si-P-Fe3+ or Si-P-Co2+ was used, the yields of propylene carbonate (PC) were 98% at 160℃ after 24 h.Reaction temperature, reaction time and the gram atomic ratio of ligand element to metal also affected the yield of PC.For example, when Si-P-Fe3+ com-plex was used, yields of PC increased from 17% to 98% with increasing temperature from 120℃ to 160℃ under Co25 MPa after 24 h.. The Si-S-Ni and Si-PMS-Co polymer metal complexes have also been tested for this reaction, but good results have not been obtained yet.