Abstract:

Stable CO₂ has to be activated by high-energy chemicals, such as epoxide. Nucleophilic reagents are acted as the trigger for the ring-opening of epoxides and CO₂ insertion. In this work, a series of polystyrene-supported N-heterocycles were tested for their difference on CO₂ cycloaddition. It is found that five-membered heterocyclic compounds exhibited higher activity than six-membered ones. A weak interaction between five-membered heterocycles and substrates is the key point to promote the ring-opening of epoxide and the activation of CO₂ insertion. By comparison, the introduction of ZnCl₂ and_{alkyl amine boosted the reaction rate, but decreased the selectivity. As a simple, cost-effective, stable and reusable material, polystyrene-supported imidazole without metal, halide, co-catalyst and solvent, is considered as a suitable catalyst for industrial application.}

Key words: CO₂, catalysis, reactivity, N-heterocycle, imidazole, synergistic effect

摘要：

稳定的CO₂ 需要高能分子的活化，如环氧化物。而亲核试剂有助于诱发三元氧环的开环，进而实现CO₂的插入活化。针对聚苯乙烯负载的有机催化剂，考察不同含氮杂环材料在催化CO₂环加成中的活性差异，发现五元氮杂环显示出了高于六元氮杂环的催化活性，五元氮杂环对底物间弱的协同效应是诱发环氧丙烷开环和活化CO₂插入的关键。进而与引入ZnCl₂、烷基胺的聚苯乙烯负载型催化剂作对比，虽然后两者反应速率得以提高，但也造成了选择性的下降。在无金属、无卤素、无添加剂、无溶剂下，PS-Im这种简单、廉价、稳定且可回收利用的聚苯乙烯负载氮杂环材料适合于工业推广。

关键词: CO₂, 催化, 活性, 氮杂环, 咪唑, 协同效应