不对称钴配合物的合成及其催化苯乙烯环氧化

Synthesis of Unsymmetrical Cobalt(II) Complexes and Catalytic Performance for Epoxidation of Styrene

摘要:

将合成的N-取代的吡啶-2-醛亚胺制备成2:1型不对称吡啶亚胺钴(II)配合物(CoLn2, n = 1, 2... 6)，并通过红外光谱、元素分析、核磁氢谱、热重分析等对相关化合物进行表征。在没有共还原剂存在的条件下，以分子氧为氧源，考察催化剂的种类、溶剂、反应温度、反应时间对苯乙烯环氧化反应性能的影响。研究表明，配合物CoL42是最有效的催化剂；配合物中亚氨氮上取代基的供电子性和空间位阻有利于提高配合物的催化活性；在优化的反应条件下，苯乙烯的转化率达99.9%，环氧苯乙烷的选择性为62.4%。

Abstract:

Unsymmetrical pyridinyl-imine complexes of cobalt (CoLn2, n = 1, 2... 6) containing functionalities attached to the alkyl or aromatic group bonded to the imino nitrogen were synthesized and evaluated as potential catalysts for epoxidation of styrene, and their related compounds were characterized by elemental analysis, 1H NMR, FT-IR, TG, et al. The influences of reaction conditions were further researched, including complexes, solvent, reaction tempreture, reaction time. The results showed that the complexes of cobalt(II) containing trimethylsiloxy attached to aromatic group bonded to the imino nitrogen (CoL42) was the most effective catalyst for epoxidation of styrene. These further explained that electron donating groups bonded to the imino nitrogen and the good steric effect of complexes increased the activity of the catalysts. Under optimal reaction conditions, the highest conversion of styrene was 99.9% with 62.4% styrene oxide selectivity.