含羧基双氮席夫碱配体对甲基三氧化铼催化烯烃环氧化反应的影响

摘要: 以2-吡啶甲醛与氨基苯衍生物缩合制备了3个双氮席夫碱配体，对其结构进行了表征。将这些席夫碱配体用作甲基三氧化铼(MTO)催化30% H2O2环氧化烯烃反应的添加物，研究了席夫碱结构对MTO催化性能的影响。结果表明，含有吸电子的羧基的双氮席夫碱配体由于具有适宜的配位能力和酸性，可显著提高MTO催化烯烃环氧化反应选择性，而反应速率没有明显降低，并且在低温下对MTO催化性能的改进更好；不具吸电子基羧基的双氮席夫碱配体尽管可以提高环氧化物的选择性，但同时却降低了MTO的催化活性。

Effects of Di-Nitrogen Schiff Base with Carboxy Group on Olefin Epoxidation Catalyzed by Methyltrioxorhenium

Abstract: Three di-nitrogen Schiff base ligands were synthesized by the condensation of 2-pyridinecarboxaldehyde with derivatives of amino benzene and fully characterized. The Schiff base ligands were used as additives for the epoxidation of olefins catalyzed by methyltrioxorhenium (MTO) with 30% H2O2 as oxidant and the effects of the structures of the ligands on the performance of MTO were studied. The results revealed that the ligand with a electron-withdrawing carboxy group has suitable coordination capacity and acidity, therefore, it can largely increase the selectivities of epoxides without concomitancy of the obvious decrease of reaction rate in the epoxidation of olefins catalyzed by MTO. Furthermore, the ligand can improve the performance of MTO much better at lower reaction temperature. Though the ligands without electron-withdrawing group can increase the selectivities of epoxides, they decrease the catalytic activity of MTO meantime.