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Enantioselective epoxidation catalyzed by silicagel supported (Salen)-Mn (Ⅲ) complex in ionic liquid

XU Xiaoqian,WEI Saili,ZHAO Ruiqin,TANG Yuhai   

  1. School of Science,Xi’an Jiaotong University,Xi’an 710061,Shaanxi,China
  • Online:2011-06-05 Published:2011-06-05

离子液体辅助硅胶型(Salen)-Mn (Ⅲ) 催化烯烃不对称环氧化

许晓倩,魏赛丽,赵瑞琴,唐玉海   

  1. 西安交通大学理学院,陕西 西安 710061

Abstract:

Asymmetric epoxidation of unfunctional olefinstyreneα-methyl styreneindenewas performed  with Jacobsen’s catalyst and silica gel supported (Salen)-Mn() complex as catalysts1,2),ionic liquids tetrafluoroborate1-methyl-3-butyl imidazoleonium saltBMIMBF4and hexafluorophosphate1-methyl-3-butyl imidazoleonium saltBMIMPF6as reaction mediumsodiumhypochlorite as oxidantammonium acetate as axial ligand. The results indicated that the ionic liquids were more effective for enhancing the conversion and enantiomeric excess than dichloromethaneandBMIMPF6was better thanBMIMBF4. At the same timethe silica gel supported (Salen)-Mn() complex demonstrated satisfactory enantioselectivity and activity even higher than homogeneous Jacobsen’s catalyst. Especiallyin the epoxidation of a-methylstyrenethe enantiomeric excess in the BMIMPF6 reached 100%and could be recycled five times without obvious loss of activity.

摘要:

进行了以Jacobsen催化剂、硅胶型 (Salen)-Mn)配合物为催化剂(1,2),以离子液体1-丁基-3-甲基咪唑四氟硼酸盐(BMIMBF4)和1-丁基-3-甲基咪唑六氟磷酸盐(BMIMPF6)为反应介质,次氯酸钠为氧化剂,乙酸铵为轴向配体催化非官能团烯烃(苯乙烯、α-甲基苯乙烯、茚)的不对称环氧化反应。通过实验对比发现,反应介质离子液体与二氯甲烷相比可以有效提高催化反应的速率和ee值,并且离子液体BMIMPF6辅助催化能力高于(BMIMBF4);硅胶载体型配合物在离子液中催化烯烃具有比均相Jacobsen催化剂更好的立体催化效果。如a-甲基苯乙烯,在离子液BMIMPF6反应中获到97%100%ee值,且反应循环5次后催化剂活性没有明显的下降。

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