Catalytic olefin epoxidation with a fluorinated organomolybdenum complex

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• 作者：Simone A. Hauser ; Mirza Cokoja ; Markus Drees ; Fritz E. K¨¹hn
• 关键词：Olefin epoxidation ; Organomolybdenum complexes ; Homogeneous catalysis ; Fluorinated solvents ; Ionic liquids
• 刊名：Journal of Molecular Catalysis A: Chemical
• 出版年：2012
• 出版时间：November, 2012
• 年：2012
• 卷：363-364
• 期：Complete
• 页码：237-244
• 全文大小：767 K

文摘

Monomeric organomolybdenum carbonyl complexes of general formula [(¦Ç⁵-C₅R₅)Mo(CO)₃X] (R = H, CH₃, CH₂Ph; X = alkyl, halide) are known to be pre-catalysts for olefin epoxidation. In this work, the application of a fluorinated complex, [CpMo(CO)₃CF₃] (Cp = ¦Ç⁵-C₅H₅), is reported. With hexafluoroisopropanol as a solvent, a turnover frequency (TOF) of >6300 h^?1 was achieved in the epoxidation of cyclooctene with tert-butyl hydroperoxide (TBHP) as oxidant. So far, only ansa compounds of formula [Mo(¦Ç⁵-C₅H₄(CH(CH₂)_n)-¦Ç¹-CH)(CO)₃] are known to deliver better performances in catalytic epoxidation reactions at room temperature. [CpMo(CO)₃CF₃] was also applied in 2-phase catalytic epoxidation reactions. The high stability of the oxidised species allows catalyst recycling for multiple catalytic runs without significant loss of activity. Besides, the fluorinated complex enables - at this stage preliminary - mechanistic ¹⁹F NMR studies, indicating the nature of the catalytically active Mo-species, which has been an unresolved subject for some time.