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首页> 外文期刊>Chemistry: A European journal >Activation of hydrogen peroxide by ionic liquids: Mechanistic studies and application in the epoxidation of olefins
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Activation of hydrogen peroxide by ionic liquids: Mechanistic studies and application in the epoxidation of olefins

机译：离子液体活化过氧化氢的机理研究及其在烯烃环氧化中的应用

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摘要

Imidazolium-based ionic liquids that contain perrhenate anions are very efficient reaction media for the epoxidation of olefins with H)2O _2 as an oxidant, thus affording cyclooctene in almost quantitative yields. The mechanism of this reaction does not follow the usual pathway through peroxo complexes, as is the case with long-known molecular transition-metal catalysts. By using in situ Raman, FTIR, and NMR spectroscopy and DFT calculations, we have shown that the formation of hydrogen bonds between the oxidant and perrhenate activates the oxidant, thereby leading to the transfer of an oxygen atom onto the olefin demonstrating the special features of an ionic liquid as a reaction environment. The influence of the imidazolium cation and the oxidant (aqueous H_2O_2, urea hydrogen peroxide, and tert-butyl hydrogen peroxide) on the efficiency of the epoxidation of cis-cyclooctene were examined. Other olefinic substrates were also used in this study and they exhibited good yields of the corresponding epoxides. This report shows the potential of using simple complexes or salts for the activation of hydrogen peroxide, owing to the interactions between the solvent medium and the active complex.
机译：含有高hen酸根阴离子的咪唑基离子液体是非常有效的反应介质，可用于以H）2O _2为氧化剂进行烯烃的环氧化，从而以几乎定量的产率提供环辛烯。该反应的机理没有遵循过氧化物络合物的通常途径，而众所周知的分子过渡金属催化剂就是这种情况。通过使用原位拉曼光谱，FTIR和NMR光谱以及DFT计算，我们发现氧化剂和高r酸盐之间形成氢键会激活氧化剂，从而导致氧原子转移到烯烃上，这证明了离子液体作为反应环境。研究了咪唑鎓阳离子和氧化剂（H_2O_2水溶液，过氧化脲尿素和叔丁基过氧化氢）对顺环辛烯环氧化效率的影响。在本研究中还使用了其他烯烃底物，它们显示出相应环氧化物的良好收率。该报告显示由于溶剂介质和活性络合物之间的相互作用，使用简单的络合物或盐活化过氧化氢的潜力。

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