We present a single-component catalyst system for the epoxidation of hydrophobic olefins in aqueous solution. The aggregation of surface-active 1-alkyl-3-methylimidazolium ionic liquids (IL) containing the catalytically active tungstate dianion leads to micelles, which solubilise apolar olefins in aqueous media. The micellisation of tungstate allows for the epoxidation of cyclooctene and other olefins in water, using environmentally benign hydrogen peroxide as oxidant. The structural characterisation of the micelles under catalysis conditions as well as the substrate uptake have been studied by cryo-TEM. ¹⁸³W-NMR studies revealed that the catalytically active species is a tetraperoxotungstate complex. The addition of organophosphonic acids results in a significant boost of the catalytic activity by formation of a tungstate–phosphonate adduct, investigated using electrospray ionisation mass spectrometry (ESI-MS). The versatile functionalisability of the imidazolium cation enables a covalent linkage of a phosphonate group, which is further increasing the catalytic activity.

中文翻译：

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离子液体表面活性剂作为多任务胶束催化剂，用于水中的环氧化

我们提出了一种用于疏水性烯烃在水溶液中环氧化的单组分催化剂体系。含有催化活性钨酸二价阴离子的表面活性1-烷基-3-甲基咪唑鎓离子液体（IL）的聚集会导致胶束，从而将非极性烯烃溶解在水性介质中。钨酸盐的胶束化可以使用环境友好的过氧化氢作为氧化剂，使环辛烯和其他烯烃在水中进行环氧化。已经通过冷冻-TEM研究了在催化条件下胶束的结构表征以及底物的吸收。¹⁸³1 H-NMR研究表明，催化活性物质是四过氧钨酸盐络合物。通过使用电喷雾电离质谱法（ESI-MS）研究发现，有机膦酸的加入可通过形成钨酸-膦酸酯加合物而显着提高催化活性。咪唑鎓阳离子的通用功能性使膦酸酯基团可以共价连接，从而进一步提高了催化活性。