An effective method for the synthesis of 2,3,6-trimethyl-1,4-benzoquinone via the oxidation of 2,3,6-trimethylphenol as the key step in the in the preparation of vitamin E was presented. An aqueous solution of H2O2 was used as the oxidant and Lewis acidic trifloaluminate ionic liquids [emim][OTf]-Al(OTf)3, χAl(OTf)3 = 0.25 or 0.15 as catalysts. Trifloaluminate ionic liquids were synthesised by the simple reaction between 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (triflate) [emim][OTf] and aluminium triflate used in sub-stoichiometric quantities. The influence of the reaction parameters on the reaction course, such as the amount and concentration of the oxidant, the amount of catalyst, the amount and the type of organic solvent, temperature, and the reaction time was investigated. Finally, 2,3,6-trimethyl-1,4-benzoquinone was obtained in high selectivity (99%) and high 2,3,6-trimethylphenol conversion (84%) at 70 °C after 2 h of oxidation using a 4-fold excess of 60% aqueous H2O2 and acetic acid as the solvent. The catalytic performance of trifloaluminate ionic liquids supported on multiwalled carbon nanotubes (loading of active phase: 9.1 wt.%) was also demonstrated. The heterogeneous ionic liquids not only retained their activity compared to the homogenous counterparts, but also proved to be a highly recyclable catalysts.

中文翻译：

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高活性三氟铝酸盐离子液体作为可回收催化剂用于2,3,6-三甲基苯酚绿色氧化成三甲基-1,4-苯醌

提出了一种以2,3,6-三甲基苯酚氧化合成2,3,6-三甲基-1,4-苯醌的有效方法作为制备维生素E的关键步骤。使用H2O2水溶液作为氧化剂，路易斯酸性三氟铝酸盐离子液体[emim][OTf]-Al(OTf)3，χAl(OTf)3=0.25或0.15作为催化剂。通过 1-乙基-3-甲基咪唑鎓三氟甲磺酸盐（三氟甲磺酸盐）[emim][OTf] 与亚化学计量的三氟甲磺酸铝之间的简单反应合成了三氟铝酸盐离子液体。考察了氧化剂用量和浓度、催化剂用量、有机溶剂用量和种类、温度、反应时间等反应参数对反应过程的影响。最终，在 70 °C 下，使用 4 氧化催化剂氧化 2 小时后，以高选择性 (99%) 和高 2,3,6-三甲基苯酚转化率 (84%) 获得了 2,3,6-三甲基-1,4-苯醌。 - 倍过量的 60% H2O2 水溶液和乙酸作为溶剂。还证明了多壁碳纳米管负载的三氟铝酸盐离子液体（活性相负载量：9.1 wt.%）的催化性能。与均相离子液体相比，多相离子液体不仅保留了其活性，而且被证明是一种高度可回收的催化剂。