One-pot oxidative transformation of alcohols into esters is very attractive, but metal-based catalysts are used in the reported routes. We discovered that the basic ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM] OAc) could effectively catalyze this kind of reaction using O₂ as an oxidant without any other catalysts or additives. The oxidative self-esterification of benzylic alcohols or aliphatic alcohols and cross-esterification between benzyl alcohols and aliphatic alcohols could all be achieved with high yields. Detailed study revealed that the cation with acidic proton and basic acetate anion could simultaneously form multiple hydrogen bonds with the hydroxyl groups of the alcohols, which catalyzed the reaction very effectively. As far as we know, this is the first work to carry out this kind of reaction under metal-free conditions.

中文翻译：

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在无金属条件下，使用氧气作为氧化剂，通过氢键将醇类转化为酯类。

醇一锅式氧化成酯的方法非常有吸引力，但是在报道的方法中使用了金属基催化剂。我们发现碱性离子液体乙酸1-乙基-3-甲基咪唑鎓乙酸盐（[EMIM] OAc）可以有效地使用O ₂催化这种反应不含任何其他催化剂或添加剂的氧化剂。苄醇或脂族醇的氧化自酯化以及苄醇和脂族醇之间的交叉酯化都可以高收率地实现。详细的研究表明，带有酸性质子和碱性乙酸根阴离子的阳离子可以与醇的羟基同时形成多个氢键，从而非常有效地催化了该反应。据我们所知，这是在无金属条件下进行这种反应的第一项工作。