Quantum chemical analysis is presented for the mechanism of promotion of S_N2 fluorination by 1-Butyl-3-methylimidazolium fluoride ([Bmim]F) reported by Magnier and co-workers (2014). At [Bmim]F: substrate molar ratio of 2:1, one of the fluorides acts as the nucleophile, but the second F⁻ plays the role as Lewis base on the two counter-cations to facilitate the reaction. We find that the Gibbs free energy(at 80 °C) of activation decreases as the [Bmim]F: substrate ratio increases from 1:1 to 2:1, in good agreement with the experimental observations of improved yield from 47 to 84%.

中文翻译：

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无溶剂环境中[Bmim] F促进S _N 2氟化的机理：量子化学分析

Magnier和同事（2014年）报道了通过1-丁基-3-甲基咪唑鎓氟化物（[Bmim] F）促进S _N 2氟化的机理的量子化学分析。在[BMIM] F：2基板摩尔比：1，氟化物中的一个用作亲核试剂，但第二个F ^-扮演在两个抗衡阳离子路易斯碱的作用，以促进反应。我们发现，随着[Bmim] F：底物比例从1：1增加到2：1，吉布斯活化能（在80°C时）降低，这与将产率从47％提高到84％的实验观察结果非常吻合。