The formation of imidazolium salt intimate (contact) ion pairs in solution.
The formation of imidazolium salt intimate (contact) ion pairs in solution.
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DOI：
10.1002/anie.201408151
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发表时间：
2014-11
影响因子：
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通讯作者：
M. Zanatta;A. Girard;Nathália M. Simon;G. Ebeling;H. Stassen;P. R. Livotto;F. P. dos Santos;J. Dup
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文献类型：
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作者：
M. Zanatta;A. Girard;Nathália M. Simon;G. Ebeling;H. Stassen;P. R. Livotto;F. P. dos Santos;J. Dup
1-n-丁基-2,3-二甲基咪唑（BMMI）离子液体在氘化溶剂中优先在咪唑的2-Me基团上进行H/D交换。这一过程主要与离子对的存在有关，而与阴离子的碱度无关。H/D交换发生在溶剂中（例如CDCl3和MeCN），其中存在密切接触离子对，阴离子在其结构中具有不稳定的H，如碳酸氢和脯氨酸。在D2 O中，形成分离的离子对，不发生H/D交换。一个合理的催化循环是，在所有的氢/氢交换过程中，IL都表现为中性碱。核磁共振实验、密度泛函计算和分子动力学模拟证实了这些假设。
1-n-Butyl-2,3-dimethylimidazolium (BMMI) ionic liquids (ILs) associated with different anions undergo H/D exchange preferentially at 2-Me group of the imidazolium in deuterated solvents. This process is mainly related to the existence of ion pairs rather than the anion basicity. The H/D exchange occurs in solvents (CDCl3 and MeCN for instance) in which intimate contact ion pairs are present and the anion possesses a labile H in its structure, such as hydrogen carbonate and prolinate. In D2 O, separated ion pairs are formed and the H/D exchange does not occur. A plausible catalytic cycle is that the IL behaves as a neutral base in the course of all H/D exchange processes. NMR experiments, density functional calculations, and molecular dynamics simulations corroborate these hypotheses.