School of Chemistry, Monash University, Clayton, Victoria 3800, Australia.
Phys Chem Chem Phys. 2010 Sep 21;12(35):10341-7. doi: 10.1039/c0cp00239a. Epub 2010 Jul 5.
Proton transfer in protic ionic liquids is poorly understood. Some acid/base proton transfer reactions do not proceed to the extent that is expected from Delta pK(a)(aq) data from aqueous solutions, yet some do. In this work we have investigated protic ionic liquids obtained by proton transfer from a common acid, acetic acid, to a range of amine bases of similar pK(a)(aq) values. Probe indicator observations, transport property data allowing the construction of Walden plots and computational studies all suggest that there is a clear distinction between the behaviour of simple primary vs. tertiary amines, the proton transfer being more complete in the former case than the latter. The origins of this seem to be related to the hydrogen bonding ability of the ammonium ions in providing a good solvating environment for the ions produced by the proton transfer.
质子在质子液体中的转移尚未被很好地理解。一些酸碱质子转移反应并没有像从水溶液中的 Delta pK(a)(aq) 数据所预期的那样进行，然而有些反应却进行了。在这项工作中，我们研究了通过质子从常见酸乙酸转移到一系列具有相似 pK(a)(aq) 值的胺碱而获得的质子液体。探针指示剂观察、允许构建 Walden 图的输运性质数据和计算研究都表明，简单伯胺和叔胺的行为之间存在明显的区别，在前一种情况下质子转移比在后一种情况下更完全。这种现象的起源似乎与铵离子的氢键能力有关，铵离子能够为质子转移产生的离子提供良好的溶剂化环境。
