Department of Physical Chemistry, University of Rostock , Dr-Lorenz-Weg-1, 18059 Rostock, Germany.
J Phys Chem B. 2011 Oct 13;115(40):11712-7. doi: 10.1021/jp207335m. Epub 2011 Sep 21.
Thermochemical studies of the ionic liquids 1-ethyl-3-methylimidazolium tricyanomethanide [C(2)MIM][C(CN)(3)] and 1-butyl-3-methylimidazolium tricyanomethanide [C(4)MIM][C(CN)(3)] have been performed in this work. Vaporization enthalpies have been obtained using a recently developed quartz crystal microbalance (QCM) technique. The molar enthalpies of formation of these ionic liquids in the liquid state were measured by means of combustion calorimetry. A combination of the results obtained from QCM and combustion calorimetry lead to values of gaseous molar enthalpies of formation of [C(n)MIM][C(CN)(3)]. First-principles calculations of the enthalpies of formation in the gaseous phase for the ionic liquids [C(n)MIM][C(CN)(3)] have been performed using the CBS-QB3 and G3MP2 theory and have been compared with the experimental data. Furthermore, experimental results of enthalpies of formation of imidazolium-based ionic liquids with the cation [C(n)MIM] (where n = 2 and 4) and anions [N(CN)(2)], [NO(3)], and [C(CN)(3)] available in the literature have been collected and checked for consistency using a group additivity procedure. It has been found that the enthalpies of formation of these ionic liquids roughly obey group additivity rules.
这项工作对离子液体 1-乙基-3-甲基咪唑三氰胺 [C(2)MIM][C(CN)(3)] 和 1-丁基-3-甲基咪唑三氰胺 [C(4)MIM][C(CN)(3)] 的热化学进行了研究。使用最近开发的石英晶体微天平 (QCM) 技术获得了蒸发焓。通过燃烧量热法测量了这些离子液体在液态下的摩尔生成焓。QCM 和燃烧量热法的结果组合得出了 [C(n)MIM][C(CN)(3)] 的气态摩尔生成焓值。使用 CBS-QB3 和 G3MP2 理论对离子液体 [C(n)MIM][C(CN)(3)] 在气相中的生成焓进行了第一性原理计算，并与实验数据进行了比较。此外，还收集了文献中阳离子 [C(n)MIM]（其中 n = 2 和 4）和阴离子 [N(CN)(2)]、[NO(3)]和 [C(CN)(3)]的咪唑基离子液体的生成焓实验结果，并使用基团加性程序检查其一致性。结果发现，这些离子液体的生成焓大致遵循基团加性规则。
