Li Wenjing, Zhang Zhaofu, Han Buxing, Hu Suqin, Xie Ye, Yang Guanying
Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
J Phys Chem B. 2007 Jun 14;111(23):6452-6. doi: 10.1021/jp071051m. Epub 2007 May 23.
The effect of water and several organic solvents on the density, viscosity, and conductivity of ionic liquids (ILs) 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-n-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), and 1-n-butyl-3-methylimidazolium trifluoroacetate ([bmim][CF3CO2]) was studied at 298.15 K in wide composition ranges. The density, viscosity, and conductivity of the three neat ILs were also determined at various temperatures. Upon the basis of the molar conductivity of the mixtures and that of the neat ILs of the same viscosity, the degree of dissociation of ILs in the solutions was investigated. It can be deduced that the organic solvents enhance the ionic association of the ILs, the effect depending on the solvent dielectric constant, while water promotes dissociation significantly due to its high dielectric constant and its ability to form strong hydrogen bonds with the anions of the ILs.
在298.15 K下，在较宽的组成范围内研究了水和几种有机溶剂对离子液体（ILs）1-正丁基-3-甲基咪唑六氟磷酸盐（[bmim][PF6]）、1-正丁基-3-甲基咪唑四氟硼酸盐（[bmim][BF4]）和1-正丁基-3-甲基咪唑三氟乙酸盐（[bmim][CF3CO2]）的密度、粘度和电导率的影响。还在不同温度下测定了这三种纯离子液体的密度、粘度和电导率。根据混合物的摩尔电导率以及相同粘度的纯离子液体的摩尔电导率，研究了离子液体在溶液中的解离程度。可以推断，有机溶剂增强了离子液体的离子缔合，其效果取决于溶剂的介电常数，而水由于其高介电常数以及与离子液体阴离子形成强氢键的能力，显著促进了解离。
