REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
J Phys Chem B. 2010 Dec 2;114(47):15605-9. doi: 10.1021/jp107094n. Epub 2010 Nov 9.
This work presents a systematic investigation into liquid-liquid phase equilibria for systems containing three various ionic liquids and four dienes as they have not been reported yet. The systems employed in this study containing dicyanamide based ionic liquids and dienes reveal the phase envelopes that have a similar shape to binodal curves with the upper critical solution temperature. Generally, 1-methyl-3-octylimidazolium dicyanamide ([C(8)mim][DCA]) was found to be a better solvent for nonpolar dienes. The 1-butyl-3-methylimidazolium dicyanamide ([C(4)mim][DCA]) ionic liquid is a much worse solvent for 1,5-cyclooctadiene, 1,3-cyclooctadiene, 1,5-hexadiene, and 1,7-octadiene compared to other ionic liquids studied. The miscibility gaps shrink for a less polar [C(8)mim][DCA] or even more for 1-dodecyl-3-methylimidazolium dicyanamide ([C(12)mim][DCA]). In the range of the studied temperatures, the solubility of dienes is significantly higher compared to the solubility of the ionic liquids containing the shorter alkyl chain in the cation. The solubility of the presented dienes in ([C(4)mim][DCA]) ionic liquid is also relatively high and may reach up to 0.19 mol fraction of the diene. The attained results demonstrate that nonpolar compounds can be dissolved to some extent in highly charged and polar solvents such as ionic liquids.
本工作系统地研究了含有三种不同离子液体和四种二烯的液-液相平衡，因为这些体系尚未有报道。本研究中使用的含双氰胺基离子液体和二烯的体系呈现出与上临界溶解温度相似的形状的相包络线。通常，1-甲基-3-辛基咪唑双氰胺([C(8)mim][DCA])被发现是一种更好的非极性二烯溶剂。与研究的其他离子液体相比，1-丁基-3-甲基咪唑双氰胺([C(4)mim][DCA])离子液体对于 1,5-环辛二烯、1,3-环辛二烯、1,5-己二烯和 1,7-辛二烯是一种差得多的溶剂。对于极性较小的[C(8)mim][DCA]或甚至 1-十二烷基-3-甲基咪唑双氰胺([C(12)mim][DCA])，混合间隙会缩小。在所研究的温度范围内，二烯的溶解度明显高于阳离子中含有较短烷基链的离子液体的溶解度。在([C(4)mim][DCA])离子液体中，所研究的二烯的溶解度也相对较高，可达 0.19 摩尔分数的二烯。所得结果表明，非极性化合物可以在高电荷和极性溶剂（如离子液体）中在一定程度上溶解。
