Institut de Chimie de Clermont-Ferrand, Equipe Thermodynamique et Interactions Moléculaires, Clermont Université, Université Blaise Pascal, BP 80026, 63171 Aubiere, France.
J Phys Chem B. 2012 Jul 5;116(26):7728-38. doi: 10.1021/jp304501p. Epub 2012 Jun 22.
We measured the densities of 1-alkyl-3-methylimidazolium (C(n)mim, n = 2,4,6) tris(pentafluoroethyl)trifluorophosphate ionic liquids (eFAP) as a function of temperature and pressure and their viscosities as a function of temperature. These ionic liquids are less viscous than those based in the same cations but with other anions such as bis(trifluoromethylsulfonyl)imide. The ionic liquids studied are only partially miscible with water, their solubility increasing with the size of the alkyl side-chain of the cation and with temperature (from x(H(2)O) = 0.20 ± 0.03 for [C(4)mim][eFAP] at 303.10 K to x(H(2)O) = 0.49 ± 0.07 for [C(6)mim][eFAP] at 315.10 K). The solubility of carbon dioxide, nitrous oxide, ethane, and nitrogen in the three ionic liquids was measured as a function of temperature and at pressures close to atmospheric. Carbon dioxide and nitrous oxide are the more soluble gases with mole fraction solubilities of the order of 3 × 10(-2) at 303 K. The solubility of these gases does not increase linearly with the size of the alkyl-side chain of the cation. The solubilities of ethane and nitrogen are much lower than those of carbon dioxide and nitrous oxide (mole fractions 60% and 90% lower, respectively). The higher solubility of CO(2) and N(2)O can be explained by more favorable interactions between the solutes and the polar region of the ionic liquids as shown by the enthalpies of solvation determined experimentally and by the calculation of the site-site solute-solvent radial distribution functions using molecular simulation.
我们测量了 1-烷基-3-甲基咪唑（C(n)mim，n = 2,4,6）三（五氟乙基）三氟磷酸盐离子液体（eFAP）的密度随温度和压力的变化关系，以及它们的粘度随温度的变化关系。这些离子液体的粘性比基于相同阳离子但具有其他阴离子（如双（三氟甲基磺酰基）亚胺）的离子液体要低。研究的离子液体仅与水部分混溶，其溶解度随阳离子烷基侧链的大小和温度的增加而增加（从 303.10 K 时 [C(4)mim][eFAP] 的 x(H(2)O) = 0.20 ± 0.03 到 315.10 K 时 [C(6)mim][eFAP] 的 x(H(2)O) = 0.49 ± 0.07）。我们还测量了二氧化碳、氧化亚氮、乙烷和氮气在这三种离子液体中的溶解度随温度和接近大气压的压力的变化关系。二氧化碳和氧化亚氮是更易溶解的气体，在 303 K 时的摩尔分数溶解度约为 3 × 10(-2)。这些气体的溶解度并不随阳离子烷基侧链的大小线性增加。乙烷和氮气的溶解度远低于二氧化碳和氧化亚氮（摩尔分数分别低 60%和 90%）。CO(2)和 N(2)O 的较高溶解度可以通过实验确定的溶剂化焓以及使用分子模拟计算的溶质-溶剂径向分布函数的位点位计算来解释，这表明溶质与离子液体的极性区域之间存在更有利的相互作用。
