Measuring and predicting ΔvapH298 values of ionic liquids
Measuring and predicting ΔvapH298 values of ionic liquids
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DOI：
10.1039/b908209c
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发表时间：
2009-01-01
影响因子：
3.3
通讯作者：
Kustov, Leonid M.
中科院分区：
文献类型：
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作者：
Deyko, Alexey;Lovelock, Kevin R. J.;Kustov, Leonid M.
我们报告了 12 种离子液体 (IL) 的汽化焓（使用质谱程序升温解吸测量），涵盖四种咪唑鎓 [C(m)C(n)Im](+)。五个吡咯烷鎓，[C(n)C(m)Pyrr](+)，两个吡啶鎓，[CnPy](+)，和一个二价，[C-3(C(1)Im)(2)](2+) 基于IL。这些阳离子与一系列阴离子配对：[BF4](-)、[FeCl4](-)、[N(CN)(2)](-)、[PF3(C2F5)(3)](-) ([FAP](-))、[(CF3SO2)(2)N](-) ([Tf2N](-)) 和 [SCN](-)。利用这些结果，加上之前发表的另外八种基于咪唑的离子液体（包括阴离子 [CF3SO3](-) ([TfO](-))、[PF6](-) 和 [EtSO4](-)）的结果，我们表明汽化焓可以分解为三个分量。第一个组成部分是离子之间的库仑相互作用，Delta U-Cou,(R)，它是 IL 摩尔体积 V-m 和参数 R-r 的函数，参数 R-r 量化从液相蒸发到气相离子对时阴离子 - 阳离子距离的相对变化。第二个和第三个分量是来自阴离子 Delta H-vdw,H-A 和阳离子 Delta H-vdw,H-C 的范德华贡献。我们得出了 R-r 的通用值，以及本研究中考虑的每种阴离子和阳离子的 Delta H-vdw、H-A 和 Delta H-vdw、H-C 的单独值。给定摩尔体积，可以估计由此处考虑的离子的任意组合组成的离子液体的汽化焓；给出了尚未进行实验研究的 14 个 IL 的值。
We report the enthalpies of vaporisation ( measured using temperature programmed desorption by mass spectrometry) of twelve ionic liquids (ILs), covering four imidazolium, [C(m)C(n)Im](+),. five pyrrolidinium, [C(n)C(m)Pyrr](+), two pyridinium, [CnPy](+), and a dication, [C-3(C(1)Im)(2)](2+) based IL. These cations were paired with a range of anions: [BF4](-), [FeCl4](-), [N(CN)(2)](-), [PF3(C2F5)(3)](-) ([FAP](-)), [(CF3SO2)(2)N](-) ([Tf2N](-)) and [SCN](-). Using these results, plus those for a further eight imidazolium based ILs published earlier ( which include the anions [CF3SO3](-) ([TfO](-)), [PF6](-) and [EtSO4](-)), we show that the enthalpies of vaporisation can be decomposed into three components. The first component is the Coulombic interaction between the ions, Delta U-Cou,(R), which is a function of the IL molar volume, V-m, and a parameter R-r which quantifies the relative change in anion - cation distance on evaporation from the liquid phase to the ion pair in the gas phase. The second and third components are the van der Waals contributions from the anion, Delta H-vdw,H-A, and the cation, Delta H-vdw,H-C. We derive a universal value for R-r, and individual values of Delta H-vdw,H-A and Delta H-vdw,H-C for each of the anions and cations considered in this study. Given the molar volume, it is possible to estimate the enthalpies of vaporisation of ILs composed of any combination of the ions considered here; values for fourteen ILs which have not yet been studied experimentally are given.