Department of Physical Chemistry, University of Rostock, Rostock, Germany.
J Phys Chem B. 2011 Nov 10;115(44):12889-95. doi: 10.1021/jp207397v. Epub 2011 Oct 17.
A new method for the determination of vaporization enthalpies of extremely low volatile ILs has been developed using a newly constructed quartz crystal microbalance (QCM) vacuum setup. Because of the very high sensitivity of the QCM it has been possible to reduce the average temperature of the vaporization studies by approximately 100 K in comparison to other conventional techniques. The physical basis of the evaluation procedure has been developed and test measurements have been performed with the common ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C(2)mim][NTf(2)] extending the range of measuring vaporization enthalpies down to 363 K. The results obtained for [C(2)mim][NTf(2)] have been tested for thermodynamic consistency by comparison with data already available at higher temperatures. Comparison of the temperature-dependent vaporization enthalpy data taken from the literature show only acceptable agreement with the heat capacity difference of -40 J K(-1) mol(-1). The method developed in this work opens also a new way to obtain reliable values of vaporization enthalpies of thermally unstable ionic liquids.
一种新的方法来确定蒸发热的极低挥发性 ILs 已发展使用新建成的石英晶体微天平 (QCM) 真空设备。由于 QCM 的灵敏度非常高，它已经有可能减少平均温度的蒸发研究约 100 K 相比，其他常规技术。物理基础的评价程序已经开发和测试测量已经与共同的离子液体 1-ethyl-3-methylimidazolium 双 (三氟甲烷磺酰) 亚胺 [C(2) mim][NTf(2)] 扩展范围测量蒸发热下来到 363 K。结果获得的 [C(2) mim][NTf(2)] 已经进行了测试热力学一致性与已经在更高温度下可用的数据进行比较。比较温度依赖蒸发热数据取自文献显示只有可接受的协议与热容差-40 J K(-1) mol(-1)。在这项工作中开发的方法也开辟了一种新的方法来获得可靠的蒸发热值的热不稳定的离子液体。
