Density and Molar Volume Predictions Using COSMO-RS for Ionic Liquids. An Approach to Solvent Design
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- 作者：José ; Palomar ; Ví ; ctor R. Ferro ; José ; S. Torrecilla ; Francisco Rodrí ; guez
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2007
- 出版时间：August 29, 2007
- 年：2007
- 卷：46
- 期：18
- 页码：6041 - 6048
- 全文大小：417K
- 年卷期：v.46,no.18(August 29, 2007)
- ISSN：1520-5045
文摘
The specific density and molar liquid volume of 40 imidazolium-based ionic liquids were predicted using theCOSMO-RS method, a thermodynamic model based on quantum chemistry calculations. A molecular modelof ion pairs was proposed to simulate the pure ionic liquid compounds. These ion-paired structures weregenerated at the B3LYP/6-31++G** computational level by combining the cations 1-methyl- (Mmim+),1-ethyl- (Emim+), 1-butyl- (Bmim+), 1-hexyl- (Hxmim+), and 1-octyl-3-methylimidazolium (Omim+) withthe anions chloride (Cl-), tetrafluoroborate (BF4-), tetrachloroferrate (FeCl4-), hexafluorophosphate (PF6-),bis(trifluoromethanesulfonyl)imide (Tf2N-), methylsulfate (MeSO4-), ethylsulfate (EtSO4-), and trifluoromethanesulfonate (CF3SO3-). Satisfactory agreement with the available experimental measurements wasobtained, showing the capability of the current computational approach to describe the effect of the anionnature and cation substituent on the volumetric properties of this family of ionic liquids. Thus, calculated andexperimental density values of ionic liquids (and also other common solvents) were fitted by linear regressionswith correlation coefficients R > 0.99 and standard deviations SD < 20 kg/m3. Consequently, molar liquidvolumes were also predicted very accurately by COSMO-RS, indicating the suitability of the ion-pair modelto describe intermolecular interactions of pure ionic liquids. In this sense, the 
-profiles of the ion-pairedmolecules were used to qualitatively analyze the influence of cation and anion natures of ionic liquids ontheir volumetric properties. As a result of the analysis, we propose the charge distribution area below the-profile (S-profile) as a simple a priori parameter to characterize the contributions of cation and anion to theionic liquid behavior as tool to design solvents.
-profiles of the ion-pairedmolecules were used to qualitatively analyze the influence of cation and anion natures of ionic liquids ontheir volumetric properties. As a result of the analysis, we propose the charge distribution area below the-profile (S-profile) as a simple a priori parameter to characterize the contributions of cation and anion to theionic liquid behavior as tool to design solvents.