Infinite Dilution Activity Coefficients and Gas–Liquid Partition Coefficients of Organic Compounds in Ionic Liquid 1-Butyl-2,3-dimethylimidazolium Thiocyanate: Measurements and LFER Calculations

Infinite dilution activity coefficients (γ i ∞ ) of 31 organic solutes (alkanes, cycloalkanes, olefins, aromatics, chlorinated alkanes, alcohols, and other polar organic solutes) in the ionic liquid (IL) 1-butyl-2,3-dimethylimidazole thiocyanate ([BMMIM][SCN]) were determined by gas–liquid chromatographic (GLC) method in the temperature range of 313.15–353.15 K. The infinite dilution partial molar excess enthalpies ( H̅ i E, ∞ ), entropies ( T ref S̅ i E, ∞ ), and Gibbs free energies ( G̅ i E, ∞ ) of the organic solutes at the reference temperature T = 298.15 K and the solubility parameters (δ 3 ) of [BMMIM][SCN] were derived from γ i ∞ . The gas–liquid partition coefficients ( K L ) of solutes at different temperatures were calculated by referring to the densities of [BMMIM][SCN]. The linear free energy relationship solvation model was used to fit the K L values, and the K L prediction model was obtained. The selectivity ( S ij ∞ ) and capacity ( k j ∞ ) of n -hexane ( i )/benzene ( j ) and cyclohexane ( i )/benzene ( j ) at infinite dilution at 323.15 K were calculated. The results were compared with the values of ILs with the thiocyanate anion in the literature.