LFER correlations for room temperature ionic liquids: Separation of equation coefficients into individual cation-specific and anion-specific contributions

Linear free energy relationship (LFER) correlations have been obtained for describing the gas-to-RTIL (room-temperature ionic liquid) and water-to-RTIL partition coefficients based on both the Abraham solvation parameter model and the Abraham model as modified by Goss. Each derived correlation contains six cation-specific and six anion-specific equation coefficients that were determined through regression analyses. The derived equations correlated the observed gas-to-RTIL and water-to-RTIL partition coefficient data to within 0.10 and 0.14 log units, respectively. Both models were found to have identical predictive/descriptive abilities. The 8 sets of cation-specific and 4 sets of anion-specific equation coefficients can be combined to yield equations capable of predicting the partition coefficients of solutes in 32 different RTILs. Two computational methods are proposed for determining additional ion-specific coefficients once more experimental data become available.