Correlations for describing gas-to-ionic liquid partitioning at 323 K based on ion-specific equation coefficient and group contribution versions of the Abraham model

Chromatographic retention measurements were measured for a wide range of solutes on 1-methyl-3-ethylimidazolium tris(pentafluoroethyl)trifluorophosphate, ([MEIm]+[FAP]−), and 1-(3-hydroxypropyl)pyridinium tris(pentafluoroethyl)trifluorophosphate, ([1-PrOHPy]+[FAP]−), stationary phases at 323 K. The measured retention factors were combined with published infinite dilution activity coefficient, gas solubility data and retention factor data to yield gas-to-anhydrous ionic liquid (IL) partition coefficients at 323 K for 2349 different solute-IL combinations. The compiled partition coefficient data were analyzed using the ion-specific equation coefficient and the functional group contribution versions of the Abraham solvation parameter model. Ion-specific equation coefficients were calculated for 25 cations and 14 anions. In addition, values were calculated for 14 cation functional groups and 14 anions. The calculated ion-specific equation coefficients and calculated functional group values described the experimental 323 K partition coefficient data to within standard deviations of 0.10 and 0.13 log units, respectively.

Research highlights▶ Gas-to-ionic liquid partition coefficients are compiled. ▶ Ion-specific Abraham model coefficients are calculated for 25 cations and 14 anions. ▶ 14 cation functional group values and 14 anion group values are calculated. ▶ Calculated equation coefficients and group values predict experimental data to 0.13 log units.