Gas to RTIL (room temperature ionic liquid) partition coefficients have been compiled for a series of solutes for a number of RTILs. These partition coefficints can be converted into water to RTIL partition coefficients using corresponding gas to water partition coefficients. The gas to RTIL and water to RTIL partition coefficients have been correlated through the Abraham solvation equations to yield equations that can be used for the prediction of further partition coefficients. The coefficients in the Abraham solvation equations yield quantitative information on solute–solvent (RTIL) interactions. It is shown that the RTILs have solvation properties quite close to those for polar aprotic organic solvents. The equations for gas to RTIL and gas to solvent partition coefficients can be used to predict the selectivity of RTILs and organic solvents towards pairs of solutes. It is shown that the selectivity of RTILs is not extraordinary, but is about the same as the selectivity of polar aprotic solvents.

Equations have been constructed for the transfer of neutral solutes from water to the solvents ethylene glycol and propylene carbonate. These equations have been extended to include ions and ionic species derived from acids by loss of a proton and bases by acceptance of a proton. Only one additional term is needed for cations and one additional term for anions. The data used include literature data on the partition coefficients of simple ions, and literature data on pK_a values for carboxylic acids and amines in water, ethylene glycol and propylene carbonate from which we derive ionic partition coefficients. Descriptors have been obtained for 22 substituted pyridinium cations, and equations derived for the prediction of descriptors for further substituted pyridinium cations. Some of the pyridinium cations are the strongest hydrogen bond acids that we have encountered.

Partition coefficients for transfer from water to wet octanol have been set out for permanent ions, and for ionic species derived from neutral molecules by loss or acceptance of a proton. A previous equation for the partition of neutral compounds from water to wet octanol has been extended to include the partition of permanent ions, and ionic species; the only additional descriptors required are J⁺ for cations and J⁻ for anions. Fourteen cations and twelve anions are included in the equation. It is shown that differences in partition coefficients between neutral species and the corresponding ionic species, as log P(oct), are not at all constant. For carboxylic acids and the corresponding anion, differences are about 5.0 log units, for phenols and the corresponding anion differences range from 2.2 to 4.9 log units, and for amines and the corresponding protonated cations there is an enormous range of differences from 0.6 to 7.1 log units.

Literature data on partitioning of compounds from the gas phase to ketones and from water to ketones has been collected and analyzed through the Abraham solvation equations. It is shown that for partition into both dry and wet ketones the main solvent factors that aid partitioning into the ketones are the polarizability/dipolarity, hydrogen-bond basicity and hydrophobicity (size) of the ketones. Reliable equations have been established for partitioning from the gas phase and from water to dry acetone, dry butanone, dry cyclohexanone and to wet methyl isobutyl ketone. It is further shown that partitioning into dry butanone and dry cyclohexanone leads to different equations than partitioning into the wet solvents, and that data on partitioning into the wet and dry ketones cannot be combined.