Comparative analysis of solvation and selectivity in room temperature ionic liquids using the Abraham linear free energy relationship

Abstract

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.