Most methods for screening and predicting activity coefficients do not work well for solutes in ionic liquids. However, although originally developed for neutral solvents, the quantum-chemistry based statistical thermodynamics method, COSMO-RS [1], does appear to work equally well for ionic liquids [2], and without any modification.

The reason for the success of COSMO-RS with ionic liquids is that this method accounts for the strong short-range polar interactions in such systems, where long-range charge interactions are of negligible importance. The advantages of this method over the alternative simulation and prediction techniques with ionic systems, has led to its adoption in academia and industry for screening ionic liquids as green alternatives for certain separation processes.

In this presentation we shall discuss the current knowledge and experience on the applicability of the COSMO-RS method, as implemented in the software package COSMOtherm[TM], to ionic liquids screening with examples from recent publications.

[1] A. Klamt, COSMO-RS: From Quantum Chemistry to Fluid Phase Thermodynamics and Drug Design, Elsevier, Amsterdam 2005

[2] M. Diedenhofen, F. Eckert, and A. Klamt, Prediction of Infinite Dilution Activity Coefficients of Organic Compounds in Ionic Liquids Using COSMO-RS, J. Chem. Eng. Data, 48 (3), 475 -479, 2003