Effect of dielectric constant on estimation of properties of ionic liquids: an analysis of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

Abstract

A series of different cationic structures based on 1-alkyl-3-methylimidazolium were combined with a single anion, bis(trifluoromethylsulfonyl)imide (C_nmimNTf₂, n = 1 to 12) for analyzing the quality of COSMO-RS based estimations. For this purpose, we have studied the structure as well as the estimations of several properties of one ionic liquid (IL). These estimations are obtained from polarization charge distribution in which the IL is embedded. Special attention has been paid to the effect of the dielectric constant value in the predictions. For this purpose, polarization charge density has been modeled using several values of dielectric constant, and properties have been estimated in each case. Thus, σ-profiles and, σ-potentials have been computed and used with COSMO-RS for estimating vapor pressure, as a function of temperature, as well as theoretical values of vaporization enthalpy, density, and viscosity at 298.15 K. The influence of the length of the alkyl chain of ionic liquid in the estimation of these properties has also been tested. Finally, the results have been compared with experimental data.