An Overview of Mutual Solubility of Ionic Liquids and Water Predicted by COSMO-RS

Abstract

To properly screen and use ionic liquids (ILs) as environmental-friendly solvents in chemical reactors and separation processes, the knowledge of their solubilities with water is essential. In the present work, mutual solubilities of 1500 ILs (50 cations, 30 anions) with water at 298.15 K were predicted by using the conductor-like screening model for real solvents (COSMO-RS) as a thermodynamic model. On the basis of the COSMO-RS calculations, the influence of the types of anion and cation, side chain modifications and substituent groups on the mutual solubility with water was extensively analyzed. The data obtained can be used for the prescreening of ILs as solvent candidates. Moreover, to understand the intrinsic solubility behavior in detail, different types of molecular interactions between ILs and water in solution were compared on the basis of the determination of multiple water−IL interaction energies from COSMO-RS computation. The results confirm that hydrogen bonding interactions between anions and water molecules have the dominant influence on the solubility. Finally, for the purpose of fast solubility estimation and solvent selection, COSMO-RS derived molecular descriptors which indicate the strength of anionic HB acceptors were calculated for typical anions and anion families.

Solubility of glucose, xylose, fructose and galactose in ionic liquids: Experimental and theoretical studies using a continuum solvation model

“…Quantum chemical based solvation model such as COSMO-RS is an alternative for such systems [32,33]. It requires only the universal parameters and component specific parameters [34,35] fitted with a small experimental data set. COSMO-RS requires chemical structure of the component as the only information [36,37].…”

Ionic Liquid–Liquid Chromatography: A New General Purpose Separation Methodology

“…This requires both experience and a database of ionic liquid properties [147][148][149]. For the separations discussed here (Table 4), the biphasic combinations of ionic liquids and molecular solvents were chosen based on previous research into ionic liquid phase behaviour and solvent extraction studies (also see Section 3.4) [40,42,124,125,129,[141][142][143]149].…”

“…13) is that hydrocarbons are immiscible with most ionic liquids, but solvents like butanol are only immiscible with ionic liquids on the far left of the chart [150]. The hydrophobicity, or hydrophilicity, of ionic liquids can also be calculated using COSMO-RS software [149]. It is a requirement that the combination of ionic liquids and molecular solvents used in ILLC forms a biphasic mixture and that there is a significant density difference between these two immiscible phases (preferably [0.10 g cm [OTf] can be used in combination with water because the ionic liquids are significantly more dense than water.…”

Mutual solubilities between water and non-aromatic sulfonium-, ammonium- and phosphonium-hydrophobic ionic liquids

“…Quantitatively, there are two important σ-moments related to hydrogen-bonding, namely HB_acc3 and HB_don3, which represent, respectively, the capability of individual atoms in the molecule to act as hydrogen bond acceptors and donors. 18,36 The σ-moments of water and of the ions composing the studied non-cyclic ILs are given in Tables S3-S10 in the ESI. †…”