Molecular interactions of choline based ionic liquids with water at different temperatures: An experimental study

To understand the molecular interactions among the components of aqueous solutions with cholinium based aprotic ionic liquids (AILs), their partial molar properties have been studied. Four cholinium based AILs-namely, cholinium propanoate ([Chl][Pro]), cholinium butanoate ([Chl][But]), cholinium pentanoate ([Chl][Pen]) and cholinium hexanoate ([Chl][Hex]) were synthesized and characterized. Thermodynamic properties of these AILs in water at various temperature (293.15 to 333.15) K and at atmospheric pressure were determined from density and speed of sound measurements. Derived thermodynamic properties and related empirical parameters at infinite dilution were also determined using the Redlich-Mayer type of equation. The studied AILs are observed to interact strongly with water, although the ion-solvent interactions decrease with increase in temperature as well as with increase in concentration.