Insight into the solute-solvent interactions by physicochemical and excess properties in binary systems of the ether- and allyl-based functionalized ionic liquids with acetonitrile

Background: Ionic liquid is a significant new media and one of the most compelling solvents mentioned in many fields. It is clear that the introduction of ether or allyl group has the advantages of low viscosity and wide application. Methods: In this work, [C1OC2pyrr][DCA], [C1OC2pyrr][NTf2] and [Amim][NTf2] were synthesized and characterized. The density, surface tension, and refractive index of the three ionic liquids and their binary systems with acetonitrile were investigated across a complete composition range. The thermal expansion coefficient (apE), excess molar volumes (VE), and refractive index deviations (DnD) are also calculated. Findings: The apE and VE are all negative while the DnD are found positive in the entire concentration range, indicating the presence of strong interactions between ionic liquids and acetonitrile. The properties are fitted to a Redlich-Kister equation and the results have been interpreted in terms of H-bonding interaction and structural effect, at the same time, the corresponding IR spectra are also carried out. The molar refraction and the molar polarizability calculated which suggest that the existent interactions between ionic liquids and acetonitrile are ion-dipole interactions. The molar Gibbs free energy can be measured and explained properly by the improved Eoeurotvoeuros equation. And the molar surface enthalpy also can be gained and is a temperatureindependent constant. (c) 2022 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.