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

Abstract

• The ether- and allyl-based functionalized ionic liquids [C 1 OC 2 pyrr][DCA], [C 1 OC 2 pyrr][NTf 2 ] and [Amim][NTf 2 ] were synthesized and characterized. • The excess properties α p E and V E values are all negative, which could be interpreted in terms of H-bonding interaction and structural effect, and Δ n D findings are also well supported by the results. • The molar refraction, R m and the molar polarizability α, which suggest that the existent interactions between ILs and acetonitrile are ion-dipole interactions. 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. In this work, [C 1 OC 2 pyrr][DCA], [C 1 OC 2 pyrr][NTf 2 ] and [Amim][NTf 2 ] 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 ( α p E ), excess molar volumes ( V E ), and refractive index deviations (Δ n D ) are also calculated. The α p E and V E are all negative while the Δ n D 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 Eӧtvӧs equation. And the molar surface enthalpy also can be gained and is a temperature-independent constant.