A Study On The Physicochemical Properties Of The Binary System Of [Hemim][Ac] And [Hemim][Pro] Ionic Liquids

As a new type of green and efficient solvent,ionic liquids have many excellent physical and chemical properties,such as low volatility,high electrochemical window,low melting point,and high thermal stability.Some ionic liquids also have good biodegradability,extraction ability,and carbon dioxide capture ability.Based on their good designability,there are various types of ionic liquids with wide applications,which have become a hot research topic at home and abroad.However,ionic liquids have the drawbacks of high viscosity and difficulty in purification.They can form binary systems with water or other organic solvents,effectively reducing the viscosity of pure ionic liquids and making them more widely used in chemical and other fields.At present,the systematic research on the binary system of ionic liquids is still in the stage of data accumulation.In this paper,two hydroxy ionic liquids,1-hydroxyethyl-3-methylimidazolium acetate（[Hemim][Ac]）and 1-hydroxyethyl-3-methylimidazolium propionate（[Hemim][Pro]）,were synthesized.The two ionic liquids were analyzed by means of nuclear magnetic resonance spectroscopy,nuclear magnetic resonance carbon spectroscopy,and thermogravimetric analysis,and the target ionic liquid was determined to be synthesized.Two ionic liquids were mixed with H₂O and DMSO to prepare a binary system mixed solution in the full concentration range.The density and viscosity values of the four binary systems were measured at a temperature range of 288.15 K-333.15 K.The average molar volume（V_m）and excess molar volume（V^E）of the mixed solution in a binary system were calculated using the density values.V^E was fitted using the Redlich-Kisser equation,which can well describe the relationship between V^E and the molar fraction（x₁）of ionic liquids.The effects of temperature and x₁ on these properties,as well as the interactions between Hemim][Ac]、[Hemim][Pro]and H₂O、DMSO,were discussed.The viscosity deviation was calculated based on the viscosity data of the binary system mixed solution（Δη）and relative viscosity（η_r）,using the Redlich-Kisser equation forΔηFit and describe theΔηRelationship with x₁,viaη_r and Eyring equations obtained the excess Gibbs free energy of viscous flow activation(ΔG^≠E).The Redlich-Kisser equation was used to fitΔG^≠E,describing the relationship betweenΔG^≠E and x₁.The effects of temperature and x₁ on these thermodynamic properties were discussed,and the interaction between[Hemim][Ac]、[Hemim][Pro]and H₂O、DMSO was discussed through data analysis of these thermodynamic properties.