Synthesis,Measurement And Physicochemical Properties Estimation Of Ether-functionalized Ionic Liquid[C₂OC₂mim][X]（X=CL,Gly）

Ionic liquids are generally defined as a subset of molten salts,which are composed of large organic cations and small inorganic anions under the action of electrostatic force.According to the difference of cations,it can be divided into aprotic ionic liquid and proton ionic liquid.According to the difference in properties,it can be divided into chiral ionic liquids or magnetic ionic liquids.The introduction of ether-functionalized groups in the cation can reduce the viscosity and improve the conductivity of ionic liquids to a certain extent.The EFILs have been widely studied and successfully used in separation technology,semiconductor,and many other areas.Therefore,it is very meaningful to explore the physicochemical properties of ionic liquids and eliminate the limitation in practical application.Two ionic liquids have been synthesized,including 1-（2-ethoxyethyl）-3-methylimidazolium glycine,1-（2-ethoxyethyl）-3-methylimidazolium chloride,and characterized by ¹H NMR、¹³C NMR and TGA in this experiment.The refractive index,n_D,density,ρ,and surface tension,γ,of these ILs were measured at the temperature range of 288.15-328.15 K at 5 K intervals.According to the experimental data of[C₂OC₂mim][Cl]and[C₂OC₂mim][Gly],the molar surface Gibbs free energy,g of EFILs was calculated using the empirical equation.The traditional E?tv?s equation was improved.Using The Gibbs free energy of molar surface as a graph of temperature,a set of lines with good linear relationships were obtained.The slope is the molar surface entropy and the intercept is the molar surface enthalpy.In the new equation,each parameter has a physical meaning.The molar surface entropy,s,molar enthalpy,h,molar surface evaporation entropy,（35）S_VS,and the ratio of molar surface thermodynamic energy to molar evaporation energy,E_r were calculated.A method for predicting the surface tension of ionic liquids was proposed,and the surface tension and polarity of ionic liquids were estimated.And it is found that the estimated values and the experimental ones were in the same order of magnitude.