Synthesis Of Ionic Liquids [C_nMIM][THR](n=2,4) And Their Physical Chemistry Properties

Ionic Liquids are liquids at temperatures below 100°C and salts completely composed of anions and cations.Therefore,they are also called low-temperature molten salts.Ionic Liquids have good thermal stability and conductivity.The acidic and super-acidic properties make them not only a solvent,but also can be used as a catalyst for certain reactions.These catalytically active ionic liquids not only avoid the pollution of other toxic catalysts,but also reduce the amount of waste generated.Ionic Liquids also have good design ability and they can obtain special functions through molecular design.Amino acid ionic liquids are a new generation of functional ionic liquids derived from natural ions.They are known as the new“natural ionic liquids”or“biological ILs”and have become one of the most rapidly developing new research areas.Amino acid ionic liquids are expected to apply in all biological,medical and pharmaceutical sciences.However,in order to find the theoretical research and practical application of amino acid ionic liquids,it is essential to understand their basic physical properties.The main purpose of this paper is to prepare the ionic liquids1-ethyl-3-methylimidazoliumthreonine?[C₂MIM][THR]?aswellas1-butyl-3-methylimidazolium threonate?[C₄MIM]][THR]?and characterize their properties.At the same time,the density,surface tension and refractive index of these ILs were measured.According to the density,surface tension and refractive index values at different temperature versus the water content,and the experimental values of pure ILs at T=288.15-328.15K were obtained.The molar surface Gibbs free energy of ionic liquid[C_nMIM][THR]?n=2,4?was calculated.In order to eliminate the influence of trace water,the standard additive method was used in this experiment.A new concept of G_s was used to improve the traditional E???tv???s equation.Then it was used to predict the surface tension of ILs.The slope of the new E???tv???s equation was found to be the molar surface entropy of ILs and the intercept of the equation was the molar surface enthalpy.