Synthesis And The Physicochemical Properties Of 1-butylmethoxy-3-methylimidazole Glycine,Alanine And Threonine Ionic Liquids

Nowadays,functionalized ionic liquids have been widely used in many fi elds.In this paper,three ether-functionalized ionic liquids with different anion s have been synthesized.They are 1-butylmethoxy-3-methylimidazole glycine s alt[COC4mim][Gly],1-butylmethoxy-3-methylimidazole alanine salt[COC4mi m][Ala]and 1-butylmethoxy-3-methylimidazole threonine salt[COC4mim][Thr].The density of the three amino acid pure ionic liquids was determined by using the standard addition method,and the density value decreased as the volume of glycine,alanine,and threonine increased.The molar volume was calculated based on the density value,and it is found that as the methylene group in the amino acid increases,the molar volume of the ionic liquid will gradually increase.The standard entropy of these three ionic liquids and the lattice energy at 298.15 K were calculated using Glasser's theory.The lattice energy of ionic liquids is found to be small,so it is a molten salt at room temperature.The surface tension of the three amino acid ionic liquids was measured by the maximum bubble method,and the surface tension value increased with the increase of amino acid volume.Based on the surface tension values,the surface entropy and surface energy of the three ionic liquids were calculated.The surface energy of ionic liquids is close to the surface energy of organic solvents.The Gibbs free energy of the ionic liquid's molar surface is used to improve the traditional Eotvos equation,and the surface tension value is predicted.The predicted surface tension value is highly similar to the experimental value.In this paper,the enthalpy of vaporization of the three ionic liquids was also calculated,and it is found that the enthalpy of vaporization of the ionic liquids will gradually increase as the volume of amino acids increases.The refractive indexes of the three amino acid ionic liquids were measured using standard addition methods.By comparison,the refractive indexes of the three ionic liquids decreased with the increase of the amino acid volume,and the molar polarizability and molar polarizability were also calculated.