Study Of Thermodynamic Properties Of The Amino Acid Ionic Liquids In Organic Solvents

In this paper,a series of the binary mixtures that composed of amino acid ionic liquids and organic solvents have been systematically studied through determination of their density, viscosity and refractive index. The changes of thermodunamic properties for the binary mixtures and the application of these ionic liquids have been inspected. The feasibility of the project that used amino acid ionic liquid as catalysts to extract biodiesel from castor oil has been discussed. The main subject of this work can be generally divided into three parts as follows.First, amino acid ionic liquids 1-butyl-3-methylimidazolium glutamic acid salt [Bmim][Glu], 1-butyl-3-methylimidazolium glycine acid salt ([Bmim][Gly]) and 1-butyl-3- methylimidazolium alanine acid salt ([Bmim][Ala]) were synthesized, and preliminarily explore the probability of producing biodiesel by amino acid ionic liquid catalysis.The volume property changes of the two binary mixtures formed by 1-butyl-3-methylimidazolium glutamic [Bmim][Glu] or 1-butyl-3-methylimidazolium glycine acid salt ([Bmim][Gly]), respectively, with benzylalcohol have been investigated. The results shown that the minimum in V_m~E reached with mole fraction of amino acid ionic liquid is different for the two binary mixtures. This is due to the difference of the anionic part (difference of the amino acids) of the corresponding amino acid ionic liquids. Moreover, the V_m~E values for [Bmim][Glu] + benzylalcohol mixtures are more negative than that of [Bmim][Gly] + methanol mixtures, which means that the ion-dipole interactions and packing effects in the [Bmim][Glu] + benzylalcohol solutions there are stronger than that of [Bmim][Gly] + benzylalcohol solutions. Furthermore, it can be speculated that the quasi-clathrates structures are probably formed in the mixtures of [Bmim][Glu] or [Bmim][Gly] + benzylalcoholSecond, the density, viscosity and refractive index parameters of the two binary mixtures formed by 1-butyl-3-methylimidazolium glutamic acid salt [Bmim][Glu] or 1-butyl-3- methylimidazolium glycine acid salt ([Bmim][Gly]), respectively, with methanol. has also been measured. The density measurement was done over the range of temperature from (298.15 to 313.15) K at intervals of 5 K and at atmospheric pressure using a vibrating-tube densimeter (DMA4500). While the viscosity and refractive index parameters were measured by Ubbelohde viscometer and Abbe refractometer respectively. Similarly, the binary mixtures formed by 1-butyl-3-methylimidazo–lium glycine acid salt ([Bmim][Gly]) with isopropanol or 1-butanol and 1-butyl-3-methylimidazolium alanine acid salt ([Bmim][Ala]) with benzylalcohol or methanol, respectively, have also been studied. The excess molar volumes V_m~E and viscosity deviationsΔ_η, as well as refractive index deviationsΔn_D for these mixtures have been calculated. Excess molar volumes have been fitted by the fourth-order Redlich–Kister equation. As a result, the value of the excess molar volumes and the viscosity deviations over the full range of mole fraction are all negative, while the refractive index deviations are all positive.