| The materials which are liquid state at a room temperature or near the room temperature are named room-temperature ionic liquids (RTILs) or room molten salts. The RTILs is the perfect substitute of conventional solvents temperature owing to its highly conductivity, wide electrochemical window, neglectable vapor tension and adjustable acidity, amenable to diverse solutes, proper viscosity, ionic liquids have been widely used in many fields such as electrochemistry, organic synthesis, catalyst and separation. And it arouses great interest in industry for it does not pollute the environment. The studies of RTILs accord with the development of green chemistry, and are paid great attention by the researchers in the world in recent years. AAIL is a new subject which is familiar to environmental chemistry because it can be cleaned out from the source. In spite of its importance, accurate values for many fundamental physical-chemical properties of this class ILs are either scarce or even absent. Meantime, these values are also very important in the fields of research, development, technological design and environmental protection of ILs. We do such work as follows:Amino acid ionic liquid has an extensive use in the fields of life sciences and medicine industry. Amino acid ionic liquid is a new generation of ionic liquid which is more friendly and cleaner to the environment because it can be decomposed by germs. According to the method by Fukumoto, et al, we synthesize the ionic liquids including 1-butyl-3-methylimidazolium glycine([C4mim][Gly]) and 1-butyl-3- methylimidazolium alanine([C4mim][Ala]) by the transitional material 1-butyl-3- methylimidazolium chloride([C4mim][Cl]) which is stable to the air and water. We also synthesize the ionic liquid 1-ethyl-3-methylimidazolium alanine([C2mim][Ala]) by 1-ethyl-3-methylimidazolium bromine([C2mim][Br]). The molar enthalpies of solution,ΔsolHm(wc), of [C4mim][Gly] with various amount of water and with various molalities were measured by the solution-reaction isoperibol calorimeter at (298.15±0.01)K. According to Archer's method, the standard molar enthalpis of solution of [C4mim][Gly] with a known amounts of water,ΔsolH0m(wc), were obtained. In order to eliminate the effect of the small amount of water in [C4mim][Gly], a linear fitting ofΔsolH0m(wc) against water content was carried out so that a good straight line was obtained and the intercept was the standard molar enthalpy of solution,ΔsolH0m(pure IL[C4mim][Gly])=(-46.02±0.19)kJ·mol-1. The ionic liquid [C4mim][Ala] is also tested by the same method and the standard molar enthalpy of solution,ΔsolH0m(pure IL[C4mim][Ala])=(-61.42±0.08)kJ·mol-1. Using Glasser's theory of lattice energy, the hydration enthalpy of anion of glycine and alanine was estimated respectively.Using the oxygen-bomb combustion calorimeter, the molar combustion enthalpi- es of the ionic liquids: 1-butyl-3-methylimidazolium glycine([C4mim][Gly]) were determined at (298.15±0.01)K. The standard molar combustion enthalpyΔCH0m and the standard molar formation enthalpyΔfH0m of ([C4mim][Gly]) were calculated, and the standard molar formation enthalpyΔfH0m of [Gly]- was also obtained.An amino acid ionic liquid [C2mim][Ala] (1-ethyl-3-methylimidazolium alanine) was prepared by the neutralization method. Using a RD496-III heat conduction microcalorimeter(Southwest Institute of Electron Engineering, China), the molar enthalpies of dilution,ΔDHm(mi→mf), of aqueous [C2mim][Ala] and [C4mim][Gly] with various molalities were measured at (298.15±0.01)K. The values of apparent relative molar enthalpy,φL, calculated using extended Debye-Hückel equation were in good agreement with that calculated from Pitzer's ion-interaction model and Pitzer's parameters were obtained. According to apparent relative molar enthalpy, the estimated values of ionic liquid [C4mim][Gly] with different concentrations are very close to the experimental values.
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