Study On The Physico-chemical Properties Of Glycine Ionic Liquids And Its Aqueous Solutions

Ionic liquids (ILs) or Room temperature ionic liquids (RTILs) are composed solely of ions and are liquid at ambient temperature. The study of RTILs accord with the development of green chemistry, and are paid great attention by the researchers in world in recent years. This dissertation selects the environment friendly ILs—glycine as the research objects and the physical-chemical properties of the ILs as the main aspects of the research, and the following works have been done:We synthesizes the amino acid ionic liquid: 1-propyl-3-methylimi-dazolium glycine ([C₃mim][Gly]) and 1-butyl-3-methylimidazolium glycine ([C₄mim][Gly]) characterized by 1^HNMR, DSC, TGA. Using the standard addition method (SAM) densities and surface tensions of amino acid ionic liquids [C₃mim][Gly] and [C₄mim][Gly] were measured, density and surface tension of pure ionic liquid(IL), molecular volume V_m, the surface excess entropy S_a, the surface excess energy E_a, the parachor P and the polarizability, were obtained. According to Glasser's theory, we calculated the standard molar entropy S⁰ (298.15 K), and the lattice energy, U_POT. Using empirical equations proposed by Kabo et al the molar enthalpy of vaporization of the [C₃mim][Gly] and [C₄mim][Gly],Δ_l^gH_m^θ(298.15 K), was estimated. The value of the thermal expansion coefficient,α, calculated by the interstice model is in good agreement with experimental one, which means the interstice model is reasonable. On the basis of exparimental data of [C₃mim][Gly] and [C₄mim][Gly], the thermodynamic properties: the molecular volume Vm, the density, the standard molar entropy S0 (298.15 K), and the lattice energy UPOT and the surface tension, the molar enthalpy of vaporizationΔlgHmθ(298.15 K), the thermal expansion coefficientsαfor the homologue of [Cnmim][Gly] (n = 2, 5, 6) were estimated.The density and surface tension of aqueous solution [C₄mim][Gly] and [C₃mim][Gly] were measured in concentration rang of 0.0400～0.5000 mol·kg^-1 at 298.15 K. Using parachor empirical formula and solution surface thermodynamics model to estimate surface tension and discuss the surface condition of these two kinds of ionic liquid aqueous solution.It has higher academic significance for research.