Phase Chemistry and Thermochemistry on Coordination Behavior of Zinc Chloride with Leucine

Abstract

Ihe solubiity property of the ZaQ-Leu-HzO (Leu = Ga-leucine) system at 298.15 K in the whole concentration range war investigated by the semimicmphafe equilibrium method. The c o e sdubiity diagram and refractive index diagram were c o m i r u~. 'Ihe results indicated that there was ow complex formed in this system, namely, Z n ( h ) q . The complex is congruently soluble in water. Based on phase equilirium data, the complex WBS prepared. Its composition and properties were rharacterized by chemical analysis, elemental analysis, IR spectra, atid TGmU;. "he thennochemical properties of coordination reaction of zinc chloride with Ga-leucine were investigatd by a miupcalorimeter. The enthalpies of solution of Ga-leucine in water and its zinc complex at in6nite dilution and the enthalpy change of solid-liquid d o n were determined at 298.15 K. Tbe enthalpy change of solid phase reaction and the standard enthalpy of formation of zinc complex werecalculated. On the basis of e x p e w and calculated redts, three thermodynamic parameters ( the activation enthalpy , the activation entropy and the activation free energy), the rate mstant and three kinetic parameters (the activation energy, the preexponential constant and the reaction order) of the reaction, and the standard enthalpy of formation of Zn(Leu)'+ (aq) were obtained.The results showed that the title reaction took place easily at studied temperature.