The Studies On Synthesis Technology, Kinetics And Thermodynamic Properties Of Decahydropyrazino [2,3-b] Pyrazine

The synthesis processes, reaction kinetics and thermodynamic properties of decahydropyrazino[2,3-b]pyrazine (DHPP) were studied in this paper.DHPP is mainly synthesized by ethylenediamine and glyoxal. The orthogonal experimental method and the once regression orthogonal experimental method were used to determine the optimal process condition and the relationship between yield and various factors. The regression equation was established. The results show that, the product yield is up to 87.76%, the most significant interaction is the time of last temperature reaction, and the regression equation is rational.Moreover, the kinetics of DHPP was investigated. Under the homogeneous environment, kinetic data of this reaction were obtained and then the kinetics equation was established.The solubilities of DHPP in methanol, ethanol and 2-propanol were measured at temperatures ranging from (274.95 to 354.75) K, and the solubilities in methanol+water, ethanol + water and 2-propanol + water with water mass fraction up to 20% have been determined from (273.75 to 307.25) K as well. The last crystal disappearance method was used to determine the solubility of DHPP. The experimental data were correlated by the van't Hoff plot, Xh (Buchowski) equation, modified Apelblat equation and two local composition models (Wilson and NRTL). In Wilson model, liquid molar volume is an important parameter, and can be determined by measuring the densities of (DHPP + water) solution from (274.25 to 355.95) K, then the liquid molar volume of DHPP, Vm1(T), has been expressed as a function of temperature and was used in Wilson model. It was found that NRTL model gave the best correlation results, the best solvent is ethanol. On the basis of the NRTL model and experimental data, the thermodynamic excess functions of DHPP + alcohols (methanol, ethanol and 2-propanol) systems were determined. Furthermore, the infinite-dilution activity coefficient and the infinite-dilution reduced excess enthalpy were derived.