Solubility and thermodynamic properties of FOX-7 in four binary mixed solvents from T = 298.15 to 333.15 K

Abstract

The solubility of 1,1-diamino-2,2-dinitroethylene (FOX-7) in four binary mixed solvents (Dimethyl sulfoxide+Acetonitrile, Cyclohexanone, 1,2-Dichloroethane, Ethyl acetate) was measured by a laser dynamic method over the temperature range from 298.15 K to 333.15 K under 0.1 MPa. Experimental results showed that the solubility increases monotonously as the temperature increases at a given solvent composition or increases with the increasing of mole fraction of good solvent (Dimethyl sulfoxide) in binary mixed solvents, whereas there exists a maximum solubility value in Dimethyl sulfoxide+ Cyclohexanone system. Solubility data were well correlated by the Apelblat equation, van't Hoff equation, general single model (GSM) and modified Jouyban-Acree model, and the Apelblat equation achieved the best fitting results. Moreover, the thermodynamic properties of FOX-7 dissolution process in the investigated mixed solvents, including standard dissolution enthalpy, standard dissolution entropy and standard Gibbs free energy, were calculated by the van't Hoff and the Gibbs equations. The results demonstrate that the dissolution of FOX-7 is a non-spontaneous and endothermic process. The solubility data, correlation models, and thermodynamics properties presented in this study would provide essential support for the further research of crystallization and spheroidization of FOX-7.