Solubility and thermodynamic properties of β-HMX in sulfolane based binary solvent systems

The experimental solubility of β-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) in binary solvent mixtures of sulfolane + (H₂O, acetonitrile, and ethanol) was measured at temperature ranging from (298.15 K to 343.15 K) by dynamic method under atmospheric pressure. The results showed that the solubility of β-HMX monotonously increases with increasing mole fraction of sulfolane at a given temperature in the studied binary solvent mixtures. Furthermore, the experimental solubility data in binary solvents were fitted using the modified Apelblat equation, the GCM model and the Jouyban-Acree model successfully. Hirshfeld surface analysis and molecular electrostatic potential (ESP) were employed to visualize close contacts and charge distribution of β-HMX and solvents. In addition, the molar dissolution thermodynamic properties of the solution of different binary solvent mixtures, such as Gibbs free energy, enthalpy and entropy, were calculated and analyzed based on the van’t Hoff equation and the experimental solubility data. Solid-liquid surface tension and surface entropy factor of β-HMX were estimated by the experimental solubility data. The solubility of β-HMX in sulfolane based binary solvent systems will provide essential support for the further study of crystallization and spheroidization of β-HMX in industry.