Revealing and visualizing the microscopic solution chemical molecular mechanism of β-HMX solubility in binary mixed solvents

• Solubility of β-HMX was measured by the laser dynamic method. • The complex intermolecular interactions were revealed by both DFT and MD simulations . • The intermolecular interactions in solution were visualized. Octogen (HMX) is one of the most powerful explosives. However, the insufficient solubility data and unclear thermodynamic molecular mechanisms might limit its further application. This study measured the solubility of HMX (form β) in two binary mixed solvents (methyl acetate + ethanol and methyl acetate + 1,2-dichloroethane) at 283.15 ∼ 313.15 K under atmospheric pressure. β-HMX’s solubility increases with methyl acetate content and temperature, and solvent composition shows more apparent effect than temperature. Moreover, DFT calculations and MD simulations were utilized to investigate the mechanism of complex intermolecular interactions on β-HMX’s solubility in mixed solvents. Both ethanol and methyl acetate molecules can form interactions with β-HMX through C-H•••O hydrogen bond, which primarily drive dissolution. Additionally, the strong O-H•••O hydrogen bond between ethanol and solvent molecules decrease solubility. This work can provide further insights on relationship between solubility properties and molecular structures, promoting industrial production and application of HMX.