Solubility measurement and solvent effect of Doxofylline in pure solvents and mixtures solvents at 278.15–323.15K

The solid-liquid phase equilibrium solubility of Doxofylline was measured and discussed in ten pure organic solvents and co-solvent mixtures of acetonitrile + ethanol (+or water) at temperature range from 278.15 to 323.15 K. Results indicated that experimental mole fraction (x) of Doxofylline in ten neat solvents followed this order: acetonitrile > tetrahydrofuran > benzene > acetone > ethyl acetate > methanol > 1-propanol ≈ 2-propanol > ethanol ≈ water, and solubility increased with temperature increasing. Moreover, experimental solubility of Doxofylline firstly increased and then declined with the mass fraction increasing of acetonitrile in acetonitrile + ethanol (+or water) mixture solvents at each temperature. Hansen solubility parameter and solvent effect were used for explaining and discussing solubility rule of Doxofylline in selected solvents. Model correlation indicated the NRTL model was the most suitable than other models to predict solubility of Doxofylline in pure solvents and Sun model was better than other models in mixture solvents with accompanied by temperature and composition. Furthermore, thermodynamic properties of standard molar enthalpy, molar Gibbs free energy and molar entropy in solution was calculated and discussed.