Solubility and Model Correlation of Doxofylline in Pure Solvents at the Temperature Range of 283.15–323.15 K

Doxofylline (DFL) is a theophylline derivative with poor solubility in water. In this paper, the solubility of DFL (as mole fraction) in 17 organic solvents including 4 esters (ethyl acetate, n-propyl acetate, n-butyl acetate, methyl propionate), 8 alcohols (methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol, n-pentanol), 3 ketones (acetone, 2-butanone, cyclohexanone), acetonitrile, and water was studied at the temperatures ranging from “T = 283.15 to 323.15 K”. The solubility of DFL in pure solvents was simulated using three semiempirical models (modified Apelblat, λh, and three-parameter Van’t Hoff) and two activity coefficient models (Wilson and NRTL). In addition, the thermodynamic mixing properties (ΔmixG, ΔmixH, ΔmixS, ln (γ1∞) and H1E,∞) were evaluated using the solubility data and the Wilson model.