Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

The equilibrium solubility of 1,1 '-sulfonylbis(4-aminobenzene) (dapsone) in neat solvents of n-propanol, isopropanol 1,4-dioxane and water and in cosolvent mixtures of n-propanol + water, isopropanol + water and 1,4-dioxane + water were determined experimentally by the saturation shake-flask method within the temperature range from 278.15 K to 323.15 K under atmospheric pressure of 101.0 kPa. The mole fraction solubility of dapsone increased with increasing temperature and mass fraction of cosolvent in each binary system. At the same temperature and mass fraction of the organic solvent, the solubility of dapsone was greater in (1,4-dioxane + water) than in the other two cosolvent mixtures. The type and extent of solvent effect was analyzed by KAT-LSER approach. The obtained solubility was mathematically represented by using the Jouyban-Acree model, van 't Hoff-Jouyban-Acree model and Apelblat-Jouyban-Acree model obtaining average relative deviations lower than 4.88% and root-mean-square deviation lower than 5.86 10-4 for correlative studies. Positive values of the apparent dissolution enthalpy illustrated that the dissolution process of dapsone in these mixed solvents was endothermic. Furthermore, the preferential solvation parameters were derived from their thermodynamic solution properties by means of the inverse Kirkwood -Buff integrals. The preferential solvation parameters for n-propanol, isopropanol or 1,4-dioxane (x1,3) were negative in water-rich mixtures but positive in compositions from 0.24 (0.19, 0.18) in mole fraction of n-propanol (isopropanol or 1,4-dioxane) to neat n-propanol (isopropanol or 1,4-dioxane). It was conjecturable that in former case the hydrophobic hydration around phenyl groups could play a more relevant role than hydrophilic hydration.