Solubility and preferential solvation of phenacetin in methanol plus water mixtures at 298.15 K

Abstract

The mole fraction solubility of phenacetin (PNC) in methanol + water binary solvent mixtures at 298.15 K was determined along with density of the saturated solutions. All these solubility values were correlated with the Jouyban-Acree model. Preferential solvation parameters of PNC by methanol (delta x(1,3)) were derived from their thermodynamic solution properties using the inverse Kirkwood-Buff integrals (IKBI) method. dx1,3 values are negative in water-rich mixtures but positive in methanol mole fraction of >0.32. It is conjecturable that in the former case the hydrophobic hydration around non-polar groups of PNC plays a relevant role in the solvation. The higher solvation by methanol in mixtures of similar cosolvent compositions and methanol-rich mixtures could be explained in terms of the higher basic behaviour of methanol.