Solubility and preferential solvation of acetaminophen in methanol + water mixtures at 298.15 K

ABSTRACT

The equilibrium solubility of acetaminophen in methanol + water binary mixtures at 298.15 K was determined and correlated with the Jouyban–Acree model. Preferential solvation parameters by methanol (δx_1,3) were derived from their thermodynamic solution properties by means of the inverse Kirkwood–Buff integrals method. δx_1,3 values are negative in water-rich mixtures but positive in compositions from 0.32 in mole fraction of methanol to pure methanol. It is conjecturable that in the former case, the hydrophobic hydration around non-polar groups 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 behavior of this cosolvent.

KEYWORDS:

• Acetaminophen
• solubility
• Jouyban–Acree model
• inverse Kirkwood–Buff integrals
• preferential solvation

Acknowledgments

We thank the Department of Pharmacy of the National University of Colombia for facilitating the equipment and laboratories used.

Disclosure statement

No potential conflict of interest was reported by the authors.