Solvatación preferencial de algunas sulfonamidas en mezclas cosolventes 1,4-dioxano + agua a 298,15 K según el método de las integrales inversas de Kirkwood-Buff

Abstract

The preferential solvation parameters, that is, the difference between the local and bulk mole fractions of the solvents in solutions of some structurally related sulfonamides in 1,4-dioxane + water binary mixtures are derived from their thermodynamic properties by means of the inverse Kirkwood-Buff integrals method. From solvent effect studies, it was found that all the sulfonamides considered were very sensitive to solvation effects, so the preferential solvation parameter, δxD,S, was negative in water-rich and 1,4-dioxane-rich mixtures but positive in intermediate co-solvent compositions. It may be possible that in water-rich mixtures the hydrophobic hydration around the non-polar groups plays a relevant role in the solvation. The greater solvation by 1,4-dioxane in mixtures of similar co-solvent compositions could be due mainly to polarity effects. Finally, the preference of these drugs for water in 1,4-dioxane-rich mixtures could be explained in terms of the acidic behavior of water interacting with the hydrogen-acceptor groups in the sulfonamides.