Solubility modelling, solution thermodynamics and preferential solvation for nitroxoline in solvent mixtures of ethyl acetate + (methanol, ethanol, n-propanol and isopropanol)

- Solubility of nitroxoline in ethyl acetate + alcohol were determined and correlated.
- Apparent dissolution enthalpies were derived.
- Preferential solvation parameters were obtained by IKBI method.
- Nitroxoline was preferentially solvated by alcohol in alcohol-rich mixtures.

Equilibrium solubility data of nitroxoline in mixed solvents of (ethyl acetate + methanol), (ethyl acetate + ethanol), (ethyl acetate + n-propanol) and (ethyl acetate + isopropanol) were obtained experimentally by using the static method within the temperature range from (278.15 to 313.15) K under atmospheric pressure of 101.1 kPa. The mole fraction solubility of nitroxoline increased with increasing temperature and mass fraction of ethyl acetate. The obtained solubility data were mathematically represented by using five cosolvency models, including Jouyban-Acree model, van't Hoff-Jouyban-Acree model, Apelblat-Jouyban-Acree model, Ma model, and Sun model. The maximum value of relative average deviation was 1.64 × 10−2, and root-mean-square deviation, 0.77 × 10−4. The dissolution process of nitroxoline in these mixed solvents was endothermic. The preferential solvation parameters were derived from their thermodynamic solution properties via the method of inverse Kirkwood-Buff integrals. The preferential solvation parameters for nitroxoline (δx1,3) were positive in intermediate compositions and ethyl acetate-rich mixtures but negative in alcohol-rich compositions. In the regions with intermediate composition, the preferential solvation magnitude of nitroxoline by the ethyl acetate is higher in {ethyl acetate (1) + ethanol (2)} mixtures than in the other solvent mixtures at 298.15 K. The higher solvation by ethyl acetate in intermediate compositions and in ethyl acetate-rich mixtures could be explained in terms of the higher basic behaviour of ethyl acetate interacting with the Lewis acidic groups of the nitroxoline.

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