Solubility, Hansen solubility parameter, solvent effect and preferential solvation of benorilate in aqueous mixtures of isopropanol, N,N-dimethylformamide, ethanol and N-methyl-2-pyrrolidinone

This contribution was devoted to the equilibrium solubility profile, solute–solvent and solvent–solvent interactions and solvation behavior of benorilate in aqueous binary mixtures of the cosolvent (i.e. ethanol, N-methyl-2-pyrrolidinone (NMP), isopropanol and N,N-dimethylformamide (DMF)) together with several mathematical associations. All experiments were conducted by a shake-flask method under ambient pressure of 101.2 kPa from 278.15 to 318.15 K. The maximum scale of equilibrium benorilate solubility in neat cosolvent at T = 318.15 K; while the minimum one was observed in pure water at 278.15 K. The equilibrium benorilate solubility was analyzed by using the Hildebrand and Hansen solubility parameters. Various solubility models including Jouyban–Acree–van’t Hoff, modified Wilson, Jouyban–Acree and mixture response surface (MRS) were employed to fit the mole fraction solubility data, attaining the average relative deviations (RAD) of no more than 9.62%. The relative significance of molecular interactions of solvent–solvent and solute–solvent species upon the equilibrium solubility of benorilate at 298.15 K analyzed through the linear solvation energy relationships specified that the dominant contributions to solubility variation were observed as solubility parameter and dipolarity-polarizability of systems. The solubility data was investigated by means of the extended Hildebrand solubility approach gaining relative average deviation values of no higher than 3.71%. In terms of solution properties, a quantitative analysis on preferential solvation of benorilate was conducted by inverse Kirkwood–Buff integrals method. The preferential solvation parameters for neat cosolvent were recorded as positive in cosolvent-rich and intermediate regions in solutions, suggesting that benorilate was preferentially solvated by the cosolvents. In the above composition regions, it is conjectured that benorilate is performing as a Lewis acid with the cosolvent molecules.