Solubility Measurement, Preferential Solvation, and Solvent Effect of 3,5-Dinitrosalicylic Acid in Several Binary Aqueous Blends

This research dealt with the equilibrium solubility, preferential solvation, and intra- and intermolecular interactions for 3,5-dinitrosalicylic acid dissolved in aqueous blends of N-methyl-2-pyrrolidinone (NMP)/ethanol/isopropanol/N,N-dimethylformamide (DMF) along with computational methodologies. All solubility experiments were performed using a shake-flask equilibration method under a pressure of 101.2 kPa from 278.15 to 323.15 K. For each aqueous blend, the minimum solubility value of 3,5-dinitrosalicylic acid was found in water at 278.15 K, and the maximum one was found in neat organic solvent at 323.15 K. The generated solubility was acceptably described by mixture response surface, van't Hoff-Jouyban-Acree, modified Wilson and Jouyban-Acree model. The relative average deviations were all no larger than 5.57%. The analysis of linear solvation energy relationships demonstrated that the solvent descriptors of dipolaritypolarizability and solubility parameter were principally responsible for the 3,5-dinitrosalicylic acid solubility. Besides, the solvation of 3,5-dinitrosalicylic acid was studied quantitatively by inverse Kirkwood-Buff integrals. The positive values of preferential solvation parameter for 3,5-dinitrosalicylic acid in middle and cosolvent-rich mixtures strongly suggest that 3,5-dinitrosalicylic acid is preferentially solvated by NMP/ethanol/isopropanol/DMF. It could be conjectured that in these composition regions, 3,5-dinitrosalicylic acid served as Lewis acid in its interactions with surrounding NMP/ethanol/isopropanol/DMF molecules.