Solubility measurement, calculation, solvent effect and preferential solvation of fenoxaprop-p-ethyl in four cosolvent mixtures at (278.15–323.15) K

Equilibrium solubility of fenoxaprop-p-ethyl in aqueous mixtures of ethanol/ isopropanol/acetonitrile/ N,N -dimethylformamide (DMF) plus water was experimentally measured by isothermal saturation method at (278.15–323.15) K under 101.2 kPa. The order of solubility (mole fraction) of fenoxaprop-p-ethyl in pure solvents from high to low is 4.233 × 10 −2 (DMF 323.15 K) > 2.044 × 10 −2 (acetonitrile 323.15 K) > 7.727 × 10 −3 (isopropanol 323.15 K) > 5.338 × 10 −3 (ethanol 323.15 K) > 2.565 × 10 −5 (water 323.15 K). Experimental results showed that temperature and type of solvent were decisive factors for the dissolution of fenoxaprop-p-ethyl. The content of fenoxaprop-p-ethyl in solution was analyzed by high-performance liquid chromatography (HPLC). Moreover, the solubility data of fenoxaprop-p-ethyl was correlated by Jouyban-Acree (J-A) model, van’t Hoff-Jouyban-Acree (V-J-A) model and Apelblat-Jouyban-Acree (A-J-A) model. The maximum of root-mean-square deviation ( RMSD ), relative average deviation ( RAD ) and standard deviation ( SD ) predicted via three thermodynamic models were 1.78 × 10 −4 (DMF + water), 2.87 × 10 −2 (acetonitrile + water) and 1.79 × 10 −4 (DMF + water), respectively. In addition, the solvent effect between solute and solvent molecules was deduced by KAT-LSER model and the result showed that dipolarity/polarizability interactions between the solute and solvent molecules were dominant in the dissolution of fenoxaprop-p-ethyl. Finally, the preferential solvation parameter ( δx 1,3 ) of fenoxaprop-p-ethyl was obtained by the method of inverse Kirkwood–Buff integrals and the preferential dissolution behavior of each concentration range is explained by Lewis acid base theory. However, for acetonitrile  + water, the change of δx 1,3 may be due to the polarization effects and it is not suitable for Lewis acid base theory.