Solubility determination, model evaluation, Hansen solubility parameter, molecular simulation and thermodynamic properties of benflumetol in four binary solvent mixtures from 278.15 K to 323.15 K

Abstract

By means of the laser dynamic method, the saturation solubility of benflumetol (BFL) in four binary mixtures ((ethyl acetate (EAC), n-propyl acetate (NPAC), n-butyl acetate (NBAC) and n-amyl acetate (NAAC)) + methanol (MtOH)) was achieved at temperatures from 278.15 K to 323.15 K and ambient pressure (p = 0.1 MPa). The solubility values (mole fraction) of BFL in above four binary mixed solvents increased as temperature elevated and obeyed the decreasing tendency with the decrease of the mass fraction of the positive solvent (EAC, NPAC, NBAC and NAAC) at a certain temperature. The Hansen solubility parameter provided a reasonable interpretation for the BFL solubility in 4 binary solvent mixtures. Then, the analysis of intermolecular interactions of solute and binary mixed solvents utilizing RDF obtained utilizing MD simulation show that the order of solute-solvent interactions and solvent-solvent interactions are both closely related to the order of the saturation solubility of BFL in binary mixed solvents researched. The saturation solubility of BFL gained through experiments was fitted by the use of five models namely modified Apelblat, λh, Jouyban-Acree, Ma and Sun. Correlation resulted that the modified Apelblat model and λh model gave much lower relative average deviations than the other models for the 4 binary mixed solvents researched. Finally, the derived apparent thermodynamic parameters (ΔsolG°, ΔsolH°, ΔsolS° ζH, ζTS) resulted in terms of the Van't Hoff equation show an entropy-driven, endothermic and spontaneous process of dissolution of BFL in chosen mixed solvents, and the main contribution of ΔsolG° comes from the positive ΔsolH°.