Solubility, solvation analysis and enthalpy–entropy compensation of musk ketone in some cosolvent solutions

Abstract

The present work was mainly devoted to the solubility and modeling, intra- and inter-molecular interactions and solvation behavior for musk ketone dissolved in aqueous solutions of ethanol, N,N-dimethylformamide (DMF), methanol and isopropanol accompanied by various computational methodology. Solubility experiments were conducted by means of the common shake-flask technique under local pressure of p = 101.2 kPa at elevated temperatures from 278.15 to 318.15 K. For each aqueous cosolvent solution, the highest solubility magnitude of musk ketone appeared in neat cosolvent (ethanol, DMF, methanol or isopropanol) at T = 318.15 K; and the lowest one, in water at 278.15 K. The solubility behavior was studied by means of the Hansen solubility parameter. The mixture response surface model, Jouyban–Acree model, modified Wilson model and Jouyban–Acree–van’t Hoff model correlated satisfactorily the solubility magnitudes in mole fraction with relative average deviations of <4.15%. The relative contributions of solute–solvent and solvent–solvent molecular interactions to variation of musk ketone solubility at 298.15 K was quantitatively investigated through the linear solvation energy relationships, demonstrating that the dipolarity-polarizability along with solubility parameter of aqueous solvent systems were chiefly responsible for musk ketone solubility. The solvation performance was studied by an extended Hildebrand solubility approach applied to the solubility in four aqueous solutions and in ethyl acetate + methanol/isopropanol/ethanol solutions at 298.15 K, acquiring RAD of <4.05%. In addition, the preferential solvation of musk ketone was investigated quantitatively by means of the inverse Kirkwood–Buff integrals method in the four aqueous and three non-aqueous solutions. Musk ketone was preferentially solvated by ethanol/DMF/methanol/isopropanol (1) in aqueous solutions within middle and rich ethanol/DMF/methanol/isopropanol (1) compositions, and by ethyl acetate (1) in non-aqueous solutions within middle and rich ethyl acetate (1) compositions. Furthermore, the dissolution and transfer properties as well as enthalpy–entropy compensation were discussed in detail.