Solubility, solvent effect, enthalpy–entropy compensation and solvation thermodynamics of 4-(bromomethyl)-2(1H)-quinolinone in several aqueous blends

Abstract

The current study was mainly devoted to solubility for the systems formed by 4-(bromomethyl)-2(1H)-quinolinone (BMQ) and blended solvents of isopropanol, N-methyl-2-pyrrolidinone (NMP), ethanol and n-propanol with water. Experiments for solubility determination were conducted by employing the shake-flask equilibration method from 278.15 to 318.15 K under 101.2 kPa. For each aqueous cosolvent mixture, the minimum solubility was recorded in water at 278.15 K; and the maximum value, in neat organic solvents at 318.15 K. The solubility performance was illustrated by Hansen solubility parameters of water, BMQ and co-solvents. No occurrence of polymorphic transformation or solvation was observed after experiments based on the XRD spectra of raw BMQ and excess solids analyzed. The satisfactory correlation results for solubility data was obtained by modified Wilson model, mixture response surface model, modified van’t Hoff-Jouyban–Acree model and Jouyban–Acree model. The relative average deviations were calculated to be no more than 8.72 %. Investigation on the relative contributions from inter- and intra-molecular interactions to the solubility variation of BMQ at temperature of 298.15 K was quantitatively performed via the linear solvation energy relationships (LSER). The descriptors of solvent blends including solubility parameter, dipolarity-polarizability and hydrogen-bond basicity were primarily responsible for the solubility variation. As well, the preferential solvation of BMQ was researched quantitatively via the inverse Kirkwood–Buff integrals method on the basis of some obtainable properties of solvent blends. The positive preferential solvation parameters for BMQ in middle and cosolvent-rich blends strongly suggest that the crystalline solute of BMQ is preferentially solvated by cosolvents of isopropanol, NMP, ethanol and n-propanol. The transfer and apparent dissolution properties including apparent Gibbs energy change (298.15 K), dissolution enthalpy and dissolution entropy (298.15 K) were derived and discussed. Analysis of enthalpy–entropy compensation indicates the entropy-driven mechanism of BMQ dissolved in all blend solvents.