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The separation of structurally similar compounds, such as cholic acid (CA) and deoxycholic acid (DCA), is challenging due to their nearly identical physicochemical properties. This study demonstrates a synergistic 'push and pull' strategy with an ionic liquid (IL) biphasic system for significantly enhanced CA/DCA separation efficiency. Ethyl acetate was selected as the feed solvent to 'push' CA into the IL-rich extractant phase, while the IL 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl) was chosen to 'pull' CA due to their strong hydrogen bonding interaction. This 'push and pull' system yielded a remarkable CA/DCA selectivity up to 47.8, much higher than the case using n-butanol which pulls both CA and DCA. The underlying separation mechanism was elucidated through computational screening with COSMO-RS, NMR analysis, and solvatochromic measurements. Results revealed the critical roles of specific hydrogen bonding between the chloride anion of [EMIM]Cl and the hydroxyl/carboxyl groups of CA/DCA, along with nonspecific interactions between the feed solvent and CA/DCA. Thermodynamic analysis of the phase transfer process confirmed the 'push and pull' synergy is energetically favorable for preferentially transferring CA from the ethyl acetate feed solution into the IL-rich extractant phase. Multi-stage simulation indicated that 99% purity and recovery of both CA and DCA can be obtained through this biphasic system under optimized conditions. Overall, strategically tuning both the feed solvent and IL extractant could significantly enhance the separation efficiency of structurally similar compounds while minimizing solvent and energy consumption. This 'push and pull' approach may shed light on improving separation processes for other structural analogues. [ABSTRACT FROM AUTHOR]

Thedesign of a biphasic system is important for the developmentof liquid–liquid extraction and biphasic catalysis. In thiswork, we report a series of ternary biphasic systems that consistof hydrophilic ionic liquid (IL), water, and ethyl acetate. The effectsof the structure of the ILs (cation, anion, and substituent group),IL/water ratio, and temperature on the phase equilibrium of thesebiphasic systems were investigated. The mutual solubility was lowerin the IL/water–ethyl acetate biphasic system than in the water–ethylacetate system when ILs with strong hydration ability were introduced,such as [EMIm]OAc, [EMIm]Cl, [EMIm]NO3, [EMIm]EtSO4, and [HOEMIm]Cl. In addition, the hydrogen-bonding basicityof the IL-containing phase could be tuned by changing the IL structureor IL/water ratio. These novel IL/water-ethyl acetate biphasic systemsmay present another option in addition to hydrophobic IL–waterand aqueous biphasic systems for liquid–liquid extraction. [ABSTRACT FROM AUTHOR]

The solubility of chrysin in N , N -dimethylformamide (DMF), acetone, ethyl acetate (EA), n -butanol, isopropanol, n -propanol, ethanol, methanol, n -hexane, and water was measured by using the static equilibrium method or the dynamic method at temperatures ranging from 293.2 to 333.2 K. Chrysin shows the easiest solvation in the dipolar aprotic solvents, followed by the polar protic solvents (alcohols), and shows poor solvation in the apolar aprotic solvents (hexane) and the strong polar water. The solubility of chrysin increases with rising temperature. The inherent microscopic solvation mechanisms were investigated qualitatively and quantitatively using a combination of the KAT-LSER model as well as σ-profile theory and molecular interaction energies calculated by COSMO–RS model. The results show the solvation process of chrysin in the different solvents is a complex process which depends on the synergistic effects of multiple molecular interactions between the solute and solvent together with the solvent and solvent. Moreover, the experimental solubility data in all solvents could be reasonably correlated by the modified Apelblat equation, λh equation, van't Hoff equation, Wilson model, and NRTL model, whereas the NRTL model and the modified Apelblat equation showed the most satisfactory fitting results. The dissolution thermodynamic properties, including enthalpy, entropy and Gibbs energy of chrysin in the dissolution process were evaluated using the van't Hoff equation. Moreover, the overall dissolution trend and the temperature-dependence of experimental solubility of chrysin in the different classes of solvents can be predicted correctly by the COSMO–RS model. Unlabelled Image • The solubility of chrysin in different classes of solvents was measured. • Solvation capacity for chrysin: dipolar aprotic > polar protic > apolar solvents. • Solvation depends on the synergistic effects of multiple intermolecular interactions. • Solute-solvent van der Waals and hydrogen bond interactions favor on the solvation. • Hydrophobic and solvent-solvent interactions are unfavorable for the solvation. [ABSTRACT FROM AUTHOR]