Mengyang Guo,Ye Jiang,Yonghong Li,Yanyu Wei,Hanxi Li
The isobaric vapor–liquid equilibria (VLE) of two binary mixtures (adiponitrile + 2-methylglutaronitrile and adiponitrile + trans-3-pentenenitrile) at 5 and 10 kPa were measured using a modified Rose–Williams still. The thermodynamic consistency of the VLE data was tested by the Wisniak method and the Fredenslund method. The isobaric VLE data were correlated with four activity coefficient models of Margules, van Laar, Wilson, and NRTL, and the parameters of the models were obtained by the ordinary least-squares method. The isobaric VLE data were compared with the original UNIFAC predictive model. Furthermore, the excess Gibbs free energy of studied mixtures was determined. The RMST and RMSy1 were determined to evaluate the regression results. The results show that the Wilson model has a better correlation effect than other models.
Yameng Wan,Haixia He,Pengshuai Zhang,Fanfan Li,Xiaoqiang Gao,Yanxun Li
Solubility behavior as a significant molecular property should be known in the field of crystal form screening, dosage form along with separation and purification in the pharmaceutical industry. In this research work, solubility data of 2-chloronicotinamide (2-CNA) in ten pure solvents including methanol (MeOH), ethanol (EtOH), ethylene glycol (EG), 2-methoxyethanol (EGME), 2-ethoxyethanol (EGEE), methyl acetate (MeAc), water, 1,4-dioxane (Diox), N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMAC) within the range of 278.15/288.15 K to 323.15 K was experimentally determined by laser monitoring method at 0.1 MPa. Solubility of 2-CNA presented a positive correlation with temperature, and increased with incremental temperature. The result was indicative of a common tendency: DMAC > DMF > EGME > EGEE > EG > MeOH > Diox > EtOH > MeAc > water. The solvation free energy, molecular electrostatic potential surface (MEPS) and Hirshfeld surface were used to study the intermolecular interactions. Moreover, six mathematical models namely “Margules, UNIQUAC, NRTL, Wilson, NRTL-SAC and Jouyban model” were utilized to correlate solubility data of 2-CNA in mono-solvents. UNIQUAC model could provide maximum regression accuracy in correlation with solubility data among six models in terms of average relative deviation (ARD) and root mean square deviation (RMSD). Finally, thermodynamic parameters obtained from UNIQUAC equation indicated that all dissolution and mixing process were always entropy-increasing, endothermic and spontaneous.
Solubility of melatonin in twelve mono-solvents including seven alcohols {methanol (MT), ethanol (ET), n -propanol ( n -PrA), n -butanol ( n -BT), i -butanol ( i -BT), n -pentanol ( n -PT) and n-hexanol ( n -HeA)} and five esters {methyl acetate (MeAC), ethyl acetate (EtAC), n -propyl acetate ( n -PrAC), n -butyl acetate ( n -BtAC) and n -pentyl acetate ( n -PtAC)} was determined by laser monitoring approach from 278.15 K to 323.15 K under 0.1 MPa. The experimental results indicate that the mole solubility of melatonin shows a positive relation with temperature variation. The solubility of melatonin in the twelve pure solvents at 298.15 K has order: MT (0.03570) > ET (0.02536) > n -PrA (0.01965) > n -BT (0.01524) > n -PT (0.01450) > i -BT (0.01267) > n -HeA (0.01136) > MeAC (0.008498) > EtAC (0.006587) > n -PrAC (0.004280) > n -BtAC (0.003410) > n -PtAC (0.02990). Moreover, the miscibility behavior of melatonin was further analyzed by the Hansen solubility parameter (HSP). The solvent effect of melatonin in tested pure solvents was investigated by using the KAT-LSER model. The four thermodynamic models including two-Suffix Margules, NRTL, NRTL-SAC and UNIQUAC models were applied to correlate the experimental solubility data of melatonin. Furthermore, the dissolution thermodynamic properties including the apparent standard dissolution enthalpy (Δ dis H o ), the apparent standard dissolution entropy (Δ dis S o ) and the apparent standard Gibbs energy change (Δ dis G o ) of melatonin in investigated solvents were calculated by van't Hoff equation.
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