Aqueous Co-solvent Mixtures Research Articles

Correlation of the solubility of isoniazid in some aqueous cosolvent mixtures using different mathematical models

AbstractSolubility is one of the most important physicochemical properties, because it is related to some industrial processes such as: formulation, preformulation, purification and quantification. The experimental determination of solubility requires rigorous processes that involve a significant amount of resources. In this context, mathematical models allow estimating solubility under conditions different from the experimental ones from a limited number of data. The objective of this research was to evaluate the pertinence of 10 mathematical models (Extended Hildebrand, van’t Hoff, Two-parameter Weibull, Buchowski–Ksiazczak $$\lambda h$$ λ h , van’t Hoff-Yaws, Apelblat, Wilson, NRTL, Modified Wilson and van’t Hoff-Modified Wilson) in the calculation of the solubility of isoniazid in PEG 200 (1) + Water (2) cosolvent mixtures, the parameters of each model were calculated using Python, Pandas and the NumPy and SciPy library. Once each model was evaluated, two models were defined as the best alternatives based on their predictive power and mathematical simplicity. Thus, the van’t Hoff and Modified Wilson models were combined to obtain an equation that allows the calculation of solubility as a function of temperature and cosolvent composition, obtaining MRD% less than 3.0. In conclusion, mathematical models represent a good prediction tool being a potential alternative in relation to the optimization of some industrial processes related to solubility.

Solubility and Preferential Solvation of Pyrazinamide in Some Aqueous-Cosolvent Mixtures at 298.15 K

Equilibrium solubility of antitubercular agent pyrazinamide in mixed solvents is scarce in the literature. Thus, the mole fraction solubility of this drug in aqueous-cosolvent mixtures of 1,4-dioxane or ethanol has been determined at 298.15 K by means of flask shake and UV–Vis analysis. Solubilities were adequately correlated with the modified Nearly Ideal Binary Solvent/Redlich–Kister model. Moreover, some expressions for the local mole fraction of cosolvents and water around the pyrazinamide molecules in solution were derived on the basis of the inverse Kirkwood Buff integrals. Pyrazinamide is preferentially solvated by water in water-rich mixtures and cosolvent-rich mixtures, but preferentially solvated by cosolvent in mixtures with intermediate compositions.

Equilibrium solubility determination, modeling and thermodynamic analysis of isophthalic acid in aqueous co-solvent mixtures of propylene glycol, ethylene glycol and glycerol

Equilibrium solubility determination, modeling and thermodynamic analysis of isophthalic acid in aqueous co-solvent mixtures of propylene glycol, ethylene glycol and glycerol

Solvatochromism, Preferential Solvation and Multiparametric Approach to the Spectral Shift of Methyl Orange in Aqueous Cosolvent Mixtures.

In this study, the solvatochromic behavior of Methyl orange was studied visible spectrophotometrically in seven aqueous binary systems from water with methanol, ethanol, propanol, DMF, DMSO, acetone and dioxane solvents. The spectral data was interpreted in terms of solute-solvent and solvent-solvent interactions. The deviation from linearity in the plots of νmax versus x2 due to preferential solvation of the Methyl orange by one component of the mixed solvent and due to solvent microheterogeneity. The preferential solvation parameters local mole fraction X2L, solvation index δs2 and exchange constant K12 were evaluated. The preference of solute to be solvated by one of the solvating species relative to others was explained. All values of K12 were less than unity that indicates the preferential solvation of Methyl orange by water, except in case the water-propanol mixture where K12 was higher than unity. The preferential solvation index δs2 values were calculated and interpreted for each binary mixture. The magnitude of preferential solvation index was highest in water-DMSO mixtures than in the all other solvent mixtures. The energy of electronic transition in maximum absorption (ET) was calculated in each binary mixture. The extent and importance of each solute-solvent interactions to ET were analyzed by the linear solvation energy relationships using the Kamlet-Taft strategy.

Preferential solvation of 5,7-dihydroxyflavone (chrysin) in aqueous co-solvent mixtures of methanol and ethanol

ABSTRACT The inverse Kirkwood-Buff integrals were used to calculate the preferential solvation parameters of the natural polyphenolic compound chrysin in binary mixtures of ethanol (1) + water (2) and methanol (1) + water (2) as a function of their thermodynamic properties. At temperatures between 298.15 K and 318.15 K, chrysin is extremely sensitive to specific solvation effects; therefore, the negative values of were found in the water-rich range of 0 < x1 < 0.30 for methanol (1) + water (2) and 0 < x1 < 0.25 for ethanol (1) + water (2) which suggested that water (2) preferentially dissolves chrysin (3). In co-solvent-rich regions, the values of were positive, and the co-solvents preferentially dissolve chrysin (3). The solvation of drugs in water-rich mixtures is likely to be facilitated by hydrophobic hydration around aromatic rings or groups.

Inter-/intra-molecular interactions, preferential solvation, and dissolution and transfer property for tirofiban in aqueous co-solvent mixtures

Using Hirshfeld surface, interaction region indicator and quantitative molecular surface analysis, the microscopic electrostatic features of basicity and acidity of the tirofiban molecule were clearly demonstrated. Both the O atoms in >SO2 and H atom in –COOH serve as primary electrophilic site and nucleophilic site, respectively. Utilizing solubility data for tirofiban in four different water-based co-solvent mixtures {isopropanol/ethylene glycol (EG)/methanol/ethanol (1) + water (2)}, the inverse Kirkwood–Buff integral method was utilized to determine the preferred solvent for the tirofiban solvation according to the results of preferential solvation analysis. In water-rich composition ranges, the drug is surrounded by water, whereas in isopropanol/methanol/ethanol-intermediate and -rich composition ranges, the drug is surrounded by ethanol/methanol/isopropanol. Isopropanol solutions had the largest magnitude of preferential solvation. Alcohols may have a greater basicity that enhances interactions with the Lewis acidic function groups of tirofiban, giving rise to selective solvation of this drug. The linear solvation energy relationships were used to determine the relative impact of solvent-solvent and solvent-solute interactions in determining the variation of solubility magnitudes. The properties of dissolution and transfer, such as entropy, enthalpy and Gibbs energy change were computed. Entropy-driven and enthalpy-driven mechanisms were shown to be responsible for the change in tirofiban solubility in the four aqueous solutions, according to the enthalpy–entropy compensation analysis.

Solubility of 6-phenyl-4,5-dihydropyridazin-3(2H)-one in aqueous mixtures of Transcutol and PEG 400 revisited: Correlation and preferential solvation

Reported equilibrium mole fraction solubility values of 6-phenyl-4,5-dihydropyridazin-3(2H)-one (PDP-6) (3) in {Transcutol (1) + water (2)} and {PEG 400 (1) + water (2)} mixtures at five temperatures from T = (293.15 to 313.15) K were analyzed based on the Hildebrand solubility parameter of the respective aqueous mixtures. Cosolvency models for representing the equilibrium solubility of PDP-6 in both binary solvent systems at various temperatures were also provided for correlation/prediction purposes. Moreover, the preferential solvation parameters of PDP-6 in these aqueous-cosolvent mixtures at T = (298.15 and 313.15) K were determined by means of the “inverse Kirkwood-Buff integrals” (IKBI). PDP-6 is preferentially solvated by water in water-rich mixtures of {Transcutol (1) + water (2)} system but preferentially solvated by Transcutol in mixtures of 0.13 < x1 < 1.00. In the former case this result could be due to hydrophobic hydration around the non-polar moieties of PDP-6. Otherwise, PDP-6 is preferentially solvated by PEG 400 in all the aqueous mixtures. Moreover, in the systems where preferentially solvation of PDP-6 by cosolvents are observed, these results could be due to the Lewis acidic behavior of PDP-6 in front of Transcutol or PEG 400 molecules because these cosolvents exhibit higher Lewis basic behavior than water.

Imidacloprid (I) in several aqueous co-solvent mixtures: Solubility, solvent effect, solvation thermodynamics and enthalpy–entropy compensation

This contribution dealt with the saturated solubility, solvation behavior, and dissolution and transfer belongings of imidacloprid in some aqueous co-solvent mixtures of n-propanol, acetone, ethanol and methanol by means of experiment and mathematical correlations. Solubility experiments were conducted via a commonly used technique, namely shake-flask method, under 101.2 kPa from 283.15 to 323.15 K. The maxima of the obtained imidacloprid solubility was recorded in neat n-propanol/acetone/ethanol/methanol at temperature T = 323.15 K, which corresponded to 227.7 × 10−5, 2851 × 10−5, 237.9 × 10−5 and 409.9 × 10−5 (mole fraction), respectively; and the minimum, in single water (0.6792 × 10−5 at 283.15 K). The Hansen solubility parameters were used here to illustrate the imidacloprid solubility behavior. Solubility modeling through Jouyban–Acree–van’t Hoff, mixture response surface (MRS), Jouyban–Acree and modified Wilson models achieved the relative average deviations of no higher than 3.01%. As well, the extended Hildebrand solubility approach analyzed the saturated solubility of imidacloprid at 298.15 K attaining the maximum of relative average deviation (RAD) of 1.16%. The key contributions of solution descriptors to the imidacloprid solubility were observed as dipolarity-polarizability and solubility parameter studied through molecular interactions of solvent-solvent and solute-solvent species to the imidacloprid solubility in terms of the linear solvation energy relationships. A quantitatively investigation upon local mole fractions was executed by utilizing the powerful tool of inverse Kirkwood–Buff integrals through considering several properties of solutions. The local mole fractions of n-propanol/acetone/ethanol/methanol were higher than that of the bulk ones in n-propanol/acetone/ethanol/methanol-rich and middle proportions, representing preferential solvation of the imidacloprid by co-solvents (n-propanol/acetone/ethanol/methanol). It is speculated within these regions imidacloprid acts as a Lewis acid with the molecules of co-solvents. Thermodynamic calculation of dissolution properties and enthalpy–entropy compensation study revealed an entropy-driven mechanism and endothermic process of imidacloprid dissolved in blended solvents. Transfer property analysis designated more advantageous solubilization ability over the intermediate and rich-co-solvent contents.

Aqueous Co-Solvent in Zwitterionic-based Protic Ionic Liquids as Electrolytes in 2.0 V Supercapacitors.

High-performance energy-storage devices are receiving great interest in sustainable terms as a required complement to renewable energy sources to level out the imbalances between supply and demand. Besides electrode optimization, a primary objective is also the judicious design of high-performance electrolytes combining novel ionic liquids (ILs) and mixtures of aqueous solvents capable of offering "à la carte" properties. Herein, it is described the stoichiometric addition of a zwitterion such as betaine (BET) to protic ILs (PILs) such as those formed between methane sulfonic acid (MSAH) or p-toluenesulfonic acid (PTSAH) with ethanolamine (EOA). This addition resulted in the formation of zwitterionic-based PILs (ZPILs) containing the original anion and cation as well as the zwitterion. The ZPILs prepared in this work ([EOAH]+ [BET][MSA]- and [EOAH]+ [BET][PTSA]- ) were liquid at room temperature even though the original PILs ([EOAH]+ [MSA]- and [EOAH]+ [PTSA]- ) were not. Moreover, ZPILs exhibited a wide electrochemical stability window, up to 3.7 V vs. Ag wire for [EOAH]+ [BET][MSA]- and 4.0 V vs. Ag wire for [EOAH]+ [BET][PTSA]- at room temperature, and a high miscibility with both water and aqueous co-solvent (WcS) mixtures. In particular, "WcS-in-ZPIL" mixtures of [EOAH]+ [BET][MSA]- in 2 H2 O/ACN/DMSO provided specific capacitances of approximately 83 F g-1 at current densities of 1 A g-1 , and capacity retentions of approximately 90 % after 6000 cycles when operating at a voltage of 2.0 V and a current density of 4 A g-1 .

Equilibrium solubility of 7-amino-4-methylcoumarin in several aqueous co-solvent mixtures revisited: Transfer property, solute-solvent and solvent-solvent interactions and preferential solvation

The preferential solvation analysis was carried out by the inverse Kirkwood–Buff integrals method on available solubility data of 7-amino-4-methylcoumarin in four aqueous co-solvent mixtures of ethylene glycol (EG, 1) + water (2), isopropanol (1) + water (2), ethanol (1) + water (2) and DMF (1) + water (2). Results show that the drug is preferentially surrounded by water in water-rich regions, and by organic solvents in other composition ranges. Among these binary mixtures, the highest preferential solvation magnitude was recorded for isopropanol solutions. Selective solvation of the drug by organic solvents may be owing to the higher basicity of solvents that facilitates interactions with the Lewis acidic groups of 7-amino-4-methylcoumarin. A solvent effect analysis was performed by using the linear solvation energy relationships to unravel the relative importance of solute-solvent and solvent-solvent interactions on the solubility variation. In addition, the transfer properties, e.g. transfer Gibbs free energy (ΔtrGo), transfer enthalpy (ΔtrHo) and transfer entropy (ΔtrSo) were derived in terms of the accessible solubility data, indicating more favorable solubilization ability in the intermediate compositions of co-solvents.

Equilibrium solubility, preferential solvation and solvent effect study of clotrimazole in several aqueous co-solvent solutions

The equilibrium solubility of clotrimazole in co-solvent mixtures of n-propanol/isopropanol/acetonitrile/1,4-dioxane + water was attained by the saturation shake-flask technique at temperatures between 278.15 K and 323.15 K under ambient pressure of 101.2 kPa. The solubility of clotrimazole in mole fraction scale increased with increasing temperature and mass fractions of n-propanol/isopropanol/acetonitrile/1,4-dioxane. The maximum value was recorded in the neat co-solvent for each mixture studied. The Jouyban-Acree model and van’t Hoff-Jouyban-Acree model were applied to mathematically describe the dependence of clotrimazole solubility upon the co-solvent content and temperature, obtaining the values of relative average deviations and root-mean-square deviations no more than 8.02 × 10−2 and 8.17 × 10−4, individually. KAT-LSER model was implemented to quantitatively acquire evidence about solvent effect upon the variation of clotrimazole solubility magnitudes. The variation in clotrimazole solubility mainly depended upon the Hildebrand solubility parameter and dipolarity-polarizability of solutions in the four aqueous systems studied. Quantitative investigation was carried out for the local mole fractions of n-propanol/isopropanol/acetonitrile/1,4-dioxane and water around solute clotrimazole by using the Inverse Kirkwood–Buff integrals way utilized to the solubility data determined. Clotrimazole was preferentially solvated by n-propanol/isopropanol/acetonitrile/1,4-dioxane for these aqueous co-solvent mixtures in intermediate and n-propanol/isopropanol/acetonitrile/1,4-dioxane-rich proportions.

Dissolution thermodynamics and preferential solvation of gliclazide in (Transcutol® + water) mixtures

ABSTRACT The equilibrium solubility of gliclazide (3) in {Transcutol (1) + water (2)} mixtures at several temperatures was reported in the literature. However, no deep attempt was made to correlate gliclazide solubility with the composition of the aqueous-cosolvent mixtures. Moreover, no apparent thermodynamic calculations for the dissolution processes were performed. Thus, the reported solubility data were modelled by means of some well-known correlation models. By using the van’t Hoff and Gibbs equations, the respective apparent thermodynamic quantities of dissolution and mixing processes, namely Gibbs energy, enthalpy, and entropy, were calculated. Non-linear enthalpy–entropy relationship was observed for gliclazide in the plot of enthalpy vs Gibbs energy exhibiting negative slope in the composition region 0.00 < w 1 < 0.10 and variant but mainly positive slopes in the other mixtures. Hence, the driving mechanism for gliclazide transfer process from more polar to less polar solvent systems is the entropy in water-rich mixtures and the enthalpy in the other solvent compositions. Furthermore, the preferential solvation of gliclazide by both solvents was analysed by using the inverse Kirkwood-Buff integrals observing that gliclazide is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by Transcutol molecules in mixtures 0.12 < x 1 < 1.00.

Griseofulvin dissolved in binary aqueous co-solvent mixtures of N,N-dimethylformamide, methanol, ethanol, acetonitrile and N-methylpyrrolidone: Solubility determination and thermodynamic studies

The equilibrium solubility of griseofulvin in five co-solvent mixtures of N,N-dimethylformamide (DMF) + water (2), methanol (1) + water (2) , ethanol (1) + water (2), acetonitrile (1) + water (2) and N-methylpyrrolidone (NMP) (1) + water (2) were acquired through experiment at temperatures covering from 278.15 K to 323.15 K by the saturation shake-flask technique. The maximum solubility appeared in the neat co-solvents of DMF/methanol/ethanol/acetonitrile/NMP for each mixture. The mole fraction solubility of griseofulvin in the five mixtures was well correlated via van’t Hoff–Jouyban-Acree model and Jouyban-Acree model acquiring values of relative average deviations<9.41% and root-mean-square deviations<10.30 × 10-4. The cavity term and KAT parameters correlated the mole fraction solubility in terms of the linear solvation energy relationships. The significant effect to the solubility variation was the cavity term and dipolarity-polarizability term in aqueous DMF/methanol/ethanol/acetonitrile/NMP mixtures. What's more, the quantitative magnitudes for local mole fractions of DMF/methanol/ethanol/acetonitrile/NMP and water around the drug griseofulvin were evaluated by using the Inverse Kirkwood–Buff integrals method applied to griseofulvin solubility. In the methanol (1) + water (2) mixture with compositions 0.31 < x1 < 1, ethanol (1) + water (2) mixture with compositions 0.25 < x1 < 1, DMF (1) + water (2) mixture with compositions 0.20 < x1 < 1, NMP (1) + water (2) mixture with compositions 0.16 < x1 < 1 and acetonitrile (1) + water (2) mixture with compositions 0.253 < x1 < 1, griseofulvin was preferentially solvated by DMF/methanol/ethanol/acetonitrile/NMP.

Thiamethoxam in aqueous co-solvent mixtures of 1,4-dioxane, N,N-dimethylacetamide, dimethyl sulfoxide and acetonitrile: Solubility solute-solvent and solvent-solvent interactions, and preferential solvation analysis

The determination of equilibrium solubilities of thiamethoxam in solutions of 1,4-dioxane (1) + water (2), N,N-dimethylacetamide (DMAC, 1) + water (2), dimethyl sulfoxide (1) + water (2) and acetonitrile (1) + water (2) was carried out through the shake-flask method from 278.15 to 323.15 K under 101.2 kPa. The relative contributions of solvent–solvent and solute–solvent interactions on the drug solubility variation were studied via the analysis of linear solvation energy relationships. The significant contributions to the solubility variation were the cavity term and dipolarity-polarizability term in aqueous solution of 1,4-dioxane; and cavity term in aqueous solutions of DMAC/DMSO/acetonitrile. The inverse Kirkwood–Buff integrals were employed to investigate the preferential solvation in light of several solution thermodynamic properties. The preferential solvation parameters for 1,4-dioxane, DMAC and acetonitrile presented positive values in the three aqueous solutions within intermediate and 1,4-dioxane/DMAC/acetonitrile-rich compositions, demonstrating that the drug thiamethoxam was solvated preferentially by 1,4-dioxane/DMAC/acetonitrile. It is conjectured that in these regions thiamethoxam serves as a Lewis acid with the 1,4-dioxane and DMAC molecules; while for the (acetonitrile + water) mixture, the preferential solvation could be attributed to polarization effects. Moreover, the solubility data in mole fraction was mathematically described by the van’t Hoff–Jouyban-Acree model and Jouyban-Acree model attaining the average relative deviations no more than 6.67%.

Thermochemical investigation of L-glutamine dissolution processes in aqueous co-solvent mixtures of acetonitrile, dioxane, acetone and dimethyl sulfoxide at T = 298.15 K

This article reports on the results of calorimetric studies of the processes of L-glutamine dissolution in some aqueous-organic mixtures, namely (H2O + acetonitrile), (H2O + 1,4-dioxane), (H2O + acetone) and (H2O + dimethyl sulfoxide) at T = 298.15 K and mole fractions of an organic solvent up to x2 ~ 0.25. The standard values of solution (ΔsolH°) and transfer (ΔtrH°) enthalpies of L-glutamine from water to a mixed solvent as well as the enthalpic coefficients of pair-wise interactions (hxy) were calculated. The interrelation between enthalpic characteristics of L-glutamine dissolution (transfer) and the composition of water-organic mixtures was determined. It is found that the values of hxy are correlated with some physicochemical properties of different organic solvents. Contributions of the organic solvent properties (molar volume, cohesion energy density, polarity/polarizability, acidity, and basicity) to the energy of pair-wise interactions of L-glutamine - organic solvent were estimated quantitatively using of a modified Kamlet-Taft equation. The parameters of pair-wise interactions were additionally used to assess the contributions of the side chains of several L-amino acids to the energy of the intermolecular interactions amino acid-organic co-solvent in aqueous solutions.

Bezafibrate in several aqueous mixtures of low alcohols: Solubility, solvent effect and preferential solvation

By using the saturation shake-flask method, the saturated solubility of bezafibrate in neat water, methanol, ethanol, n-propanol and isopropanol and aqueous co-solvent mixtures of methanol (1) + water (2), ethanol (1) + water (2), isopropanol (1) + water (2) and n-propanol (1) + water (2) was experimentally acquired at temperatures from 283.15 Kto 323.15 K and local atmospheric pressure. The maximum solubility magnitudes in mole fraction were recorded in the neat solvents of methanol/ethanol/n-propanol/isopropanol for corresponding solutions. The mole fraction solubility was described mathematically by using the van’t Hoff-Jouyban-Acree and Jouyban-Acree models. The largest value of relative average deviations was 6.23%; and, root-mean-square deviations, 8.92 × 10−5. The local mole fractions of water and co-solvent (methanol, ethanol, n-propanol or isopropanol) around the drug bezafibrate were quantitatively investigated by the use of Inverse Kirkwood–Buff integrals method. Results indicated that the bezafibrate was preferentially solvated by methanol (ethanol, n-propanol or isopropanol) in alcohol-rich and intermediate compositions in the alcohol mixtures; while in water-rich compositions, bezafibrate was preferentially solvated by water. The main factors relating to solvent effect were inspected through Kamlet and Taft linear solvation energy relationships, demonstrating that the cavity formation energy and dipolarity-polarizability in methanol solutions, cavity formation energy and basicity in ethanol solutions, and cavity formation energy in n-propanol (isopropanol) solutions played the principal role upon the bezafibrate solubility variation.

Apixaban (I) in several aqueous co-solvent mixtures: Solubility, solvent effect and preferential solvation

Equilibrium apixaban (I) solubility in isopropanol (1) + water (2), ethanol (1) + water (2), acetone (1) + water (2) and methanol (1) + water (2) mixtures was acquired by a shake-flask method from 288.15 K to 328.15 K under atmospheric pressure of 101.2 kPa. At a certain temperature, the highest apixaban (I) solubility in mole fraction scale was observed in neat solvents of acetone/methanol for the acetone/methanol (1) + water (2) solutions; while for the ethanol/isopropanol (1) + water (2) solutions, the solubility data presented a maximum value with the ethanol/isopropanol mass fraction of about 0.8. The determined solubility values were treated by linear solvation energy relationships in order to explain the solvent effect and find its major descriptors. The preferential solvation was studied by the method of inverse Kirkwood–Buff integrals based on some thermodynamic solution properties. In the methanol (1) + water (2) mixture with compositions 0.31 < x1 < 1, ethanol (1) + water (2) mixture with compositions 0.25 < x1 < 0.58, isopropanol (1) + water (2) mixture with compositions 0.25 < x1 < 0.53, acetone (1) + water (2) mixture with compositions 0.20 < x1 < 1 and 1,4-dioxane (1) + water (2) mixture with compositions 0.175 < x1 < 0.570, the preferential solvation parameters for methanol/ethanol/isopropanol/acetone/1,4-dioxane were positive values, indicating that apixaban (I) was preferentially solvated by the co-solvents. It is conjecturable that in these regions apixaban (I) serves as a Lewis acid with the molecules of organic solvents. Moreover, the drug solubility was correlated through the Jouyban-Acree and van’t Hoff-Jouyban-Acree models attaining average relative deviations less than 9.64%.

5,7-Dibromo-8-hydroxyquinoline dissolved in binary aqueous co-solvent mixtures of isopropanol, N,N-dimethylformamide, 1,4-dioxane and N-methyl-2-pyrrolidone: Solubility modeling, solvent effect and preferential solvation

The solubility of 5,7-dibromo-8-hydroxyquinoline in four co-solvent mixtures of isopropanol + water, N,N-dimethylformamide (DMF) + water, N-methyl-2-pyrrolidone (NMP) + water and 1,4-dioxane + water was acquired through the saturation shake-flask method at temperatures from 288.15 to 333.15 K. The solubility magnitudes were maximum in the neat solvents of DMF (isopropanol, NMP or 1,4-dioxane) for the four co-solvent mixtures. The 5,7-dibromo-8-hydroxyquinoline solubility was correlated very well with the help of the Jouyban-Acree model and van’t Hoff-Jouyban-Acree model, obtaining relative average deviations less than 6.07% and root-mean-square deviations less than 4.81 × 10−4. The local mole fractions of isopropanol (DMF, NMP or 1,4-dioxane) and water nearby the 5,7-dibromo-8-hydroxyquinoline were quantitatively evaluated through the method of Inverse Kirkwood–Buff integrals. 5,7-Dibromo-8-hydroxyquinoline was preferentially solvated by water for these mixtures in water-rich compositions; while within intermediate and co-solvent-rich compositions, 5,7-dibromo-8-hydroxyquinoline was preferentially solvated by isopropanol (DMF, NMP or 1,4-dioxane). Additionally, the Kamlet and Taft linear solvation energy relationships were used to rationalize the solvent effect on the solubility. Results indicated that the variation of solubility was mainly governed by the change in cavity formation energy in all the aqueous mixtures.

6-Phenyl-3(2H)-pyridazinone dissolved in some aqueous co-solvent mixtures of alcohols: Equilibrium solubility, solvent effect and preferential solvation

The saturated solubility of 6-phenyl-3(2H)-pyridazinone in aqueous co-solvent mixtures of methanol, ethanol, isopropanol and ethylene glycol (EG) was determined through experiment by employing the saturation shake-flask method at temperatures from 278.15 to 318.15 K and local atmospheric pressure. For all the co-solvent mixtures, the maximum value of solubility was observed in neat methanol (ethanol, isopropanol or EG). The 6-phenyl-3(2H)-pyridazinone solubility in mole fraction scale was well correlated by using the Jouyban-Acree model and van’t Hoff-Jouyban-Acree model, obtaining the values of relative average deviations smaller than 3.98%; and root-mean-square deviation, lower than 7.81 × 10−5. The local mole fractions of methanol (ethanol, isopropanol or EG) and water nearby the 6-phenyl-3(2H)-pyridazinone were quantitatively calculated by means of the Inverse Kirkwood-Buff integrals method. 6-Phenyl-3(2H)-pyridazinone was preferentially solvated by the solvent of water in water-rich compositions; while within the regions of co-solvent-rich and intermediate compositions, 6-phenyl-3(2H)-pyridazinone was preferentially solvated by the solvent of methanol (ethanol, isopropanol or EG). The mole fraction solubility was fitted by using the Kamlet and Taft linear solvation energy relationships to inspect the key factors describing solvent effect. The variation in cavity formation energy and hydrogen-bond acidity played the chief role upon the 6-phenyl-3(2H)-pyridazinone solubility in aqueous solutions of methanol and ethanol; and the hydrogen bond acidity and dipolarity/polarizability term, in the aqueous of mixtures isopropanol and EG .

Solvent effect, transfer property and preferential solvation of artesunate in aqueous co-solvent mixtures of some alcohols

ABSTRACT The preferential solvation of artesunate in mixtures of ethanol (1) + water (2), methanol (1) + water (2), propylene glycol (PG, 1) + water (2) and isopropanol (1) + water (2) was investigated through the obtainable solubility data by the method of inverse Kirkwood–Buff integrals. In co-solvent-rich and intermediate compositions, artesunate was preferentially solvated by the co-solvent (methanol, ethanol or isopropanol). However, artesunate was not preferentially solvated by the solvent PG. A quantitative description of the solvent effect was obtained by modelling the change in Gibbs-free energy of solubility using linear solvation energy relationships. In addition, the transfer properties such as enthalpy, Gibbs-free energy and entropy were resulted.