Solubility and preferential solvation of benzocaine in {methanol (1) + water (2)} mixtures at 298.15 K

The equilibrium solubility of benzocaine (BZC) in several {methanol (1) + water (2)} mixtures at 298.15 K was determined. Solubility values are expressed in mole fraction and molarity and were calculated with the Jouyban–Acree model. Preferential solvation parameters of BZC by methanol (δx_1,3) were derived from their thermodynamic solution properties using the inverse Kirkwood–Buff integrals method. δx_1,3 values are negative in water-rich mixtures (0.00 < x₁ < 0.32) but positive in the other mixtures (0.32 < x₁ < 1.00). To explain the preferential solvation by water in the former case, it is conjecturable that the hydrophobic hydration around non-polar groups of BZC plays a relevant role in the solvation. Moreover, the higher solvation by methanol in mixtures of similar cosolvent compositions and methanol-rich mixtures could be explained in terms of the higher basic behaviour of methanol regarding water.     

Solubility and preferential solvation of acetaminophen in methanol + water mixtures at 298.15 K

The equilibrium solubility of acetaminophen in methanol + water binary mixtures at 298.15 K was determined and correlated with the Jouyban–Acree model. Preferential solvation parameters by methanol (δx_1,3) were derived from their thermodynamic solution properties by means of the inverse Kirkwood–Buff integrals method. δx_1,3 values are negative in water-rich mixtures but positive in compositions from 0.32 in mole fraction of methanol to pure methanol. It is conjecturable that in the former case, the hydrophobic hydration around non-polar groups plays a relevant role in the solvation. The higher solvation by methanol in mixtures of similar cosolvent compositions and methanol-rich mixtures could be explained in terms of the higher basic behavior of this cosolvent.     

Preferential solvation of some antiepileptic drugs in {cosolvent (1) + water (2)} mixtures at 298.15 K

The solubility of lamotrigine (LTG), clonazepam (CZP) and diazepam (DZP) in some {cosolvent (1) + water (2)} mixtures expressed in mole fraction at 298.15 K was calculated from reported solubility values expressed in molarity by using the densities of the saturated solutions. Aqueous binary mixtures of ethanol, propylene glycol and N-methyl-2-pyrrolidone were considered. From mole fraction solubilities and some thermodynamic properties of the solvent mixtures, the preferential solvation of these drugs by both solvents in the mixtures was analysed by using the inverse Kirkwood–Buff integrals. It is observed that LTG, CZP and DZP are preferentially solvated by water in water-rich mixtures in all the three binary systems analysed. In {ethanol (1) + water (2)} mixtures, preferential solvation by water is also observed in ethanol-rich mixtures. Nevertheless, in {propylene glycol (1) + water (2)} and {N-methyl-2-pyrrolidone (1) + water (2)} mixtures preferential solvation by the cosolvent was observed in cosolvent-rich mixtures.     

Solution thermodynamics and preferential solvation of triclocarban in {1,4-dioxane (1) + water (2)} mixtures at 298.15 K

The equilibrium solubility and preferential solvation of triclocarban in {1,4-dioxane (1) + water (2)} mixtures at 298.15 K was reported. Mole fraction solubility varies continuously from 2.85 × 10^–9 in neat water to 2.39 × 10^–3 in neat 1,4-dioxane. Solubility behaviour was adequately correlated by means of the Jouyban-Acree model. Based on the inverse Kirkwood-Buff integrals, preferential solvation parameters were calculated. Triclocarban is preferentially solvated by water in water-rich mixtures (0.00 < x₁ < 0.18) and also in 1,4-dioxane-rich mixtures (0.78 < x₁ < 1.00) but preferentially solvated by 1,4-dioxane in mixtures with similar solvent compositions.     

Solubility and preferential solvation of some non-steroidal anti-inflammatory drugs in methanol + water mixtures at 298.15 K

The equilibrium solubilities of naproxen (NAP), ketoprofen (KTP), and ibuprofen (IBP) in methanol + water binary mixtures at 298.15 K were determined and the preferential solvation parameters were derived by means of the inverse Kirkwood–Buff integrals (IKBI) method. These drugs are very sensitive to specific solvation effects. The preferential solvation parameters by methanol δx_1,3 are negative in water-rich mixtures but positive in compositions from 0.32 in mole fraction of methanol to pure methanol. It is conjecturable that in the former case the hydrophobic hydration around aromatic rings and/or methyl groups plays a relevant role in the solvation. The higher solvation by methanol in mixtures of similar co-solvent compositions and in methanol-rich mixtures could be explained in terms of the higher basic behaviour of this co-solvent interacting with the hydroxyl group of the drugs. Moreover, drug solubilities were correlated by using the modified nearly ideal binary solvent/Redlich–Kister model obtaining average percentage deviations (APDs) lower than 9.0%.     

Preferential solvation of some n-alkyl p-substituted benzoates in propylene glycol + water cosolvent mixtures

The preferential solvation parameters by propylene glycol (PG) of the homologous series of the n-alkyl esters of p-hydroxybenzoic and p-aminobenzoic acids, namely, methyl, ethyl, propyl and butyl derivatives, were derived from their thermodynamic properties of solution by means of the inverse Kirkwood–Buff integrals (IKBI) method. The preferential solvation parameters by the cosolvent, δx_1,3, are negative in water-rich mixtures, but positive in PG-rich mixtures, and the relative magnitudes of δx_1,3 are proportional to the alkyl chain length despite of the solvent involved in the preferential solvation, i.e. PG or water. It is possible that the hydrophobic hydration around aromatic ring and/or methylene groups plays a relevant role in the drugs solvation in water-rich mixtures. The more solvation by PG in PG-rich mixtures could be due mainly to polarity effects and acidic behaviour of the hydroxyl or amine groups of the compounds in front to the more basic solvent present in the mixtures, i.e. PG.     

Extended Hildebrand solubility approach applied to some sulphapyrimidines in some {methanol (1) + water (2)} mixtures

Extended Hildebrand solubility approach (EHSA) was applied to analyse the equilibrium solubility of sulphadiazine, sulphamerazine and sulphamethazine in some {methanol (1) + water (2)} mixtures at 298.15K. Reported experimental solubilities and some fusion properties of these drugs were used for EHSA calculations. A good predictive character of EHSA (with mean deviations lower than 4.0%) was found by using regular polynomials in order 4 when correlating the interaction parameter (W) and the Hildebrand solubility parameter of solvent mixtures free of drug (δ₁₊₂). Nevertheless, the predictive character of EHSA was almost the same as obtained when logarithmic drug solubilities (log x₃) were correlated with δ₁₊₂.     

Extended Hildebrand solubility approach applied to sulphadiazine,sulphamerazine and sulphamethazine in some {1-propanol (1) + water (2)} mixtures at 298.15 K

Extended Hildebrand solubility approach (EHSA) was applied in this research to analyse the equilibrium solubility of sulphadiazine, sulphamerazine and sulphamethazine in some {1-propanol (1) + water (2)} mixtures at 298.15 K. Reported experimental solubilities and some fusion properties of these drugs were used for EHSA calculations. A good predictive character of EHSA (with mean deviations lower than 4.0%) was found by using regular polynomials in order five when correlating the interaction parameter (W) and the Hildebrand solubility parameter of solvent mixtures free of drug (δ₁₊₂). Nevertheless, the predictive character of EHSA was almost the same as obtained when logarithmic drug solubilities (log x₃) were correlated with δ₁₊₂ by using a fifth-degree regular polynomial.     

Solution thermodynamics and preferential solvation of hesperidin in aqueous cosolvent mixtures of ethanol,isopropanol, propylene glycol,and n-propanol

The solubility of hesperidin in some {cosolvent (1) + water (2)} mixtures expressed in mole fraction at temperatures from 293.15 K to 333.15 K reported by Xu et al. has been used to calculate the apparent thermodynamic functions, Gibbs energy, enthalpy, and entropy, of the dissolution processes by means of the van’t Hoff and Gibbs equations. Non-linear enthalpy–entropy relationships were observed for this drug in the plots of enthalpy vs. Gibbs energy of dissolution with positive or negative slopes regarding mixtures composition and/or cosolvent. Moreover, the preferential solvation of hesperidin by the cosolvents was analysed by using the inverse Kirkwood–Buff integrals observing that this drug is preferentially solvated by water in water-rich but preferentially solvated by cosolvents in mixtures 0.20 (or 0.24) ≤ x₁° ≤ 1.00. Furthermore, a new mathematical model was proposed for correlating/predicting the solubility of hesperidin in binary solvent mixtures at various temperatures.     

Solubility of celecoxib in carbitol + water mixtures at various temperatures: experimental data and mathematical modelling

ABSTRACT

A brief review on various solubilisation techniques of coxibs is provided and the solubility of celecoxib (CXB) in binary solvent mixtures of {carbitol (1) + water (2)} is reported at temperatures ranging from 298.2 to 313.2 K. Three cosolvency models, i.e. Yalkowsky model, Jouyban–Acree model and the Jouyban–Acree–van’t Hoff model, have been used for correlating the reported data, and the mean relative deviations are employed to evaluate the accuracy of the fitness. Solubilities are also predicted by the generally trained version of the Jouyban–Acree model and its combined model with Abraham solute parameters previously proposed for {carbitol (1) + water (2)} binary mixtures. Furthermore, the apparent thermodynamic properties of dissolution process of CXB in all -investigated solvents were calculated according to van’t Hoff and Gibbs equations.     

Solubility of bosentan in {propylene glycol + water} mixtures at various temperatures: experimental data and mathematical modelling

Solubility measurements were performed for bosentan (BST) in binary mixtures of propylene glycol (PG) and water at atmospheric pressure within the temperature range, T = 293.2 – 313.2 K by employing a shake-flask method. Generated solubility data were correlated with Jouyban-Acree-van’t Hoff model and the accuracies of the predicted solubilities and model performance were illustrated by mean relative deviations (MRD). Furthermore, the apparent thermodynamic properties of BST dissolving in all the mixed solvents were calculated, and the obtained results show that the dissolution process is endothermic. By using the inverse Kirkwood–Buff integrals, it was observed that BST is preferentially solvated by water in water-rich solvent mixtures and preferentially solvated by PG (as a cosolvent) in the composition range of 0.20 < x₁ < 1.00 at 298.2 K.     

Structure and molecular interactions in {ethanol + (propan-1-ol/propan-2-ol)} mixtures at 303.15 K

In view of industrial importance of binary {ethyl alcohol + (propan-1-ol/propan-2-ol)} mixtures, the densities (ρ) and refractive indices (n _D ) of these alkanols mixtures were measured for different compositions at 303.15 K. Molar volumes (V _m) and excess molar volumes (V ^E) of these binary mixtures were calculated from experimental density data of pure solvents and solvents mixtures. The measured refractive index and density data was used to calculate specific refractions (R _D ), molar refractions (R _M) and apparent molar refractions (R _{φ, i} ) of binary mixtures. From mole fraction dependence of apparent molar refractions, the limiting apparent molar refractions (R _{φ, i} ^○ ) of propan-1-ol and propan-2-ol have been determined. The graphical values of R _{φ, i} ^○ for propan-1-ol and propan-2-ol were found to be 9.5664 and 7.405 cm³ mol^?1 respectively. Structural changes, geometrical fittings and molecular interactions in binary mixtures of these alkanols have been discussed.     

Densities,speeds of sound and refractive indices for binary and ternary mixtures of {diethylcarbonate (1) + p-chloroacetophenone (2) + 1-hexanol (3)} at 303.15 K for the liquid region and at ambient pressure

Densities (ρ), speeds of sound (u) and refractive indices (n_D ), of the ternary mixture (diethylcarbonate + p-chloroacetophenone + 1-hexanol) and the involved binary mixtures (diethylcarbonate + p-chloroacetophenone, diethylcarbonate + 1-hexanol, and p-chloroacetophenone + 1-hexanol) have been measured over the whole composition range at 303.15 K for the liquid region and at ambient pressure. The data obtained are used to calculate isentropic compressibilities k_s , isentropic compressibility deviations Δk_s and refractive index deviations Δn_D , of the binary and ternary mixtures. The data of isentropic compressibility deviations and refractive index deviations of the binary systems were fitted to the Redlich–Kister equation while the best correlation method for the ternary system was found using the Cibulka equation. The experimental data of the constitute binaries and ternaries are analysed to discuss the nature and strength of intermolecular interactions in these mixtures.     

Physicochemical properties of {1-methyl piperazine (1) + water (2)} system at T = (298.15 to 343.15) K and atmospheric pressure

Densities (ρ) and viscosities (η) of aqueous 1-methylpiperazine (1-MPZ) solutions are reported at T = (298.15 to 343.15) K. Refractive indices (n_D) are reported at T = (293.15 to 333.15) K, and surface tensions (γ) are reported at T = (298.15 to 333.15) K. Derived excess properties, except excess viscosities (Δη), are found to be negative over the entire composition range. The addition of 1-MPZ reduces drastically the surface tension of water. The temperature dependence of surface tensions is explained in terms of surface entropy (S^S) and enthalpy (H^S). The measured and derived properties are used to probe the microscopic liquid structure of the bulk and surface of the aqueous amine solutions.     

Blood porphyrins in binary mixtures of N,N-dimethylformamide with 1-octanol and chloroform: The energetics of solvation, (solute + cosolvent) interactions and model calculations

This study provides the first accurate analysis of the energetics of solvation of blood porphyrins in binary solvents which are considered as appropriate models for a smooth transition from a polar protein-like phase to an apolar lipid-like environment. Our results do indicate that hematoporphyrin dimethylether dimethylester (HDEDE) and deuteroporphyrin dimethylether (DDE), as well as the model of their ester side-chains ethyl acetate (EtOAc), reveal more exothermic solvation in chloroform (CHCl₃) than in dimethylformamide (DMF) and, especially, in 1-octanol (OctOH). The energetics of pair interaction between dissolved species and cosolvent molecules both in a protein-like and a lipid-like environment are clearly associated with these solvation effects. The interaction between blood porphyrins and DMF in OctOH is accompanied by large negative enthalpy changes at both temperatures, whereas in chloroform, forming strong H-bonds with dissolved species, the interaction is strongly thermochemically repulsive. All solute molecules interact in the energetically unfavorable way with OctOH and CHCl₃ in DMF, the effect being much stronger pronounced for chloroform. The most significant result of this work is that it is possible to connect this pair interaction in a highly diluted solution with the solute behavior in the entire range of the binary mixture. The approach proposed is independent of a solute and solvent structure, it provides a good prediction of the energetics of solvation in mixed solvents and can be extended for a lot of other biologically active solutes.     

Experimental and thermodynamic analysis on the solubility of valsartan in ethyl acetate + (butanone,isopropyl ether) binary solvent mixtures (from 278.15 to 323.15 K)

The solubility of valsartan in ethyl acetate + (butanone, isopropyl ether) binary solvent mixtures was measured at temperatures T = 278.15–323.15 K and pressure p = 0.1 MPa with a laser monitoring dynamic technique by a synthetic method. The experimental data were regressed by the modified Apelblat equation, the general single model and the hybrid model. The experimental data are well correlated with the above models because the mean deviations (MDs) are less than 3.79%. The mole fraction solubility of valsartan increases with increase in temperature and enrichment in butanone content, while it decreases with increased mole fraction of isopropyl ether at constant temperature. In addition, thermodynamic studies, including Gibbs energy, entropy and enthalpy, were calculated by van’t Hoff analysis. The results showed that the dissolution of valsartan in mixed solvents is endothermic, spontaneous and entropy-driven.     

High-pressure densities and derived volumetric properties (excess, apparent, and partial molar volumes) of binary mixtures of {methanol (1) + [BMIM][BF4] (2)}

The density of seven {(0.0087, 0.0433, 0.1302, 0.2626, 0.4988, 0.7501, and 0.9102) mole fraction of [BMIM][BF₄]} binary {methanol (1) + [BMIM][BF₄] (2)} (1-butyl-3-methylimidazolium tetrafluoroborate) mixtures has been measured with a vibrating-tube densimeter. Measurements were performed at temperatures from (298 to 398) K and at pressures up to 40 MPa. The total uncertainties of density, temperature, pressure, and concentration measurements was estimated to be less than 0.15 kg · m⁻³, 15 mK, 5 kPa, and 10⁻⁴, respectively. The uncertainties reported in this paper are expanded uncertainties at the 95% confidence level with a coverage factor of k = 2. The effect of temperature, pressure, and concentration on the density and derived volumetric properties such as excess, apparent, and partial molar volumes was studied. The measured densities were used to develop a Tait-type equation of state for the mixture. The structural properties such as direct and total correlation function integrals and cluster size were calculated using the Krichevskii function concept and the equation of state for the mixture at infinite dilution.