Apparent Thermodynamic Functions Research Articles

Solubility measurements and thermodynamic modelling of organoaluminum supported by unsymmetrical β-diketimine ligand

Organoaluminum supported by unsymmetrical β-diketimine ligands had special spatial and electronic effects. They were widely used in organic transformation, medicinal chemistry, and catalysis. Surveys the solubility of LH (1) and LAliBu2(2) in four pure solvents by the static analysis. The solubility data were correlated by seven thermodynamic models. All models demonstrated excellent fitting effect (absolute relative deviation (ARD) < 3 %, root mean square deviation (RMSD) < 0.01 %). For LAliBu2(2), Hirshfeld surface analysis was used to visualize the intermolecular interactions, and the simulation result showed that H···H contacts dominated major contact interactions. Further, the apparent thermodynamic functions were derived. It showed that, under the experimental conditions, the dissolution process of LH (1) and LAliBu2(2) was endothermic and entropy-driven. The results of the experiment have important implications for catalytic reactions and purification operations and the design of LH (1) and LAliBu2(2) in industrial production.

Solubility, dissolution thermodynamics, Hansen solubility parameter and molecular simulation of 4-chlorobenzophenone with different solvents

Equilibrium mole fraction solubility of 4-chlorobenzophenone in eleven organic solvents, as well as in neat water, was determined at temperatures ranging from 278.15 K to 323.15 K. Solubility of 4-chlorobenzophenone in these solvents increased with rising of temperatures, and the data was adequately correlated with several well-known thermodynamic models with the average relative deviations (100ARD) of 0.03 to 12.91%, suggesting good correlation. The effects of solvent polarity on solubility were also investigated, and 4-chlorobenzophenone dissolved more in less polar solvents (ester solvents) than in strong polar solvents (alcohol solvents) due to the weak polarity functional groups of 4-chlorobenzophenone. Respective apparent thermodynamic functions, i.e. Gibbs energy, enthalpy, and entropy, for the dissolution process, were calculated using the Wilson equation. Results showed that the dissolution process of 4-chlorobenzophenone was endothermic and spontaneous. Furthermore, Hansen solubility parameters (HSPs) were applied to further discuss the miscibility of 4-chlorobenzophenone in the selected solvents. Molecular dynamics simulation explored the molecular interaction between 4-chlorobenzophenone and solvents, and strong interaction between 4-chlorobenzophenone and ester solvents contributed to the higher solubility.

Solubility of paracetamol in binary mixtures of biodegradable betaine/ethylene glycol deep eutectic solvent and water: measurement and correlation

ABSTRACT The goal of this work is determining paracetamol (PCM) equilibrium solubilities in aqueous pseudo-binary mixtures of betaine/ethylene glycol deep eutectic solvent (Bet/EG DES) through the shake-flask technique from 293.15 to 313.15 K and atmospheric pressure (≈ 85 kPa). The equilibrium solid phase crystal of PCM is characterized with X-ray powder diffraction analysis to identify no polymorphic transformation, solvate formation or crystal transition during the whole solvent crystallization process. The results indicate that addition of DES to water significantly enhances PCM solubility; so that, by adding 0.9 mass fraction of Bet/EG DES to water increases PCM solubility by more than 42.9 times. Moreover, the solubility data are successfully represented with the commonly used cosolvency models including Jouyban Acree, Jouyban-Acree-van’t Hoff and so on together with the activity coefficient models of NRTL and Wilson. The accuracy of each model is determined through calculation of average relative deviations (ARD%) and the results present that the Jouyban-Acree (ARD% = 6.3) and Wilson activity model (ARD% = 0.8) have better capabilities in PCM solubility correlation than the others. Finally, thermodynamic behavior of PCM in Bet/EG DES + water is studied by determination of apparent thermodynamic functions of dissolution obtained from the van’t Hoff and Gibbs equations.

Thermodynamic Analysis for the Solubility of Allopurinol in Aqueous and Non-aqueous Mixtures at Various Temperatures

The solubility of allopurinol was measured at several temperatures (15–35 ºC) in ethanol–water, ethanol–ethyl acetate, and ethyl acetate–hexane mixtures. The mole fraction solubility shows two solubility maxima against the co-solvent (ethanol) ratio (70 % ethanol–water and 100 % ethyl acetate) at each of the five temperatures studied. The authors correlated the solubility data in binary solvent mixtures at various temperatures using a modified version of the Jouyban–Acree model. The respective apparent thermodynamic functions Gibbs energy, enthalpy, and entropy of solution were obtained from the solubility data through the van’t Hoff equations. The apparent enthalpies of solution are endothermic and display a maximum at 20 % ethanol in water, as ethanol is added to water, the entropy of the system increases. In the non-aqueous mixture (ethanol–ethyl acetate), enthalpy is the driving force throughout the whole solvent composition. An enthalpy–entropy compensation analysis confirms a non-linear enthalpy–entropy relationship in plots of enthalpy vs. Gibbs energy of solution, i.e., two different mechanisms involved in the solubility enhancement. An inverse Kirkwood–Buff integral analysis of the preferential solvation indicated that in ethanol-rich mixtures, the drug is preferentially solvated by water, and it is acting mainly as a Lewis base in front to water.

Solubility determination and thermodynamic analysis of organic zinc supported by β-diimine ligands in pure solvents

In this work, a static analysis method was used to determine the solubility data of β-diimine ligand (1) (L1 = HC(CMeNAr)2, Ar = 2,6-Me2C6H3), and organic zinc compounds: L1ZnEt (2), L2ZnEt (3) (L2 = HC(CMeNAr)2, Ar = 2,6-iPr2C6H3) in six pure solvents (methanol, ethanol, n-hexane, toluene, ether, dichloromethane, tetrahydrofuran) under nitrogen atmosphere. Experimental data are crucial for optimizing the purification, recrystallization process and the design of homogeneous catalysis for compounds 1, 2, and 3 in the industry. Six common thermodynamic models were utilized to correlate the experimental solubility data: Apelblat model, Polynomial empirical equation, λh model, Yaws model, NRTL model and Scatchard-Hildebrand activity coefficient model. These thermodynamic models were evaluated by average absolute relative deviation (AARD) to come to the best fitting model. Among them, the Polynomial empirical equation and the Scatchard-Hildebrand activity coefficient model had wide applicability, and the average AARD was <1. For compounds 1 and 3, Hirshfeld surface analysis was utilized to study the intermolecular interaction. The simulation results showed that H···H contact was obviously predominant in all contact interactions. In addition, apparent thermodynamic functions were derived. Results showed that the dissolution process was entropy increasing and endothermic under the experimental conditions, and the difference in solubility could be explained by spontaneous energy.

Equilibrium solubility of vanillin in some (ethanol + water) mixtures: determination, correlation, thermodynamics and preferential solvation

Equilibrium mole fraction solubility of vanillin in nine aqueous-ethanolic mixtures, as well as in neat water and neat ethanol, was determined at seven temperatures from T = 293.15 to T = 323.15 K. Vanillin solubility in these mixtures was adequately correlated with several well-known correlation models with the mean percentage deviations of 5.9 to 18.3%. Respective apparent thermodynamic functions, i.e. Gibbs energy, enthalpy, and entropy, for the dissolution, mixing and solvation processes, were computed using the van’t Hoff and Gibbs equations. The enthalpy–entropy relationship for vanillin was non-linear in the plot of enthalpy vs. Gibbs energy of dissolution with positive slopes from neat water to the mixture of w1 = 0.10 and the interval 0.50 < w1 < 0.90 but negative in the interval 0.10 < w1 < 0.50 and from w1 = 0.90 to neat ethanol. Accordingly, in the first cases the vanillin transfer from more polar to less polar solvent systems is enthalpy-driven but entropy-driven for the last ones. Moreover, by means of the inverse Kirkwood-Buff integrals is observed that vanillin is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in mixtures of 0.23 < x1 < 1.00.

Solubility of coumarin in (ethanol + water) mixtures: Determination, correlation, thermodynamics and preferential solvation

Equilibrium mole fraction solubility of coumarin in nine aqueous-ethanolic mixtures, as well as in neat water and neat ethanol, was determined at seven temperatures from (293.15 to 323.15) K. Coumarin solubility in was adequately correlated with several well-known correlation models with the mean percentage deviations of 5.1–10.8%. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) for the dissolution, mixing and solvation processes were computed using the van’t Hoff and Gibbs equations. The enthalpy-entropy relationship for coumarin was non-linear in the plot of enthalpy vs. Gibbs energy of dissolution with negative slope from neat water to the mixture of w1 = 0.10 but positive from this mixture to neat ethanol. Accordingly, in the first case the coumarin transfer from neat water to the mixture of w1 = 0.10 is entropy-driven, which could be attributed to water molecules release originally bounded as “icebergs” around the non-polar groups of this drug. Otherwise, in mixtures of w1 ≥ 0.10 the driving mechanism for the transfer of coumarin from the more polar solvent systems to those less polar is the enthalpy, probably owing the better drug solvation. Moreover, by means of the inverse Kirkwood-Buff integrals is observed that apparently coumarin is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in mixtures of 0.23 < x1 < 1.00.

Solubility of trans-resveratrol in {ethanol (1) + water (2)} mixtures revisited: Correlation, dissolution thermodynamics and preferential solvation

ABSTRACT Reported equilibrium mole fraction solubility values of trans-resveratrol in some aqueous-ethanolic mixtures in the temperature interval from (273.2 to 323.2) K were correlated by means of some cosolvency models, like multi-linear models of Jouyban-Acree and Jouyban-Acree-van’t Hoff and non-linear models of the modified Wilson and Buchowski-Ksiazczak. Apparent thermodynamic functions of the dissolution processes were computed using the van’t Hoff and Gibbs equations. Gibbs energy and enthalpy were positive in all cases, while negative and positive entropies were observed. The plot of enthalpy vs. Gibbs energy of dissolution was non-linear with negative slopes in the region of 0.00 ≤ x 1 ≤ 0.60 but positive slope in the region of 0.60 ≤ x 1 ≤ 0.90. Further, by means of the inverse Kirkwood-Buff integrals is observed that trans-resveratrol is preferentially solvated by water in water-rich mixtures but preferentially solvated by ethanol in the composition interval of 0.24 < x 1 < 1.00.

Solubility of fluconazole in (ethanol + water) mixtures: Determination, correlation, dissolution thermodynamics and preferential solvation

In this research, the equilibrium mole fraction solubility of fluconazole (FLC) in some aqueous-ethanolic mixtures was determined at seven temperatures from (293.15 to 323.15) K. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) for the dissolution, mixing and solvation processes were computed using the van’t Hoff and Gibbs equations. The enthalpy–entropy relationship for FLC was non-linear in the plot of enthalpy vs. Gibbs energy of solution with negative slope in the composition regions of 0.00 ≤ w1 ≤ 0.40 and 0.70 ≤ w1 ≤ 1.00. Thus, the driving mechanism for FLC transfer processes in water-rich mixtures is the entropy. In addition, by means of the inverse Kirkwood-Buff integrals is observed that FLC is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in the mixtures of 0.23 < x1 < 1.00.

Solubility and dissolution thermodynamics of 5-fluorouracil in (ethanol + water) mixtures

Equilibrium mole fraction solubility of 5-fluorouracil (5-FU) in 19 aqueous-ethanolic mixtures, as well as in neat water and neat ethanol, was determined at seven temperatures from (293.15 to 323.15) K. 5-FU solubility in these mixtures was adequately correlated with several well-known correlation models. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) for the dissolution, mixing and solvation processes were computed using the van’t Hoff and Gibbs equations. The enthalpy–entropy relationship for 5-FU was non-linear in the plot of enthalpy vs. Gibbs energy of solution with variant but positive slope in almost all the composition regions. Thus, the driving mechanism for 5-FU transfer processes was the enthalpy. In addition, by means of the inverse Kirkwood-Buff integrals is observed that apparently 5-FU is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in ethanol-rich mixtures.

Solubility, dissolution thermodynamics and preferential solvation of 4-nitroaniline in (ethanol + water) mixtures

ABSTRACT In this research, the equilibrium mole fraction solubility of 4-nitroaniline (4-NA) in some aqueous-ethanolic mixtures was determined at seven temperatures from (293.15 to 323.15) K. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy) of the dissolution processes were computed using the van’t Hoff and Gibbs equations. The enthalpy-entropy relationship for 4-NA was non-linear in the plot of enthalpy vs. Gibbs energy of solution with negative slopes from neat water to the mixture w 1 = 0.10 and from w 1 = 0.20 to neat ethanol but positive slope from w 1 = 0.10 to w 1 = 0.20. Therefore, the driving mechanism for 4-NA transfer processes is the entropy in water-rich mixtures. Additionally, by means of the inverse Kirkwood-Buff integrals is observed that 4-NA is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in the mixtures of 0.23 ≤ x 1 ≤ 1.00.

Dissolution thermodynamics and preferential solvation of 2,4-dinitrotoluene in (ethanol + water) mixtures

In this research, the equilibrium mole fraction solubility of 2,4-dinitrotoluene (2,4-DNT) in some aqueous-ethanolic mixtures was determined at seven temperatures from (293.15 to 323.15) K. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy of the dissolution processes) were computed using the van't Hoff and Gibbs equations. The enthalpy-entropy relationship for 2,4-DNT was non-linear in the plot of enthalpy vs. Gibbs energy of solution with negative slope in the composition region 0.00 ≤ w1 ≤ 0.40 but positive slope in the region 0.40 ≤ w1 ≤ 1.00. Therefore, the driving mechanism for 2,4-DNT transfer processes is the entropy in water-rich mixtures and the enthalpy in ethanol-rich mixtures. In addition, by means of the inverse Kirkwood-Buff integrals is observed that 2,4-DNT is preferentially solvated by water molecules in water-rich mixtures but preferentially solvated by ethanol molecules in the mixtures of 0.23 ≤ x1 ≤ 1.00.

Solubility measurements and thermodynamic modeling of Salen ligand and Organoaluminum-Salen complex in selected solvents

Solvent selection plays a significant role in the purification process and homogeneous reaction. Solubility data is the most intuitive data to reflect the dissolution effect. The solubility of N, N′ - bis - (salicylaldehyde) ethylenediamine (1) (SalenH2) and N, N′ - ethylenebis (salicylideneiminato) methylaluminum (2) (SalenAlMe) in selected solvents was measured from 268.15 K to 318.15 K under an inert atmosphere. All the operations were carried out using standard Schlenk line techniques or in a glove box. The difference in solubility can be attributed to cohesive energy density, polarity, steric hindrance, as well as intermolecular interactions. Van't Hoff equation, Apelblat model, Polynomial equation, NRTL model, Wilson model, and UNIQUAC model were applied for correlating the experimental solubility data. These thermodynamic models were evaluated by the average relative deviation (ARD). Among those, the Apelblat model had wide applicability with an average ARD < 2%. The NRTL model showed the best correlation results for compound 1 in aprotic solvents with an average ARD of 0.74%, and the correlation of the Polynomial equation was significantly greater for compound 2 with an average ARD of 0.71%. The results of model correlation can be used to predict the solubility of compounds 1 and 2. Furthermore, apparent thermodynamic functions were calculated. It was proved that the dissolution process was entropy-increasing endothermic under the experimental conditions. The experiment data would be essential for optimizing purification and recrystallization processes, as well as the design of homogeneous catalysis for compounds 1 and 2 in industry.

Enhancement of curcumin solubility by some choline chloride-based deep eutectic solvents at different temperatures

Curcumin (CUR) is a biologically active substance and a natural antioxidant, but it is almost insoluble in water and has low bioavailability. A possible solution to this barrier could be to use solvents that exhibit low toxicity and are biodegradable. Choline chloride-based deep eutectic solvents (DESs) can be used as a co-solvent to increase the solubility of curcumin. The objectives of this study are to introduce and prepare DESs, to measure the solubility of CUR in water and DESs as well as in water-DES mixtures with different weight fractions. In this perspective, the solubility of CUR is measured in the mixtures of water with some DESs based on choline chloride (ChCl) and in pure solvents at T = 298.15 K to 318.15 K. The measured solubility data were correlated by the activity coefficients models e-NRTL and UNIQUAC. Finally, the apparent thermodynamic functions entropy, enthalpy, and Gibbs free energy were estimated for dissolution process using van't Hoff equation.

Dissolution thermodynamics and preferential solvation of ketoconazole in some {ethanol (1) + water (2)} mixtures

In this research, the equilibrium mole fraction solubility of ketoconazole in some aqueous-ethanolic mixtures was calculated from previously measured solubility data reported in molarity scale at temperatures from 298.2 to 313.2 K. Experimental mole fraction solubility values were adequately correlated with the Jouyban-Acree and Jouyban-Acree-van't Hoff models. The respective apparent thermodynamic functions (Gibbs energy, enthalpy, and entropy of the dissolution processes) were computed using the van't Hoff and Gibbs equations. The enthalpy–entropy relationship for ketoconazole was non-linear in the plot of enthalpy vs. Gibbs energy of solution with negative slope in the composition region 0.00 ≤ w1 ≤ 0.20 but positive slope in the region 0.20 ≤ w1 ≤ 0.70. Beyond this composition, the behavior is more complex. Therefore, the driving mechanism for ketoconazole dissolution process is the entropy in water-rich mixtures and the enthalpy in mixtures 0.20 ≤ w1 ≤ 0.70. In addition, the inverse Kirkwood-Buff integrals were used to investigate the preferential solvation of ketoconazole which is preferentially solvated by water molecules in water-rich and also in ethanol-rich mixtures but preferentially solvated by ethanol molecules in mixtures 0.24 ≤ x1 ≤ 0.75. Dissolution thermodynamics and preferential solvation computations were carried out employing whole experimental solubility data points and the simulated data using a minimum number of seven data points as training set, in which there were no significant differences in the obtained numerical values except for enthalpy-entropy compensation data.

Solubility modelling and solvent effect on solid-liquid equilibrium of 2,2-bis(hydroxymethyl)butyric acid at different temperatures

In this work, the solid-liquid equilibrium of 2,2-bis(hydroxymethyl)butyric acid (DMBA) was investigated experimentally in various solvents: namely, ethylacetate, butylacetate, methyl isobutyl ketone, cyclopentyl methyl ether, toluene, gamma-butyrolactone and 1,4-dioxane over the temperature range (298.15 to 353.15) K. The experimental solubility data were correlated with the Apelblat equation, Buchowski–Książczak λh equation and NRTL model. Results showed that the mole fraction solubility of DMBA increased, as temperature increased. The Apelblat equation and NRTL model indicated a good correlation with the experimental solubility data and can be used to describe the solid-liquid equilibrium. Further, the apparent thermodynamic dissolution functions and thermodynamic functions of mixing were evaluated from the solubility data.

Solubility and thermodynamic properties of mesalazine in {2-propanol + water} mixtures at various temperatures

The solubility of mesalazine in presence of 2-propanol as cosolvent in aqueous media was reported at T = (293.2 to 313.2) K. It was observed that the solubility of mesalazine is maximal in the 0.4 weight fraction of 2-propanol in the binary solvents. The performances of mathematical models of Jouyban-Acree, Apelblat-Jouyban-Acree, Jouyban-Acree-van't Hoff, modified Wilson, combined nearly ideal binary solvent/Redlich-Kister, UNIQUAC, NRTL and Wilson models in the solubility data representation were investigated. Two versions of Yalkowsky model were employed to estimate the solubility data. Dissolution and mixing apparent thermodynamic functions for mesalazine in studied solvents were also evaluated. Moreover, by means of inverse Kirkwood-Buff integrals method it is demonstrated that this drug is preferentially solvated by water in all the mixtures.

Thermodynamic analysis of the solubility and preferential solvation of sulfamerazine in (acetonitrile + water) cosolvent mixtures at different temperatures

Solubility studies are valuable tools for the pharmaceutical industry and research centres and are currently becoming increasingly relevant in the environmental sciences field. This study presents the thermodynamic and preferential solvation analyses of solubility of sulfamerazine (SMR) in {acetonitrile (1) + water (2)} cosolvent mixtures at different temperatures (278.15–318.15 K). The maximum solubility of SMR was obtained at 318.15 K when mass fraction is w1 = 0.90, whereas the minimum solubility of SMR was obtained in pure water at 278.15 K. Based on the solubility data, the Gibbs and van't Hoff equations were used for obtaining the apparent thermodynamic dissolution functions, while the IKBI model was used for obtaining the preferential solvation coefficients. Thus, the dissolution process is endothermic and is heavily dependent on the polarity of the medium, favoring the entropy of thermodynamic solution functions in every case. With respect to the preferential solvation coefficients, the results indicate that SMR is preferentially hydrated in water- and acetonitrile-rich mixtures and that it is preferentially solvated by acetonitrile in mixtures having intermediate compositions (0.25 < x1 < 0.85). The Jouyban-Acree-van't Hoff model is applied for modeling the generated solubility data with reasonable accuracy.

Experimental determination and correlation of bosentan solubility in (PEG 200 + water) mixtures at T= (293.15–313.15) K

ABSTRACTThe solubility of bosentan (BST) in the aqueous mixtures of polyethylene glycol 200 (PEG 200) at the temperature range, T = (293.15–313.15) K, has been studied using a shake-flask method. The experimental solubility data were correlated with Jouyban–Acree, Jouyban-Acree-van’t Hoff, modified Wilson and Yalkowsky models. Deviations of the calculated solubility from experimental one were determined by percent average relative deviations and relative deviations. In addition, to represent the thermodynamic behaviour of BST in PEG 200 solutions, the apparent thermodynamic functions, Gibbs energy, enthalpy and entropy of dissolution were obtained by using the van’t Hoff and Gibbs equations.

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

ABSTRACTThe 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.