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The saturated thermodynamic solubilities of micoflavin in four mixtures of dimethyl sulfoxide (DMSO, 1) + water (2), isopropanol (1) + water (2), propylene glycol (PG, 1) + water (2), and ethanol (...

By using the shake-flask method, the acetoguanamine solubilities in water, acetonitrile, methanol, n-butanol, isopropanol, isobutanol, ethanol, n-propanol, N,N-dimethylformamide (DMF), 1,4-dioxane,...

The solubilities of d-tryptophan in neat n-propanol, ethyl acetate, ethylene glycol (EG), n-butanol, acetonitrile, 1-octanol, and dimethyl sulfoxide and of l-tyrosine in ethyl acetate, EG, isopropa...

Solubilities of gimeracil (form P) in aqueous co-solvent mixtures of isopropanol, N,N-dimethylformamide (DMF), ethylene glycol (EG) and dimethylsulfoxide (DMSO) were investigated via the isothermal dissolution equilibrium method at (283.15–328.15) K under ambient pressure p = 101.2 kPa. Experimental solubility was increased with increasing temperature and mass fraction of each co-solvent. The largest solubility was found in neat co-solvents. The solids equilibrated with liquid phase were characterized by X-ray power diffraction, indicating no polymorphic transformation, solvate formation or crystal transition according to the spectral data. The Jouyban-Acree model was adopted to correlate the obtained solubility. The highest RAD and RMSD values were, respectively, 2.61 × 10−2 and 14.96 × 10−4. Quantitative values for the local mole fraction of DMF (EG, DMSO or isopropanol) and water around gimeracil (form P) were acquired by using the Inverse Kirkwood–Buff integrals method. The preferential solvation parameters for isopropanol were positive in the isopropanol mixtures in intermediate and isopropanol-rich compositions, which indicated that gimeracil (form P) was preferentially solvated by isopropanol. Gimeracil (form P) could act mainly as a Lewis acid interacting with proton-acceptor functional group of isopropanol. Within the same region, gimeracil (form P) was not preferentially solvated by DMF, EG and DMSO. Furthermore, the method of linear solvation energy relationships was performed with a suitable combination of solvent polarity descriptors to explain the nature of intermolecular interactions resulting in the solubility variation in the co-solvent mixtures.

The o-nitrophenylacetonitrile solubilities in some pure solvents such as n-propanol, methanol, toluene, ethanol, isopropanol, acetonitrile, acetone, cyclohexane, ethyl acetate, n-butanol, 2-butanon...

The mole fraction solubility of bioactive iminodibenzyl in aqueous co-solvent mixtures of ethanol, ethylene glycol (EG), dimethyl sulfoxide (DMSO) and isopropanol was examined by the saturation shake-flask method over the temperature range from 283.15 K to 328.15 K at pressure of 101.2 kPa. The experimental solubility increased with increasing temperature at a given co-solvent composition and decreased with the increasing mass fraction of water in each binary system. The maximum solubility was found in pure co-solvent. Given the same temperature and mass fraction of the co-solvent, the solubility of iminodibenzyl was greater in (DMSO + water) than in the other three co-solvent systems. The solid crystal examples of iminodibenzyl was tested by X-ray power diffraction showing no polymorphic transformation, solvate formation or crystal transition during entire experiments. The Jouyban-Acree model was employed to correlate the measured solubility. The calculated data were in alignment to measured values and RAD and RMSD data were no more than 3.08% and 10.37 × 10−4, respectively. Furthermore, quantitative values for the local mole fraction of ethanol (EG, DMSO or isopropanol) and water around the iminodibenzyl were acquired by using the Inverse Kirkwood–Buff integrals method. The preferential solvation parameters for ethanol, EG, DMSO or isopropanol were positive in the four co-solvent mixtures in intermediate and co-solvent-rich compositions, which indicated that iminodibenzyl was preferentially solvated by the co-solvent. iminodibenzyl could act mainly as a Lewis acid interacting with proton-acceptor functional groups of the co-solvents.

Experimental measurement of drug quinocetone solubility in water-co-solvent mixtures of ethanol, isopropanol, dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF) were determined by the static equilibrium method at temperature range of (283.15–328.15) K under ambient condition (101.2 kPa). The solid phase equilibrated with liquor was examined by X-ray power diffraction, resulting in no polymorphic transformation, solvate formation or crystal transition compared to the raw material. Quantitative knowledge about the solvent effect on the solubility was obtained with the help of linear solvation energy relationships in the terms of dipolarity-polarizability, hydrogen-bond donor and acceptor ability, and cavity term of mixtures. The preferential solvation was investigated from their thermodynamic solution properties by means of the inverse Kirkwood-Buff integrals. The preferential solvation parameters (δx1,3) for ethanol, isopropanol, DMSO or DMF were negative in the four co-solvent mixtures with water-rich compositions, which indicated that quinocetone was preferentially solvated by water. Temperature has a little effect on the preferential solvation magnitudes for the ethanol and isopropanol mixtures. The higher solvation by water could be explained in terms of the higher acidic behavior of the solvents interacting with the Lewis basic groups of the quinocetone. In addition, thermodynamic co-solvency models including the Jouyban-Acree model, van’t Hoff-Jouyban-Acree model and Modified Apelblat-Jouyban-Acree model were employed to describe the solubility of this drug obtaining average relative deviations lower than 2.14% and root-mean-square deviations lower than 1.75 × 10−4 for correlative studies. The standard dissolution enthalpies of quinocetone in the solvent mixtures were positive, demonstrating that the dissolution process of quinocetone was endothermic.

The equilibrium solubility data of allopurinol in aqueous co-solvent mixtures of ethanol, isopropanol, N,N-dimethylformamide (DMF) and 1-methyl-2-pyrrolidone (NMP) was experimentally determined by a saturation shake-flask method within the temperatures from 293.15 K to 333.15 K under atmospheric pressure. It was found that in the (DMF + water) and (NMP + water) systems, the solubilities of allopurinol increased with increasing temperature and DMF (NMP) composition. However in the (ethanol + water) and (isopropanol + water) systems, they increased at first and then decreased with an increase in mass fractions of ethanol and isopropanol. The determined solubility values were correlated by using the Jouyban-Acree, van’t Hoff-Jouyban-Acree and Apelblat-Jouyban-Acree models obtaining average relative deviations lower than 6.84% for correlative studies. Preferential solvation parameters of allopurinol were derived by means of the inverse Kirkwood-Buff integrals method. There were significant different behaviours of the allopurinol between in ethanol (isopropanol) + water and DMF (NMP) + water mixtures. The preferential solvation parameter δx1,3 by co-solvent is positive in the regions of 0.25

The equilibrium solubilities of chlorhexidine in four solvent mixtures of methanol (1) + water (2), ethanol (1) + water (2), DMF (1) + water (2) and 1,4-dioxane (1) + w water (2) at temperature range from (278.15 to 318.15) K were reported. At the same composition of methanol, ethanol, DMF or 1,4-dioxane and temperature, the mole fraction solubility of chlorhexidine was highest in DMF (1) + w water (2) mixtures, and lowest in ethanol (1) + w water (2) mixtures. By using the Jouyban-Acree model, van’t Hoff-Jouyban-Acree model and Apelblat-Jouyban-Acree model, chlorhexidine solubility was well correlated obtaining RAD lower than 1.69% and RMSD lower than 0.87 × 10−4. The dissolution process of chlorhexidine in solvent solutions was endothermic for the dissolution process. To study the solvent effect, solubility data were correlated to KAT parameters and cavity term on the basis of linear solvation energy relationships concept. Results indicate the key effect of cavity term and π∗ in aqueous methanol and ethanol mixtures; cavity term in aqueous DMF mixtures; and cavity term, β and π∗ in aqueous 1,4-dioxan mixtures. Quantitative values for the local mole fraction of methanol (ethanol, DMF or 1,4-dioxane) and water around the chlorhexidine were computed by using the IKBI method applied to the determined solubility data. Chlorhexidine was preferentially solvated by water for the four solvent mixtures in water-rich compositions; while in intermediate and co-solvent-rich composition for ethanol (DMF, 1,4-dioxane) (1) + w water (2) mixtures, chlorhexidine is preferentially solvated by the co-solvent. The preferential solvation magnitude of chlorhexidine was highest in 1,4-dioxane mixtures than in the other three solvent mixtures.

The D-tryptophan solubility in aqueous solutions of methanol, ethanol, isopropanol and N,N-dimethylformamide (DMF) was measured by the saturation shake-flask method at temperatures ranging from 283.15 K to 333.15 K. The maximum solubility was found in water for alcohol (1) + water (2) mixtures, and in neat DMF for DMF (1) + water (2) mixture. When the same temperature and mass fraction of the water is given, the highest mole fraction solubility of D-tryptophan was found in (DMF + water). The solid phases were tested by X-ray powder diffraction (XPRD) showing no polymorphic transformation, solvate formation or crystal transition. Three solubility models, i.e. the Jouyban-Acree, van’t Hoff-Jouyban-Acree and Apelblat-Jouyban-Acree were employed to correlate the experimental solubility values so as to obtain thermodynamic parameters. The RAD and RMSD data were no more than 1.65% and 9.40 × 10−5, respectively. Linear solvation energy relationship analysis based on Kamlet-Taft parameters indicated that the variation of D-tryptophan solubility depended on π∗ for methanol (ethanol, isopropanol) (1) + water (2), and cavity term for DMF (1) + water (2). The preferential solvation parameters (δx1,3) for methanol, ethanol, isopropanol and DMF derived by means of the inverse Kirkwood–Buff integrals were negative in the four solvent mixtures with intermediate and alcohol-rich compositions, which indicated that D-tryptophan was preferentially solvated by water. The higher solvation by water could be explained in terms of the higher acidic behaviour of the solvents interacting with the Lewis basic groups of the D-tryptophan. However D-tryptophan is preferentially solvated neither by water nor by DMF in DMF + water mixture.

The mole fraction solubility of 6-chloropurine in aqueous mixtures of methanol, ethanol, N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA) was measured by a saturation shake-flask method over the temperature range of (283.15–328.15) K at pressure of 101.2 kPa. The solubility of 6-chloropurine increased positively with increasing temperature at a given solvent composition and decreased with increasing mass fraction of water in each binary system. The maximum solubility was found in neat methanol, ethanol, DMF and DMA. Given the same temperature and mass fraction of the organic solvent, the solubility of 6-chloropurine was greater in (DMF + water) than in the other three solvent mixtures. The X-ray power diffraction (XPRD) analysis showed that no polymorphic transformation, solvate formation or crystal transition took place during the experiments. Linear solvation energy relationships concept was used to describe the variation in the solubility based on the solvent effect. The preferential solvation parameters were derived from their thermodynamic solution properties using inverse Kirkwood–Buff integrals. The preferential solvation parameters (δx1,3) for methanol, ethanol, DMF and DMA were negative in the four solvent mixtures with water-rich compositions, which indicated that 6-chloropurine was preferentially solvated by water. Temperature has little effect on the preferential solvation magnitudes. The higher solvation by water could be explained in terms of the higher acidic behavior of the solvents interacting with the Lewis basic groups of the 6-chloropurine. Furthermore, several mathematical cosolvency models were adopted to correlate the measured solubility values. The relative average deviation and root-mean-square deviation were no more than 2.36% and 1.026 × 10−3, respectively.

The solubility of trimetazidine hydrochloride in 12 neat solvents namely ethanol, methanol, isopropyl alcohol, n-propanol, acetone, toluene, 2-butanone, ethyl acetate, n-butanol, acetonitrile, N,N-dimethylformamide (DMF), and 1,4-dioxane and binary liquid mixtures methanol + (ethanol, DMF, or ethyl acetate) was measured using the isothermal method over the temperature range from 278.15 to 323.15 K under local atmospheric pressure of 101.2 kPa. The observed mole fraction solubility was the largest in methanol and smallest in toluene. The experimental data in monosolvents was correlated through the Apelblat equation; while in mixed solvents, by the van’t Hoff–Jouyban–Acree model, Jouyban–Acree model and Apelblat–Jouyban–Acree model. Consequently, for the selected monosolvents, the largest relative average and root-mean-square deviations were 0.79% and 0.227 × 10–4, respectively; and for the binary solvent mixtures, 3.00% and 2.22 × 10–4. Solvent–solvent and solute–solvent interactions were analyzed in the 1...

To obtain a clearer understanding of the catalytic bio-oil reforming mechanism, we performed density functional theory calculations on the decomposition of formic acid over a stepped Ni surface. Formic acid was selected as a model bio-oil compound. Fourteen elementary reactions were considered. All the zero-point-energy corrected activation energies and reaction energies were obtained. The kinetic parameters of the reaction rate constants and thermodynamic equilibrium constants in the temperature range of 300–1000 K were revealed. COOH formation and its subsequent dissociation are energetically easier than that of HCOO. When combined with kinetic modeling, the most preferable pathway for formic acid dissociation on the surface is HCOOH → COOH → CO. The rate-determining step is COOH dehydroxylation to CO, associating with an activation energy of 0.51 eV and a rate constant of 5.16 × 109 s−1 at 773 K. In addition, HCOO will be slowly accumulated on the surface as the temperature rises.

The thiamphenicol solubility in aqueous cosolvent solutions of ethanol (1), methanol (1), 1,4-dioxane (1), and N,N-dimethylformamide (DMF, 1) was measured via the isothermal dissolution equilibrium method at temperatures ranging from 278.15 to 318.15 K under local pressure (101.1 kPa). At fixed composition of ethanol (methanol, 1,4-dioxane, or DMF) and temperature, the solubility of thiamphenicol was larger in DMF + water mixtures than in the ethanol/methanol/1,4-dioxane mixtures. The local solvent proportions were acquired with the method of inverse Kirkwood–Buff integrals. The absolute value of these preferential solvation parameters were all lower than 1.0 × 10–2 for ethanol (1) + water (2) and 1,4-dioxane (1) + water (2) solutions in water-rich compositions and for methanol (1) + water (2) solutions in whole compositions. In the former two cosolvent mixtures in intermediate compositions and cosolvent-rich regions, thiamphenicol was preferentially solvated by cosolvent. However, for the DMF (1) + water...

This work reports the synthesis and characterization of a new efficient visible-light photocatalyst comprising SnO2 nanoparticles and cyclized polyacrylonitrile (CPAN). SnO2/CPAN nanocomposite was synthesized through two steps: first, adsorption of polyacrylonitrile (PAN) in N,N-Dimethylformamide solution by SnO2 nanoparticles to form SnO2/PAN nanocomposite; second, cyclization of PAN in the SnO2/PAN nanocomposite by heating at 250 °C for 2 h. The characterization by X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, N2 adsorption-desorption curves, and UV–vis diffuse reflection spectra indicated the synthesis of large surface area SnO2/CPAN nanocomposite with remarkable visible-light-harvesting ability. SnO2/CPAN nanocomposite exhibited exceptionally high photocatalytic activity in the reduction of aqueous Cr(VI) under visible-light (λ > 420 nm) irradiation (the reaction rate constant of photocatalytic reduction of Cr(VI) by SnO2/CPAN is about 16.6 times that by SnO2). The possible mechanism for the high visible-light-driven photocatalytic activity of SnO2/CPAN nanocomposite was proposed.

The preferential solvation parameters (δx 1,3) of Boscalid in solvent mixtures of ethanol (1) + ethyl acetate (2), and isopropanol (1) + ethyl acetate (2) were derived from their available solubility data by means of the inverse Kirkwood–Buff integrals method. The values of δx 1,3 vary non-linearly with the solvent (1) proportion in the two solvent mixtures. For the ethanol (1) + ethyl acetate (2) system, the values of δx 1,3 are negative in ethanol-rich and ethyl acetate-rich mixtures, but positive in intermediate compositions; for the isopropanol (1) + ethyl acetate (2) system, the values of δx 1,3 are positive in ethyl acetate-rich mixtures and in intermediate compositions, but negative in isopropanol-rich mixtures. The δx 1,3 values are positive indicating that Boscalid is preferentially solvated by ethyl acetate. The magnitude of the preferential solvation of Boscalid by ethyl acetate is higher in isopropanol (1) + ethyl acetate (2) mixtures than in ethanol (1) + ethyl acetate (2) mixtures at 298.15, 308.15 and 313.15 K. The ethyl acetate action may be related to the disordered structure of ethanol or isopropanol molecules around the polar moieties of Boscalid, which increases the solvation, with maximum values near x 1 = 0.40–0.45 for the two solvent mixtures.

Equilibrium solubility data of nitroxoline in mixed solvents of (ethyl acetate + methanol), (ethyl acetate + ethanol), (ethyl acetate + n-propanol) and (ethyl acetate + isopropanol) were obtained experimentally by using the static method within the temperature range from (278.15 to 313.15) K under atmospheric pressure of 101.1 kPa. The mole fraction solubility of nitroxoline increased with increasing temperature and mass fraction of ethyl acetate. The obtained solubility data were mathematically represented by using five cosolvency models, including Jouyban–Acree model, van’t Hoff-Jouyban-Acree model, Apelblat-Jouyban-Acree model, Ma model, and Sun model. The maximum value of relative average deviation was 1.64 × 10−2, and root-mean-square deviation, 0.77 × 10−4. The dissolution process of nitroxoline in these mixed solvents was endothermic. The preferential solvation parameters were derived from their thermodynamic solution properties via the method of inverse Kirkwood–Buff integrals. The preferential solvation parameters for nitroxoline (δx1,3) were positive in intermediate compositions and ethyl acetate-rich mixtures but negative in alcohol-rich compositions. In the regions with intermediate composition, the preferential solvation magnitude of nitroxoline by the ethyl acetate is higher in {ethyl acetate (1) + ethanol (2)} mixtures than in the other solvent mixtures at 298.15 K. The higher solvation by ethyl acetate in intermediate compositions and in ethyl acetate-rich mixtures could be explained in terms of the higher basic behaviour of ethyl acetate interacting with the Lewis acidic groups of the nitroxoline.

The solid–liquid equilibrium for thiamphenicol in 13 neat solvents (ethanol, methanol, n-propanol, isopropyl alcohol, n-butanol, acetone, acetonitrile, ethyl acetate, 2-butanone, toluene, water, N,N-dimethylformamide, and 1,4-dioxane) was built with the static method at temperatures T = (278.15 to 318.15) K under pressure of 101.2 kPa, and the thiamphenicol solubilities in the selected solvents were measured by using high-performance liquid chromatography. Generally, the solubility data in mole fraction in the selected solvents ranked as N,N-dimethylformamide > acetone > methanol >1,4-dioxane >2-butanone > ethanol > acetonitrile > ethyl acetate > n-propanol > isopropyl alcohol > water > n-butanol > toluene. The nonrandom two-liquid model, Wilson model, modified Apelblat equation, and λh equation were employed to describe the solubility behavior of thiamphenicol in theses solvents. The maximum values of the RMSD and RAD were 4.08 × 10–4 and 2.02%, respectively, and the correlation results by using the modi...

The preferential solvation parameters ( δx 1,3 ) of diazepam in binary solvent mixtures of {ethanol (1) + water (2)}, {propylene glycol (1) + water (2)}, {NMP (1) + water (2)} and {1,4-dioxane (1) + water (2)} at 298.2 K and { tert -butanol (1) + water (2)} at (299.2–313.2) K were derived from their available solubility values by using the inverse Kirkwood–Buff integrals method. The values of δx 1,3 vary non-linearly with the co-solvent (1) proportion in all the aqueous mixtures. For the former four co-solvent mixtures, the preferential solvation magnitude of diazepam by the co-solvent is highest in {1,4-dioxane (1) + water (2)} mixtures and lowest in {ethanol (1) + water (2)} mixtures. For the former four systems, the values of δx 1,3 are negative in water-rich mixtures, which indicates that diazepam could act as a Lewis base to establish hydrogen bonds with the proton-donor functional groups of the co-solvents (1) (with the exception of 1,4-dioxane). The same behaviour was also observed for ethanol (1) + water (2) mixtures with co-solvent-rich composition. In the {ethanol (1) + water (2)} mixtures with composition 0.241 x 1 x 1 x 1 x 1 tert -butanol (1) + water (2)} mixtures and the other four co-solvent mixtures were found.

The preferential solvation parameters (δx1,3) of rosmarinic acid in binary solvent mixtures of ethanol + water and methanol + water were derived from their thermodynamic properties by means of the inverse Kirkwood–Buff integrals method. δx1,3 was negative in water-rich mixtures but positive in solvent compositions from 0.20 or 0.24 to 1 in mole fraction of methanol or ethanol, respectively. It was conjecturable that in water-rich mixtures, the hydrophobic hydration around the nonpolar aromatic groups of rosmarinic acid played a relevant role in the solvation. The higher solvation by methanol or ethanol in mixtures of similar co-solvent compositions could be mainly due to polarity effects. The preference of rosmarinic acid in intermediate compositions and in methanol-rich or ethanol-rich mixtures could be explained in terms of the higher acidic behavior of rosmarinic acid molecules interacting with the hydrogen acceptor groups in methanol or ethanol. The calculations were required in the pharmaceutical and chemical industries to save time and money in the optimization of the solubilization and/or crystallization process designs.

The preferential solvation parameters (δx1,3) of dehydroepiandrosterone acetate (DHEA acetate) in three co-solvent mixtures of methanol (1) + ethyl acetate (2), ethanol (1) + ethyl acetate (2), and isopropanol (1) + ethyl acetate (2) were derived from their available solubility data by means of the inverse Kirkwood–Buff integrals method. The values of δx1,3 vary non-linearly with the co-solvent (1) proportion in all the co-solvent mixtures. For the studied systems, the values of δx1,3 are negative in alcohol-rich mixtures, but positive in ethyl acetate-rich mixtures. The preferential solvation magnitude of DHEA acetate by the ethyl acetate is highest in {methanol (1) + ethyl acetate (2)} mixtures at 293.15 K and 303.15 K. While at 313.15 K, it is highest in {isopropanol (1) + ethyl acetate (2)} mixtures. The δx1,3 values are positive indicating that DHEA acetate is preferentially solvated by ethyl acetate. The co-solvent action may be related to the disordered structure of ethyl acetate molecules around the non-polar moieties of DHEA acetate which increases the solvation having maximum values near to x1 = 0.25–0.35 for the three co-solvent mixtures.

The knowledge of solubility and solution thermodynamics for 4-methyl-2-nitroaniline in different solvents is essential for its preparation, purification and further theoretical studies. In this work, the solid-liquid equilibrium for 4-methyl-2-nitroaniline in fourteen organic solvents (methanol, ethanol, n -propanol, isopropanol, n -butanol, toluene, ethyl acetate, acetonitrile, 2-butanone, 1,4-dioxane, N , N -dimethylformamide, carbon tetrachloride, 1,2-dichloroethane and chlorobenzene) was built with the isothermal saturation method at temperatures T = (278.15–318.15) K under pressure of 101.2 kPa, and the solubility values of 4-methyl-2-nitroaniline in these solvents were determined by a high-performance liquid chromatography (HPLC). Generally, the mole fraction solubilities obeyed the following order from high to low in different solvents: 2-butanone > N , N -dimethylformamide > ethyl acetate > 1,4-dioxane > (acetonitrile, 1,2-dichloroethane) > chlorobenzene > (toluene, n -butanol) > n -propanol > isopropanol > ethanol > methanol > carbon tetrachloride. The obtained solubility data of 4-methyl-2-nitroaniline in the selected solvents were correlated with the modified Apelblat equation, λh equation, Wilson model and NRTL model. Results showed that the largest values of relative average deviation and root-mean-square deviation acquired with the four models were no greater than 1.03% and 6.89 × 10 −4 , respectively. The modified Apelblat equation provided better correlation results than the other three models. Moreover, the mixing properties, including mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration and reduced excess enthalpy were computed. The mixing process of 4-methyl-2-nitroaniline in the studied solvents was spontaneous and endothermic. The obtained solubility and thermodynamic studies would be very helpful for optimizing the preparation and purification process of 4-methyl-2-nitroaniline.

The solubility of 3-nitrobenzaldehyde in mixed solvents of N,N-dimethylformamide + ethanol, N,N-dimethylformamide + n-propanol and N,N-dimethylformamide + n-butanol were determined experimentally by using the isothermal dissolution equilibrium method within the temperature range from (273.15 to 298.15) K under 101.2 kPa. The mole fraction solubility of 3-nitrobenzaldehyde increased with increasing temperature and mass fraction of the N,N-dimethylformamide (DMF). At the same temperature and mass fraction of DMF, the mole fraction solubility of 3-nitrobenzaldehyde in ethanol was greater than those in the other two systems. The obtained solubilities were correlated by employing Jouyban-Acree, van't Hoff-Jouyban-Acree and Apelblat-Jouyban-Acree models. The largest value of RAD was 0.30 × 10− 2, and of RMSD, 8.10 × 10− 4. Dissolution of 3-nitrobenzaldehyde in these mixed solvents was an endothermic process. Preferential solvation parameters of 3-nitrobenzaldehyde were also derived by means of the inverse Kirkwood-Buff integrals method. The preferential solvation parameter δx1,3 was negative in ethanol, n-propanol or n-butanol-rich mixtures but positive in DMF-rich mixtures. The solubility data presented in this work expand the physicochemical information about 3-nitrobenzaldehyde in binary solvent mixtures.

Solid-liquid phase equilibrium and solubility for the quaternary system of (adipic acid + succinic acid + glutaric acid + ethanol) at (283.15, 303.15, and 313.15) K were determined by using an isothermal saturation method under atmosphere pressure (101.2 kPa). Based on the determined mutual solubility, the quaternary phase diagrams were constructed at the studied temperatures according to the Janeck method. At each temperature, the quaternary phase diagram included three crystallization regions of pure solid, three co-saturated curves and one eutectic point. The three pure solids corresponded to pure adipic acid, pure succinic acid and pure glutaric acid, which were confirmed by Schreinemaker’s method of wet residue and X-ray powder diffraction. At the same temperature, the crystallization regions of succinic acid and adipic acid are larger than that of glutaric acid. Furthermore, the quaternary solid-liquid phase equilibrium was calculated by using the Wilson and NRTL models. The calculated quaternary phase diagrams agreed well with experimental results. The values of RMSD were 2.46 and 1.08 for Wilson model and NRTL model, respectively. The solid-liquid equilibrium phase diagrams and the thermodynamic models for the quaternary system could provide the fundamental basis for the separation process of a specific dibasic acid from its mixtures via solvent crystallization.

Separation of 3-nitro-o-toluic acid from its isomeric mixtures has essential significance in industry. In this work, by using isothermal saturation method, the solid-liquid equilibrium for 3-nitro-o-toluic acid in nine organic solvents (acetonitrile, methanol, ethanol, n-propanol, isopropanol, ethyl acetate, acetone, 1,4-dioxane and 2-butanone) were obtained experimentally within a temperature range from (283.15 to 318.15) K under atmosphere pressure of 101.2 kPa, and the solubility values of 3-nitro-o-toluic acid in these solvents were determined by a high-performance liquid chromatography. Within the studied temperature range, the mole fraction solubility of 3-nitro-o-toluic acid in selected organic solvents increased with increasing temperature. Except for ethyl acetate, the descending order of the mole fraction solubility values were as follow: 1,4-dioxane > acetone > 2-butanone > methanol > ethanol > isopropanol > n-propanol > acetonitrile. The solubility values determined for 3-nitro-o-toluic acid in the selected solvents were correlated and back calculated with the modified Apelblat equation, λh equation, Wilson model and NRTL model. The largest values of RAD and RMSD obtained with the four models were 0.67% and 4.02 × 10−4, respectively. In general, the four thermodynamic models were all acceptable for describing the solubility behaviour of 3-nitro-o-toluic acid in these solvents. In addition, the apparent mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration and reduced excess enthalpy were calculated. The acquired solubility data and thermodynamic studies would be very important in optimizing the separation process of 3-nitro-o-toluic acid from its isomeric mixtures.

The preferential solvation parameters (δx1,3) of pioglitazone hydrochloride in four binary solvent mixtures of {ethanol (1) + water (2)}, {N-methyl pyrrolidone (NMP) (1) + water (2)}, {propylene glycol (1) + water (2)} and {N,N-dimethylsulfoxide (DMSO) (1) + water (2)} were derived from their available solubility data by means of the inverse Kirkwood–Buff integrals method. The values of δx1,3 vary non-linearly with the co-solvent (1) proportion in all the aqueous mixtures. The preferential solvation magnitude of pioglitazone hydrochloride by the co-solvent is highest in {ethanol (1) + water (2)} mixtures and lowest in {propylene glycol (1) + water (2)}. For the systems of (ethanol + water) and (NMP + water), the values of δx1,3 are negative in water-rich mixtures and co-solvent-rich mixtures, but positive in intermediate compositions. However, for the {propylene glycol (1) + water (2)} and {DMSO (1) + water (2)} mixtures with composition 0.20

The reaction mechanism of ethanol synthesis from dimethyl ether (DME) and syngas was studied via density functional theory calculations. Various possible pathways for ethanol formation, and byproduct formations of methanol, acetic acid, methane, carbon dioxide, and water over an active cobalt stepped surface were calculated. The most favorable pathway for ethanol synthesis starts with the dissociation of dimethyl ether to CH 2 , followed by carbon monoxide insertion to form CH 2 CO, and then undergoes successive hydrogenations to give ethanol. CH 3 CHO hydrogenation to CH 3 CHOH becomes the rate–determining step with a reaction barrier of 1.48 eV. DME decomposition and CH 2 carbonylation occur easily with low barriers of 0.61 eV and 0.48 eV, respectively. Carbon monoxide insertion into CH 2 is more facile than into CH 3 and CH. Hydrogenation at the carbon atom occurs prior to the oxygen atom in the order of α–carbon > carbonyl carbon > oxygen. The calculations demonstrate that ethanol synthesis via DME carbonylation and hydrogenation is thermodynamically favored and is kinetically faster than that via syngas direct synthesis. Methane and acetic acid are two dominant competing byproducts.

In this work, the solid-liquid phase equilibrium data for ternary system of 4-nitrobenzaldehyde + 3-nitrobenzaldehyde + ethyl acetate were determined by using an isothermal saturation method at three temperatures of 278.15 K, 288.15 K, and 298.15 K under atmosphere pressure (101.2 kPa). Three isothermal phase diagrams were built based on the measured solubility data. There were two pure solids formed in the ternary system at a certain temperature, which corresponded to pure 3-nitrobenzaldehyde and pure 4-nitrobenzaldehyde, and were confirmed by Schreinemaker's method of wet residue and X-ray powder diffraction. The crystallization region of 4-nitrobenzaldehyde was larger than that of 3-nitrobenzaldehyde at each temperature. Two thermodynamic models, NRTL and Wilson were employed to correlate and calculate the mutual solubility data for the system of 4-nitrobenzaldehyde + 3-nitrobenzaldehyde + ethyl acetate. The largest value of RMSD for the ternary system was 5.95 × 10 − 3 , and the maximum value of RAD was 3.02%. The calculated results with NRTL model agreed well than those with Wilson model. The solid-liquid equilibrium phase diagrams and the thermodynamic models for the ternary system can provide the foundation for separating high purity3-nitrobenzaldehyde or 4-nitrobenzaldehyde from its isomeric mixtures.

The solubility of 2-amino-4-chlorobenzoic acid in eleven organic solvents including N -methyl-2-pyrrolidone, ethanol, n -propanol, isopropanol, ethyl benzene, toluene, n -butanol, acetonitrile, ethyl acetate, 1,4-dioxane and acetone were determined experimentally using the isothermal saturation method over a temperature range from (278.15 to 313.15) K under 101.2 kPa. Within the temperature range studied, the mole fraction solubility of 2-amino-4-chlorobenzoic acid in the solvents increased with a rise of temperature. On the whole, they obeyed the following order from high to low in the selected solvents: N- methyl-2-pyrrolidone > acetone > 1, 4-dioxane > ethyl acetate > ethanol > isopropanol > n -propanol > n -butanol > acetonitrile > toluene > ethyl benzene. The solubility values obtained for 2-amino-4-chlorobenzoic acid were correlated with the modified Apelblat equation, λh equation, Wilson model and NRTL model. The largest values of root-mean-square deviation ( RMSD ) and relative average deviation ( RAD ) were 8.25 × 10 −4 and 3.35%, respectively. The modified Apelblat equation correlated the experimental solubility best on the basis of the result of AIC analysis. Furthermore, the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient ( γ 1 ∞ ) and reduced excess enthalpy ( H 1 E, ∞ ) at infinitesimal concentration were determined. Solubility and thermodynamic studies are very important for optimizing the purification process of 2-amino-4-chlorobenzoic acid.

Errors are discovered in the authors’ computed the apparent molar volume from the reported density of aqueous solutions of lithium tetraborate based on the equation. All the apparent molar volumes presented in Table 3 of the published paper by Guo and co-workers are in error. When the composition of Li 2 B 4 O 7 is high, the difference between our calculated V ϕ values and those reported by Guo is small. However, large difference is found with low compositions of Li 2 B 4 O 7 in solutions.

In order to make a better understanding of dehydrogenation mechanisms of liquid organic hydrogen carriers, cyclohexane was selected as a model compound to carry out its decomposition studies over Pt(1 1 1), Pd(1 1 1), Rh(1 1 1), and Ni(1 1 1) surfaces via periodic density functional theory calculations. The adsorption geometries and adsorption energies of reaction intermediates were presented. Similar linear relationships of the adsorption energies with respect to the number of hydrogen removal over these four surfaces were revealed for C6Hx* (x = 8–12). Seven elementary reactions for cyclohexane successive dehydrogenation to C6H5* were considered. The initial dehydrogenation of C6H12* to generate C6H11* were identified as the rate-determining steps over all surfaces, association with activation energies of 1.04, 1.06, 0.96, and 1.14 eV for Pt(1 1 1), Pd(1 1 1), Rh(1 1 1), and Ni(1 1 1), respectively. The reactivity of dehydrogenation was in the order of Rh(1 1 1) > Pt(1 1 1) > Pd(1 1 1) > Ni(1 1 1).

The solubility of 3,5-dinitrobenzoic acid in acetone at the temperatures ranging from (283.15 to 318.15) K and the mutual solubility of the ternary m -nitrobenzoic acid + 3,5-dinitrobenzoic acid + acetone system at (283.15, 298.15 and 313.15) K were determined experimentally by using the isothermal saturation method under atmosphere pressure (101.2 kPa). Three isothermal ternary phase diagrams were constructed according to the measured mutual solubility data. In each ternary phase diagram, there was one co-saturated point, two boundary curves, and three crystalline regions. The modified Apelblat equation, λh equation, NRTL model and Wilson model were used to correlate the solubility of 3,5-dinitrobenzoic acid in acetone; and the NRTL and Wilson models, the mutual solubility for the ternary m -nitrobenzoic acid + 3,5-dinitrobenzoic acid + acetone system. The value of root-mean-square deviation ( RMSD ) was 8.53 × 10 −4 for the binary system of 3,5-dinitrobenzoic acid + acetone; and the largest value of RMSD was 81.08 × 10 −4 for the ternary system.

The solubility was measured for 3-nitrobenzaldehyde in methanol, ethanol, isopropanol, n -butanol, acetonitrile, acetone, ethyl acetate, toluene, N , N -dimethylformamide, acetic acid, cyclohexane and n -propanol by using a high-performance liquid chromatography analysis under pressure of 101.2 kPa. The temperatures of solubility determination were from (273.15 to 303.15) K. The mole fraction solubility of 3-nitrobenzaldehyde increased with the increase in temperature, and obeyed the following order from high to low in different solvents: N , N -dimethylformamide > (acetone, acetonitrile) > ethyl acetate > toluene > methanol > acetic acid > ethanol > n -propanol > n -butanol > isopropanol > cyclohexane. Four models, modified Apelblat equation, λh equation, Wilson model and NRTL model were employed to correlate the experimental mole fraction solubility. The largest root-mean-square deviation ( RMSD ) was 6.98 × 10 −3 , and the largest relative average deviation ( RAD ) was 1.93% for each set of solubility results. On the whole, the calculated solubility values were in good agreement with the experimental results for the four selected models, and the NRTL provided the best results. Moreover, the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration ( γ 1 ∞ ) and reduced excess enthalpy ( H 1 E, ∞ ) were computed based on the NRTL model. The experimental solubility, thermodynamic models and thermodynamic properties are very important in the purification process of isomeric mixtures of nitrobenzaldehydes.

Density functional theory calculations and microkinetic modeling were used to study the decomposition mechanisms of the bio-oil model compound formic acid over a cobalt-stepped surface. Zero-point-energy-corrected activation barriers and reaction energies and the rate and equilibrium constants of various elementary reactions were obtained. Formic acid dissociation likely starts from dehydrogenation and dehydroxylation, with activation barriers of less than 0.5 eV. The generation of an HCOO intermediate is thermodynamically favored, but such a compound is energetically difficult to convert. COOH formation is fast and dominant at low temperatures, and it is converted rapidly after 450 K. The most favorable formic acid decomposition pathway is HCOOH → COOH → CO. Its rate-determining step is CO–OH scission, with an activation barrier of 0.66 eV and strong exothermicity of −1.19 eV.

The solubility of 3-amino-1,2,4-triazole in ten organic solvents including ethanol, isopropanol, n -propanol, methanol, ethyl acetate, acetone, acetonitrile, 1,4-dioxane, N -methyl-2-pyrrolidone and 2-butanone was determined experimentally by the isothermal saturation method over a temperature range from T = 283.15 K to T = 318.15 K under 101.1 kPa. For the studied temperature range, the solubility of 3-amino-1,2,4-triazole in mole fraction in the solvents increased with a rise of temperature. On the whole, they obeyed the following order from high to low in different solvents: N -methyl-2-pyrrolidone > methanol > ethanol > n -propanol > (isopropanol, acetone) > 1,4-dioxane > 2-butanone > (ethyl acetate, acetonitrile). The determined solubility results of 3-amino-1,2,4-triazole in the solvents studied were correlated using the modified Apelblat equation, Buchowski–Ksiazaczak λh equation, Wilson model and NRTL model. The maximum values of root-mean-square deviation ( RMSD ) and relative average deviation ( RAD ) were 9.45 × 10 −4 and 2.16%, respectively. In general, the four thermodynamic models were all acceptable for describing the solubility behaviour of 3-amino-1,2,4-triazole in these solvents. Furthermore, the mixing properties including the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration ( γ 1 ∞ ) and reduced excess enthalpy ( H 1 E, ∞ ) were acquired. The solution process of 3-amino-1,2,4-triazole was spontaneous and favourable in the selected solvents. The solubility values obtained and the thermodynamic studies would be very useful for optimizing the purification process of 3-amino-1,2,4-triazole.

The mole fraction solubility of paclobutrazol ((R,R) and (S,S)) mixture in nine pure solvents including ethanol, isopropanol, n-propanol, 1-butanol, ethyl acetate, toluene, acetone, acetonitrile and 1,4-dioxane was determined experimentally by using the isothermal saturation method over a temperature range from (278.15 to 318.15) K under atmospheric pressure. The mole fraction solubility of paclobutrazol in the selected solvents increased with a rise of temperature. In general, at a certain temperature, they decreased according to the following order in different solvents except for ethyl acetate: toluene > 1,4-dioxane > acetone > 1-butanol > n-propanol > ethanol > isopropanol > acetonitrile. The paclobutrazol solubility showed stronger dependency on temperature in ethyl acetate than in the other solvents. The solubility determined for paclobutrazol in the selected solvents was correlated with the modified Apelblat equation, λh equation, Wilson model and NRTL model. The maximum values of root-mean-square deviation (RMSD) and relative average deviation (RAD) were 3.98 × 10−4 and 1.53%, respectively. On the whole, the four thermodynamic models were all acceptable for describing the systems of paclobutrazol in these solvents. Furthermore, the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration ( γ 1 ∞ ) and reduced excess enthalpy ( H 1 E, ∞ ) were obtained. The mixing process of paclobutrazol was spontaneous and exothermic in the solvents studied. The solubility determined and the thermodynamic properties derived should be very helpful for optimizing the purification process of paclobutrazol.

Solubilities of hymecromone in neat solvents of N,N-dimethylformamide (DMF), methanol, ethanol and n-propanol, and their binary mixed solvents of DMF + methanol, DMF + ethanol and DMF + n-propanol were determined using an isothermal dissolution equilibrium method within the temperature range from 278.15 K to 313.15 K under 101.1 kPa. They were correlated with the Jouyban–Acree, van't Hoff–Jouyban–Acree and Apelblat–Jouyban–Acree models obtaining relative average deviations (RAD) lower than 0.51% and root-mean-square deviation (RMSD) lower than 4.42 × 10−4. Positive values of the dissolution enthalpy illustrated that the dissolution process of hymecromone in these mixed solvents was endothermic. Furthermore, the preferential solvation parameters were derived by using the inverse Kirkwood–Buff integrals. The preferential solvation parameters (δx1,3) were negative in alcohol-rich mixtures but positive in compositions from 0.35 (0.43, 0.50) in the mole fraction of DMF to neat DMF.

The solubility of ethyl 5-amino-4-cyano-3-(2-ethoxy-2-oxoethyl)-2-thiophenecarboxylate (ACET) in binary (acetone + methanol), (acetone + ethanol), (acetone + 1-butanol) and (acetone + isopropanol) solvent mixtures was investigated by the isothermal dissolution equilibrium method under 101.3 kPa. This study was carried out at different mass fractions of acetone ranging from 0.1 to 0.9 at T = (273.15–318.15) K. For the nine groups with each solvent mixture studied, the solubility of ACET in the mixed solutions increased with increasing temperature and mass fraction acetone. At the same temperature and mass fraction of acetone, the solubility of ACET was greater in (acetone + methanol) than in the other three solvent mixtures. The experimental solubility values were correlated by three co-solvency models (Jouyban-Acree model, van’t Hoff-Jouyban-Acree model and Apelblat- Jouyban-Acree model). The relative average deviations (RAD) and the root-mean-square deviations (RMSD) were all less than 1.49 × 10−2 and 8.99 × 10−4, respectively. The Apelblat-Jouyban-Acree model provided best representation of the experimental solubility. Furthermore, the standard molar enthalpy of the ACET during the dissolving process ( Δ sol H o ) was also derived in this work, and the results showed that the dissolution process is endothermic. The experimental solubility and the models used in this work would be helpful in purifying of ACET from its crude mixtures.

C1–C4 primary carboxylic acids were selected as model compounds to observe the nature and stability of bio-oil adsorption in zeolite HZSM-5 via DFT-D2 theoretical calculation. Adsorptions with and without solvents of water, dimethyl sulfoxide, methanol, and ethanol were studied. The most stable adsorption configuration is hydrogen bonding (HB) through the carbonyl oxygen of acid over the Bronsted acid site of zeolite with the strong energies range from −133.2 to −154.8 kJ/mol. Partial transfer of the Bronsted proton to the acid was observed. Strength of intramolecular-zeolite acid site interaction increases in the order: carbonyl oxygen HB > hydroxyl oxygen HB > CH3 physisorption. The vdW interactions increase notably with the size of the acids. The adsorption energies are significantly reduced by solvation effect.

Although both graphene and layered double hydroxides (LDHs) have similar two-dimensional lamellar structure, most of their properties are distinct and just complementary. Besides, both graphene nanosheets and LDH nanosheets encounter the common problem of aggregation during the process of application. In view of these, combination of both exciting materials together to form a novel nanocomposite can take full advantages of each kind of materials, which is an effective way for the preparation of multifunctional materials with extraordinary properties. The properties of graphene, LDHs, and the combined nanocomposite are described first. Then, the routes for the synthesis of this nanocomposite, including self-assembly of the exfoliated graphene nanosheets and LDH nanosheets, in situ growth of LDHs on graphene sheets, and in situ growth of graphene within or on LDHs are presented. The obtained graphene/LDH nanocomposite shows excellent performance as a multifunctional material for its promising applications in the fields of energy storage, catalysis, environmental protection, drug delivery, and material science. At the end, the possible future research directions on this emerging nanocomposite are highlighted.

The stable solid–liquid phase equilibrium for ternary systems of terephthaldialdehyde + 4-hydroxybenzaldehyde + ethyl acetate and terephthaldialdehyde + 4-hydroxybenzaldehyde + acetone was determined using the isothermal saturation method at 293.15, 303.15, and 313.15 K under ambient pressure of 101.2 kPa. In terms of the obtained mutual solubility data, the isothermal phase diagrams of the two systems were constructed. At a given temperature, there were two pure solids formed, pure 4-hydroxybenzaldehyde and pure terephthaldialdehyde, which were identified by Schreinemakers’ wet residue method and X-ray powder diffraction analysis. The crystallization zones of pure 4-hydroxybenzaldehyde and pure terephthaldialdehyde increased with rising temperature. The crystalline zone of terephthaldialdehyde was larger than that of 4-hydroxybenzaldehyde at the same temperature. The mutual solubility data of solid–liquid phase equilibrium were correlated with nonrandom two-liquid (NRTL) and Wilson models. The calculated...

In the present work, ethanol has been selected as a model compound to represent the typical alcohols found in bio-oil. A stable Ni/CeO2 catalyst has been designed for the production of hydrogen from catalytic steam reforming of ethanol in a continuous-flow fixed-bed reactor. The influence of reaction temperature, liquid hourly space velocity, and steam-to-carbon ratio were investigated. The Ni/CeO2 catalyst performed with high activity for 30 h at optimal conditions and did not show any deactivation. Using density functional theory, the elementary reactions involved in the decomposition of ethanol on the Ni(111) surface have been systematically calculated. The optimal pathway for the ethanol steam reforming reaction process on the surface of the catalyst is proposed.

Graphical abstract, Highlights • Solubility of ribavirin (II) in co-solvent + water were determined and correlated. • Apparent dissolution enthalpy was computed. • Preferential solvation parameters were obtained by Inverse Kirkwood–Buff integrals. • Ribavirin (II) was preferentially solvated by water in intermediate composition and co-solvent-rich mixtures., The equilibrium solubility of ribavirin in solvent mixtures of {methanol (1) + water (2)}, {n-propanol (1) + water (2)}, {acetonitrile (1) + water (2)} and {1,4-dioxane (1) + water (2)} was determined experimentally by using isothermal dissolution equilibrium method within the temperature range from (278.15 to 318.15) K under atmospheric pressure (101.1 kPa). At the same temperature and mass fraction of methanol (n-propanol, acetonitrile or 1,4-dioxane), the mole fraction solubility of ribavirin is greater in (methanol + water) than in the other three solvent mixtures. The preferential solvation parameters were derived from their thermodynamic solution properties by means of the inverse Kirkwood–Buff integrals. The preferential solvation parameters for methanol, n-propanol, acetonitrile or 1,4-dioxane (δx1,3) were negative in the four solvent mixtures with a very wide compositions, which indicated that ribavirin was preferentially solvated by water. Temperature had little effect on the preferential solvation magnitudes. The higher solvation by water could be explained in terms of the higher acidic behaviour of water interacting with the Lewis basic groups of the ribavirin. Besides, the solubility of the drugs was mathematically represented by using the Jouyban-Acree model, van’t Hoff-Jouyban-Acree model and Apelblat-Jouyban-Acree model obtaining average relative deviations lower than 1.57% for correlative studies. It is noteworthy that the solubility data presented in this work contribute to expansion of the physicochemical information about the solubility of drugs in binary solvent mixtures and also allows the thermodynamic analysis of the respective dissolution and specific solvation process.

Errors are discovered regarding the published equation coefficients of Wu and co-workers {J. Chem. Thermodynamics 105 (2017) 345–351} for mathematically describing the solubility behaviour of ethyl vanillin in neat solvents using the λh equation. The calculated values using the published equation coefficients are not the mole fraction solubility as stated in the published paper. The authors inadvertently magnified by 104 times the equation coefficient λ except for the solvent ethanol. As a result all of the λ parameters given in Table 4 of the published paper by Wu and co-workers are in error.