Average Relative Deviation Values Research Articles

Solubility and thermodynamics of terbinafine hydrochloride in different neat and binary solvents: Measurement, correlation and molecular interactions

The solubility of terbinafine hydrochloride in four pure solvents, including methanol, ethanol, n-propanol and ethyl acetate and their binary solvent mixtures, including (methanol+ethyl acetate), (ethanol+ethyl acetate) and (n-propanol+ethyl acetate) performed at different mass fractions of methanol, ethanol or n-propanol ranging from 0.1 to 0.9, was determined by using isothermal saturation method with temperatures ranging from (278.15 to 313.15) K. The descending order of the mole fraction solubility in pure solvents was as follow: methanol>ethanol>n-propanol>ethyl acetate, and for the three mixture with given initial composition, the solubility of terbinafine hydrochloride increased with increasing temperature and mass fraction of alcohol for the three systems including (methanol+ethyl acetate), (ethanol+ethyl acetate) and (n-propanol+ethyl acetate). At the same mass fraction of methanol, ethanol or n-propanol and temperature, the solubility of terbinafine hydrochloride was greater in (methanol+ethyl acetate) than in the other mixed solvents. The maximum mole fraction solubility of terbinafine hydrochloride was observed in methanol (6.297×10−2 at 313.15K), followed by that in ethanol (3.785×10−2 at 313.15K), n-propanol (3.007×10−2 at 313.15K) and ethyl acetate (1.497×10−2 at 313.15K)·The obtained solubility data were correlated with Jouyban-Acree model, van't Hoff-Jouyban-Acree model, modified Apelblat-Jouyban-Acree model and CNIBS/R-K model. The correlation showed good agreement with experimental results, the largest values of relative average deviations (RAD) and the root-mean-square deviations (RMSD) between the experimental and calculated solubility were 4.32×10−2 and 15.28×10−4, respectively. On the basis of the obtained solubility, the standard enthalpy of solution (ΔHsolo), the standard Gibbs energy (ΔGsolo) of solution and the standard entropy of solution (ΔSsolo) of terbinafine hydrochloride dissolved in pure and mixed solvents were obtained by the famous van't Hoff calculations. Thermodynamic treatment of solubility data of terbinafine hydrochloride in these pure and mixed solvents by “Apparent thermodynamic analysis” indicated that the dissolution is an endothermic and entropy-driven process. The experimental solubility and the models in this study could be helpful in purifying the crude terbinafine hydrochloride.

Measurement and Correlation for Solubilities of Adipic Acid, Glutaric Acid, and Succinic Acid in Dimethyl Adipate + Methanol Mixtures

The solubilities of adipic acid, glutaric acid, and succinic acid in dimethyl adipate + methanol solvent mixtures were measured by the method of dynamic laser under 101.3 kPa. The mass fraction of dimethyl adipate in the solvent mixtures ranged from 0.0 to 1.0, and the temperature ranged from 283.95 to 328.15 K. It was found that with the increase of mass fraction for dimethyl adipate in mixed solvents, the measured solubilities of adipic acid, glutaric acid, and succinic acid would decrease at the same temperature, and with the gradually increase of temperature the measured solubilities of adipic acid, glutaric acid, and succinic acid would increase at the constant proportion solvent mixtures. The experimental data were correlated by the Apelblat model, λh model, and the modified nonrandom two liquid activity coefficient model. Results showed that the largest values of relative average deviation and root-mean-square deviations obtained by the three models were 4.49% and 0.35%, respectively. The three mod...

Equilibrium solubility, dissolution thermodynamics and preferential solvation of adenosine in aqueous solutions of N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide and propylene glycol

The equilibrium solubility of adenosine in co-solvent mixtures of {(N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide and propylene glycol)+water} were determined experimentally by the isothermal dissolution equilibrium method in the temperature range of (278.15–323.15) K under atmospheric pressure of 101.0kPa. The maximum solubility was observed in neat N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylsulfoxide or propylene glycol. The mole fraction solubility of adenosine increased with increasing temperature and mass fraction of co-solvent in each binary system. At the same temperature and mass fraction of the organic solvent, the solubility of adenosine was greater in (N-methyl-2-pyrrolidone+water) than in the other three mixed solvents. The Jouyban-Acree model, Van’t Hoff-Jouyban-Acree model and Apelblat-Jouyban-Acree model were employed to correlate the measured solubility data. The largest values of relative average deviation and root-mean-square deviation were 4.87×10−2 and 3.52×10−4, respectively. Positive values of the dissolution enthalpy illustrated that the dissolution process of adenosine in these mixed solvents was endothermic. Moreover, the preferential solvation parameters were derived from their thermodynamic solution properties by using the inverse Kirkwood–Buff integrals. For the four co-solvent mixtures with intermediate composition and co-solvent-rich mixtures, adenosine is preferentially solvated neither by organic solvent nor by water. However, adenosine is preferentially solvated by water in water-rich mixtures. Adenosine could act mainly as a Lewis base interacting with acidic hydrogen atoms of water.

Solubility of cetilistat in neat solvents and preferential solvation in (acetone, isopropanol or acetonitrile) + water co-solvent mixtures

The solubility of cetilistat in neat solvents of acetone, isopropanol, acetonitrile and water were determined experimentally by using the isothermal dissolution equilibrium method within the temperature range from (278.15 to 323.15) K under atmospheric pressure of 101.1kPa. At the fixed temperature, the mole fraction solubility of cetilistat was greater in acetone than in the other three neat solvents. They ranked as acetone>isopropanol>acetonitrile>water. The obtained solubilities were correlated with Apelblat equation. The largest value of relative average deviation was 0.86×10−2, and of root-mean-square deviation, 15.55×10−4. Furthermore, the preferential solvation parameters (δx1,3) of cetilistat in co-solvent mixtures of acetone (1)+water (2), isopropanol (1)+water (2) and acetonitrile (1)+water (2) were derived from their thermodynamic properties by means of the inverse Kirkwood–Buff integrals method. The values of δx1,3 varied non-linearly with the co-solvent (1) proportion in all the aqueous mixtures. The preferential solvation parameter was negative in water-rich mixtures but positive in intermediate composition and co-solvent-rich mixtures. In the latter case, it was conjecturable that cetilistat was acting as a Lewis acid with co-solvent molecules. The co-solvent action might be related to the breaking of the ordered structure of water around the polar moieties of cetilistat which increased the solvation of this drug. The solubility data and thermodynamic study expanded the physicochemical information about cetilistat in binary solvent mixtures, which was required in the pharmaceutical and chemical industries to save time and money in the optimization of the solubilization and/or crystallization process designs.

Solubility and preferential solvation of 2-methyl-4-nitroaniline in mixed solvents of ethyl acetate + (methanol, ethanol, n-propanol and isopropanol)

The mole fraction solubility of 2-methyl-4-nitroaniline in binary mixed solvents of (ethyl acetate+methanol), (ethyl acetate+ethanol), (ethyl acetate+n-propanol) and (ethyl acetate+isopropanol) was determined experimentally by using static method at temperatures from (278.15 to 313.15)K under atmospheric pressure. The solubility increased with increasing temperature and mass fraction of ethyl acetate. At the same temperature and mass fraction of ethyl acetate, the mole fraction solubility in (ethyl acetate+methanol) was greater than those in the other mixed solvents. The solubility values were correlated with Jouyban–Acree model, van’t Hoff-Jouyban-Acree model, modified Apelblat-Jouyban-Acree model, Ma model, and Sun model. The maximum values of relative average deviations and root-mean-square deviations were 0.47×10−2 and 2.26×10−4, respectively. Preferential solvation parameters of the solute were also derived by means of the inverse Kirkwood-Buff integrals (IKBI) method. The preferential solvation parameters δx1,3 are negative in alcohol-rich composition, but positive in intermediate and ethyl acetate-rich composition. The ethyl acetate action may be related to the breaking of the ordered structure of alcohol around the polar moieties of 2-methyl-4-nitroaniline. The positive δx1,3 values could be explained based on the higher acidic behaviour of 2-methyl-4-nitroaniline molecules interacting with the hydrogen acceptor groups present in ethyl acetate. This work expands the physicochemical information about solid in binary solvent mixtures.

Solubility modelling, solution thermodynamics and preferential solvation for nitroxoline in solvent mixtures of ethyl acetate + (methanol, ethanol, n-propanol and isopropanol)

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 101.1kPa. 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 298.15K. 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.

Thermodynamic functions for solubility of 2-mercaptobenzothiazole in eleven pure organic solvents at temperatures from 273.15 K to 318.15 K and mixing properties of solutions

The solid-liquid equilibrium of 2-mercaptobenzothiazole in eleven solvents of methanol, n-propanol, i-propanol, n-butanol, i-butanol, acetonitrile, ethyl acetate, toluene, 2-butanone, chloroform and 1,4-dioxane was investigated by the isothermal dissolution equilibrium method under atmosphere pressure of 101.2kPa, and the solubilities were determined by a high-performance liquid chromatography at T=(273.15, 275.65, 278.15, 280.65, 283.15, 285.65, 288.15, 290.65, 293.15, 295.65, 298.15, 300.65, 303.15, 305.65, 308.15, 310.65, 313.15, 315.65 and 318.15)K. For the eleven solvents, the mole fraction solubility of 2-mercaptobenzothiazole increased with increasing temperature. Thee obeyed the following order from high to low in different solvents: 2-butanone>1,4-dioxane>ethyl acetate>n-butanol>n-propanol>i-butanol>i-Propanol>methanol>chloroform>acetonitrile>toluene. The solubility values obtained for 2-mercaptobenzothiazole in the selected solvents were correlated with four models, which corresponded to modified Apelblat equation, λh equation, Wilson model and NRTL model. The largest values of relative average deviation and the root-mean-square deviation acquired with the four models were 0.59 % and 4.86×10−4, respectively. Generally, the four thermodynamic models were all acceptable for describing the solubility behaviour of 2-mercaptobenzothiazole in the solvents. In addition, based on the Wilson model, the mixing thermodynamic properties (mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration and reduced excess enthalpy) of solutions were derived. The results indicated that the dissolution of 2-mercaptobenzothiazole in all studied cases was spontaneous and favourable. The solubility values and thermodynamic relations of 2-mercaptobenzothiazole in selected solvents would be invoked as fundamental data and models regarding the purification process of 2-mercaptobenzothiazole.

Solubility, solution thermodynamics and preferential solvation for 4-bromopyrazole in mixed solvents of (methanol/ethanol + water) from T = (283.15 to 318.15) K

The solubility of 4-bromopyrazole in binary (methanol+water) and (ethanol+water) solvent mixtures were investigated by using the isothermal dissolution equilibrium method under atmosphere pressure. The maximum solubility was observed in neat methanol or ethanol. At the same mass fraction of methanol or ethanol and temperature, the solubility of 4-bromopyrazole was greater in (ethanol+water) than in (methanol+water) mixed solvents. The obtained solubility data were correlated with Jouyban-Acree model, modified Apelblat-Jouyban-Acree model and van’t Hoff-Jouyban-Acree model. The largest values of relative average deviation and the root-mean-square deviation were 3.59×10−2 and 6.60×10−3, respectively. Positive apparent enthalpies showed that dissolution of 4-bromopyrazole in these mixed solvents was an endothermic process. Preferential solvation parameters of 4-bromopyrazole were also derived by means of the inverse Kirkwood-Buff integrals method. The preferential solvation parameter was negative in water-rich mixtures but positive in intermediate composition and alcohol-rich mixtures. In the latter case, it is conjecturable that 4-bromopyrazole is acting as a Lewis acid with alcohol molecules. The co-solvent action may be related to the breaking of the ordered structure of water around the polar moieties of 4-bromopyrazole which increases the solvation of this solute. The solubility data and thermodynamic study expanded the physicochemical information about 4-bromopyrazole in binary solvent mixtures.

4-(Methylsulfonyl)benzaldehyde Solubility in Binary Solvent Mixtures of Acetonitrile + (Methanol, Ethanol and Isopropanol): Determination and Modelling

The solubilities of 4-(methylsulfonyl)benzaldehyde in the binary mixed solvents acetonitrile + methanol, acetonitrile + ethanol and acetonitrile + isopropanol were determined experimentally using an isothermal dissolution equilibrium method within the temperature range from 283.15 to 318.15 K under atmospheric pressure. The solubility of 4-(methylsulfonyl)benzaldehyde increased with increasing temperature and mass fraction of acetonitrile in each binary system. At the same temperature and mass fraction of acetonitrile, the mole fraction solubility of 4-(methylsulfonyl)benzaldehyde is greater in (acetonitrile + methanol) than in the other two mixed solvents. The solubility data were correlated using the CNIBS/R-K model, Jouyban–Acree model, van’t Hoff–Jouyban–Acree model, Apelblat–Jouyban–Acree model, Ma model and Sun model. The maximum values of relative average deviation (RAD) and root-mean-square deviation (RMSD) are 1.53% and 1.17 × 10−4, respectively. All of the selected models provided good representation of the experimental solubilities. Furthermore, the standard enthalpies of dissolution were calculated. The dissolution process for 4-(methylsulfonyl)benzaldehyde in these mixed solvents is endothermic. The experimental solubility and the models presented in this work are important for the production and purification of 4-(methylsulfonyl)benzaldehyde.

Solubility and solution thermodynamics of 4-hydroxybenzaldehyde in twelve organic solvents from T = (278.15 to 318.15) K

In this study, the solid-liquid equilibrium of 4-hydroxybenzaldehyde in twelve solvents including methanol, ethanol, n-propanol, 1-butanol, isopropanol, ethyl acetate, 2-butanone, acetonitrile, toluene, N,N-dimethylformamide, 1,4-dioxane and acetone were constructed by the isothermal dissolution equilibrium method at a temperature range from (278.15 to 318.15)K under atmospheric pressure (101.2kPa), and the solubility values of 4-hydroxybenzaldehyde in these solvents were determined by a high-performance liquid chromatography. The mole fraction solubility increased with increasing temperature and obeyed the following order from high to low in different solvents except for 1,4-dioxane: N,N-dimethylformamide>2-butanone>acetone>ethyl acetate>(1-butanol, isopropanol)>n-propanol>ethanol>methanol>acetonitrile>toluene. The modified Apelblat equation, λh equation, Wilson model and NRTL model were used to correlate the solubility of 4-hydroxybenzaldehyde in different solvents. Results showed that the largest values of relative average deviation and root-mean-square deviation obtained with the four models were 2.66% and 78.9×10−3, respectively. Moreover, the mixing properties including the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration and reduced excess enthalpy were calculated. The solution process of 4-hydroxybenzaldehyde was spontaneous and favorable in the selected solvents. The solubility data and thermodynamic studies would be invoked as fundamental data and models regarding purification process of 4-hydroxybenzaldehyde and optimization conditions for its bromination process.

Solubility determination and modelling for 4-nitrobenzaldehyde in N,N-dimethylformamide + (ethanol, n-propanol or n-butanol) mixed solvents

The solubility of 4-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 method within the temperatures ranging from (273.15 to 313.15)K under atmosphere pressure (101.2kPa). The solubility of 4-nitrobenzaldehyde increased with increasing temperature and mass fraction of N,N-dimethylformamide for the binary systems of (N,N-dimethylformamide+ethanol), (N,N-dimethylformamide+n-propanol) and (N,N-dimethylformamide+n-butanol). At the same temperature and mass fraction of N,N-dimethylformamide, the mole fraction solubility of 4-nitrobenzaldehyde in ethanol was greater than those in the other two systems. The obtained solubility data were correlated by employing CNIBS/R-K model, Jouyban–Acree model, van't Hoff–Jouyban–Acree model, modified Apelblat–Jouyban–Acree and Sun model. The largest values of relative average deviation (RAD) and root-mean-square deviation (RMSD) between the experimental and calculated solubility were 0.92×10−2 and 6.22×10−4, respectively, which were obtained with Jouyban–Acree model for the system of N,N-dimethylformamide+n-propanol. On the whole, the CNIBS/R-K model was proven to provide better representation of the experimental solubility data. Based on the measured solubility, the dissolution enthalpies of the dissolution process were computed. Dissolution process of 4-nitrobenzaldehyde in these mixed solvents was endothermic. The experimental solubility and solubility models could be helpful in purifying 4-nitrobenzaldehyde from its isomeric mixtures.

Solubility determination and thermodynamic modelling of 3,5-dimethylpyrazole in nine organic solvents from T = (283.15 to 313.15) K and mixing properties of solutions

Solubility of 3,5-dimethylpyrazole in nine organic solvents including ethanol, isopropanol, n-propanol, 1-butanol, methanol, ethyl acetate, toluene, acetone, acetonitrile was determined experimentally by using the isothermal saturation method over a temperature range from (283.15 to 313.15)K under 101.3kPa. For the temperature range studied, the solubility of 3,5-dimethylpyrazole in the solvents increased with a rise of temperature. In general, they obeyed the following order from high to low in different solvents: 1-butanol>n-propanol>(ethanol, isopropanol, methanol, ethyl acetate, acetone)>toluene>acetonitrile. The acquired solubility data of 3,5-dimethylpyrazole in the studied solvents were correlated by using 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 3.293×10−3 and 2.62%, respectively. The RAD values acquired with the modified Apelblat equation were smaller than those with the other three models for a certain solvent except for the system of n-propanol. Generally, the four thermodynamic models were all acceptable for the systems of 3,5-dimethylpyrazole in these solvents. Furthermore, the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration (γ1∞) and reduced excess enthalpy (H1E,∞) were obtained. The solution process of 3,5-dimethylpyrazolewas spontaneous in the studied solvents. The obtained solubility and thermodynamic studies would be very helpful for optimizing the purification process of 3,5-dimethylpyrazole.

Solubility of 4-methyl-2-nitroaniline in fourteen organic solvents from T = (278.15 to 313.15) K and mixing properties of solutions

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 101.2kPa, 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.

High pressure densities for mixed ionic liquids having different functionalities: 1-butyl-3-methylimidazolium chloride and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

In this work, high pressure density measurements were made of mixed ionic liquid systems (1-butyl-3-methylimidazolium chloride ([bmim]Cl) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N])) for the purpose of developing efficient reaction and separation systems for processing biomass. The mixed ionic liquids were prepared at mole ratios, [bmim]Cl:[bmim][Tf2N] of 0.75: 0.25, 0.50: 0.50 and 0.25: 0.75. Density data were measured (10–200MPa, 312–392K) and correlated (up to 100MPa) with the ε∗-modified Sanchez-Lacombe equation of state (ε∗-mod SL EoS). The density of the binary mixed ionic liquid system was modeled in two ways: (i) as a single pseudo-component or (ii) as two discrete components. By treating the mixed ionic liquids as a single pseudo-component, the ε∗-mod SL EoS could correlate the high pressure density data to within a maximum average relative deviation (ARD) of 0.06%. On the other hand, by treating the mixed ionic liquids as discrete components, higher ARD values (0.15%) were obtained from the ε∗-mod SL EoS that can be attributed to the EoS mixing rules. Both approaches for modeling the ionic liquid mixtures had sufficiently low deviations and will be applied to multicomponent CO2-containing systems in future works.

Prediction of Thermal Conductivity and Viscosity of Ionic Liquid-Based Nanofluids Using Adaptive Neuro Fuzzy Inference System

ABSTRACTNowadays, ionic liquid-based nanofluids are introduced as a new class of heat transfer fluids, which exhibit superior thermal properties compared to their base ionic liquids. Potential applications of these nanofluids make it necessary to know their thermophysical properties such as thermal conductivity and viscosity. Therefore, adaptive neuro fuzzy inference system (ANFIS) has been successfully developed to predict thermal conductivity and viscosity of ionic liquid-based nanofluids. The developed models have investigated the influence of temperature, nanoparticle concentration, and ionic liquid molecular weight on the thermophysical properties of nanofluids. After developing ANFIS structure, the capability and accuracy of the developed neuro fuzzy models have been evaluated by comparison of model predictions with experimental data extracted from the literature and calculation of statistical parameters such as coefficient of determination (R2) and average relative deviation (ARD). The ARD of ANFIS model in prediction of thermal conductivity of nanofluids is 0.72%, with a high R2 of 0.9959. The values of ARD and R2 for estimation of nanofluids viscosity are 5.1% and 0.9934, respectively, which indicates a satisfactory degree of accuracy for the proposed models.

Solubility determination and modelling for phthalimide in mixed solvents of (acetone, ethyl acetate or acetonitrile + methanol) from (278.15 to 313.15) K

The solubilities of phthalimide in mixed solvents of (acetone+methanol), (ethyl acetate+methanol) and (acetonitrile+methanol) were determined experimentally by using the isothermal dissolution equilibrium method within the temperature range from (283.15 to 318.15)K under atmospheric pressure (101.1kPa). For the three systems of (acetone+methanol), (ethyl acetate+methanol) and (acetonitrile+methanol), at a fixed composition of acetonitrile, acetone or ethyl acetate, the solubility of phthalimide increased with an increase in temperature; however, at the same temperature, they increased at first and then decreased with the increase in mass fraction of acetonitrile, acetone or ethyl acetate. At the same temperature and mass fraction of acetonitrile, acetone or ethyl acetate, the mole fraction solubility of phthalimide in (acetone+methanol) was greater than those in the other mixed solvents. The solubility values obtained were correlated with Jouyban-Acree model, van’t Hoff-Jouyban-Acree model, modified Apelblat-Jouyban-Acree model and CNIBS/R-K model. The maximum values of relative average deviations (RAD) and root-mean-square deviations (RMSD) between the experimental and calculated solubility were 5.64×10−2 and 11.56×10−4, respectively. The CNIBS/R-K model proved to provide the best representation of the experimental results. In addition, the standard dissolution enthalpies of the dissolution process were calculated on the basis of the measured solubility. Dissolution of phthalimide in these mixed solvents is an endothermic process.

Determination and thermodynamic modelling for 2-methyl-6-nitroaniline solubility in binary solvent mixtures of ethyl acetate + (methanol, ethanol, n-propanol and isopropanol)

The solubility of 2-methyl-6-nitroaniline in binary mixed solvents of (ethyl acetate+methanol), (ethyl acetate+ethanol), (ethyl acetate+n-propanol) and (ethyl acetate+isopropanol) was determined experimentally by using the isothermal dissolution method within the temperature range from (278.15–313.15)K under atmosphere pressure. The solubility of 2-methyl-6-nitroaniline increased with increasing temperature and mass fraction of ethyl acetate in each binary system. At the same temperature and mass fraction of ethyl acetate, the mole fraction solubility of 2-methyl-6-nitroaniline was greater in (ethyl acetate+n-propanol) than in the other three mixed solvents. The achieved solubility values were correlated by employing Jouyban-Acree model, van’t Hoff-Jouyban-Acree model, Apelblat-Jouyban-Acree model, Ma model, Sun model and CNIBS/R-K model. The values of relative average deviations (RAD) and root-mean-square deviations (RMSD) were no greater than 1.79% and 20.56×10−4 for the six models. In general, the Jouyban-Acree model proved to provide better representation of the experimental solubility. Furthermore, the dissolution enthalpies of the dissolution process were calculated. Positive values of dissolution enthalpy showed that the dissolution process of 2-methyl-6-nitroaniline in these mixed solvents was endothermic. The experimental solubility results and models presented in the present work are essential in the practical process for production and purification of 2-methyl-6-nitroaniline.

Thermodynamic study of solubility for 2-amino-4-chloro-6-methoxypyrimidine in twelve organic solvents at temperatures from 273.15 K to 323.15 K

The solubility of 2-amino-4-chloro-6-methoxypyrimidine in methanol, ethanol, chloroform, toluene, ethyl acetate, acetonitrile, n-propanol, acetone, N,N-dimethylformamide, isopropanol, 1,4-dioxane and ethyl benzene was obtained experimentally using the high-performance liquid chromatography analysis at temperatures ranging from (273.15 to 323.15)K under atmospheric pressure. The solubility of 2-amino-4-chloro-6-methoxypyrimidine in a fixed solvent increased with an increase in temperature. At a certain temperature, the mole fraction solubility in different solvents decreased according to the following order: N,N-dimethylformamide>dioxane>acetone>ethyl acetate>chloroform>(acetonitrile, n-propanol)>(ethanol, isopropanol)>methanol>toluene>ethyl benzene. Four models, modified Apelblat equation, λh equation, Wilson model and NRTL model were applied to correlate of the experimental solubility results. The largest values of relative average deviation and root-mean-square deviation acquired by the four models are 1.21% and 10.71×10−4, respectively. The modified Apelblat model is regarded as the best one for describing the experimental values. Furthermore, the mixing Gibbs energy, mixing enthalpy, and mixing entropy, activity coefficient and reduced excess enthalpy at infinitesimal concentration were obtained based on the mole fraction solubility. The mixing process of 2-amino-4-chloro-6-methoxypyrimidine in the selected solvents is discussed.

Solubility of 3-methyl-4-nitrobenzoic acid in binary solvent mixtures of {(1,4-dioxane, N-methyl-2-pyrrolidone, N,N-dimethylformamide) + methanol} from T = (283.15 to 318.15) K: Experimental determination and thermodynamic modelling

The solubility of 3-methyl-4-nitrobenzoic acid (MNBA) in binary (1,4-dioxane+methanol), (N-methyl-2-pyrrolidone (NMP)+methanol) and (N,N-dimethylformamide (DMF)+methanol) solvent mixtures were investigated by the isothermal dissolution equilibrium method under atmospheric pressure. The studies were performed at different mass fractions of 1,4-dioxane, DMF or NMP ranging from 0.1 to 0.9 at temperature T=(283.15 to 318.15)K. The solubility of MNBA in mixed solutions increased with increasing temperature and mass fraction of 1,4-dioxane, DMF or NMP for the three systems including (1,4-dioxane+methanol), (NMP+methanol) and (DMF+methanol). At the same mass fraction of 1,4-dioxane, DMF or NMP and temperature, the solubility of MNBA was greater in (DMF+methanol) than in the other mixed solvents. The obtained solubility data were correlated with Jouyban-Acree model, van’t Hoff-Jouyban-Acree model, modified Apelblat-Jouyban-Acree model, Ma model, Sun model and CNIBS/R-K model. The largest values of relative average deviations (RAD) and the root-mean-square deviations (RMSD) between the experimental and calculated solubility were 4.62×10−2 and 2.41×10−3, respectively. The calculated solubility with the six models agreed well with the experimental results. On the basis of the solubility obtained, the standard dissolution enthalpy of the dissolution process was calculated. Dissolution of MNBA in these mixed solvents was an endothermic process. The experimental solubility and the models in this study could be helpful in purifying the crude MNBA.

Thermodynamic modelling for solubility of 5-chloro-1-methyl-4-nitroimidazole in eleven organic solvents from T = (283.15 to 318.15) K

Solubilities of 5-chloro-1-methyl-4-nitroimidazole in eleven organic solvents of methanol, ethanol, isopropanol, n-propanol, N-methyl-2-pyrrolidone, ethyl acetate, toluene, acetone, 2-butanone, trichloromethane and 1,4-dioxane were measured by using an isothermal saturation method at temperatures between 283.15K and 318.15K under 101.3kPa. For the temperature range investigated, the solubilities of 5-chloro-1-methyl-4-nitroimidazole in these solvents increased with the increase in temperature. Overall, the mole fraction solubility obeyed the following order from high to low in different solvents: N-methyl-2-pyrrolidone>acetone>2-butanone>trichloromethane>ethyl acetate>1,4-dioxane>methanol>ethanol>toluene>n-propanol>isopropanol. The solubility values obtained for 5-chloro-1-methyl-4-nitroimidazole in the selected solvents were correlated via the λh equation, modified Apelblat equation, NRTL model and Wilson model. The largest value of root-mean-square deviation (RMSD) was 9.20×10−4, and the relative average deviation (RAD), 2.86%. The RAD values obtained with the modified Apelblat equation were smaller than those with the other three models except for the solvents of acetone and ethanol. Generally, the four thermodynamic models were all acceptable for describing the solubility of 5-chloro-1-methyl-4-nitroimidazole in the solvents. Moreover, the mixing Gibbs energy, mixing enthalpy, mixing entropy, activity coefficient at infinitesimal concentration (γ1∞) and reduced excess enthalpy (H1E,∞) were achieved. The solution process of 5-chloro-1-methyl-4-nitroimidazole was spontaneous and favourable in the solvents selected. The solubility values and thermodynamic studies would provide a fundamental basis for optimizing the purification process of 5-chloro-1-methyl-4-nitroimidazole.