Buchowski Ksiazaczak Λh Model Research Articles

Determination of Gibberellin A3 solubility in different solvents based on mathematical models, solvent effect and thermodynamic analysis

For gibberellin A3, one of the important phytohormones, solubility parameters and characterisation are the basis of data for its isolation and purification. In this work, the solubility of GA3 was determined in twelve pure solvents (ethanol, isopropanol, 1-butanol, n-hexane, n-heptane, trichloromethane, ethyl acetate, acetone, xylene, tetrahydrofuran, dimethylsulfoxide and acetonitrile) and three binary mixed solvents (trichloromethane + ethanol, acetonitrile + ethanol and n-hexane + ethanol) at temperatures ranging from 278.15 K to 323.15 K. The experimental results showed that the solubility of GA3 in various solvents was positively correlated with the temperature, with better solubility in ethanol. The measured data were fitted with the modified Apelblat model, the Buchowski-Ksiazaczak λh model, the CNIBS/R-K model and the Jouyban-Acree model. Then, the solvent effect was analyzed using the KAT-LSER model, which showed that the dipole polarisation rate of the solvent had the greatest effect on the solubility of GA3. In addition, the dissolution thermodynamic properties of GA3 were studied with the van't-Hoff equation, concluding that the dissolution of GA3 was an entropy-driven heat absorption process. The data obtained from this research will contribute to improve the purity of GA3 in the recrystallisation process, and ensure its efficacy and stability, thereby playing a certain guiding role in the industrial production of GA3.

Solubility determination and thermodynamic model analysis of nefopam hydrochloride in eight plain solvents and three binary solvents from 273.15 K to 323.15 K

Nefopam hydrochloride (NPH) is a non-narcotic analgesic with antipyretic, analgesic, and muscle relaxant effects. Solubility is an important molecular property that can inform the crystallization and purification of drugs. In the present study, NPH solubility was measured in eight plain solvents and three binary solvents at 273.15 K-323.15 K. Results showed that in the plain solvents, NPH had the greatest solubility in methanol and the least in acetone. The solubility in the solvent system of methanol + acetone and ethanol + acetone becomes greater with the increase of the molar fraction of the positive solvent, while it becomes greatest in the system of water + acetone when the molar fraction of the positive solvent is 0.8 and at molar fractions>0.8 the solubility begins to decrease, which may be owing to the existence of the phenomenon of co-solubility. NPH solubility in plain solvents and binary solvents is positively correlated with temperature. By XRD and TG-DSC, the crystal structure of NPH in solvent did not change and the weight loss and melting temperatures were 500.49 K and 518.34 K respectively, which were much higher than the experimental temperatures. Selection of Hansen solubility parameter to predict the solubility effect of NPH in different solvents. The analysis was carried out using five thermodynamic models, ranging from Modified Apelblat model, Buchowski-Ksiazaczak λh model, CNIBS/R-K model, Jouyban-Acree model and SUN model, to fit the solubility data, out of which Modified Apelblat model and CNIBS/R-K model had more accurate prediction results.

Solubility study and thermodynamic modelling of succinic acid and fumaric acid in bio-based solvents

The solubility and involved energies of organic acids in green solvents are relevant to the design of sustainable biorefinery downstream processes. In this work, the solubility of two important bio-based organic acids such as succinic acid and fumaric acid, in water and four bio-based solvents (i.e., ethyl acetate, 1,8-cineole, cyclopentyl methyl ether, and 2-methyl tetrahydrofuran) were measured within a temperature range of [283 – 313] K. A gravimetric methodology was adopted, previously validated using the organic acid aqueous solubilities available in the literature. The reported data present an average estimated uncertainty of measurement, with a level of confidence of 95%, of 5.2·10-4 mol·mol−1. Experimental results were correlated with the van’t Hoff equation, and the Buchowski–Ksiazaczak λh model, where the root mean squared deviations were <3.9·10-4 for all systems. From the experimental data and the COSMO-RS molecular simulation method, the solid–liquid equilibria were modelled to estimate the excess energies and the solute activity coefficients of the saturated solutions. Excess enthalpy contribution analysis shows that attractive hydrogen-bonding interactions between the organic acids and the green solvents drive the dissolution phenomena. The magnitude of the hydrogen-bonding interactions increases with temperature for all systems, agreeing with the observed solubility trends. The organic acid energies of solution were estimated from the van’t Hoff equation, demonstrating an enthalpy–entropy compensation effect. The energetic analysis shows that the dissolution phenomenon is an enthalpy-driven process for fumaric acid, whereas no predominant effect is observed for succinic acid.

Solubility parameter and solution thermodynamic properties of Form I Trimebutine maleate in six mono-solvents and three binary mixed solvents at different temperatures

The solubility information of drugs in solution is of great significance in the fields of chemistry and pharmacy. Trimebutine maleate is a commonly used drug for treating gastrointestinal disorders, and its solid–liquid balance data are critical for a preliminary study of industrial application. This study investigated the solubility of medicinal crystal form (Form Ⅰ) of Trimebutine maleate at T = 283.15–328.15 K. The molar fraction solubility of Form Ⅰ in six mono-solvents and three binary mixtures were studied. The modified Apelblat equation, the general Buchowski-Ksiazaczak λh model and the new correlative model were used for correlation analysis of the solubility of Form Ⅰ in mono-solvents. The general cosolvency model and Jouyban-Acree-van't Hoff model were used for correlation analysis of the solubility of Form Ⅰ in binary mixed solvents. By comparing the models, the modified Apelblat equation and the general cosolvency model provided more accurate experimental data for predicting the solubility of Form Ⅰ in mono-solvents and binary mixed solvents, respectively. Finally, the apparent thermodynamic properties were calculated by the van't Hoff analysis.

Solubility determination and thermodynamic model analysis of nevirapine in different organic solvents from 278.15 K to 328.15 K

Nevirapine (NVP) is the first non-nucleoside reverse transcriptase inhibitor drug to be marketed for the treatment of HIV. The solubility of NVP under atmospheric pressure in eleven pure solvents and three mixtures was measured from 278.15 to 323.15 K. XRD and DSC were used to detect the crystal form and stability of NVP in this work. Overall, the solubility of NVP gradually increases as the temperature rises. In addition, under the same temperature conditions, the solubility of NVP increases with the ratio of the positive solvents in binary solvents. In the mixture (DMF + acetonitrile), when the proportion of DMF reaches 0.8, the solubility in the binary solvent is greater than that in pure DMF. The experimental data was fitted by five thermodynamic models (Buchowski-Ksiazaczak λh model, the Modified Apelblat model, Jouyban-Acree model, SUN model, and CNIBS/R-K model). Subsequently, the largest mean square deviation value (RMSD) is only 2.31E-04, which demonstrates that the correlation of the solubility data and the five models is relatively good. Additionally, KAT-LSER model was used to explore the effects of solute–solvent interactions on solubility at 298.15 K. The analysis results indicated that the dipolarity/polarizability (π∗) of pure solvents plays a crucial role in the dissolution of NVP and its proportion of the total solvent effect reaches 30.92 %. This research was explored and developed the important systems (1-propyl alcohol and DMF + acetonitrile) for the industrial crystallization purification of NVP.

Solubility determination and analysis of methimazole in different solvent systems at T = 278.15–323.15 K

Methimazole is a commonly used drugs for treatment ofhyperthyroidism. Researching the solubility property of methimazole in multifarious solvent systems can be used for optimizing the purification process of methimazole in industry. In this study, the solubility properties of methimazole in twelve pure solvents (methanol, ethanol, 1-propanol, isopropanol, 1-butanol, isobutanol, 1,4-dioxane, methyl acetate, acetonitrile, ethyl acetate, tetrahydrofuran, acetone) and four binary mixed solvents (methanol + ethyl acetate, methanol + acetonitrile, methanol + isopropanol, methanol + methyl acetate) were tested within 278.15 K to 323.15 K under 101.325 kPa. The results show that methimazole has the highest solubility in methanol and the smallest solubility in ethyl acetate. In addition, solubility is positively correlated with temperature in pure solvents and mixed solvents. The XRD spectrum results show that the crystal form of methimazole before and after dissolving in twelve pure solvents do not change. The DSC test shows that the melting point of methimazole is 417.27 K, and it is also proved that methimazole do not decompose before reaching the melting point. Herein, the Modified Apelblat model and Buchowski-Ksiazaczak λh model were used to fit the solubility data of methimazole in pure solvents. Jouyban-Acree model, CNIBS/R-K model and SUN model were used to fit the solubility data of methimazole in binary mixed solvents. The results show that Modified Apelblat model and CNIBS/R–K model have the best correlation with the solubility of methimazole. Analysis using the KAT-LSER model reveals that the influence of the interaction between part of the solvent and solute molecule on solubility. The results show that the impact of dipolarity/polarizability is dominant.

Determination and analysis of solubility of brassinolide in different solvent systems at different temperatures (T = 278.15–323.15 K)

Brassinolide is a new environmental protection plant growth regulator. With the aim of knocking down selfcost and scale up agriculture market-place emulation, come what will manufacture method is adopted, the final step crystallization is significant for getting exclusive substances. The purpose of this study is to provide some authentic and general energetics data for the actual industrial production of brassinolide. In the research, the solid–liquid equilibrium of brassinolide in twelve pure solvents (tetrahydrofuran, dimethyl sulfoxide, ethanol, acetone, methanol, trichloromethane, acetonitrile, 1-butanol, isopropanol, xylenes, n-hexane and n-heptane) and three binary solvent mixtures (trichloromethane + tetrahydrofuran, acetonitrile + tetrahydrofuran and n-hexane + tetrahydrofuran) were tested by the circumstance of atmosphere pressure at range temperatures between 278.15 K and 323.15 K. Four models like the Buchowski–Ksiazaczak λh model, the modified Apelblat model, the Jouyban-Acree-van't-Hoff model and the Redich-Kister (CNIBS/R-K) model were employed to describe the change trend of solubility. On the groundwork of a series of data analysis, tetrahydrofuran is a better organic solvent and n-hexane can be applied as an effective anti-solvent when separating out brassinolides. These solubility data are very important for optimizing the extraction process and recrystallization of brassinolide.

Solubility determination and thermodynamic modelling of Progesterone in twelve pure solvents and three binary solvents at 278.15 to 323.15 K

The solubility of Progesterone at T = 278.15–323.15 K was measured by static equilibrium method combined with HPLC in twelve solvents (methanol, ethanol, isopropanol, n-propanol, n-butanol, acetone, tetrahydrofuran, 1,4-dioxane, n-heptane, ethyl acetate, acetonitrile, and toluene) and three binary solvents (tetrahydrofuran + n-heptane, 1,4-dioxane + n-heptane, and toluene + n-heptane). The results showed that progesterone has the highest solubility in toluene (0.2249 in mole fraction) and other low-dielectric constant solvents, and the smallest in n-heptane (1.120 × 10−4 in mole fraction). Moreover, the solubility increases as the temperature rise both in pure and mixed solvents. As expected, the DSC and XRDP results showed that there was no crystal form difference between the raw material and all the precipitate. Herein, the Modified Apelblat model, Buchowski-Ksiazaczak λh model, Jouyban-Acree model, CNIBS/R-K model, and SUN model were employed to fit the experimental data. As a result, the maximum RAD doesn't exceed 5.0%, and the maximum RMSD was less than 0.1%. Furthermore, we chose KAT-LSER model to explore the solubility of progesterone and the solute-solvent interaction relationships. The results showed that when hydrogen bond acidity and polarizability/dipolarity of solvents increases, the solubility of progesterone increases. Meanwhile, comparing the experimental data and the fitting results, it can be concluded that the experimental data was reliable and almost consistent with the fitting results. Furthermore, it also proved that the above mentioned five thermodynamic equations were advantageous and trustworthy.

Solubility measurement, Hansen solubility parameter and thermodynamic modeling of etodolac in four binary solvents from 278.15 K to 323.15 K

In this study, the laser monitoring method was used to measure the solubility of etodolac in four binary mixtures ((n-propanol, methyl acetate, n-butyl acetate and acetone) + n-hexane) at 278.15 K–323.15 K. The results show that under a certain solvent composition, the solubility of etodolac increases with the increase of temperature. Except for the mixture of acetone + n-hexane, the solubility of etodolac in the other three mixing systems increases with the increase of the mass fraction of the co-solvent (n-propanol, methyl acetate and n-butyl acetate) at a certain temperature. For the acetone + n-hexane system, the order of solubility is: acetone > acetone (ω1 = 0.6000) + n-hexane > acetone (ω1 = 0.8000) + n-hexane > acetone (ω1 = 0.4000) + n-hexane > acetone (ω1 = 0.2001) + n-hexane, indicating that a co-dissolution phenomenon may occur when the mass fraction of acetone is 0.6000. The Hansen solubility parameter was used to explain the solubility order of etodolac in four binary mixed solvents. At the same time, five models (modified Apelblat model, Buchowski-Ksiazaczak λh model, Wilson model, Three-Suffix Margules model and Uniquac model) were used to correlate the solubility data, which shows that all the five models have a good correlation. Through the comparison of ARD and RMSD, it was found that the modified Apelblat model can get more satisfactory results.

Saturated Solubility and Thermodynamic Evaluation of l-Tryptophan in Eight Pure Solvents and Three Groups of Binary Mixed Solvents by the Gravimetric Method at T = 278.15–333.15 K

In this research, solubility of l-tryptophan in water, methanol, ethanol, acetone, isopropanol, n-butanol, acetonitrile, ethyl acetate, organic pure solvent, and in three binary mixed solvents (water + acetonitrile), (water + methanol), and (water + isopropanol) at the temperature range of T = 278.15–333.15 K was determined with the gravimetric method. The experimental results show that the solubility of l-tryptophan in the above solvents increased as temperature rose, and it achieved the highest dissolution efficiency in water. The improved Apelblat model, the Buchowski–Ksiazaczak λh model, the Redlich–Kister (CNIBS/R–K) model, and the Jouyban–Acree model were used to nonlinearly fit the experimental data of solubility, and the consistency was good. The physicochemical information of l-tryptophan provided in this report may be helpful for its extraction/separation, recrystallization, purification, and formulation development.

Thermodynamic Models for Determination of Solid–Liquid Equilibrium of the Buprofezin in Pure and Binary Organic Solvents

Buprofezin is a kind of insecticide and an important chemical intermediate product. Data on solid–liquid equilibrium of buprofezin in different solvents is essential for the area of industrial applications. In this work, the solubility of buprofezin in methanol, ethanol, isopropanol, n-butanol, acetonitrile, n-hexane, ethyl acetate, N,N-dimethylformamide, and two binary solvent mixtures (methanol + ethyl acetate and acetonitrile + ethyl acetate) was measured at the temperature range of 278.15–328.15 K at atmospheric pressure by the gravimetric method. The experimental values showed that elevated temperatures increased the solubility of buprofezin in all selected solvents. The modified Apelblat model, the Buchowski–Ksiazaczak λh model, combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R-K) model, Jouyban–Acree model, and an ideal model were used to describe and predict the diversification trend of solubility.

Solubility Study of (2E)-1-(3-Pyridyl)-3-(dimethylamino)-2-propen-1-one in Different Pure Solvents and Binary Solvent Mixtures from 278.15 to 328.15 K

In this study, the solubility of (2E)-1-(3-pyridyl)-3-(dimethylamino)-2-propen-1-one in methanol, n-propanol, acetone, dimethylformamide, 1,4-dioxane, ethyl acetate, tetrahydrofuran, cyclohexane, and binary solvent mixtures of (dimethylformamide + acetone), (1,4-dioxane + cyclohexane), and (dimethylformamide + ethyl acetate) at temperatures from 278.15 to 328.15 K and under a pressure of 0.1 MPa was measured by a gravimetric analysis method. The experiment results and data showed that the increased solubility in selected pure and binary solvents is the result of increasing temperature. The solubility data of (2E)-1-(3-pyridyl)-3-(dimethylamino)-2-propen-1-one were fitted well with the modified Apelblat equation, the Buchowski–Ksiazaczak λh model, the combined nearly ideal binary solvent/Redlich–Kister model, and the Jouyban–Acree model.

Thermodynamic study of three anhydrous polymorphs of d-mannitol in different binary solvent mixtures from T = (258.15 to 278.15) K

In this work, the solubility of three pure anhydrous polymorphs of d-mannitol (α form, β form, and δ form) in binary solvent mixtures, including (methanol-water) and (ethanol-water), was determined by a HPLC method with the temperature ranging from (258.15 to 278.15) K at atmospheric pressure (0.1 MPa). The experimental results indicate that the solubility of the three polymorphs increases with temperature and decreases with the rise of the organic component (methanol and ethanol) ratio in the binary solvents. Moreover, the solubility of three d-mannitol polymorphs ranks as (δ form) > (α form) > (β form) under the same condition. Additionally, the modified Apelblat model, Buchowski-Ksiazaczak λh model, Ma model and NRTL model are used to correlate the solubility data in binary solvents. Furthermore, the thermodynamic properties of mixing process of d-mannitol polymorphs, including the Gibbs energy change, entropy and enthalpy, were also calculated and discussed.

Solubility evaluation and thermodynamic modeling of β-lapachone in water and ten organic solvents at different temperatures

Although β-lapachone is a promising drug with pharmacological activity, issues concerning its low aqueous solubility are known. The objective of this study was to measure the solubility of β-lapachone in water and ten organic solvents at temperatures ranging from 298.15 K to 318.15 K under atmospheric pressure. The modified Apelblat model, the Buchowski-Ksiazaczak λh model, and the ideal model were used to correlate experimentally obtained solubility values. Moreover, thermodynamic analysis of β-lapachone dissolution was performed based on experimental solubility data using the van't Hoff equation. The highest mole fraction solubility of β-lapachone at 298.15 K was found in acetone (2.05 × 10−2), followed by acetonitrile (1.80 × 10−2), ethyl acetate (8.53 × 10−3), 1-butanol (7.43 × 10−3), 1-propanol (6.69 × 10−3), 2-butanol (5.65 × 10−3), methanol (5.40 × 10−3), ethanol (4.99 × 10−3), 2-propanol (3.76 × 10−3), propylene glycol (3.06 × 10−3), and water (2.85 × 10−6). Correlation results showed that the modified Apelblat model was more accurate than the Buchowski-Ksiazaczak λh model and the ideal model. Thermodynamic analysis indicated that β-lapachone dissolution was endothermic and entropy-driven process in all solvents studied. Data on solubility and thermodynamic properties in various solvents obtained in this study could be helpful in formulation development, purification, and crystallization of β-lapachone.

Apparent thermodynamic models for determination of the solubility of N-acetyl-1,3-phenylenediamine in eight pure solvents and two different miscible systems at T = (278.15–323.15) K

In this paper, a gravimetric method was utilized to measure the solubility of the N-acetyl-1,3-phe-nylenediamine under atmospheric pressure in N,N-dimethylformamide, ethyl acetate, acetone, methanol, water, tetrahydrofuran, acetonitrile, isopropanol, (isopropanol+tetrahydrofuran) and (ethyl acetate+tetrahydrofuran) binary mixtures with temperatures from T=(278.15–323.15) K. The experiment values have proved that rising temperature leads to increasing the solubility of the N-acetyl-1,3-phenylenediamine in all selected solvents. Solubility data of all pure solvents were fitted using the modified Apelblat model and the Buchowski–Ksiazaczak λh model. Solubility data of (isopropanol+tetrahydrofuran) and (ethyl acetate+tetrahydrofuran) binary solvent mixtures were fitted using the tow of the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K) model and the Jouyban–Acree model. During the research, the computational values match the experimental results well according to the calculations founded on all selected equations, and the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K) model provides a superior correlation in the binary solvent systems. In addition, the apparent thermodynamic properties of the solution process, including the Gibbs energy, enthalpy, and entropy were calculated by the van't Hoff analysis.

Thermodynamic models for determination of solid-liquid equilibrium of the 4-methylbenzoic acid in pure and binary organic solvents

Data on corresponding solid-liquid equilibrium of 4-methylbenzoic acid in different solvents are essential for a preliminary study of industrial applications. In this paper, the solid-liquid equilibrium of 4-methylbenzoic acid in methanol, ethanol, isopropanol, 1-butanol, acetone and acetonitrile pure solvents and (acetone+acetonitrile) mixture solvents were explored in the temperatures (from 278.15 to 323.15K) under atmosphere pressure. For the temperature range investigated, the solubility of 4-methylbenzoic acid in the solvents increased with increasing temperature. The modified Apelblat model, the Buchowski-Ksiazaczak λh model, and the ideal model were adopted to describe and predict the change tendency of solubility. Computational results showed that the modified Apelblat model had more advantages than the other two models. The solubility data were fitted using a modified Apelblat equation, a variant of the combined nearly ideal binary solvent/Redich-Kister (CNIBS/R-K) model, Jouyban-Acree model and Ma model in (acetone+acetonitrile) binary solvent mixture. In addition, the calculated thermodynamic parameters indicated that in each studied solvents the dissolution of 4-methylbenzoic acid is endothermic and entropy-driven process.

Thermodynamic parameters on corresponding solid-liquid equilibrium of hydroxyapatite in pure and mixture organic solvents

The thermodynamic parameters on corresponding solid-liquid equilibrium of hydroxyapatite in different solvents are essential for a preliminary study of pharmaceutical engineering and industrial applications. In this paper, a gravimetric method was used to correct the solid-liquid equilibrium of hydroxyapatite in water, methanol, ethanol, 1-butanol, acetone, acetonitrile, ethyl acetate, dimethyl formamide and tetrahydrofuran pure solvents as well as in the (1-butanol + acetonitrile) mixture solvents in the temperatures (from 278.15 K to 328.15 K) under 0.1 MPa. For the temperature range investigation, the solubility of hydroxyapatite in the solvents increased with increasing temperature. The solubility of hydroxyapatite in 1-butanol is superior to other selected pure solvents. The modified Apelblat model, the Buchowski-Ksiazaczak λh model, and the ideal model were adopted to describe and predict the change tendency of solubility. Computational results showed that the modified Apelblat model stood out to be more suitable with the higher accuracy. The solubility data were fitted using a modified Apelblat model, a variant of the combined nearly ideal binary solvent/Redich-Kister (CNIBS/R-K) model, Jouyban-Acree model and Ma model in (1-butanol + acetonitrile) binary solvent mixture. Computational results showed that the CNIBS/R-K model had more advantages than other models. In addition, the calculated thermodynamic parameters indicated that in each studied solvents the dissolution of hydroxyapatite is endothermic, non-spontaneous and entropy-drive process.

Equilibrium study and diversified models of drug Norfloxacin in eight pure organic and binary solvents at T = (278.15–328.15) K

Research on relevant solid–liquid equilibrium of drug Norfloxacin (NFLX) in different solvents is necessary for an elementary study of industrial implantation. In this work, the solid–liquid equilibrium of NFLX in ethanol, 1-butanol, isopropanol, acetone, acetonitrile, ethyl acetate, N-hexane, N,N-dimethylformamide single pure solvent and in (N,N-dimethylformamide + ethyl acetate) binary solvent mixtures were probed under atmosphere pressure at desired temperatures from 278.15 K to 328.15 K. The Gibbs energy, enthalpy, and entropy of solution were obtained from these solubility data. The modified Apelblat model, the Buchowski–Ksiazaczak λh model, Redich-Kister (CNIBS/R-K) model, Jouyban-Acree model, ideal model and the Van't Hoff analysis were applied to depict and forecast the diversification tendency of solubility. The satisfactory simulation results were obtained. Moreover, the thermodynamic functions for NFLX dissolution from calculation, using the van't Hoff and Gibbs equations, imply that in each studied solvent and in binary solvent mixtures, the process of NFLX dissolution is endothermic. Based on the above analysis, N,N-dimethylformamide is checked as the best solvent and ethyl acetate can be used as an effective anti-solvent in the crystallization process of NFLX.

Thermodynamic models for determination of solid–liquid equilibrium of the 6-benzyladenine in pure and binary organic solvents

Data on corresponding solid–liquid equilibrium of 6-benzyladenine in different solvents are essential for a preliminary study of industrial applications. In this paper, the solid–liquid equilibrium of 6-benzyladenine in methanol, ethanol, 1-butanol, acetone, acetonitrile, ethyl acetate, dimethyl formamide and tetrahydrofuran pure solvents and (dimethyl formamide+actone) mixture solvents was explored within the temperature range from (278.15 to 333.15) K under 0.1MPa. For the temperature range investigated, the solubility of 6-benzyladenine in the solvents increased with increasing temperature. The solubility of 6-benzyladenine in dimethyl formamide is superior to other selected pure solvents. The modified Apelblat model, the Buchowski-Ksiazaczak λh model, and the ideal model were adopted to describe and predict the change tendency of solubility. Computational results showed that the modified Apelblat model has more advantages than the other two models. The solubility results were fitted using a modified Apelblat equation, a variant of the combined nearly ideal binary solvent/Redich-Kister (CNIBS/R-K) model, Jouyban-Acree model and Ma model in (dimethyl formamide+acetone) binary solvent mixture. Computational results showed that the modified Apelblat model is superior to the other equations.

Determination and correlation thermodynamic models for solid–liquid equilibrium of the Nifedipine in pure and mixture organic solvents

Knowledge of thermodynamic parameters on corresponding solid-liquid equilibrium of nifedipine in different solvents is essential for a preliminary study of pharmaceutical engineering and industrial applications. In this paper, a gravimetric method was used to correct the solid-liquid equilibrium of nifedipine in methanol, ethanol, 1-butanol, acetone, acetonitrile, ethyl acetate and tetrahydrofuran pure solvents as well as in the (tetrahydrofuran+acetonitrile) mixture solvents at temperatures from 278.15K to 328.15K under 0.1MPa. For the temperature range investigation, the solubility of nifedipine in the solvents increased with increasing temperature. The solubility of nifedipine in tetrahydrofuran is superior to other selected pure solvents. The modified Apelblat model, the Buchowski-Ksiazaczak λh model, and the ideal model were adopted to describe and predict the change tendency of solubility. Computational results showed that the modified Apelblat model stood out to be more suitable with the higher accuracy. The solubility values were fitted using a modified Apelblat model, a variant of the combined nearly ideal binary solvent/Redich-Kister (CNIBS/R-K) model and Jouyban-Acree model in (tetrahydrofuran+acetonitrile) binary solvent mixture. Computational results showed that the CNIBS/R-K model had more advantages than other models.