Determination of the Solubility, Dissolution Enthalpy, and Entropy of Icariin in Acetone, Acetoacetate, Chloroform, and Light Petroleum

The solubility of icariin in acetone, acetoacetate, chloroform, and light petroleum in the 283.2‐318.2 K range was measured by ultraviolet-visible spectrophotometry. As the temperature increased, the solubility of icariin in the 4 solvents gradually increased. The solubility data correlated with the modified Apelblat equation. The dissolution enthalpy and entropy of icariin were determined using van’t Hoff plots. The dissolution enthalpy and entropy of icariin in the 4 solvents increases as acetone >acetoacetate >chloroform >light petroleum, which can be explained by the difference of the polarity indices between them. The polarity indices of the solvents affect the solubility behavior.

Solubility of dicarbohydrazide bis[3-(5-nitroimino-1,2,4-triazole)] in common pure solvents and binary solvents at different temperatures

The solubility of dicarbohydrazide bis[3-(5-nitroimino-1,2,4-triazole)] (DCBNT) was first measured under the different pure solvents and binary solvents by the dynamic method over the temperature range of 290–360 K at atmospheric pressure. Results in all the solvents were positively correlated with temperature, namely increased with increasing temperature. The experiment data were correlated by the Apelblat equation, the Yaws equation and the polynomial equation. The conclusion showed that these three models all agreed well with the experimental data. Simultaneously, the dissolution enthalpy, dissolution entropy and Gibbs free energy of DCBNT in different solvents were calculated from the solubility data by using the Apelblat model. The results indicate that the dissolution process of DCBNT in these solvents is driven by entropy, which provides theoretical guidance for further research on the crystallization of DCBNT.

Measurement and Correlation of the Solubility of β-Cyclodextrin in Different Solutions at Different Temperatures and Thermodynamic Study of the Dissolution Process

A new improved formulation was studied to improve the rehydration properties of freeze-dried dumplings. To provide basic data for industrial applications, the solubility capabilities of β-Cyclodextrin in sucrose, NaCl, and a mixed solution were measured at temperatures ranging from 303.15 to 353.15 K using a laser monitoring method. The experimental values indicated that the solubility of β-Cyclodextrin in solvents increased with increasing temperature. The simplified Apelblat model, Apelblat model, and λh model were employed to analyze the experimental results using correlation tests. The relative average deviation (RAD) values between the experimental and calculated values were less than 0.095, 0.075, and 0.103 for the simplified Apelblat equation, Apelblat equation, and λh equation, respectively. Apparent thermodynamic analysis of β-Cyclodextrin dissolution was also performed at the mean temperature using the model parameters of Apelblat equation. Furthermore, thermodynamic properties of the solution process, including the enthalpy, entropy, and Gibbs free energy, were also calculated and analyzed. This study provides the basic data for applications in industrial production, and is specifically of great significance for the improved formulation of freeze-dried dumplings.

Metal-Free Photocatalysts C3N3S3 and its Polymers: Solubility in Water and Application in Benzylic Alcohols Oxidation Under Visible Light

Metal-free photocatalysts trithiocyanuric acid (C3N3S[Formula: see text] and its polymers were one-step synthesized and used for selective aerobic oxidation of benzyl alcohol under visible light. The S–S bridged C3N3S3 polymers showed higher oxidation activity with increasing polymerization time and reached a maximum at 40[Formula: see text]h. As a major factor, catalysts’ solubility in water at different temperatures (from 298.15[Formula: see text]K to 368.15[Formula: see text]K) was measured at atmospheric pressure. The obtained data were correlated by polynomial empirical equation and modified Apelblat equation, respectively. Experimental results proved that the solubility of C3N3S3 and its polymers increased with increasing temperature. The solubility of C3N3S3 polymers with lower polymerization degree (DP) were better than that of parent C3N3S3 owing to the hydrophilicity caused by a low symmetry and disorder structure, whereas the higher DP could lead to the decrease of polymer solubility and further affect the photocatalytic activity. Thermodynamic properties of the solution system including the enthalpy ([Formula: see text] and heat capacity ([Formula: see text]) were calculated by the modified Apelblat equation.

Solubility and Thermodynamic Properties of L-Proline in Methanol-Dichloromethane Mixtures

The solubility of L-proline in binary solvents of methanol and dichloromethane were measured by a dynamic method via a laser monitoring technique. In the binary solvent mixtures, the solubility increases with the increasing of temperature and proportion of the methanol. The experimental solubility were fitted to modified Apelblat equation and Van’t Hoff equation in this work can be used as essential data and models in the purification process of L-proline. The dissolving process is endothermic and the dissolution driving force converts from enthalpy-driving to entropy-driving.

Solubility and solution thermodynamics of rhein in eight pure solvents from (288.15 to 313.15) K

Solubility of rhein in water, dichloroethane, glycol, ethanol, methanol, ethyl acetate, propanol, and butanol was measured. Two equations including the modified Apelblat equation, and λh equation can correlate the solubilities of rhein.

Measurement and Correlation for Solubility of Some Pyrimidine Derivatives in Different Solvents

Some new pyrimidine derivatives have been synthesized and their characterization was done by IR, NMR, and mass spectral data. The solubility of these synthesized compounds has been studied in methanol, N,N dimethylformamide (DMF), and carbon tetrachloride (CCl4) by gravimetrical method from 298.15 to 328.15 K under atmospheric pressure and the solubility data were correlated against temperature. The solubility is found to increase with temperature and order of solubility is DMF > methanol > CCl4. The experimental solubility data is correlated with the modified Apelblat equation. Some thermodynamic parameters such as dissolution enthalpy, Gibbs energy of dissolution, and entropy of mixing have also been calculated.

Chalcones: A Solubility Study at Different Temperatures

Some new chalcones are synthesized by the condensation of aryl ketones with aromatic aldehydes and solubility of these synthesized chalcones is determined in chloroform and dichloromethane at temperatures ranging between 293.15 K and 313.15 K by gravimetric method. The experimental data was correlated well with modified Apelblat equation. Further, from the experimental solubility data, some thermodynamic parameters such as dissolution enthalpy, Gibb’s energy and entropy etc. were evaluated using van’t Hoff equation. The positive Gibb’s energy and negative entropy suggests spontaneous dissolution and more ordered structure in solution.

Measurement and Correlation of Solubilities and Surface Tension of Caffeine in Water

The solubility of caffeine in water between 323.15 and 353.15 K was measured using the balance method. The solubility trend was modeled by use of the modified Apelblat equation and Yaws equation. The calculated solubility values according to the two empirical equations compare favorably with the experimental data. Besides, the relationship between supersaturated ratio and induction time was studied with the method of laser, basing on which, the surface tension of caffeine at 283.15 K, 293.15 K and 298.15 K in water was calculated.

Measurement and Correlation of Solubility for 2,4-Dinitrotoluent in Mixed Solvents of Water and Nitric Acid

The solubility data of 2,4-dinitrotoluent (2,4-DNT) in mixed solvents of water and nitric acid with nitric acid mass fraction vary from 0.1 to 0.5 were determined at 283.15-323.15K by the equilibrium method. It indicates that the solubility increases with the increase of temperature and decreases with the decrease of mass fraction of nitric acid. The experimental data were correlated with λ-h equation, Apelblat equation and C.L.Yaws equation, average relative deviations of which between the calculated values and the experimental values of 25 data points in 5 systems were 3.666%, 2.737% and 3.121% respectively. The results show that three equations could well correlate the solubility data of 2,4-DNT in above electrolyte systems and the accuracy of the correlation can satisfy the engineering requirement.