The solid–liquid equilibria (SLE) in the ternary system of 2-methyl-1,4-naphthoquinone (2-MNQ) + phthalic anhydride (PA) + 1,4-dioxane were determined experimentally by using the isothermal dissolution equilibriam method within temperatures 283.15, 293.15, and 303.15 K, respectively. The ternary phase diagram could be helpful in the separation of 2-MNQ and PA. On the basis of the experimental data on solubilities the phase diagrams of the system were plotted. Two pure solid phases were formed at 283.15, 293.15 and 303.15 K, including pure PA and pure 2-MNQ, which were confirmed and determined by Schreinemakers’ wet residue method. The phase diagram at 283.15 K is similar to those at 293.15 and 303.15 K and the crystalline regions of 2-MNQ and PA decrease with increasing temperature. NRTL and Wilson model were employed to correlate and calculate the solubility data for the ternary system. A comparison between the two models shows that the NRTL model agrees better with the experimental data than those with the Wilson model. In addition, the densities of equilibrium liquid phase were obtained at the corresponding temperatures versus composition in the system.

•The DSC of 2-chloro-3-(trifluoromethyl)pyridine was conducted.•The solubility of the solute was measured in six pure and binary solvents.•The four models were used to correlate the solubility data.•The thermodynamic properties were evaluated based on the van't Hoff equation.The solubility of 2-chloro-3-(trifluoromethyl)pyridine was measured at 273.15 K–303.15 K under atmospheric pressure in methylbenzene, dichloromethane, ethanol, n-propanol, n-hexane, n-heptane and ethanol + 1-propanol binary solvents. The solubility of 2-chloro-3-(trifluoromethyl)pyridine in pure and ethanol + n-propanol binary solvents increases with the increase of temperature. But in ethanol + n-propanol binary solvents, the solubility of 2-chloro-3-(trifluoromethyl)pyridine also increases with the increasing the mole fraction of ethanol. The van't Hoff equation, modified Apelblat equation, λh equation, and Wilson model were used to correlate the solubility data in different pure solvents, and the van't Hoff equation, modified Apelblat equation, and λh equation were used to correlate the solubility data in ethanol + n-propanol binary solvents. In six pure and binary solvents, the thermodynamic properties of the standard dissolution enthalpy, the standard entropy, and the standard mole Gibbs energy were evaluated based on the van't Hoff equation.

The solid–liquid equilibrium or the ternary system of 2-methyl-1,4-naphthoquinone + phthalic anhydride + acetone were determined at three temperatures of (283.15, 293.15 and 303.15) K, respectively. Three isothermal phase diagrams of the system were constructed on the basis of the measured solubility. Two pure solid phases were formed at (283.15, 293.15 and 303.15) K, including pure PA and pure 2-MNQ, which were confirmed and determined by the method of Schreine makers' wet residue. The densities of equilibrium liquid phase were determined experimentally at the corresponding temperatures versus mass fraction of component. The phase diagram at 283.15 K is similar to those at (293.15 and 303.15) K and the crystalline fields of 2-MNQ and PA decrease with an increase in temperature. The ternary diagram can provide the fundamental basis for separation of 2-MNQ and PA.

•Solubility for 2-naphthaldehyde + o-phthalic anhydride + 1,4-dioxane were measured.•Three isothermal phase diagrams were plotted based on solubility data.•Experimental solubility data were correlated by NRTL and Wilson models.In this research, solid-liquid equilibrium for the ternary system (2-naphthaldehyde + o-phthalic anhydride + 1,4-dioxane) was measured at 283.15 K, 293.15 K and 303.15 K, respectively. Three isothermal phase diagrams of the system were plotted using the values of the experimental solubility. Pure 2-naphthaldehyde and o-phthalic anhydride were formed at (283.15, 293.15 and 303.15) K, and were determined by Schreinemaker’s wet residue method. The crystallization region of o-phthalic anhydride was found to be much larger than that of 2-naphthaldehyde at a certain temperature. The experimental solubility at multiple temperatures was correlated by the NRTL and Wilson models. The NRTL model was more accurate than the Wilson model in this system. The diagram of density versus component was also constructed.

In this experiment, the solubility data of 4,4′-diaminodiphenylmethane in different pure solvents, including methanol, ethanol, 2-propanol, 1-butanol, toluene, chloroform, and benzene, were measured by a synthetic method from (293.15 to 333.15) K at atmospheric pressure. It is indicated that the solubility of 4,4′-diaminodiphenylmethane in each solvent increases with increasing temperature. The modified Apelblat, λh, and van’t Hoff equations were employed to correlate experimental solubility data, and each selected correlation equation could give a good fitting result of the relationship between solubility and temperature. The modified Apelblat equation shows the best agreement, in general. Furthermore, the standard molar enthalpy, standard molar Gibbs energy, and standard molar entropy of 4,4′-diaminodiphenylmethane in the dissolution process were calculated based on the van’t Hoff analysis and Gibbs equation.

The solid–liquid equilibria (SLE) data of the ternary system succinic acid + glutaric acid + water were measured at the three given temperatures (298.15, 303.15, and 308.15) K using the isothermal solution dissolution equilibrium method, and the densities of equilibrium liquid phase were determined experimentally at the corresponding temperatures. The corresponding isothermal phase diagrams and the diagrams of densities versus mass fraction of component were constructed on the basis of the experimental results. There existed two pure solid phases at (298.15, 303.15 and 308.15) K, including pure succinic acid and pure glutaric acid, which were confirmed and determined by the method of Schreinemaker’s wet residue and X-ray diffraction. The results indicate obviously that there was no solid solution formed in the studied system. The phase diagram at 298.15 K is similar to those at (303.15 and 308.15) K and the crystallization region of glutaric acid is far smaller than that of succinic acid at each temperature. The crystalline fields of succinic acid increase with rising temperature, while crystalline fields of glutaric acid decrease with an increase in temperature.