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The solubility of pyrazinamide in ten solvents (water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, acetone, acetonitrile and ethyl acetate) at temperatures ranging from (278.15 to 323.15) K was determined by using the gravimetric method. The experimental results indicated that in different solvents, the solubility of pyrazinamide was temperature dependent and increased with the increasing temperature. Besides, the modified Apelblat equation, λh equation, Wilson model and NRTL model were employed to correlate the solubility data in the solvents. The results show that the correlated data are in good agreement with the experimental solubility. Furthermore, the mixing thermodynamic properties of pyrazinamide in different solvents were calculated based on the Wilson model. The outcome indicates that the mixing process of pyrazinamide is endothermic.

The solubility of boscalid in five pure solvents, including methanol, ethanol, isopropanol, ethyl acetate and n-propyl acetate, and two binary solvent mixtures, including (ethanol + ethyl acetate) and (isopropanol + ethyl acetate), was determined by a gravimetric method with temperatures ranging from (288.15 to 313.15) K. It turns out that the solubility of boscalid increases with the increasing of temperature in all selected solvents. Moreover, it is interesting that the solubility of boscalid in the two binary solvent mixtures performed a maximum effect with the decreasing mole fraction of ethyl acetate at a given temperature. The solubility of boscalid in pure solvents was correlated by the modified Apelblat model and λh model while that in binary solvent mixtures was correlated by the modified Apelblat model, CNIBS/R-K model and Jouyban-Acree model. It is found that all the models could give satisfactory correlation results with less than 3% of all the ARD values. Furthermore, the thermodynamic properties of the mixing processes in all solvents selected were calculated and discussed based on the NRTL model.

Solid-liquid phase equilibrium solubility of prothioconazole in seven mono-solvents and (2-propanol ± cyclohexane, 1-butanol ± cyclohexane) binary solvent mixtures was determined by gravimetric method from 283.15 K to 313.15 K at atmospheric pressure. The solubility of prothioconazole increased with increasing temperature in all tested solvents. In mono-solvents, the solubility values at a fixed temperature ranked as: 1-butanol > 1-propanol > 2-propanol > methanol > 2-butanol > acetonitrile > toluene. In binary solvent systems, the maximum solubility values were achieved at a certain solvent composition. The Apelblat equation, λh equation and NRTL model were employed to correlate the solubility data in mono-solvents, and the Apelblat equation in two binary solvent mixtures. The selected thermodynamic models can all give acceptable results. Furthermore, the apparent standard Gibbs free energy, enthalpy and entropy for the dissolution of prothioconazole were calculated, which indicates that the dissolution process of prothioconazole is an endothermic and entropy favorable process.