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The thiamphenicol solubility in aqueous cosolvent solutions of ethanol (1), methanol (1), 1,4-dioxane (1), and N,N-dimethylformamide (DMF, 1) was measured via the isothermal dissolution equilibrium method at temperatures ranging from 278.15 to 318.15 K under local pressure (101.1 kPa). At fixed composition of ethanol (methanol, 1,4-dioxane, or DMF) and temperature, the solubility of thiamphenicol was larger in DMF + water mixtures than in the ethanol/methanol/1,4-dioxane mixtures. The local solvent proportions were acquired with the method of inverse Kirkwood–Buff integrals. The absolute value of these preferential solvation parameters were all lower than 1.0 × 10–2 for ethanol (1) + water (2) and 1,4-dioxane (1) + water (2) solutions in water-rich compositions and for methanol (1) + water (2) solutions in whole compositions. In the former two cosolvent mixtures in intermediate compositions and cosolvent-rich regions, thiamphenicol was preferentially solvated by cosolvent. However, for the DMF (1) + water (2) solutions, water solvated preferentially thiamphenicol in water-rich compositions and by DMF in intermediate and DMF-rich compositions. This case by cosolvent might be illustrated based on higher basic behavior of water, which interacted with Lewis acidic groups of thiamphenicol. In addition, the solubility of thiamphenicol was described with the van’t Hoff–Jouyban–Acree, Jouyban–Acree, and Apelblat–Jouyban–Acree models. The obtained average relative deviations were no greater than 1.85%. Furthermore, the solvent effect treatment through the KAT-LSER model indicated that the solubility variation was significantly affected by the cavity term.

The solubility of terephthaldialdehyde in N-methyl-2-pyrrolidone (NMP) at temperatures ranging from T = 293.15 to 318.15 K and the mutual solubility for ternary systems of terephthalic acid + terephthaldialdehyde + N,N-dimethylformamide (DMF) and terephthalic acid + terephthaldialdehyde + NMP at T = 298.15, 308.15, and 318.15 K were measured with the technique of isothermal saturation under 101.2 kPa. Six phase diagrams were built on the basis of the determined solubility. There were two solids formed in each ternary system, which were terephthalic acid and terephthaldialdehyde. Each diagram consisted of one cosaturated point, three crystalline areas, and two cosaturated curves. Furthermore, the nonrandom two-liquid mode and Wilson model were used in correlating and calculating the solubility of terephthaldialdehyde in NMP and the mutual solubility data for terephthalic acid + terephthaldialdehyde + DMF/NMP systems. The maximum rootmean-square deviation was 3.58 × 10 −3 , and maximum value of relative average deviation was 1.74%. The liquid−solid phase diagram and the thermodynamic analysis could provide the basis for obtaining terephthalic acid with high purity.

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