Study on 2-Hydrazino-4-methylbenzothiazole in Nine Monosolvents and Four Mixed Solvents at 273.15 to 318.15 K: Solubility Determination and Modeling

In this paper, the mole fraction solubility of 2-hydrazino-4-methylbenzothiazole (MHB) in acetone, toluene, methanol, ethanol, water, ethyl acetate, n-propanol, isopropanol, 1-butanol, and methanol/ethanol/n-propanol/acetone + water was determined by the isothermal saturation method at 273.15 to 318.15 K under 101.2 kPa. Meanwhile, high-performance liquid chromatography was used to detect the solubility of MHB. The mole fraction of MHB increased with the increase of temperature in monosolvents, and the composition of solvent mixtures also played a decisive role in the solubility of MHB in mixed systems. Then, four models for five monosolvents (Apelblat, van’t Hoff, λh, NRTL, and the Jouyban model) and three models for mixed solvents [Jouyban–Acree (J–A), van’t Hoff–Jouyban–Acree (V–J–A), and modified Apelblat–Jouyban–Acree (A–J–A) model] were utilized to correlate the mole fraction of MHB. The maximum deviations [relative average deviation (RAD) and root-mean-square deviation (RMSD)] between the experimental data and the solubility data calculated by the models for monosolvents were 7.13% and 6.11 × 10^–4 (from the Jouyban model in pure ethyl acetate), respectively. The maximum RAD and RMSD for mixed systems were 1.58% (from the A–J–A model in methanol + water) and 1.35 × 10^–4 (from the J–A and A–J–A models in acetone + water), respectively.