Equilibrium Solubility Investigation and Thermodynamic Computational Modeling of Halosulfuron-methyl in a Series of Cosolvent Mixtures at a Temperature Range of 278.15-323.15 K

Water as an auxiliary solvent is added to various alcohol solvents (methanol, ethanol, and isopropanol) and N,N-dimethylformamide (DMF) to form a variety of liquid mixtures, which are divided into different types according to different proportions. Starting from pure water, 0.1 mass fraction of organic solvents is added at a time until the ratio of organic solvent is 1. The abovementioned liquid mixtures are used as solvents to dissolve halosulfuron- methyl at 278.15-323.15 K under 101.2 kPa by means of the isothermal static technique. The experimental solubility of halosulfuron-methyl was calculated and validated by using three various computational models, i.e., Jouyban-Acree model, modified Apelblat-Jouyban-Acree model, and van't Hoff-Jouyban-Acree model. Considering that there are many factors that change the experimental results, this experiment mainly selected temperature and water content as two factors as the main independent variables. From the point of view of temperature, it changes from a low value to a high value, so it is obvious that the solute mole fraction also follows its footsteps. Unlike the temperature, as the organic solvent is continuously diluted by water, the solute solubility changes in the opposite direction to the water content. By controlling the variable method to ensure that the above two variables remain unchanged, DMF has the best dispersion ability for all the selected solvents to dissolve halosulfuron-methyl. The solubility maximum of 2.542 X 10(-3) at 323.15 K was found in pure DMF, and four systems followed the descending order as (DMF + water) > (ethanol + water) > (methanol + water) > (isopropanol + water). The largest relative average deviation and root-mean-square deviation values were 5.70 x 10(-3) and 6.90 X 10(-6), respectively. For drugs with poor water solubility and dissolution rate, measuring their solubility and understanding their dissolution properties could effectively help solve the problem of nonwetting and nondiffusion. The obtained equilibrium solubility and correlation parameters of halosulfuron-methyl in studied cosolvency systems could be favorable for the industrial production, recrystallization, and purification processes of API halosulfuron-methyl.