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 × 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 × 10–3 and 6.90 × 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.