2-Methyl-4-methylamino-6-methoxy-1,3,5-triazine
is an important intermediate of tribenuron-methyl with poor aqueous
solubility. In this study, we have considered five pure solvents as
raw materials and formed four sets of mixed solvents according to
their pairs by mixing methanol, ethanol, ethylene glycol (EG), and N,N-dimethyl formamide (DMF) in water. Taking 278.15 K as
the starting temperature and referring to the principle of the isothermal
static state, the temperature was gradually increased at 5 K intervals
until it reached 323.15 K. Under normal pressure (101.1 kPa), when
the mole fraction of the solute did not change, the value obtained
by high-performance liquid chromatography (HPLC) was the equilibrium
solubility of 2-methyl-4-methylamino-6-methoxy-1,3,5-triazine. The
mole fraction of 2-methyl-4-methylamino-6-methoxy-1,3,5-triazine at
323.15 K obeyed the following descending sequence: DMF (0.4557) >
methanol (0.1852) > ethanol (0.1364) > EG (0.05972). From the
point of view of temperature, the influence on the solute cannot be
ignored. The amount of 2-methyl-4-methylamino-6-methoxy-1,3,5-triazine
dissolved increased from a low value to a high value when the temperature
increased from low to high. In addition, a difference observed was
that the water content of the mixed solvent was repulsive to the dissolution
of the solute. When the water content increased from low to high,
the mole fraction of 2-methyl-4-methylamino-6-methoxy-1,3,5-triazine
decreased from high to low. In any temperature environment, the same
proportion of water was added to the four organic solvents. Compared
with other solvents, the mixture of DMF and water had an absolute
dissolution advantage. We adopted three cosolvency models including
the Jouyban–Acree, van’t Hoff–Jouyban–Acree,
and modified Apelblat–Jouyban–Acree models to calculate
and correlate the saturated solubility data of 2-methyl-4-methylamino-6-methoxy-1,3,5-triazine.
The RAD and RMSD values were 8.90 × 10–3 and
6.36 × 10–4, respectively, as obtained from
the van’t Hoff–Jouyban–Acree model, and the Jouyban–Acree
model demonstrated a better fitting effect. The determination of solubility
helps to obtain solubility parameters, which are a measure of intermolecular
forces. Solubility is required in the fields of recrystallization
and fractional crystallization in the chemical industry, as well as
the synthesis and separation of compounds.