Solubility Measurement and Data Correlation of Pyrimethamine in 13 Pure Solvents at Temperatures from 278.15 to 318.15 K

The solubility of PMN in 13 organic solvents (methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, acetone, acetonitrile, methyl acetate, ethyl acetate, n-propyl acetate, and isopropyl acetate) was determined by the gravimetric method over the temperatures ranging from 278.15 to 318.15 K at 0.1 MPa. The solubility of all selected solvents increases with increasing temperature; however, the change in methanol is substantially more than that in other solvents. Four models, including the modified Apelblat equation, the lambda h equation, the NRTL, and the van't Hoff equation, were applied to correlate the experimental solubility data, which showed that a relative deviation is less than 3% with the four models. In addition, a KAT-LSER model was employed to quantitatively evaluate and describe the solvent effect, which indicate that the hydrogen bonding basicity of solvents has a greater effect on the solubility of PMN.