The solubility of sulfadiazine (SD) in some methanol + water cosolvent mixtures was measured at five temperatures from 293.15 to 313.15 K in all the polarity range. The mole fraction solubility of thisdrug was maximal in neat methanol and minimum in pure water at all the temperatures studied. The thermodynamic functions Gibbs energy, enthalpy, and entropy ofsolution were obtained from these solubility data by using the van't Hoff and Gibbs equations. Thermodynamic quantities of mixing were also calculated by using ideal solubility values reported in the literature. Non-linear enthalpy.entropy relationship was observed for SD in the plot of enthalpy vs.Gibbs energy of mixing, thus, delta-mixH vs. delta-mixG plot shows two different trends according to the slopes obtained when the mixtures composition changes. Accordingly, the driving mechanism for SD solu-tion process in water-rich is the entropy; whereas, from 0.20 in mass fraction of methanol to neat methanol the process is enthalpy-driven. Additionally, the preferential solvation of this drug by thesolvents was analyzed by means of the inverse Kirkwood-Buff integrals observing that it is preferentially solvated by water in water-rich mixtures but preferentially solvated by methanol in methanol-richmixtures.
Compounds
#
Formula
Name
1
C10H10N4O2S
4-amino-N-2-pyrimidinylbenzenesulfonamide
2
CH4O
methanol
3
H2O
water
Datasets
The table above is generated from the ThermoML associated json file (link above).
POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied;
the numbers refer to the table of compounds on the left.