Solubility Measurement and Correlation of 2-Amino-3-chloropyrazine and 2-Amino-3,5-dibromopyrazine in a Series of Mixed Solvent Systems at T = (278.15 to 323.15) K

The solubility of 2-amino-3-chloropyrazine (ACPY) in some binary cosolvent mixtures of (methanol, isopropyl alcohol, ethylene glycol (EG), N,N-dimethylformamide (DMF)) plus water and the experimental solubility of 2-amino-3,5-dibromopyrazine (ADPY) in (ethanol + water), (isopropyl alcohol + water), (EG + water), and (PG + water) were all determined by the isothermal saturation method from 278.15 K to 323.15 K at 101.2 kPa. The trend of the system temperature and the change of the solvent partner are both factors that affect the dissolution. As the temperature goes higher, the amount of dissolution follows, but the higher is the water content of the solvent, the less solute will be dissolved. The combination of DMF and water is best for the dissolution of ACPY, and the addition of ethanol to water shows an advantage of dissolving ADPY over other combinations. The experimentally obtained dissolution data were then calculated by using three models for the two miscible solvent systems. For ADPY, RAD and RMSD maximums were 2.63 × 10–2 and 2.10 × 10–5. For ACPY, RAD and RMSD were no greater than 6.55 × 10–2 and 6.83 × 10–4.