Solubility and Data Correlation of 2-Bromo-5-hydroxypyrazine in Four Cosolvent Mixtures and Ten Mono-Solvents from 278.15 to 323.15 K

Abstract

The experimental solubility of 2-bromo-5-hydroxypyrazine dissolved in 10 mono-solvents (methanol, ethanol, isopropanol, N,N-dimethylformamide (DMF), npropanol, acetonitrile, acetone, ethylene glycol (EG), propylene glycol (PG), water) and cosolvent mixtures of methanol + water, ethanol + water, isopropanol + water, and DMF + water was determined by the isothermal saturation method between 278.15 and 323.15 K at 101.2 kPa. The largest solubility was observed in DMF + 2-bromo-5hydroxypyrazine for mono-solvent systems and in DMF + water for mixed solvent systems. The Jouyban−Acree model (J−A), van't Hoff−Jouyban−Acree model (V−J− A), and Apelblat−Jouyban−Acree model (A−J−A) were utilized to correlate the 2bromo-5-hydroxypyrazine solubility in mixtures, and the Apelblat model, van't Hoff model, λh model, and Jouyban model were used to correlate the 2-bromo-5hydroxypyrazine solubility in 10 mono-solvents. The preferential solvation of 2bromo-5-hydroxypyrazine in mixed solvents was researched by calculation of δx 1,3 . This study presents insights into modulating the 2-bromo-5-hydroxypyrazine crystallization process and in understanding equilibrium behaviors in different solvents.

Solubility Measurement and Modeling of Methyl 2-Aminopyridine-4-carboxylate in Four Binary Blends and Eight Monosolvents from 278.15 to 323.15 K

“…Methyl 2-aminopyridine-4-carboxylate (yield 51–89%) is prepared by 2-amino-4-methylpyridine. – However, there are few literature studies about the description of the purification of methyl 2-aminopyridine-4-carboxylate. – So, this work has made the following contributions: (1) the solubility of methyl 2-aminopyridine-4-carboxylate in four mixed systems and eight monosolvents was determined by the isothermal saturation method, (2) the solubility data was calculated by different models, and (3) the thermal characterization [differential scanning calorimetry (DSC)] of methyl 2-aminopyridine-4-carboxylate was made, which provided the basic data for the purification of methyl 2-aminopyridine-4-carboxylate. – …”