Example 108A Synthesis of 5-chloro-4-methyl-3-nitropyridin-2-amine: 2-amino-5-chloro-4-methylpyridine (30 g, 210 mmol) was dissolved in concentrated sulfuric acid (150 mL) and the solution was cooled to -10 °C. Nitric acid (36 mL, 806 mmol) was slowly added dropwise with stirring. After the dropwise addition was completed, the reaction mixture was warmed to 55°C and stirred continuously at this temperature for 3 hours. Upon completion of the reaction, the mixture was carefully poured into an ice/water mixture and the pH was adjusted to 8 by slow addition of 22% concentrated aqueous ammonium hydroxide solution.Subsequently, the suspension in the reaction mixture was filtered, the resulting solid was washed with water, and finally dried under vacuum to afford the target product 5-chloro-4-methyl-3-nitropyridin-2-amine (23 g, 123 mmol, 58.3% yield).
