To a beaker immersed in an ice bath add 17 mL of cold fuming nitric acid (d=1.5) and 14 mL of conc. sulfuric acid, a slow addition of 2,2′,4,4′-tetranitrodiphenylamine is started with stirring while the temperature is maintained below 25°C. Then the solution is stirred for 3h at 30°C, after which 72 mL of cold distilled water is added to the solution, the mixture is filtered and washed with 70 mL of distilled water. The product is then recrystallized from hot ethanol.
Addition of the Tetranitrodiphenylamine
The crude product