12 g of picric acid is dissolved in 120 mL of 5% HCl under an ice bath, then a solution is prepared by combining 3.6 g of sodium nitrite and 10 mL of water. The solution is slowly added to the first solution with rapid stirring, the temperature should be maintained below 10°C, the solution is stirred for additional 10 minutes, then filtered and washed with some water. The crude amorphous diazodinitrophenol is recrystallized in hot acetone.
Addition of the solution
The mixture gradually lightens
Stirring for additional time
The product after the filtration and washing
The recrystallized product