50 g of acetylsalicylic acid is dissolved in 250 mL of concentrated sulfuric acid with stirring and then heated to 90°C for 10 minutes. Then a medium slow addition of 74 g of dry sodium nitrate is started, the temperature is maintained below 45°C with an ice bath. After which the solution is heated at 120°C for 15 minutes, the solution is then poured into 1200 mL of iced water. The mixture is filtered, washed with cold water and recrystallized from hot 50% aq.ethanol.
Sulfonation of the ASA
Nitration of the compound
The fully nitrated product
After the addition of iced water
The crude product