Synthesis
The general procedure for the synthesis of 5-aminouracil from 5-nitropyrimidine-2,4(1H,3H)-dione is as follows:
1. to a 5 liter four-necked round-bottomed flask was added water (2.871 L), ammonia (116.1 mL) and 5-nitropyrimidine-2,4(1H,3H)-dione (180 g, 1.15 mol, 1.00 equiv.).
2. sodium conidiosulfite (Na2S2O2, 860 g, 6.06 mol, 4.30 eq.) was added in batches.
3. The pH of the reaction solution was adjusted to 8 using 25% ammonia.
4. The reaction mixture was stirred at 75 °C for 3 hours.
5. After completion of the reaction, the mixture was cooled to 15 °C using an ice/water bath.
6. The solid product was collected by filtration to afford 5-aminopyrimidine-2,4(1H,3H)-dione (118 g, 81% yield) as a yellow solid.
References
[1] Patent: US2011/207713, 2011, A1. Location in patent: Page/Page column 58
[2] American Chemical Journal, 1905, vol. 33, p. 443
[3] Justus Liebigs Annalen der Chemie, 1899, vol. 309, p. 255,256
[4] Justus Liebigs Annalen der Chemie, 1889, vol. 251, p. 238
[5] Justus Liebigs Annalen der Chemie, 1885, vol. 229, p. 17
