6-Bromo-1,2,4-triazine-3,5(2H,4H)-dione

2H- [1, 2,4] triazin-3,5-dione (50 g, 442 mmol) is placed in 60 ml of bromine in 800 ml of water at 60°C for 10 h. The reaction medium is then run slowly onto an aqueous ammonia solution until pH = 5. It is then extracted with ethyl acetate and the organic phases are dried over MgS04. After filtration and concentration to dryness, 6-Bromo-1,2,4-triazine-3,5(2H,4H)-dione is isolated as a white solid (79.2 g, yield = 93 percent).