5-Bromo-2(1H)-pyrazinone

Preparation c-120 Sodium nitrite (1. 35 g, 19. 53 MMOL) was added portionwise to concentrated sulfuric acid (9. 8 mL) at 0 °C. The mixture was heated at 50 °C until all of the sodium nitrite had dissolved and the mixture was again cooled to 0 °C. A solution of 5- BROMO-PYRAZIN-2-YLAMINE (2. 57 g, 14. 68 MMOL) in concentrated sulfuric acid (14. 7 mL) was added dropwise to the nitronium solution at 0 °C. The ice bath was removed, the mixture warmed to ambient temperature and stirred for 15 minutes before heating to 45 °C for seven minutes. After cooling to ambient temperature, the mixture was poured slowly with precaution into crushed ice water (100 mL). The aqueous phase was neutralized to pH 4 with 20percent aqueous sodium hydroxide then extracted with ethyl acetate (3 x 100 mL). The combined organic extracts were washed with water (50 mL), dried (anhydrous magnesium sulfate), filtered, and evaporated to afford the title compound (1. 88 g, 73percent) as a yellow solid. 'H NMR (CDCl3, 300 MHz) ; 8. 07 (1 H, s), 7. 62 (1 H, D, J = 3. 0 Hz).Sodium nitrite (0.54 g, 7.53 mmol) was added portionwise to concentrated HConcentrated H2SO4 (55 mL) was cooled to approximately 0° C. in a round-bottomed flask. NaNO2 (8.23 g, 119.3 mmol) was added portion-wise to the flask over approximately 5 min. After the addition was complete, the solution was allowed to mix and warm to ambient temperature over 30 min. The solution was cooled again in an ice bath, and a separate solution of the product from Part A (18.33 g, 105.3 mmol) in concentrated H2SO4 (90 mL) was added dropwise while maintaining a temperature of less than 10° C. After addition was complete, the solution was mixed in the ice bath for 15 min and then warmed to 40° C. for 15 min. The resulting mixture was allowed to cool to ambient temperature and then slowly poured into 500 g of ice. The resulting aqueous mixture was extracted with diethyl ether (3'500 mL). The organic extracts were dried over MgSO4, filtered, and concentrated in vacuo to solids. The solids were slurried in hexanes (100 mL) at ambient temperature for approximately 1 hr, filtered, and desiccated to produce 9.55 g (51.8percent) of solids.

Molecular Weight:174.98
XLogP3:0.2
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:2
Exact Mass:173.94288
Monoisotopic Mass:173.94288
Topological Polar Surface Area:41.5
Heavy Atom Count:8
Complexity:173
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes