反应详情

To a stirred suspension of 5-bromobenzene-1,2,3-triamine (81.5 g, 403 mmol) in HCl conc (2400 mL) at rt was added formic acid (46 mL, 1210 mmol, 3 eq). After stirring at reflux for 90 min, water (500 mL) was added to the suspension, and the pH was adjusted to 8 using ammonia (33% aqueous solution). After extraction with ethyl acetate (3×1000 mL), the organic phase was washed with saturated sodium chloride solution, dried over sodium sulphate and evaporated in vaccuo. The crude product was trituarated with diethyl ether (200 mL), filtered and dried to yield 82.3 g 6-bromo-1H-benzimidazol-4-amine (96.3%).

1. temperatureat reflux for 90 min
2. extractionAfter extraction with ethyl acetate (3×1000 mL)
3. washthe organic phase was washed with saturated sodium chloride solution
4. dry with materialdried over sodium sulphate
5. customevaporated in vaccuo
6. filtrationfiltered
7. customdried