反应详情

A solution of crude 5-bromo-3-fluoropyridine-2-carboxamide (40.50 g, 184.9 mmol) in HCl (12N, 539.4 mL, 6.472 mol) was heated to 120° C. for 1 hour. The reaction was cooled to room temperature, and NaOH (20%) was added slowly to pH˜6. The solution was concentrated in vacuo, and azeotroped 3×with toluene. The residue was extracted thoroughly with 40% MeOH/CHCl3 and filtered. This was repeated three times. The combined filtrates were concentrated and azeotroped 3×with toluene to provide 5-bromo-3-fluoropyridine-2-carboxylic acid that gave a mass ion (ES+) of 218.1 for M+H+(79Br).

1. concentrationThe solution was concentrated in vacuo
2. customazeotroped 3×with toluene
3. extractionThe residue was extracted thoroughly with 40% MeOH/CHCl3
4. filtrationfiltered
5. concentrationThe combined filtrates were concentrated
6. customazeotroped 3×with toluene