Water → 2-Chloro-5-fluoro-3-nitropyridine

Temperature

100 °C

To a mixture of phosphorus pentachloride (9.41 g, 45.2 mmol) and phosphorus oxychloride (4.2 mL, 45.1 mmol) at 60° C. was added in portions 5-fluro-2-hydroxy-3-nitropyridine (6.5 g, 41.1 mmol). The mixture was stirred in an oil bath at 100° C. under nitrogen overnight, cooled to room temperature and poured into ice/water. After addition of more water and ethyl acetate, the mixture was filtered through Celite® to remove dark insoluble material. The organic phase was washed with brine, filtered again to remove more dark material, dried over MgSO4 and concentrated. The residue was subjected to flash chromatography on silica gel using chlorform as eluant. Fractions containing the title compound were combined and concentrated to provide a yellow oil (3.51 g, 48%) which solidified on standing at 5° C. overnight.

1. temperaturecooled to room temperature
2. filtrationthe mixture was filtered through Celite®
3. customto remove dark insoluble material
4. washThe organic phase was washed with brine
5. filtrationfiltered again
6. customto remove more dark material
7. dry with materialdried over MgSO4
8. concentrationconcentrated
9. additionFractions containing the title compound
10. concentrationconcentrated

ORD record

ord-0755d20b4e91429cac7ab12ad558e778

Source dataset

uspto-grants-1998_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05811432