Water → 4-Bromopyridine-2-carboxylic acid

A stirred solution of pyridyl bromide 153 (5.03 g, 29.0 mmol) in water (130 mL) is treated at RT with KMnO4 (4.72 g, 29.5 mmol) in one portion then heated to reflux 1.5 h. At this juncture more KMnO4 is added (4.72 g, 29.5 mmol) and the solution heated at reflux a further 2 h. Another portion of KMnO4 is then added (9.43 g, 59 mmol), the reaction heated at reflux a further 3 h then filtered whilst still hot, washing the isolated solids with boiling water (200 mL). The aqueous filtrate is then concentrated in vacuo to approximately 40 mL, acidified to pH 4 by careful addition of 1 M HCl and the resultant white precipitate isolated by filtration. The filtrate is then reduced in vacuo to approximately 10 mL and the forthcoming precipitate also isolated by filtration. Combining these two isolated precipitates gives the title compound.

1. temperaturethen heated
2. temperatureto reflux 1.5 h
3. temperaturethe solution heated
4. temperatureat reflux a further 2 h
5. temperaturethe reaction heated
6. temperatureat reflux a further 3 h
7. filtrationthen filtered whilst still hot,
8. washwashing the isolated solids with boiling water (200 mL)
9. concentrationThe aqueous filtrate is then concentrated in vacuo to approximately 40 mL
10. additionacidified to pH 4 by careful addition of 1 M HCl
11. customthe resultant white precipitate isolated by filtration
12. customthe forthcoming precipitate also isolated by filtration
13. customisolated
14. customprecipitates

ORD record

ord-5cc45d69043c4d97a8a2ff23b40b7e5c

Source dataset

uspto-grants-2012_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08273747B2