Water → 4-Bromopyridine-2-carboxylic acid

Participants

Reaction Steps

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.

Provenance & Evidence