Hydrogen Bromide → HCID 178526735, compound

Participants

Reaction Steps

5-Fluoro-2-hydroxypyridine (5-fluoro-2-pyridone) was prepared from commerially available 5-amino-2-fluoropyridine as described by Nesnow and Heidelberger (J. Heterocyclic Chem., 10, 779 (1973)) except that refluxing 48% hydrobromic acid was used to carry out the final hydrolysis of 2-fluoro-5-methoxypyridine rather than the literature conditions (25% hydrochloric acid in a sealed glass tube at 145° C.). 5-Fluoro-2-hydroxypyridine (11.16 g, 98.7 mmol) was added in portions to concentrated sulfuric acid (90 mL) at 0° C. Fuming nitric acid was then added dropwise. The reaction mixture was allowed to warm to room temperature and was then heated at 55°-60° C. for 3 hours. The mixture was cooled to room temperature and was then poured into ice/water. The yellow product was collected by filtration, washed with water and dried in the air to yield 8.24 g (53%) of the title compound. The filtrate was adjusted to pH 2 by the addition of solid NaHCO3 and was extracted with ethyl acetate. The combined extracts were dried (MgSO4) and concentrated to yield an additional amount of the title compound (1.71 g, 11%).

Provenance & Evidence