Phosphorus pentachloride → 4-Chloro-3-nitropyridine

Participants

Reaction Conditions

Reaction Steps

Take up 4-hydroxy-3-nitro-pyridine (6.18 g, 44.2 mmol) in phosphorus oxychloride (16 ml) and heat to 45° C. Once at 45° C., add phosphorus pentachloride (8.04 g, 38.6 mmol) in a single portion. Stir the resulting yellow slurry vigorously and heat under reflux (oil bath to 125° C.) under an inert atmosphere. After 3 h at 125° C., the yellow slurry becomes a clear yellow solution. Cool the mixture to room temperature, concentrate to an oil, cool to 0° C. in an ice bath and treat with 10 ml of water and 20 ml of dichloromethane while stirring vigorously. Basify the aqueous layer with saturated sodium bicarbonate solution and extract with dichloromethane (×3). Dry the combined organic layers over anhydrous sodium sulfate, filtered and concentrate to give 6.98 g of 4-Chloro-3-nitro-pyridine, which crystallizes on standing (99% yield).

Provenance & Evidence