Phosphorus pentachloride → 4-Chloro-3-nitropyridine

Temperature

45 °C

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).

1. temperatureheat
2. temperatureunder reflux (oil bath to 125° C.) under an inert atmosphere
3. temperatureCool the mixture to room temperature
4. concentrationconcentrate to an oil
5. temperaturecool to 0° C. in an ice bath
6. additiontreat with 10 ml of water and 20 ml of dichloromethane
7. stirringwhile stirring vigorously
8. extractionBasify the aqueous layer with saturated sodium bicarbonate solution and extract with dichloromethane (×3)
9. dry with materialDry the combined organic layers over anhydrous sodium sulfate
10. filtrationfiltered
11. concentrationconcentrate

ORD record

ord-6bb0ce088fd047b0a783bc96a31b9e9e

Source dataset

uspto-grants-2008_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07393868B2