Nitric Acid → 3-Chloro-4-nitropyridine N-oxide

Fuming H2SO4 (25 mL) is added dropwise to a solution of crude 3-chloro-pyridine-1-oxide in concentrated H2SO4 (25 mL) under cold conditions (0° C.) with stirring. HNO3 (fuming, 90%, 60 mL) is added carefully to the above mixture with caution to keep the offset of any exotherm under control, and then allowed to warm to room temperature slowly. The resulting mixture is then heated at 120° C. for 4 h with stirring, cooled, poured into ice-cold water, and extracted with CHCl3. The combined organic phase is washed successively with saturated aqueous NaHCO3, water, brine, dried over Na2SO4, and concentrated in vacuo to afford 3-Chloro-4-nitro-pyridine-1-oxide as an yellow solid. 1H NMR (300 MHz, CDCl3): δ 8.31 (d, J=1.5 Hz, 1H), 8.13 (dd, J=1.5, 5.4 Hz, 1H), 7.95 (d, J=7.2 Hz, 1H).

1. temperatureThe resulting mixture is then heated at 120° C. for 4 h
2. stirringwith stirring
3. temperaturecooled
4. additionpoured into ice-cold water
5. extractionextracted with CHCl3
6. washThe combined organic phase is washed successively with saturated aqueous NaHCO3, water, brine
7. dry with materialdried over Na2SO4
8. concentrationconcentrated in vacuo

ORD record

ord-6cd1584de7ba4320b5ff00abd90db80b

Source dataset

uspto-grants-2005_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06916819B2