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

Temperature

0 °C

Fuming H2SO4 (25 mL) is added dropwise to a solution of crude 3-chloro-pyridine-1-oxide in concentrated H2SO4 (25 mL) with cooling (0° C.) and 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 up to room temperature slowly. The resulting mixture is then heated at 120° C. for 4 hours with stirring, cooled, and 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 (10 g) ; 1H NMR (300 MHz, CDCl3): 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. temperatureto warm up to room temperature slowly
2. temperatureThe resulting mixture is then heated at 120° C. for 4 hours
3. stirringwith stirring
4. temperaturecooled
5. additionpoured into ice-cold water
6. extractionextracted with CHCl3
7. washThe combined organic phase is washed successively with saturated aqueous NaHCO3, water, brine
8. dry with materialdried over Na2SO4
9. concentrationconcentrated in vacuo

ORD record

ord-b5677e32875048728df7195ea0bfadd6

Source dataset

uspto-grants-2005_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06916827B2