Nitric Acid → 2-Chloro-4-nitropyridine 1-oxide

2-Chloro-pyridine-1-oxide (10 g) is in an ice bath and treated with concentrated H2SO4 (15 ml), followed by the dropwise addition of a mixture of concentrated H2SO4 (15 ml) and fuming HNO3 (27 ml, s.g. 1.5) over a 70 minute period. The acidic solution is heated in a steam bath for 2.5 hours, then allowed to reach room temperature and poured onto ice water (600 ml), stirring being continued until all the ice has melted . The resultant solid is filtered off and dissolved in hot chloroform, the solution being dried and the solvent evaporated in vacuo to give a yellow solid. The aqueous filtrate obtained after the removal of the original solid is neutralised with saturated aqueous Na2CO3 and extracted continuously with chloroform, the extract being dried and evaporated in vacuo to yield a yellow solid. The two yellow solids are combined and recrystallised from ethanol to give 2-chloro-4-nitro-pyridine-1-oxide as yellow crystals (7.46 g, 56%).

1. temperatureThe acidic solution is heated in a steam bath for 2.5 hours
2. customto reach room temperature
3. additionpoured onto ice water (600 ml)
4. filtrationThe resultant solid is filtered off
5. dissolutiondissolved in hot chloroform
6. customthe solution being dried
7. customthe solvent evaporated in vacuo
8. customto give a yellow solid
9. customThe aqueous filtrate obtained
10. customafter the removal of the original solid
11. extractionextracted continuously with chloroform
12. customthe extract being dried
13. customevaporated in vacuo
14. customto yield a yellow solid
15. customrecrystallised from ethanol

ORD record

ord-e335134418c34b51a31884289197ec2d

Source dataset

uspto-grants-1993_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

USRE034313