Ethanol → ethyl 5-nitro-1H-pyrazole-3-carboxylate

To a solution of 5-nitropyrazol-3-carboxylic acid (19.9 g) in ethanol (200 mL) was added dropwise thionyl chloride (9.7 mL) over a period of 5 minutes and the mixture was refluxed for 4 hours. After cooling to room temperature, the reaction mixture was diluted with water (25 mL) and ethanol (50 mL) and to the mixture was neutralized with sodium hydrogencarbonate (54 g). The mixture was filtered and the residue was washed with ethanol. The filtrate and the washings were combined and concentrated in vacuo. The residue was azeotropically distilled with ethanol and the residue was dissolved in ethyl acetate, dried over magnesium sulfate and filtered. The filtrate was concentrated in vacuo and to the residue was added isopropylether. The precipitates were collected by filtration and washed with ethyl acetate/diisopropylether (1/2) to give ethyl 5-nitropyrazol-3-carboxylate (20 g, yield: 85%) as a colorless solid.

1. temperaturethe mixture was refluxed for 4 hours
2. filtrationThe mixture was filtered
3. washthe residue was washed with ethanol
4. concentrationconcentrated in vacuo
5. distillationThe residue was azeotropically distilled with ethanol
6. dissolutionthe residue was dissolved in ethyl acetate
7. dry with materialdried over magnesium sulfate
8. filtrationfiltered
9. concentrationThe filtrate was concentrated in vacuo and to the residue
10. additionwas added isopropylether
11. filtrationThe precipitates were collected by filtration
12. washwashed with ethyl acetate/diisopropylether (1/2)

ORD record

ord-ef892678d68b465bbbee788d1f4593ec

Source dataset

uspto-grants-2012_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08188097B2