Hydrochloric Acid → 4-nitro-1H-pyrazole-3-carbonitrile

A suspension of 4-nitro-1H-5-pyrazolecarboxamide (7.80 g, 50 mmol) in dichloromethane (300 mL) and pyridine (30 mL) was treated with a solution of phosgene in toluene (20%, 50 mL). The mixture was stirred for 16 hours at ambient temperature then water (20 mL) was slowly added to the mixture, followed by 6 N aqueous hydrochloric acid (50 mL) and brine (15 mL). The mixture was extracted with dichloromethane (5×50 mL) and ethyl acetate (3×50 mL). The organic solutions were combined and dried over magnesium sulfate, filtered and the filtrate concentrated to a volume of about 150 mL then it was extracted with 1N aqueous hydrochloric acid (25 mL) and then brine (15 mL). The organic layer was dried over magnesium sulfate then filtered and the filtrate concentrated under reduced pressure to yield the title compound as a tan solid (6.36 g, 92%): 1H NMR (DMSO-d6, 400 MHz) δ 14.99 bs, 1H), 9.15 (s, 1H); RP-HPLC (Hypersil HS C18, 5 μm, 100 A, 250×4.6 mm; 5%-100% acetonitrile-0.05 M ammonium acetate over 25 min, 1 mL/min) tr 12.05 min; MS: MH+ 137.0

1. extractionThe mixture was extracted with dichloromethane (5×50 mL) and ethyl acetate (3×50 mL)
2. dry with materialdried over magnesium sulfate
3. filtrationfiltered
4. concentrationthe filtrate concentrated to a volume of about 150 mL
5. extractionit was extracted with 1N aqueous hydrochloric acid (25 mL)
6. dry with materialThe organic layer was dried over magnesium sulfate
7. filtrationthen filtered
8. concentrationthe filtrate concentrated under reduced pressure

ORD record

ord-cf22b27d091f4b988c8d89ed9c855bfe

Source dataset

uspto-grants-2010_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07829570B2