4-Fluorophenylhydrazine hydrochloride → 2-(4-fluorophenyl)-4-methyl-2H-1,2,3-triazole 1-oxide

Temperature

23 °C

To a stirred solution of anti-pyruvic aldehyde 1-oxime (3.4 g, 39 mmol) in diethyl ether (75 mL) was added 4-fluorophenylhydrazine hydrochloride (5.85 g, 36 mmol). The reaction mixture was stirred at 23° C. for 16 h, and then concentrated under reduced pressure. The crude residue was dissolved in pyridine (120 mL). A solution of copper(II) sulfate pentahydrate (18 g, 72 mmol) in water (55 mL) was added dropwise over 4 min. The resulting mixture was stirred at reflux for 2 h. The mixture was concentrated under reduced pressure to remove excess pyridine. To the mixture was added 1.0 M aqueous hydrochloric acid. The mixture was extracted with ethyl acetate and the organic layer was separated and washed with 1.0 M aqueous hydrochloric acid until a clear amber organic layer was obtained. The organic layer was dried (MgSO4), filtered, and evaporated under reduced pressure to afford the title compound (6.6 g) as a colorless solid. The title compound was used directly in the next step without further purification.

1. concentrationconcentrated under reduced pressure
2. dissolutionThe crude residue was dissolved in pyridine (120 mL)
3. stirringThe resulting mixture was stirred
4. temperatureat reflux for 2 h
5. concentrationThe mixture was concentrated under reduced pressure
6. customto remove excess pyridine
7. additionTo the mixture was added 1.0 M aqueous hydrochloric acid
8. extractionThe mixture was extracted with ethyl acetate
9. customthe organic layer was separated
10. washwashed with 1.0 M aqueous hydrochloric acid until a clear amber organic layer
11. customwas obtained
12. dry with materialThe organic layer was dried (MgSO4)
13. filtrationfiltered
14. customevaporated under reduced pressure

ORD record

ord-80c695a5e9c641f3a17b8e5a9a48124c

Source dataset

uspto-grants-2016_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09302999B2