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

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence