Hydrochloric Acid → 1-(4-bromophenyl)-1H-pyrazole

Participants

Reaction Steps

To a stirring suspension of (4-bromophenyl)hydrazine hydrochloride (3.28 g, 14.7 mmol) in EtOH (25 mL) was added concentrated HCl (0.147 mL, 1.47 mmol) and 1,1,3,3-tetraethoxypropane (3.87 mL, 16.1 mmol). The reaction mixture was heated at reflux for 2 h then cooled to room temperature. The reaction mixture was poured onto water (150 mL) and hexanes (20 mL) and stirred for 1 h. A brown precipitate was collected by filtration and washed with water (2×10 mL) and hexanes (10 mL). The resultant solid was dried in air then washed with toluene (10 mL) to afford 2 g (61%) of 1-(4-bromophenyl)-1H-pyrazole INT-84 as a light brown powder. LCMS-ESI (m/z) calculated for C9H7BrN2: 223; found 223/225 [M+H]+, tR=2.14 min (Method 10).

Provenance & Evidence