Hydrochloric Acid → 1-(2,5-Difluorophenyl)-1H-pyrazole

Reaction equation

CO[CH:3](OC)[CH2:4][CH:5](OC)OC.[F:12][C:13]1[CH:18]=[CH:17][C:16]([F:19])=[CH:15][C:14]=1[NH:20][NH2:21].Cl>C(O)C>[F:12][C:13]1[CH:18]=[CH:17][C:16]([F:19])=[CH:15][C:14]=1[N:20]1[CH:5]=[CH:4][CH:3]=[N:21]1

Participants

Procedure

Add 1,1,3,3-tetramethoxypropane (8.2 g, 50 mmol) to a mixture of 2,5-difluorophenylhydrazine (9.022 g, 62.6 mmol) and hydrochloric acid (5M, 5 mL, 25 mmol) in ethanol (50 mL) and heat and stir under reflux under nitrogen for 17 hr. Cool the mixture, evaporate the ethanol in vacuo, suspend the residue in DCM (80 mL), filter the DCM solution and pass through an SCX-2 column. Collect the eluent and pass through a second SCX2 column and evaporate the eluent to give 1-(2,5-difluoro-phenyl)-1H-pyrazol as a liquid (8.79 g, 97%). MS (m/z): 181 (M+1).