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

HRID 604297Notes

Reaction equation

HRID 604297 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

5

Reactant 3

HCID 313Hydrochloric AcidHCID 66019TetramethoxypropaneHCID 5889572,5-Difluorophenylhydrazine

Product 1

HCID 594382511-(2,5-Difluorophenyl)-1H-pyrazoleYield 97.6%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

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).

Workup

  1. temperatureheat
  2. temperatureunder reflux under nitrogen for 17 hr
  3. temperatureCool the mixture
  4. customevaporate the ethanol in vacuo
  5. filtrationfilter the DCM solution and pass through an SCX-2 column
  6. customCollect the eluent
  7. customevaporate the eluent

Sources & evidence

ORD record
ord-66b657553e3f4520b9978e0d95e629ba
Source dataset
uspto-grants-2011_03
Patent number
US07910588B2

Reaction notes

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