反应详情

7.18 g (156 mmol) of methylhydrazine are added dropwise to a solution of 30.9 g (142 mmol) of (1E)-1-ethoxy-4,4,5,5,5-pentafluoropent-1-en-3-one (preparation: Synthesis 2000, 5, 738-742) in 56 ml of methanol, and the reaction mixture is heated under reflux for 18 hours. The majority of the methanol is distilled off at atmospheric pressure and the residue is poured on to ice. The aqueous phase is extracted three times with dichloromethane and the organic phase is then washed three times with saturated sodium chloride solution. After drying over sodium sulphate, the solvent is distilled off at reduced pressure on a rotary evaporator. This gives 15.8 g of 1-methyl-3-pentafluoroethyl-1H-pyrazole (52%) as an oil.

1. temperaturethe reaction mixture is heated
2. temperatureunder reflux for 18 hours
3. distillationThe majority of the methanol is distilled off at atmospheric pressure
4. additionthe residue is poured on to ice
5. extractionThe aqueous phase is extracted three times with dichloromethane
6. washthe organic phase is then washed three times with saturated sodium chloride solution
7. dry with materialAfter drying over sodium sulphate
8. distillationthe solvent is distilled off at reduced pressure on a rotary evaporator