反应详情

温度

-78 °C

Under an argon atmosphere, 5.00 g (24.99 mmol) of 1-methyl-3-pentafluoroethyl-1H-pyrazole are initially introduced in diethyl ether and the solution is cooled to −78° C. 11.09 ml (27.73 mmol) of 2M lithium diisopropylamide solution in THF/heptane are added dropwise and, at −30° C. with vigorous stirring, 450 g of crushed dry ice are added. When the evolution of gas has finished, the reaction mixture is admixed with 235 ml of water and adjusted to a pH of 11 with 1N sodium hydroxide solution. The alkaline solution is extracted three times with ethyl acetate and then adjusted to pH 2 with 1N hydrochloric acid. The aqueous phase is extracted three times with ethyl acetate and the organic phase is dried over sodium sulphate. Distilling off the solvent on a rotary evaporator under reduced pressure gives 1.20 g (17.75% of theory) of 1-methyl-3-pentafluoroethyl-1H-pyrazole-5-carboxylic acid as a solid.

1. additionare added
2. extractionThe alkaline solution is extracted three times with ethyl acetate
3. extractionThe aqueous phase is extracted three times with ethyl acetate
4. dry with materialthe organic phase is dried over sodium sulphate
5. distillationDistilling off the solvent
6. customon a rotary evaporator under reduced pressure