Carbon Dioxide → 1-methyl-3-pentafluoroethyl-1H-pyrazole-5-carboxylic acid

HRID 1843077Notes

Reaction equation

[CH3:1][N:2]1[CH:6]=[CH:5][C:4]([C:7]([F:13])([F:12])[C:8]([F:11])([F:10])[F:9])=[N:3]1.C([N-]C(C)C)(C)C.[Li+].[C:22](=[O:24])=[O:23].[OH-].[Na+]>O1CCCC1.CCCCCCC.O.C(OCC)C>[CH3:1][N:2]1[C:6]([C:22]([OH:24])=[O:23])=[CH:5][C:4]([C:7]([F:12])([F:13])[C:8]([F:9])([F:10])[F:11])=[N:3]1

Participants

Conditions

Temperature: -78 °C

Procedure

Under an argon atmosphere, 5.00 g (25.0 mmol) of 1-methyl-3-pentafluoroethyl-1H-pyrazole are initially introduced into diethyl ether and the solution is cooled to −78° C. 11.1 ml (27.7 mmol) of 2M lithium diisopropylamide solution in tetrahydrofuran/heptane are added dropwise and, at −30° C. and with vigorous stirring, 450 g of crushed dry ice are added. When the evolution of gas has stopped, the reaction mixture is admixed with 235 ml of water and adjusted to pH 11 with 1M 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 of the solvent on a rotary evaporator under reduced pressure gives 1.20 g of 1-methyl-3-pentafluoroethyl-1H-pyrazole-5-carboxylic acid (18%) as a solid.

Workup

additionare added
extractionThe alkaline solution is extracted three times with ethyl acetate
extractionThe aqueous phase is extracted three times with ethyl acetate
dry with materialthe organic phase is dried over sodium sulphate
distillationDistilling of the solvent on a rotary evaporator under reduced pressure

Sources & evidence

ORD record: ord-41c8ce546ecc4c64be692adc50335656
Source dataset: uspto-grants-2015_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08946234B2

Reaction notes

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