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

HRID 1843109Notes

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+]>C(OCC)C.C1COCC1.CCCCCCC.O>[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 (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.

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 off the solvent
customon a rotary evaporator under reduced pressure

Sources & evidence

ORD record: ord-a023707af7ef45beae0c96f207a2211d
Source dataset: uspto-grants-2015_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08946234B2

Reaction notes

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