Water → 4-Chloro-3-difluoromethyl-N-methylpyrazole

HRID 1692049Notes

Reaction equation

[Cl:1]N1C(=O)CCC1=O.[F:9][CH:10]([F:17])[C:11]1[CH:15]=[CH:14][N:13]([CH3:16])[N:12]=1.FC(F)C1N(C)N=CC=1.O>CN(C)C=O>[Cl:1][C:15]1[C:11]([CH:10]([F:17])[F:9])=[N:12][N:13]([CH3:16])[CH:14]=1

Participants

Conditions

Temperature: 60 °C

Procedure

At 0-5° C., a solution of N-chlorosuccinimide (NCS, 12.6 g, 0.09 mol) in dimethyl-formamide (DMF, 70 ml) was added dropwise to a solution of 3-difluoromethyl-N-methylpyrazole (14.9 g, 0.09 mol, 83.7% pure according to GC analysis) comprising, as minor component, 4.1% of 5-difluoromethyl-N-methylpyrazole, based on the total amount of the isomer mixture, in DMF (30 ml). The reaction mixture was then heated at 60° C. and stirred for a further 12 h. With stirring, the reaction mixture was then poured into water (1000 ml) and extracted twice with methyl tert-butyl ether (MTBE, 150 ml). The organic phases were combined, washed with a saturated aqueous solution of NaCl, dried over magnesium sulfate, filtered and then freed from the solvent under reduced pressure. 4-Chloro-3-difluoromethyl-N-methylpyrazole was obtained as an oil (17.6 g; purity: 78.4% according to GC analysis) comprising 3.7% of unreacted 5-difluoromethyl-N-methylpyrazole. This corresponds to a yield of 88%.

Workup

stirringWith stirring
extractionextracted twice with methyl tert-butyl ether (MTBE, 150 ml)
washwashed with a saturated aqueous solution of NaCl
dry with materialdried over magnesium sulfate
filtrationfiltered

Sources & evidence

ORD record: ord-717c12a859ae47b2912ea90d6bec6775
Source dataset: uspto-grants-2012_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08153820B2

Reaction notes

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