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

Participants

Reaction Conditions

Reaction Steps

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%.

Provenance & Evidence