Sodium Hydroxide → 3-(Difluoromethyl)-1-methyl-1H-pyrazole

3-Dichloromethyl-N-methylpyrazole (40.0 g; 0.21 mol; 84.8% pure according to GC analysis) comprising, as minor component, 5-dichloromethyl-N-methylpyrazole was stirred with triethylamine trishydrofluoride (199 g, 1.23 mol) at 160° C. under intrinsic pressure (<1 bar) for 1 h. The reaction mixture was vented and poured onto ice (500 g), made alkaline using aqueous sodium hydroxide solution and extracted three times with methyl tert-butyl ether (100 ml). The organic phases were combined, washed successively with hydrochloric acid (dilute, 100 ml) and a saturated aqueous NaCl solution (100 ml), dried over magnesium sulfate and freed from the solvent under reduced pressure. The residue obtained was 3-difluoromethyl-1-methylpyrazole (24.8 g, yield: 78%) in a purity of 85.4% (according to GC analysis) comprising, as minor component, 5-difluoromethyl-N-methylpyrazole.

1. additionpoured onto ice (500 g)
2. extractionextracted three times with methyl tert-butyl ether (100 ml)
3. washwashed successively with hydrochloric acid (dilute, 100 ml)
4. dry with materiala saturated aqueous NaCl solution (100 ml), dried over magnesium sulfate
5. customThe residue obtained

ORD record

ord-0b43e29d9dad45c3803663e222971515

Source dataset

uspto-grants-2012_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08153820B2