Ethanol → 5-(difluoromethyl)-1-methyl-1H-pyrazole

Over a period of 10 minutes, hydrazine hydrate (80% pure, 0.52 g, 0.008 mol) was added dropwise to a solution of 4-butoxy-1-chloro-1,1-difluorobut-3-en-2-one (1.2 g, 0.005 mol) in ethanol (6 ml). The mixture was then stirred under reflux conditions for 5 h. The resulting yellow-brown suspension was concentrated on a rotary evaporator. The residue was taken up in ethyl acetate (20 ml) and water (20 ml). After separation of the phases, the aqueous phase was re-extracted with ethyl acetate (20 ml). The organic phases were combined, dried over MgSO4 and filtered, and volatile components were removed under reduced pressure. The light-red oily residue (0.35 g) consisted to about 65% of 3-difluorochloromethyl-NH-pyrazole and to 35% of ethyl pyrazole-3-carboxylate.

1. concentrationThe resulting yellow-brown suspension was concentrated on a rotary evaporator
2. customAfter separation of the phases
3. extractionthe aqueous phase was re-extracted with ethyl acetate (20 ml)
4. dry with materialdried over MgSO4
5. filtrationfiltered
6. customvolatile components were removed under reduced pressure

ORD record

ord-6f454637bff44385a54df311e39daaea

Source dataset

uspto-grants-2012_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08153820B2