1,1-Dimethylhydrazine → 3-Dichloromethyl-1-methyl-1h-pyrazole

Temperature

34 °C

At 20° C., 1,1,4-trichloro-3-buten-2-one (15 g, 0.078 mol) was added dropwise over a period of 37 min to a solution of 1,1-dimethylhydrazine (9.5 g, 0.156 mol) in methyl tert-butyl ether (MTBE, 500 ml), with warming to 34° C. After 2 h, a sticky brown suspension had formed, which was filtered through kieselguhr. The filtrate was concentrated under reduced pressure. The residue (7.6 g of a viscous oil) was subjected to fractional distillation under reduced pressure. As the main fraction, 3 g of 3-dichloromethyl-N-methylpyrazole were obtained in a purity of 96.4% (GC area) (boiling point 65° C./0.3 mbar), and the product crystallized on standing. Recrystallization gave a sample having a purity of >99% (GC area).

1. customa sticky brown suspension had formed
2. filtrationwhich was filtered through kieselguhr
3. concentrationThe filtrate was concentrated under reduced pressure
4. distillationThe residue (7.6 g of a viscous oil) was subjected to fractional distillation under reduced pressure

ORD record

ord-c1ac2d727be74ee4b5d5639779150eea

Source dataset

uspto-grants-2012_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08153820B2