Reaction #710573

Reaction equation

methylhydrazine

methylene chloride

perfluoro-2-methyl-2-pentene

Et3N

→

N-Methyl-3-Pentafluoroethyl-4-Trifluoromethyl-5-Fluoro-1H-Pyrazole

Solvents

water

water

Conditions

Workup

1. 1
   OtherIn a 3-kneck flask equipped with condenser
2. 2
   Otherranging from 0° C. to 5° C
3. 3
   workup.STIRRINGThe reaction mixture was stirred for 1 h at 5° C. and finally for 1.5 h at 20° C
4. 4
   WashThe mixture was washed with water (3×50 ml)
5. 5
   Dryingthe organic layer was dried over Na2SO4
6. 6
   workup.DISTILLATIONthe solvent was distilled off under atmospheric pressure
7. 7
   workup.DISTILLATIONThe crude product was purified via vacuum distillation

Procedure

In a 3-kneck flask equipped with condenser, thermometer, and a dropping funnel 130 ml methylene chloride and perfluoro-2-methyl-2-pentene (19.6 g, 0.065 mol) was placed and then 15 ml water were added. The mixture was cooled to 0° C. and Et3N (16.4 g, 0.16 mol) was added at a temperature ranging from 0° C. to 5° C. The mixture was stirred at this temperature for 15 min and 40% solution of methylhydrazine in water (7.4 g) was slowly added to this mixture at 0° C. The reaction mixture was stirred for 1 h at 5° C. and finally for 1.5 h at 20° C. The mixture was washed with water (3×50 ml), the organic layer was dried over Na2SO4 and the solvent was distilled off under atmospheric pressure. The crude product was purified via vacuum distillation. The yield of N-methyl-3-pentafluoroethyl-4-trifluoromethyl-5-fluoro-1H-pyrazole was 13.9 g. (75%), boiling point 62-65° C. at 17 mbar.

Source