Reaction #710574

Reaction equation

N-methylhydrazine

methylene chloride

perfluoro-2-methyl-2-pentene

Et3N

→

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

Yield 85.0%

Solvents

water

water

Conditions

Workup

1. 1
   OtherIn a 21 3-kneck flask equipped with condenser
2. 2
   Otherranging from −5° to 5° C
3. 3
   workup.STIRRINGThe reaction mixture was stirred for 15-20 h at 20° C
4. 4
   WashThe mixture was washed with water
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 21 3-kneck flask equipped with condenser, thermometer, and a dropping funnel 1300 ml methylene chloride and perfluoro-2-methyl-2-pentene (197 g, 0.65 mol) was placed, and then 117 ml water were added. The mixture was cooled to −0° C. and Et3N (164 g, 1.62 mol) was added at a temperature ranging from −5° to 5° C. The mixture was stirred at this temperature for 15 min and a solution of 75 ml N-methylhydrazine in water (40% w.w.) was slowly added to this mixture at 5° C. within 2 h. The reaction mixture was stirred for 15-20 h at 20° C. The mixture was washed with water, 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 158 g (85% yield). Boiling point 62-67° C. at 15-20 mbar.

Source