Water → 1-Methyl-3-(perfluoroethyl)-4-(trifluoromethyl)-1H-pyrazole-5-carbonitrile

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Reaction Steps

42.0 g (147 mmol) of 5-fluoro-1-methyl-3-pentafluoroethyl-4-trifluoromethylpyrazole [synthesis see Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya 1990, (11), 2583-9] and 11.5 g (235 mmol) of sodium cyanide are suspended in 150 ml of acetonitrile and then heated at reflux temperature under a protective gas atmosphere. After cooling, the reaction mixture is poured onto a mixture of 300 ml of distilled water and 300 ml of diethyl ether. The aqueous phase is extracted three times with diethyl ether. The combined organic phases are washed twice with water and once with saturated aqueous sodium chloride solution. The organic phase is dried over sodium sulphate and then filtered. The solvent is removed under reduced pressure on a rotary evaporator and the residue obtained in this way is subjected to fractional distillation in vacuo. This gives 37.0 g of 5-cyano-1-methyl-3-pentafluoroethyl-4-trifluoromethylpyrazole (82%) as a colourless liquid (b.p. 74° C./10 mbar).

Provenance & Evidence