Sulfuric Acid → 5-Amino-1-(2,6-dichloro-4-trifluoromethylphenyl)-pyrazole

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Reaction Steps

25 ml (27.6 g/0.3 mol) of 2-chloro-acrylonitrile are added dropwise to 24.5 g (0.1 mol) of 2,6-dichloro-4-trifluoromethylphenylhydrazine and 20 mg of disodium ethylenediamine-tetraacetate (Titriplex III) in 150 ml of methanol at the reflux temperature. When the addition has ended, the mixture is heated at the reflux temperature for a further 8 hours, 9 ml (0.16 mol) of 96% strength sulphuric acid are added dropwise and the mixture is heated at the reflux temperature for a further 6 hours. 33.5 g (0.3 mol) of anhydrous sodium carbonate are added to the cooled reaction mixture. After 4 hours, the solvent is removed in vacuo, the residue is taken up in 500 ml of water and the mixture is stirred at room temperature for 10 hours. The precipitate which has separated out is filtered off, rinsed with water and dried in vacuo at 50° C. 28.5 (96% of theory) of 5-amino- 1-(2,6-dichloro-4-trifluoromethylphenyl)-pyrazole of melting point 103°-105° C. are obtained.

Provenance & Evidence