Hydrogen Peroxide → HCID 178510672, Verbindung

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

1.5 liter of methylene dichloride & 421.0 gms of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluromethylphenyl)-4-trifluromethylthio pyrazole was charged in a reactor flask with overhead stirring & condenser system. This mass was cooled to 12-15° C. and 68.0 gms of H2O2 (50.0% w/w) & 500.0 gms of H2SO4 (90.0% w/w) were simultaneously added to the mass over a period of 3.0-4.0 hours. The reaction temperature was then raised to 28-30° C. & maintained for about 2.0 hours. The reaction mass obtained thereafter was slowly added into 1700 ml of chilled water at a temperature of about 10-20° C. over a period of 2.0 hours. To this mass, 1500 ml of methylene dichloride was added and the mixture was heated to 60° C. to separate the aqueous and organic layers. The organic phase was washed with water & then with 5% NaHCO3 solution, followed by water wash, till a neutral pH was obtained. The crude yield obtained was 425.0 gms. The obtained crude fipronil was then crystallized from same solvent after partial evaporation to yield crystalline Fipronil (325 gms) with 94.0% purity.

Herkunft & Nachweise