1,2-Dichloroethane → HCID 178510672, compound

Participants

Reaction Conditions

Reaction Steps

3.0 liter of ethylene 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 a temperature of about 5-10° C. 95.0 gms of H2O2 (50.0% w/w) & 2000.0 gms H2SO4 (85.0% w/w) were simultaneously added over a period of 3-4 hours. The reaction temperature was maintained at 12-15° C. for about 2.0 hours with monitoring of reaction conversion. The reaction mass obtained thereafter was slowly added into 800 ml of chilled water at a temperature of about 10-20° C. over a period of 2.0 hours. This mass was heated to a temperature of about 60-65° C. to separate the aqueous and organic layers. The organic phase was washed with water & then with 5% NaHCO3, followed by water wash, till a neutral pH was obtained. The crude yield of fipronil after removal of solvent was 435.0 gms. The crude fipronil was then crystallized to yield 350.0 gms of fipronil with 95.50% purity.

Provenance & Evidence