Hydrogen Peroxide → HCID 178510672, compound

Participants

Reaction Conditions

Reaction Steps

1.5 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 then 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 over a period of 3.0 to 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 10-20° C. over a period of 2.0 hours. To this mass, 1500 ml of ethylene dichloride was added and the mixture was heated to 60° C. in order to separate the aqueous and organic layers. The obtained organic phase was washed with water & then with 5% NaHCO3 solution followed by water wash, till a neutral pH was obtained. The crude yield of fipronil after removal of solvent was 425.0 gms. The crude fipronil was crystallized from same solvent after partial evaporation to yield 325 gms of crystalline fipronil with 94.0% purity.

Provenance & Evidence