The synthesis and iodination reaction of 5-amino-3-cyano-1- (2,6-dichloro-4-trifluoromethylphenyl) pyrazole

5-amino-3-cyano-1- (2,6-dichloro-4-trifluoromethylphenyl) pyrazole is an arylated pyrazole derivative, which is a white to light yellow solid powder at room temperature and pressure. It has significant alkalinity and can undergo acid-base neutralization reactions with common acidic substances. 5-amino-3-cyano-1- (2,6-dichloro-4-trifluoromethylphenyl) pyrazole is mainly used as an intermediate in the synthesis of pesticide molecules, and this substance can be used for the preparation of the pesticide insecticide fipronil.

synthetic method 

There is a study reporting the synthesis method of 5-amino-3-cyano-1- (2,6-dichloro-4-trifluoromethylphenyl) pyrazole, which includes: adding an ethanol solution of 2,6-dichloro4-trifluoromethylaniline salt and a sodium nitrite solution with a mass concentration of 40-45% to a hydrochloric acid ethanol solution of 2,3-dicyanopropionic acid ethyl ester at 0-5 ℃, and keeping the reaction solution at 0-5 ℃ for 2-12 hours until the 2,6-dichloro4-trifluoromethylaniline in the reaction solution is ≤ 0.5%. Then, a reducing reagent is added dropwise to the reaction solution to remove excess nitrite in the reaction solution until nitrite is completely removed. At 10-15 ℃, ammonia water is added to the reaction solution. Ethanol makes the pH of the reaction solution ≥ 11, and the resulting reaction mixture is stirred at this temperature for about 8-24 hours to obtain the target product molecule 5-amino-3-cyano-1- (2,6-dichloro-4-trifluoromethylphenyl) pyrazole. This synthesis method breaks the technical bias of technicians in this field, saves costs, and significantly reduces the generation of "three wastes".

Iodination reaction

At room temperature, 5-amino-3-cyano-1- (2,6-dichloro-4-trifluoromethylphenyl) pyrazole (5.0 g) was stirred in acetonitrile (60 ml), and N-iodobutyrimide (3.52 g) was added in proportion for 5 minutes. The obtained reaction mixture was stirred at room temperature for about 1 hour, then evaporated to dryness, and extracted with dichloromethane and water. The resulting organic layer was dried with anhydrous sodium sulfate, filtered to remove the desiccant, and the filtrate was concentrated under vacuum. The residue was purified by silica gel column chromatography to obtain the target product molecule.