Hydrochloric Acid → Carfentrazone

Participants

Reaction Steps

To a reaction flask was added a mixture of 156 g of 1-(5-amino-4-chloro-2-fluorophenyl)-4-difluoromethyl-3-methyl-1H-1,2,4-triazol-5-one and 900 g of acetone. The mixture was stirred and dissolved, and then 54 g of hydrogen chloride was introduced while maintaining a temperature between 0˜5° C. 600 g of acrylic acid, 6 g of cuprous chloride and 8 g of lithium chloride were successively added. Then 150 g of a 45% aqueous solution of sodium nitrite was added dropwise below a liquid level. After the adding was completed, the mixture was stirred for additional 0.5 hour. The reaction mixture was concentrated under reduced pressure. The residue was diluted with 1000 ml of methyl benzene, washed with 300 ml of water and twice with 300 ml of a 5% diluted hydrochloride acid and then with 400 ml of water, and then concentrated under reduced pressure. After cooling, crystallized products were collected by filtration and dried, to give 170 g of 2-chloro-3-{2-chloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]-4-fluorophenyl}propionic acid as white solids with a purity of 98.5%.

Provenance & Evidence