Sodium Phosphate, Dibasic → 1-(6-Amino-5-nitro-2-pyridyl)-2-(2,4-difluorophenyl)ethane-1,2-dione

Participants

Reaction Conditions

Reaction Steps

6-[2-(2,4-Difluorophenyl)ethynyl]-3-nitro-pyridin-2-amine (2.0 kg, 7.3 mol) and acetone (40.5 L) are added to a reactor under a nitrogen atmosphere and the mixture is cooled to 0-10° C. with stirring. A buffering solution of water (38.3 L), sodium dihydrogen phosphate (3.3 kg), and disodium hydrogen phosphate (0.7 kg) is added at 0-15° C. The mixture is cooled to 3-6° C. and is charged with solid potassium permanganate (4.1 kg, 25.9 mol) at 3-6° C. The mixture is stirred for 3 h to 5 h, and then portions of the reaction mixture are transferred to a vessel containing water (9.3 L) and sodium thiosulfate pentahydrate (3.6 kg) at 15-20° C. The mixture is stirred at 15-25° C. Water (50 L) is added and the mixture stirred for 0.5-1 h and is filtered. The filtrate is concentrated under reduced pressure below 45° C. When the distillation of solvent is complete, water (40 L) is added at 20-25° C. and the mixture is stirred for 0.5-1 h. The solids are collected by filtration and the filtercake is dried below 40° C. to obtain the title compound as a yellow solid (1.7 kg, 75%).

Provenance & Evidence