Methanesulfonyl chloride → Sulfentrazone

Participants

Reaction Steps

The reaction was carried out using the same equipment as described in Example 1. The flask was charged with 53.9 g (0.143 mole, 82% assay) of 2-(5-amino-2,4-dichlorophenyl)-4-(difluoromethyl)-2,4-dihydro-5-methyl-3H-1,2,4-triazol-3-one and 24 grams of toluene. The mixture was heated to reflux and 15.6 mL (23 g, 0.20 mole) of methanesulfonyl chloride (Aldrich, 99.5%) added dropwise over 22 minutes. The solution was heated at reflux for 4.5 hours after the completion of the addition, and a further 3.9 mL (5.75 g, 0.05 mole) of methanesulfonyl chloride was added over 10 minutes. After an additional 2.5 hours at reflux, the reaction mixture was diluted with 75 mL of toluene, allowed to cool to room temperature, and stirred over the weekend (62 hours). The resulting slurry was warmed to dissolve the solids, transferred to a 1-L round bottomed flask equipped with a mechanical stirrer, and rinsed in with 200 mL of toluene. The mixture was warmed to 80° C. and washed twice with 150 mL portions of water, with the washes being removed via pipette. The solution was allowed to cool slowly to 40° C. and the resulting slurry then cooled in an ice bath for 2.5 hours. The product was collected by filtration and the filter cake washed with a total of 120 mL of cold toluene and dried in a vacuum oven to provide 48.6 g (79% yield) of 90% assay of N-[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]phenyl]methanesulfonamide as a tan solid.

Provenance & Evidence