Water → 5-Amino-3-bromo-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-methylsulphinylpyrazole

Participants

Reaction Conditions

Reaction Steps

A solution of 5-amino-3-bromo-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-methylthiopyrazole (2.0 g) [preparation described in Example 15] in methanol (45 ml) at -25° C. was treated with a rapidly added solution of potassium hydrogen persulphate (1.66 g), followed immediately by the addition of water (22 ml). The mixture was stirred for 30 minutes at 0° C., and potassium hydrogen persulphate (0.4 g) added. After 21/2 hours stirring at room temperature, the mixture was poured onto water (300 ml) and saturated sodium bisulphite solution (35 ml) added. This was extracted with dichloromethane (2×150 ml) and the extract washed with water (2×50 ml), dried over anhydrous magnesium sulphate, and evaporated in vacuo. The crude product was purified by chromatography eluting with dichloromethane/ethyl acetate (4:1) to give 5-amino-3-bromo-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-methylsulphinylpyrazole (0.9 g) as a white solid, m.p. 135°-136° C.

Provenance & Evidence