Chlorosulfonic acid → 4-(1-Methyl-1H-pyrazol-4-yl)benzenesulfonyl chloride

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Reaction Steps

0.5 g of 1-methyl-4-phenyl-1H-pyrazole (3.16 mmol) were dissolved in 20 ml of dichloromethane. At 0° C., 0.232 ml of chlorosulfonic acid were added and the reaction mixture was stirred for 1 h under ice cooling. Additional 0.7 ml of chlorosulfonic acid were added, the mixture was stirred at 0° C. for 30 minutes and then 90 minutes at 50° C. The two phases were separated and the lower layer put on ice, extracted twice with diethyl ether, dried over magnesium sulfate, filtered, and the solvent evaporated under reduced pressure to yield 0.496 g of the product.

Provenance & Evidence