Chlorine → 5-Chloro-1,3-dimethyl-1h-pyrazole-4-carbonyl chloride

Participants

Reaction Conditions

Reaction Steps

To a solution of 48 g of 5-chloro-1,3-dimethyl-1H-pyrazole-4-carbaldehyde in 230 ml of chlorobenzene under protective gas, 19.2 g of chlorine gas are introduced while illuminating with a mercury lamp at 30° C. within 4 hours. After the gas introduction has ended, the reaction solution is stirred with illumination at 30° C. for a further 20 minutes. The reaction solution is cooled to 5° C. and the solid is filtered off and washed with a little chlorobenzene. After the solvent has been removed, 5-chloro-1,3-dimethyl-1H-pyrazole-4-carbonyl chloride is obtained in a yield of 87%.

Provenance & Evidence