Thionyl Chloride → 5-chloro-1,3-dimethyl-1H-pyrazole-4-sulfonyl chloride

Participants

Reaction Conditions

Reaction Steps

Into 150 xl of chlorosulfonic acid was added dropwise under cooling at 5° C. or lower, 30 g (0.23 ml) of 5-chloro-1,3-dimethylpyrazole. After the addition, the mixture was stirred at 100° C. for 8 hours. Then, the reaction mixture was cooled to 80° C., followed by dropwise addition of 36 g of thionyl chloride over 30 minutes After the addition, the mixture was stirred at 100° C. for an additional 2 hours. The reaction mixture was cooled on ice and poured carefully into ice-water, whereby crude 5-chloro-1,3-dimethylpyrazole-4-sulfonylchloride (50 g) was formed as crystals. Subsequently, into a solution of 40 g of dimethylamine in 250 ml of THF, the above compound was added under cooling and the reaction mixture was stirred at room temperature for 3 hours. After the reaction, THF was evaporated under reduced pressure and into the residue was added ether and washed with water. After drying and evaporating the etherial solution, there was obtained 47 g of the title compound m.p. 53 -55° C.

Provenance & Evidence