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

Temperature

5 °C

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.

1. additionAfter the addition
2. temperatureThen, the reaction mixture was cooled to 80° C.
3. additionAfter the addition
4. stirringthe mixture was stirred at 100° C. for an additional 2 hours
5. temperatureThe reaction mixture was cooled on ice

ORD record

ord-a0c3fa6813de4b13a2aa9d3119414520

Source dataset

uspto-grants-1990_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04954164