反应详情

30 g of 3-(2,4-dichlorophenyl)-5-hydroxy-1H-pyrazole from Example 3.1 were initially charged in 750 ml of toluene. 23.1 g of dimethyl sulfate and 7.5 g of potassium carbonate were added, and the mixture was heated at reflux for 2 h. After cooling to room temperature, the mixture was made alkaline using ammonia and stirred overnight. The mixture was acidified by addition of hydrochloric acid (pH about 1) and cooled to room temperature, and the precipitated solid was filtered off. Drying gave 21.4 g of 3-(2,4-dichlorophenyl)-5-hydroxy-1-methyl-1H-pyrazole (purity according to GC 99.2%, yield 66.8%). M.p.: 128° C.

1. temperaturethe mixture was heated
2. temperatureat reflux for 2 h
3. temperaturecooled to room temperature
4. filtrationthe precipitated solid was filtered off
5. customDrying