反应详情

19.9 g (0.1 mol) of ethyl 4-chloro-phenylacetate are heated with 23.8 g (0.2 mol) of dimethylformamide dimethyl acetal to 100° C. for 5 hours. All volatile components are then distilled off at this temperature in a vacuum from a water pump. The oily residue, which essentially consists of ethyl α-dimethylaminomethylene-4-chlorophenylacetate, is dissolved in 140 ml of ethanol without further purification, and 11 g (0.1 mol) of 2-hydrazinopyrimidine and 10 ml of concentrated hydrochloric acid are added. The mixture is heated under reflux for 5 hours and cooled to room temperature, and, after the addition of 9 g of concentrated sodium hydroxide solution, is stirred for 5 hours at room temperature. After it has been neutralized with dilute hydrochloric acid, the mixture is diluted with 1 l of water. The precipitated crystals are filtered off under suction, washed with water and dried in the air. 7.2 g (26.4% of theory) of 1-pyrimid-2-yl-4-(4 -chlorophenyl)-pyrazolin-5-one of melting point 190° to 191° C. (methanol) are obtained.

1. distillationAll volatile components are then distilled off at this temperature in a vacuum from a water pump
2. additionare added
3. temperatureThe mixture is heated
4. temperatureunder reflux for 5 hours
5. filtrationThe precipitated crystals are filtered off under suction
6. washwashed with water
7. customdried in the air