反应详情

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

1. distillationAll the volatile constituents are then distilled off at this temperature under a waterpump vacuum
2. dissolutionis dissolved, without further purification, in 140 ml of ethanol
3. temperatureThe mixture is heated
4. temperatureunder reflux for 5 hours
5. customThe crystals which have separated out
6. filtrationare filtered off with suction
7. washwashed with water
8. customdried in air