反应详情

To a stirred mixture of 8.0 g (0.042 mole) of 4-chloro-2-fluoro-5-methoxyphenylhydrazine and 8.4 g (0.05 mole) of ethyl difluoroacetylcarbamate in 120 mL of xylene was added 2.1 g of phosphorus pentoxide. After complete addition the mixture was heated at reflux for one hour. While still hot, the reaction mixture was decanted from a dark residue into a clean flask. This residue was washed with xylene and the wash was combined with the decanted reaction mixture. The resultant mixture was stirred at room temperature for one hour. A precipitate formed and was removed by filtration and saved for later purification. The filtrate was extracted with three 150 mL portions of an aqueous 10% sodium hydroxide solution. The basic washes were combined and extracted with xylene. During the extraction an oil formed a third phase in the bottom of the separatory funnel and was removed from the other two phases. The basic aqueous phase was separated from the organic phase and filtered through a celite pad. The filtrate was washed with two portions of diethyl ether and acidified with concentrated hydrochloric acid. The acidified aqueous mixture was stirred at room temperature forming a brown precipitate. Collection of the precipitate by filtration yielded 1.5 g of 1-(4-chloro-2-fluoro-5-methoxyphenyl)-3-difluoromethyl-4,5-dihydro-1,2,4-triazol-5(1H)-one. The precipitate which was previously saved for purification was stirred in 70 mL of an aqueous 10% sodium hydroxide solution. The basic mixture was filtered through a celite pad to remove insoluble materials. The filtrate was acidified with concentrated hydrochloric acid producing a white solid. This solid was collected by filtration to yield an additional 0.7 g of product (mp 188°-190° C.).

1. additionAfter complete addition the mixture
2. temperaturewas heated
3. temperatureat reflux for one hour
4. customWhile still hot, the reaction mixture was decanted from a dark residue into a clean flask
5. washThis residue was washed with xylene
6. customthe wash was combined with the decanted reaction mixture
7. customA precipitate formed
8. customwas removed by filtration
9. customsaved for later purification
10. extractionThe filtrate was extracted with three 150 mL portions of an aqueous 10% sodium hydroxide solution
11. extractionextracted with xylene
12. extractionDuring the extraction an oil
13. customformed a third phase in the bottom of the separatory funnel
14. customwas removed from the other two phases
15. customThe basic aqueous phase was separated from the organic phase
16. filtrationfiltered through a celite pad
17. washThe filtrate was washed with two portions of diethyl ether
18. customforming a brown precipitate
19. customCollection of the precipitate
20. filtrationby filtration