反应详情

温度

50 °C

Dimethoxyethane (43 parts) was charged to a reactor and ammonia was bubbled in to form a saturated solution. The ammonia addition was maintained while a solution of 1.84 parts of 4,5-difluorophthalic anhydride in 13 parts of dimethoxyethane was added slowly over a period of 0.5 hours. The reaction mixture was stirred for an additional 5 minute period and the dimethoxyethane was removed by vacuum distillation. The remaining white solid (the ammonium salt of 4,5-difluorophthalamic acid) was dissolved in 20 parts of aqueous sodium hydroxide (40% NaOH) and the solution was de-gassed under moderately reduced pressure to remove any remaining ammonia; then heated at atmospheric pressure, to 50° C. and maintained at tha temperature while 14.1 parts of a 5.78% aqueous sodium hypochlorite solution was added. The solution was then heated to 60°-65° C. and maintained at that temperature, with stirring for about 30 minutes; then cooled to about 20°-25° C. and acidified to a pH of 4-6, by addition of concentrated hydrochloric acid. A precipitate formed and the mixture was extracted with chloroform. The acidification procedure was repeated until no additional precipitate formed. The combined extracts were dried over anhydrous sodium sulfate, filtered, and the chloroform removed by vacuum distillation to yield 1.34 parts of solid 4,5-difluoroanthranilic acid having a melting point of 180°-181° C. The chemical structure of the product was confirmed by infra-red analysis.

1. customammonia was bubbled in
2. customto form a saturated solution
3. additionwas added slowly over a period of 0.5 hours
4. customthe dimethoxyethane was removed by vacuum distillation
5. dissolutionThe remaining white solid (the ammonium salt of 4,5-difluorophthalamic acid) was dissolved in 20 parts of aqueous sodium hydroxide (40% NaOH)
6. customthe solution was de-gassed under moderately reduced pressure
7. customto remove any remaining ammonia
8. temperaturemaintained at tha temperature while 14.1 parts of a 5.78% aqueous sodium hypochlorite solution
9. additionwas added
10. temperatureThe solution was then heated to 60°-65° C.
11. temperaturemaintained at that temperature
12. stirringwith stirring for about 30 minutes
13. temperaturethen cooled to about 20°-25° C.
14. additionacidified to a pH of 4-6, by addition of concentrated hydrochloric acid
15. customA precipitate formed
16. extractionthe mixture was extracted with chloroform
17. customformed
18. dry with materialThe combined extracts were dried over anhydrous sodium sulfate
19. filtrationfiltered
20. customthe chloroform removed by vacuum distillation