Nitric Acid → 6-Nitroindoline

Temperature

10 °C

5.96 g (50 mmol) of indoline were dissolved in 25 ml of concentrated sulfuric acid, and a mixture of 3.75 ml of concentrated nitric acid (61%) and 25 ml of concentrated sulfuric acid was added to the solution while ice-cooling so that the internal temperature was maintained at 10° C. or lower. The mixture was then stirred while ice-cooling for 2 hours. At the end of this time, a 75% w/v aqueous solution of sodium hydroxide was added to the reaction mixture while ice-cooling to neutralize the reaction mixture, while maintaining the internal temperature at 60° C. or lower. The mixture was then extracted with ethyl acetate. The organic extract was dried over anhydrous magnesium sulfate and, after filtration, the solvent was removed from the filtrate by distillation under reduced pressure to obtain 7.8 g (47.5 mmol) of the title compound as crystals, melting at 65°-68° C. (yield: 95%).

1. additionwas added to the solution while ice-
2. temperaturecooling so that the internal temperature
3. temperaturecooling for 2 hours
4. temperaturecooling
5. temperaturewhile maintaining the internal temperature at 60° C.
6. extractionThe mixture was then extracted with ethyl acetate
7. extractionThe organic extract
8. dry with materialwas dried over anhydrous magnesium sulfate
9. filtrationafter filtration
10. customthe solvent was removed from the filtrate by distillation under reduced pressure

ORD record

ord-aa921106f70d4e07a49b555073d90623

Source dataset

uspto-grants-1998_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05773618