Sulfuric Acid → 5-Fluoroisatin

HRID 1693013Notes

Reaction equation

HRID 1693013 reaction equation
S(=O)(=O)(O)[OH:2].[F:6][C:7]1[CH:12]=[CH:11][C:10]([NH:13][C:14](=[O:18])[CH:15]=NO)=[CH:9][CH:8]=1>C(OCC)(=O)C>[F:6][C:7]1[CH:12]=[C:11]2[C:10](=[CH:9][CH:8]=1)[NH:13][C:14](=[O:18])[C:15]2=[O:2]

Participants

4

Reactant 2

HCID 1118Sulfuric AcidHCID 6400930HCID 6400930, compound

Product 1

HCID 2365665-Fluoroisatin

Reagents, catalysts & solvents 1

HCID 8857Ethyl AcetateSolvent

Conditions

Temperature
90 °C

Procedure

Concentrated sulfuric acid (200 mL) was heated at 50° C., and N-(4-fluorophenyl)-2-hydroxyiminoacetamide was slowly added. The black solution was carefully heated at 90° C. At this temperature, some slight cooling was necessary to keep the temperature at 90° C. When no more heat had developed, the reaction mixture was heated at 90° C. for an additional half hour. The dark-red solution was cooled to room temperature and poured onto 3 L ice water and 1 L ethyl acetate with vigorous stirring. The layers were separated, and the aqueous layer was extracted with ethyl acetate (1×1 L, 1×0.5 L). The combined organic extracts were dried over sodium sulfate, filtered, and evaporated to dryness. Yield: 35.3 g (52%) of a dark red solid, 5-fluoro-1H-indole-2,3-dione.

Workup

  1. temperatureAt this temperature, some slight cooling
  2. customat 90° C
  3. temperatureWhen no more heat
  4. temperaturethe reaction mixture was heated at 90° C. for an additional half hour
  5. temperatureThe dark-red solution was cooled to room temperature
  6. customThe layers were separated
  7. extractionthe aqueous layer was extracted with ethyl acetate (1×1 L, 1×0.5 L)
  8. dry with materialThe combined organic extracts were dried over sodium sulfate
  9. filtrationfiltered
  10. customevaporated to dryness

Sources & evidence

ORD record
ord-69ddda0eb7924ee9b9a699ecb690d15e
Source dataset
uspto-grants-2012_04
Patent number
US08158637B2

Reaction notes

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