Hydrochloric Acid → 6,7-Difluoro-1H-indole-2,3-dione

HRID 2174200Notes

Reaction equation

HRID 2174200 reaction equation
[F:1][C:2]1[C:8]([F:9])=[CH:7][CH:6]=[CH:5][C:3]=1[NH2:4].Cl[C:11](Cl)(Cl)[CH:12]=[O:13].Cl.ON.S([O-])([O-])(=O)=[O:20].[Na+].[Na+].Cl>O>[F:9][C:8]1[C:2]([F:1])=[C:3]2[C:5]([C:12](=[O:13])[C:11](=[O:20])[NH:4]2)=[CH:6][CH:7]=1

Participants

7

Reactant 5

HCID 313Hydrochloric AcidHCID 6407ChloralHCID 24436Sodium SulfateHCID 782782,3-DifluoroanilineHCID 443297Hydroxyamine hydrochloride

Product 1

HCID 222743996,7-Difluoro-1H-indole-2,3-dioneYield 116.8%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
50 °C

Procedure

15.7 g of 2,3-difluoroaniline were added to 825 ml of water followed by adding 24.2 g of trichloroacetaldehyde, 30.8 g of hydroxyamine hydrochloride and 138.6 g of anhydrous sodium sulfate and stirring the mixture for 10 hours at 50° C. After allowing to cool to room temperature, 44 mL of 2N hydrochloric acid were added thereto, followed by stirring the mixture for 30 minutes. Subsequently, crystals were removed by filtration. The resulting crystals were dried, and then added to hot concentrated sulfuric acid at 70° C., followed by stirring the mixture for 1 hour at 80° C. to 90° C. The reaction solution was then poured over ice and extracted with ethyl acetate. The organic layer was washed with saturated saline and dried with magnesium sulfate followed by distilling off the solvent under reduced pressure to obtain 26 g of a crude product of 6,7-difluoroisatin.

Workup

  1. temperatureto cool to room temperature
  2. stirringby stirring the mixture for 30 minutes
  3. customSubsequently, crystals were removed by filtration
  4. customThe resulting crystals were dried
  5. additionadded to hot concentrated sulfuric acid at 70° C.
  6. stirringby stirring the mixture for 1 hour at 80° C. to 90° C
  7. additionThe reaction solution was then poured over ice
  8. extractionextracted with ethyl acetate
  9. washThe organic layer was washed with saturated saline
  10. dry with materialdried with magnesium sulfate
  11. distillationby distilling off the solvent under reduced pressure

Sources & evidence

ORD record
ord-dcbeb4f3f2384034a15d85878dbabf73
Source dataset
uspto-grants-2015_06
Patent number
US09060517B2

Reaction notes

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