Potassium Carbonate → 5,6-Difluorobenzofuran-2-carboxylic acid

HRID 618708Notes

Reaction equation

HRID 618708 reaction equation
[F:1][C:2]1[C:9]([F:10])=[CH:8][C:5]([CH:6]=O)=[C:4]([OH:11])[CH:3]=1.Br[CH:13](C(OCC)=O)[C:14]([O:16]CC)=[O:15].C(=O)([O-])[O-].[K+].[K+].[OH-].[K+]>C(O)C.CC(CC)=O>[F:10][C:9]1[C:2]([F:1])=[CH:3][C:4]2[O:11][C:13]([C:14]([OH:16])=[O:15])=[CH:6][C:5]=2[CH:8]=1

Participants

7

Reactant 4

HCID 11430Potassium CarbonateHCID 14797Potassium HydroxideHCID 69637Diethyl bromomalonateHCID 154345534,5-Difluoro-2-hydroxybenzaldehyde

Product 1

HCID 154345545,6-Difluorobenzofuran-2-carboxylic acidYield 60.8%

Reagents, catalysts & solvents 2

HCID 702EthanolSolventHCID 6569Methyl Ethyl KetoneSolvent

Procedure

A mixture of 6.5 g (41.1 mmol) of 4,5-difluoro-2-hydroxybenzaldehyde, 10.4 ml (61.7 mmol) of diethyl bromo-malonate, 11.3 g (82.2 mmol) of potassium carbonate and 50 ml of ethyl methyl ketone was boiled at reflux for 3 hours while stirring, filtered and concentrated in a vacuum. The brown oil obtained was dissolved in 65 ml of ethanol, treated with 6.5 g of potassium hydroxide pellets and heated at reflux for one hour while stirring. The mixture was concentrated in a vacuum and the residue was treated with 65 ml of water and 65 ml of 3N sulfuric acid and heated at reflux over 30 minutes. Subsequently, the mixture was filtered and the residue was washed with water and triturated in 50 ml of hexane over 30 minutes. The solid was filtered off and dried. There were obtained 4.95 g (60%) of 5,6-difluorobenzofuran-2-carboxylic acid as a light yellow solid with m.p. 270°.

Workup

  1. temperatureat reflux for 3 hours
  2. filtrationfiltered
  3. concentrationconcentrated in a vacuum
  4. customThe brown oil obtained
  5. temperatureheated
  6. temperatureat reflux for one hour
  7. stirringwhile stirring
  8. concentrationThe mixture was concentrated in a vacuum
  9. additionthe residue was treated with 65 ml of water and 65 ml of 3N sulfuric acid
  10. temperatureheated
  11. temperatureat reflux over 30 minutes
  12. filtrationSubsequently, the mixture was filtered
  13. washthe residue was washed with water
  14. customtriturated in 50 ml of hexane over 30 minutes
  15. filtrationThe solid was filtered off
  16. customdried

Sources & evidence

ORD record
ord-dbf6806df07a401986d5a71c926d3cd0
Source dataset
uspto-grants-1999_09
Patent number
US05955495

Reaction notes

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