Sulfuric Acid → 5-Fluoro-1-benzofuran-2-carboxylic acid

HRID 648219Notes

Reaction equation

HRID 648219 reaction equation
[F:1][C:2]1[CH:9]=[C:6]([CH:7]=O)[C:5]([OH:10])=[CH:4][CH:3]=1.C([O:13][C:14](=[O:22])[CH:15](Br)C(OCC)=O)C.C(=O)([O-])[O-].[K+].[K+].S(=O)(=O)(O)O.[OH-].[K+]>C(C(C)=O)C>[F:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][C:15]([C:14]([OH:22])=[O:13])=[CH:7][C:6]=2[CH:9]=1

Participants

7

Reactant 5

HCID 1118Sulfuric AcidHCID 11430Potassium CarbonateHCID 14797Potassium HydroxideHCID 69637Diethyl bromomalonateHCID 27373285-Fluorosalicylaldehyde

Product 1

HCID 109868725-Fluoro-1-benzofuran-2-carboxylic acidYield 19.4%

Reagents, catalysts & solvents 1

HCID 6569Methyl Ethyl KetoneSolvent

Procedure

5-Fluorosalicylaldehyde (4.4 g), diethylbromomalonate (11.3 g) and methyl ethyl ketone (35 ml) were stirred together. Anhydrous potassium carbonate (8.7 g) was added and the mixture was heated at reflux for 4 hours. Excess dilute sulphuric acid was added and the mixture was extracted with diethyl ether. The combined extracts were washed with water, dried and evaporated to leave an oil which was treated with 10% w/v ethanolic KOH (60 ml) and heated at reflux for 45 minutes. The solvent was evaporated and the residue treated with excess dilute sulphuric acid and heated briefly on a steam bath. After cooling the crude acid was filtered off. Recrystallisation from ethylacetate/ethanol gave a fawn coloured product (1.1 g), m.p. 261°-266° (decomp), I.R. νmax 1685 cm-1.

Workup

  1. temperaturethe mixture was heated
  2. temperatureat reflux for 4 hours
  3. extractionthe mixture was extracted with diethyl ether
  4. washThe combined extracts were washed with water
  5. customdried
  6. customevaporated
  7. customto leave an oil which
  8. temperatureheated
  9. temperatureat reflux for 45 minutes
  10. customThe solvent was evaporated
  11. additionthe residue treated with excess dilute sulphuric acid
  12. temperatureheated briefly on a steam bath
  13. temperatureAfter cooling the crude acid
  14. filtrationwas filtered off
  15. customRecrystallisation from ethylacetate/ethanol

Sources & evidence

ORD record
ord-56b195bf9af24788865628570bcd6060
Source dataset
uspto-grants-1983_10
Patent number
US04411908

Reaction notes

Loading…