Hydrochloric Acid → 5-Bromo-7-methoxy-2-benzofurancarboxylic acid

HRID 1901313Notes

Reaction equation

HRID 1901313 reaction equation
[OH-:1].[Na+].BrBr.[C:5]([C:8]1[O:9][C:10]2[C:16]([O:17][CH3:18])=[CH:15][C:14]([Br:19])=[CH:13][C:11]=2[CH:12]=1)(=[O:7])C.Cl>O1CCOCC1>[Br:19][C:14]1[CH:15]=[C:16]([O:17][CH3:18])[C:10]2[O:9][C:8]([C:5]([OH:7])=[O:1])=[CH:12][C:11]=2[CH:13]=1

Participants

6

Reactant 4

HCID 313Hydrochloric AcidHCID 14798Sodium HydroxideHCID 24408BromineHCID 14913661-(5-Bromo-7-Methoxy-1-Benzofuran-2-Yl)Ethan-1-One

Product 1

HCID 33589715-Bromo-7-methoxy-2-benzofurancarboxylic acid

Reagents, catalysts & solvents 1

HCID 312751,4-DioxaneSolvent

Conditions

Temperature
60 °C

Procedure

To 107.6 ml of 5N sodium hydroxide aqueous solution was added dropwise 26.8 g of bromine at a temperature of -5° C. or below. To this was further added dropwise and slowly a 100 ml dioxane solution containing 15.0 g of 2-acetyl-5-bromo-7-methoxybenzofuran obtained in the above step a). After completion of the dropwise addition, the temperature of the resulting reaction solution was increased gradually to 60° C. and then stirred for 30 minutes. After cooling, the resulting reaction solution was adjusted to pH 2 with concentrated hydrochloric acid and then extracted with ethyl acetate. The resulting organic layer was concentrated to dryness, and crystals thus precipitated were collected by filtration to obtain 5-bromo-7-methoxy-2-benzofurancarboxylic acid. The thus obtained crystals were suspended in 200 ml of ethanol, and 10 ml of thionyl chloride was added dropwise to the suspension with stirring at room temperature. The resulting reaction solution was refluxed under heating for 2 hours. After cooling, the thus treated reaction solution was neutralized with saturated sodium bicarbonate aqueous solution, and then mixed with water to collect precipitated crystals by filtration. The crystals thus collected were purified by silica gel column chromatography using chloroform as an eluant to obtain 11.33 g of ethyl 5-bromo-7-methoxy-2-benzofurancarboxylate.

Workup

  1. additionTo this was further added dropwise
  2. customobtained in the above step a)
  3. additionAfter completion of the dropwise addition
  4. customthe temperature of the resulting reaction solution
  5. temperatureAfter cooling
  6. customthe resulting reaction solution
  7. extractionextracted with ethyl acetate
  8. concentrationThe resulting organic layer was concentrated to dryness, and crystals
  9. customthus precipitated
  10. filtrationwere collected by filtration

Sources & evidence

ORD record
ord-ed2b5fda01cb4d32a2b38a1e895c1dc9
Source dataset
uspto-grants-1996_11
Patent number
US05576343

Reaction notes

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