Hydrogen Bromide → 6-Hydroxy-chroman-4-one

HRID 500436Notes

Reaction equation

HRID 500436 reaction equation
Br.CO[C:4]1[O:5][C:6]2[CH:14]=[CH:13][CH:12]=[CH:11][C:7]=2[C:8](=[O:10])[CH:9]=1.[OH-:15].[K+].Cl>O.C(O)(=O)C>[OH:15][C:12]1[CH:13]=[CH:14][C:6]2[O:5][CH2:4][CH2:9][C:8](=[O:10])[C:7]=2[CH:11]=1

Participants

7

Reactant 4

HCID 260Hydrogen BromideHCID 313Hydrochloric AcidHCID 14797Potassium HydroxideHCID 124165262-Methoxy-4H-1-benzopyran-4-one

Product 1

HCID 70989446-Hydroxy-chroman-4-oneYield 81.2%

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolventHCID 962WaterSolvent

Procedure

Glacial acetic acid and HBr (>40%) each 20 ml are successively added to methoxy benzopyran-4-one 2.9 g (0.0163 mol), stirred and refluxed for 1 h, and then the reactant liquor is modulated pH for 10-11 by KOH, the water layer is modulated pH for 2-3 by concentrated hydrochloric acid, and then extracted by ethyl acetate; the organic layers are combined and dried over anhydrous Na2SO4, cooled to precipitate black solid, and recrystallized by ethyl acetate, to obtain bright yellow crystal 2.17 g, m.p.: 142-144° C., yield: 81.2%.

Workup

  1. temperaturerefluxed for 1 h
  2. extractionextracted by ethyl acetate
  3. dry with materialdried over anhydrous Na2SO4
  4. temperaturecooled
  5. customto precipitate black solid
  6. customrecrystallized by ethyl acetate

Sources & evidence

ORD record
ord-f2b194bb3c384111addc5ebefd1d4739
Source dataset
uspto-grants-2010_08
Patent number
US07772230B2

Reaction notes

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