Potassium Carbonate → 2-bromo-1-(2H-chromen-3-yl) ethanone

HRID 2051646Notes

Reaction equation

HRID 2051646 reaction equation
[C:1]([C:4]1[CH2:5][O:6][C:7]2[C:12]([CH:13]=1)=[CH:11][CH:10]=[CH:9][CH:8]=2)(=[O:3])[CH3:2].[Br:14]Br.C(=O)([O-])[O-].[K+].[K+]>C(OCC)C.CO>[Br:14][CH2:2][C:1]([C:4]1[CH2:5][O:6][C:7]2[C:12]([CH:13]=1)=[CH:11][CH:10]=[CH:9][CH:8]=2)=[O:3]

Participants

6

Reactant 3

HCID 11430Potassium CarbonateHCID 24408BromineHCID 400671-(2H-1-Benzopyran-3-yl)ethanone

Product 1

HCID 230077702-bromo-1-(2H-chromen-3-yl) ethanone

Reagents, catalysts & solvents 2

HCID 887MethanolSolventHCID 3283Diethyl EtherSolvent

Procedure

3-Acetyl-2H-chromene (0.2 mole) is dissolved in diethyl ether (250 ml) and methanol (10 ml). The solution is cooled to 0°-5° C. Bromine (0.21 mole) is added dropwise thereto, with stirring. The resulting material is left aside 2 hours at room temperature. Anhydrous potassium carbonate (25 g) is then added and the material is evaporated to dryness. The pasty residue is placed in a flask with 600 ml hexane, and is refluxed for 1 hour. The reaction mixture is decanted hot, allowed to cool, and the organic solution is placed in the freezer. Brown-yellow crystals having a sufficient purity for the next step separate out. After two recrystallizations from hexane, a sample gives long pale yellow needles, M.p.=87° C.

Workup

  1. temperatureThe solution is cooled to 0°-5° C
  2. customthe material is evaporated to dryness
  3. customThe pasty residue is placed in a flask with 600 ml hexane
  4. temperatureis refluxed for 1 hour
  5. customThe reaction mixture is decanted hot
  6. temperatureto cool
  7. customseparate out
  8. customAfter two recrystallizations from hexane
  9. customa sample gives long pale yellow needles, M.p.=87° C.

Sources & evidence

ORD record
ord-a2240ba10c6e4c69a4e2f2fb4c32d6c9
Source dataset
uspto-grants-1980_01
Patent number
US04181722

Reaction notes

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