反应详情

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.

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.