反应详情

In 80 volume parts of dimethylformamide are dissolved 25 parts of orthohydroxyacetophenone and, while the solution is externally cooled to about -20° C. with dry ice-acetone, 80 volume parts of tetrachloropyrophosphoric acid are added dropwise to the solution. The resulting mixture is stirred at room temperature for 13 hours. Then, the reaction mixture is poured into ice water and the resulting crystals are recovered by filtration, washed with water and ethanol and finally recrystallized from acetone. The procedure yields of 4-oxo-4H-1-benzopyran-3-carboxaldehyde as colorless crystals melting at 152°-153° C.

1. additionare added dropwise to the solution
2. filtrationthe resulting crystals are recovered by filtration
3. washwashed with water and ethanol
4. customfinally recrystallized from acetone