反应详情

A solution of 10.0 g. (0.0458 mole) of methyl 2-methyl-4-oxo-4H-1-benzopyran-3-carboxylate in 100 ml. of conc. hydrochloric acid was maintained at 80°-90° for 20 minutes. Ice (400 g.) was added and the separated tacky solid was filtered and washed well with water. The crude product was dissolved in 300 ml. of 5% sodium bicarbonate and the insoluble portion was extracted away with 300 ml. of ether. The aqueous phase was acidified with conc. hydrochloric acid to give 6.4 g. (68.3%) of white acid; m.p. 120°-135°. Recrystallization from 2-propanol gave pure product; m.p. 145°-147°.

1. filtrationthe separated tacky solid was filtered
2. washwashed well with water
3. dissolutionThe crude product was dissolved in 300 ml
4. extractionof 5% sodium bicarbonate and the insoluble portion was extracted away with 300 ml
5. customto give 6.4 g
6. customRecrystallization from 2-propanol
7. customgave pure product