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37.6 g. (0.14 mol) of 8-methoxy-4-hydroxy-3-phenylcoumarin are brought to reflux for 1 hour in a mixture of 750 ml. of 62% hydrobromic acid, 375 ml. of glacial acetic acid and 375 ml. of acetic anhydride. The mixture is poured on to 5.3 kg. of ice, filtered and dried. 25.3 g. of a solid are obtained, which is recrystallised from a mixture of dioxane and diisopropyl ether (50:50). Weight 13 g., yield 38.1% (theoretical yield 34.2 g.); M.P. 220° C.

1. temperatureto reflux for 1 hour in a mixture of 750 ml
2. additionThe mixture is poured on to 5.3 kg
3. filtrationof ice, filtered
4. customdried
5. customof a solid are obtained
6. customwhich is recrystallised from a mixture of dioxane and diisopropyl ether (50:50)