Acetic Acid → Apigeninidin

Participants

Reaction Steps

A mixture of 500 mg 4', 5,7-triacetoxyflavan, 750 mg chloranil, 25 ml acetic acid, 5 ml H2O and 1.5 ml 6 N HCl was heated with stirring at 100° for 1 hour. After cooling in ice, the solution was diluted to 250 ml with 0.01 N HCl in MeOH and passed through a 4.5 × 10 cm column of acid-treated POLYCAR AT[1] (slurry packed) (POLYCLAR AT is a trademark for polyvinylpyrollidine sold by G.A.F.). The column was washed with a second 250 ml of 0.01 N HCl in methanol and the combined eluants concentrated on a rotary evaporator to 25 ml. This solution was then freeze dried to give a red-orange solid. After washing twice with 10 ml ethyl acetate to remove unreacted chloranil, there was obtained 144 mg (36% yield) of crude apigeninidin chloride (E1% (476 nm) = 840). A sample of purified material recrystallized from EtOH-4 N CHl had E1% (476 nm) = 1010 and was identical by IR (KBr) and TLC (cellulose) comparison with an authentic sample prepared by Robinson's procedure [2] ; the yield of purified material was 30%.

Provenance & Evidence