Hydrogen Bromide → 6-Hydroxy-chroman-4-one

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Reaction Steps

Glacial acetic acid and HBr (>40%) each 20 ml are successively added to methoxy benzopyran-4-one 2.9 g (0.0163 mol), stirred and refluxed for 1 h, and then the reactant liquor is modulated pH for 10-11 by KOH, the water layer is modulated pH for 2-3 by concentrated hydrochloric acid, and then extracted by ethyl acetate; the organic layers are combined and dried over anhydrous Na2SO4, cooled to precipitate black solid, and recrystallized by ethyl acetate, to obtain bright yellow crystal 2.17 g, m.p.: 142-144° C., yield: 81.2%.

Provenance & Evidence