2,4-Dihydroxybenzaldehyde → HCID 56692933, Verbindung

Beteiligte Stoffe

Reaktionsschritte

89.5 g (0.43 mol) of 4-butoxyphenylacetic acid (prepared by the method of McElvain, Carney; J. Am. Chem. Soc. 1946 (68), 2592-2599) and 30.0 g (0.22 mol) of 2,4-dihydroxybenzaldehyde are heated at 120° C. for 5 h in 100 ml of acetic anhydride and 120 ml of triethylamine. The still-hot solution is subsequently added to 3 l of ice-water, and the precipitated product is filtered off with suction and suspended in 1 l of water and 1.4 l of ethanol. After dropwise addition of 190 ml of conc. sulfuric acid, the batch is heated under reflux for 4 h and added to 3 l of water, and the precipitated product is filtered off with suction. The crude product is filtered through silica gel with hot toluene/ethyl acetate (1:1), the solvent is evaporated in vacuo, and the residue is recrystallised from toluene, giving 3-(4-butoxyphenyl)-7-hydroxychromen-2-one as colourless crystals.

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