Acetaldehyde → 2-(1-hydroxyethyl)-3-hydroxy-6-methyl-pyran-4(1H)-one
Reaktionsgleichung
[CH3:1][C:2]1[O:8][CH:7]=[C:6]([OH:9])[C:4](=[O:5])[CH:3]=1.[CH:10](=[O:12])[CH3:11]>O>[OH:12][CH:10]([C:7]1[O:8][C:2]([CH3:1])=[CH:3][C:4](=[O:5])[C:6]=1[OH:9])[CH3:11]Komponenten
4
Edukt 2
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 1
Versuchsvorschrift
Allomaltol (12.6 g, 100 mmol, 1 eq.) was added to 100 ml water and the pH of the solution was adjusted to 10.5 using 50% aqueous sodium hydroxides. Acetaldehyde (5.5 g, 125 mmol, 1.25 eq.) dissolved in 25 ml water was slowly added dropwise over 1 hour and the solution allowed to stir overnight. After adjustment to pH 1 with 37% hydrochloric acid, the reaction mixture was extracted with 3×150 ml of dichloromethane. The combined organic extracts were dried over anhydrous sodium sulphate, filtered and concentrated to yield the crude product. Recrystallisation from toluene afforded the pure product (14.1 g, 83%) as white needles. m.p. 127-130° C. [lit. 126-128° C.]. Ellis (1993)