Formation of Aromatic Compounds from Carbohydrates. Part III. Reaction of D-Glucose and D-Fructose in Slightly Acidic, Aqueous Solution.

Abstract

The reaction of D-fructose in aqueous solutions of pH 4.6 at 96 or 160?C yielded 5-(hydroxy-methyl)-2-furaldehyde (1), 5,5΄-oxy-dimethyl-ene-bis(2-furaldehyde) (2), 5-(acetoxymethyl)-2-furaldehyde (3), 1-(2-furyl)-2-hydroxyethanone (4), 1,2-benzenediol (5), 1,2,3-benzenetriol (6), 6,7-dihydroxy-1(3H)-isobenzofuranone (7), 3-methyl-1,2,benzenediol (8), 4-methyl-l,2-benzenediol (9), 4-methyl-1,2,3-benzenetriol (10), 3-hydroxy-6-hydroxymethyl-2-methyl-4H-1-benzopyran-4-one (11), 1-(3,4-dihydroxy-6-methylphenyl)-2-hydroxyethanone (12), 3,4- dihydroxybenzaldehyde (13), and 2-methyl-benzofuran-5,6-diol (14). The reaction of D-glucose at pH 4.5 and 96?C gave the same compounds but in lower yields. Compounds 7, 11, 12, and 14 as well as the synthesised 4,5-dihydroxy isomer of 7 seem to be new compounds. The 1H NMR-spectra of o-dihydroxy-and o-dimethoxy-1-(3H)-isobenzofuranones are discussed.