Formation of Aromatic Compounds from Carbohydrates

Abstract The reaction of d -glucuronic acid in aqueous solutions of pH 3.5 and 4.5 at 96° yielded 2-furaidehyde ( 1 ), 2-furoic acid ( 12 ), 2,3-dihydroxy-2-cyclopentcn-l -one (reductic acid) ( 2 ), 1,2-dihydroxybenzene ( 7 ), 1,2,3-trihydroxybenzene ( 8 ), 2,3-dihydroxytoluene ( 10 ), 2,3-dihydroxybenzoic acid ( 9 ), 2,3-dihydroxyacetophenone ( 11 ), 3,8-dihydroxy-2-methylchromo.le ( 3 ), 5,6,7,8-tetrahydro-3,5-dihydroxy-2-methyl-8oxobenzopyrone ( 4 ), and 3-acetyl-l-oxocyclohexane-2,3,6-trioI ( 18 ). The last two compounds were shown to be precursors of 3 and 11 , respectively. Two compounds of formula C 10 H 8 O 5 , ( 5, bd6 ) were also isolated. From the reaction of d -galacturonic acid at pH 4.5, most of the above compounds were isolated, but in lower yields, and from d -xylose, compounds 1,3,4,6, 10, 11 , and C 10 H 8 O 4 were obtained. l -Arabinose yielded the same main components as d -xylose (except for the absence of 6 ) but in lower yields.*Dedicated to Professor M. Stacey, C.B.E., F.R.S., in honour of his 65th birthday.