Furan, 2-hydroxyacetyl

Heating sucrose to 300°C in a stream of nitrogen produces volatile furan compounds namely 2-methyl furan, furan, 2-hydroxyacetyl furan, and other volatile reaction products (methanol, acetone, acrolein, propanol, and acetaldehyde) [230]. A major compound (2-furfural) and volatile thermal degradation products (2-furyl methyl ketone, 2-furyl propyl ketone, methyl-benzo( )furan, and 5-methyl-3-hydro-furan-2-one) were identified by heating sucrose in an open evaporation dish at 180°C for 90 min [233]. 

Scheme 8.—Formation of 2-(2-Hydroxyacetyl)furan from o-Fructose.

The formation of oxygen-containing heterocyclic compounds is also a consequence of the Maillard reaction. Amines and amino acids have a catalytic effect upon the formation of 2-furaldehyde (5), 5-(hydroxy-methyl)-2-furaldehyde (11),2-(2-hydroxyacetyl)furan (44),2 and 4-hy-droxy-5-methyl-3(2//)-furanone (111) (see Ref. 214). This catalytic effect can be observed with several other non-nitrogenous products, including maltol. The amino acid or amine catalysis has been attributed to the transient formation of enamines or immonium ions, or the 1,2-2,3 eno-lization of carbohydrates. Of interest is the detection of A -(2-furoyl-... 

The major products formed from hexoses that react in aqueous acidic solution are 5-(hydroxymethyl)-2-furaldehyde, levulinic acid, and polymeric materials. In addition, many minor dehydration products are found. In a study41 of D-fructose, 2-(2-hydroxyacetyl)furan (13), 2-acetyl-3-hydroxyfuran (isomaltol 16), 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, and 3,4,5-trihydroxy-3,5-hexadien-2-one (acetylformoin) were identified. Products not formed solely by dehydration mechanisms include acetone,56 formaldehyde, acetalde-... 

Hydroxyacetyl)furan (2-Furyl hydroxymethyl ketone) coch2oh... 

Furfuryl alcohol 2-Hydroxyacetyl furan 5-Hydroxymethyl furfural Isomaltol... 

Table II presents the quantitative results of those components volatile enough for GC analysis. At low pH the furan compounds predominate when both glucose and xylose are exposed to 300 C. This is not unexpected since all pentoses form 2-furaldehyde(2) in high yield when exposed to aqueous acid solution( ). However, the presence of 2 in the glucose reaction mixture is of interest. The major product obtained from hexoses at elevated temperatures and aqueous acid is 5-hydroxymethyl-2-furaldehyde(1) with minor amounts of 2-(hydroxyacetyl)furan(15). The 2-furaldehyde has been detected after acidic treatment of fructose(1 ), glucose(15,17), and is a major component after the thermolysis of cellulose in distilled water( ). One plausible explanation for the formation of 2 may involve loss of formaldehyde(18) from glucose with consequent pentose formation. It should be noted that the pyrolysis of 1 does produce a small amount of 2( ). However, the reaction conditions are sufficiently different to suggest a different mechanism for hydrothermolysis.

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