Alkaline Dehydration, Fragmentation, and Oxidation Reactions of Carbohydrates

3 Alkaline Dehydration, Fragmentation, and Oxidation Reactions of Carbohydrates 

Under even stronger alkaline conditions and higher temperatures, other reactions take place of which dehydrations are the most frequent and important. Wolfrom and colleagues [4,5] studied the alkaline dehydration reactions for the breakdown of o-glucose and o-xylose. The dehydration reactions lead to the formation of 5-(hydroxymethyl) furfural. Hydroxymethyl furfural itself can undergo further dehydration and fragmentation to give levulinic acid as shown in Fig. 3.5. 

The alkaline process of cleavage of o-fructose to give dihydroxy acetone and o-glyceraldehyde is similar to the important glycolysis reaction catalyzed by the enzyme aldolase (see Chapter 11) which reacts with o-fructose-1,6-bisphosphate at 37°C to give 3-phospho-o-glyceraldehyde and dihydroxy acetone phosphate. The comparison of the alkaline and enzyme cleavage and mechanisms of reaction are shown in Fig. 3.7. 

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