Carbohydrates aldonic acids, degradation

Much of the chemistry of monosaccharides is the familiar chemistry of alcohols and aldehydes/ketones. Thus, the hydroxyl groups of carbohydrates form esters and ethers. The carbonyl group of a monosaccharide can be reduced with NaBH4 to form an alditol, oxidized with aqueous Br2 to form an aldonic acid, oxidized with HNO3 to form an aldaric acid, oxidized enzymatically to form a uronic acid, or treated with an alcohol in the presence of acid to form a glycoside. Monosaccharides can also be chain-lengthened by the multistep Kiliani-Fischer synthesis and can be chain-shortened by the Wohl degradation. 

Smith and coworkers152 published a relatively complete paper on the thin-layer chromatography, on silica gel, of carbohydrates of low molecular weight. Bancher and coworkers153 reported the thin-layer chromatography of degradation products of carbohydrates, including aldonic acids and aldonolactones. 

At American University, Harriet Frush and Horace Isbell worked on the mechanism of oxidation of carbohydrates by peroxides. They discovered that, in aqueous alkaline hydrogen peroxide, aldoses are quantitatively degraded to formic acid, so that hexoses produce six moles of this acid and pentoses produce five moles. A detailed study of the mechanism of the reaction revealed that degradation takes place by several pathways, the most rapid one involving the formation of peroxy radicals and hydroxy radicals. Thus, when a hydroperoxide-aldose adduct reacts with hydrogen peroxide, a peroxy radical is formed, which decomposes to a hydroxy radical, formic acid, and the next lower aldose. It was also found that, under basic conditions, hydroxy radicals oxidize alditols and aldonic acids to carbonyl compounds in much the same way they do with Fe2+ in the Fenton reaction. During the years she spent at American University, Dr. Frush was able to publish 10 papers without help from any research assistant or laboratory technician. This brought her total to more than 70 papers. 

Sodium hypochlorite Degradation of carbohydrates via aldonic acids... 

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