Monosaccharides aldehydo

The similarity of the products obtained by ammonolysis, either of acylated nitriles, or of acylated aldehydo monosaccharides having one carbon atom less than the corresponding nitriles, was verified12 by ammonolysis of 2,3,4,5,6-penta-O-acetyl-aWehydo-D-glucose (20), which afforded the same N-acetyl-a-D-glucofuranosylamine (15) as that obtained from the peracetylated heptononitrile 14. 

The great use of acetolysis in polysaccharide chemistry is in degradation of the polysaccharides, imder mild conditions, to oligosaccharide per-acetates. More-drastic conditions afford monosaccharide peracetates, including those of the aldehydo forms of the sugars. " The many oligosaccharides obtained from the partial acetolysis of various polysaccharides are excellently documented in a book by Bailey, and the reader searching for particular examples is referred thereto. 

The anomeric pairs of different sugars have been obtained as stable crystalline compounds but in aqueous solution the optical rotation of the a-D-form (XCIV) decreases and that of the /S-D-form (XCVI) increases until they reach the same equilibrium value. In effect one isomeric form is being transformed into the other, most probably through the intermediate production of the aldehydic form (XCV) of which a very small proportion is considered to be present in solution . Cantor and Peniston estimated the amount of the reducible aldehydo form in solution of a number of the common monosaccharides by reduction at the dropping mercury cathode References p. 63... 

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