Rhamnose oxime

The oxime of D-lyxose has not been prepared, but L-rhamnose oxime (XX) with ithe same spatial configuration about carbon atoms 2, 3 and 4 reacts in an open-chain form when submitted to mild acetylation, and gives only the nitrile this reactivity is confirmed when the oxime is submitted to mild propionylation, for only the hexapropionyl-aWe%do-L-rhamnose oxime is produced and that in high yield. As already mentioned, the oximes of D-mannose (XXI), and D-gala-L- reawno-heptose (XXII),having the same configuration as rhamnose about carbon atoms 2, 3 and 4, react in a similar manner. 

The first benzoylated nitrile of an aldonic acid was prepared by Brigl, Muhlschlegel and Schinle by benzoylation of the n-manno-n- oZa-heptononitrile the hexabenzoyl derivative was obtained. A series of benzoylated nitriles has recently been prepared by Restelli de Labriola and Deulofeu by treatment of the oximes of L-rhamnose, D-glucose, D-galactose and D-mannose with benzoyl chloride and pyridine. They were the sole products and were obtained in high yields. 

The oximes of arabinose, rhamnose (Legay, 1952), and fructose (Bredereck et ai, 1956) display a weak band at 1653 cm, which may indicate the acyclic form, but it is possible that the N—H of the cyclic form... 

The monosaccharide composition of peat hydrolysates was successfully determined by g.l.c. of the trimethylsilylated oxime derivatives. Amongst the sugars recognized were o-xylose, L-arabinose, D-ribose, L-rhamnose, d-galactose, and D-glucose. 

The arabinose, rhamnose, xylose, and glucosamine oximes yield only the nitriles as a result of low-temperature acetylation glucose gives the cyclic hexaacetate and mannose and fucose the acyclic hexaacetates galactose yields a mixture of all three types. At higher temperatures, the proportion of the nitrile in the reaction mixture increases considerably. 

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