An n.m.r. study of the products of oxidation of cellulose and (1 → 4)-β-d-xylan with sodium nitrite in orthophosphoric acid

✍ Scribed by Rolf Andersson; James Hoffman; Nilufar Nahar; Elisabeth Scholander

• Publisher: Elsevier Science
• Year: 1990
• Tongue: English
• Weight: 463 KB
• Volume: 206
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(90)80072-b

✦ Synopsis

Oxidation of polysaccharides with sodium nitrite in orthophosphoric acid converts a substantial portion of the monosaccharides having primary hydroxyl groups unsubstituted into uranic acids'-'. The extent of oxidation at secondary positions, particularly position 3 in dextran, was high when the concentration of the polysaccharide in the orthophosphoric acid was low'. Oxidation of a (1+4)-/3-D-xylan with aqueous bromine yielded a product with a high proportion of ulose residuesg.

However, because of their sensitivity towards acid and alkali, determination of the quantity and type of ulose residues in oxidised polysaccharides is difficult and, hitherto, the resolution of n.m.r. spectra studies has not been adequate for this purpose"". We now report on the oxidation of cellulose and a (1+4)-/3-D-xylan with sodium nitrite in orthophosphoric acid and the 2D 400-MHz 'H-n.m.r. spectroscopy of the products.

The xylan was obtained from retted jute sticks and contained n-xylose (89%), L-rhamnose (1 %), D-galactose (trace), D-glucose (trace), and 4Gmethylglucuronic acid (10%) 2-linked to xylose "L'~ The xylan and cellulose were each oxidised with ,