ANALYSIS OF PRODUCTS FROM PERIODATE OXIDATION AND FROM METHYLATION OF A RHAMNAN

Abstract

A synthetic L-rhamnan containing both rhamnofuranosyl and rhamnopyranosyl units has been used as a model substance in the application of vapor phase chromatography (v.p.c.) to the study of the structure of rhamnose containing polysaccharides. Groups of isomeric methylated sugars obtained from the methylated rhamnan were analyzed by converting them to methylated alditols which had widely different retention times. A Smith periodate degradation of the rhamnan gave 1,2-dihydroxypropane, 1-deoxy-D-erythritol, L-rhamnose, and 5-deoxy-L-arabinose, which were separated by paper chromatography. There were also obtained l-deoxy-3-O-(α-L-rhamnopyranosyl)-D-erythritol and the β-anomer, and 1-deoxy-2-O-(L-rhamnopyranosyl)-D-erythritol, separable by v.p.c. as their trimethylsilyl ethers. 1-Deoxy-D-erythritol was synthesized and characterized as the tri-p-nitrobenzoate. Of the terminal units in the synthetic rhamnan 35% were furanose and 2,3-di-O-methyl-L-rhamnose constituted 75% of the dimethyl fraction indicating that the principal linkage was (1 → 4).