Polysaccharides partial acid hydrolysis

Structural studies on the oligosaccharide derivatives obtained by partial, acid hydrolysis of fully methylated polysaccharides often furnish valuable information on the positions at which the oligosaccharides were linked in the original polysaccharide. When the folly methylated Klebsiella O group 9 lipopolysaccharide,27 which contains D-galactopyranose and D-galactoforanose residues, was subjected to mild, acid hydrolysis, and the product reduced with lithium aluminum deuteride and remethylated with trideuteriomethyl iodide, a good yield of the disaccharide derivative 10 was obtained. 

In 1951, Whistler and Durso reported68 the isolation of epimelibiose by partial, acid hydrolysis of the polysaccharide guaran, followed by charcoal-column fractionation of the products. ThA material was obtained in anhydrous crystalline form from a mixture of methyl and butyl alcohols it had m.p. 201°, [a]26D + 120.9° — +124.6° in 36 hr. (c 2, in water). The yield was 2.2% of the weight of guaran used. Epimelibiose has also been produced72" in crystalline form following the ammonia-catalyzed alkaline isomerization of melibiose. 

Oat /3-glucan (or oat lichenin) is constituted similarly to the barley polysaccharide, but contains (1 — 4)- and (1 — 3)-linkages in the proportions of60 2 1 or61 3 1. Partial, acid hydrolysis of the polysaccharide yields cel-lobiose, laminaribiose, cellotriose, and the two trisaccharides XLVI and XLVII containing both (1 — 3)- and (1 — 4)-linkages.61 On the basis of these results, the following partial structure (XLVIII) has been proposed.61... 

SCHEME 11. Two branched oligosaccharides, 44 and 45, obtained after treatment of a polysaccharide from Porphyridium sp. with lithium in ethylenediamine,721 and the structure 46 I m — 2 or 3) of a backbone of this polymer (R = H, sulfate, terminal Gal, or terminal Xyl) proposed according to the data of partial acid hydrolysis.722... 

Being composed of linear chains of a highly crystalline polysaccharide, linked by 1 — 4, D-anhydroglucopyranose bonds that are hydrolyzed with relative ease, cellulose has long been the subject of partial acid hydrolysis to mixtures of hydrocolloid particles [65]. Hydrolysis of the disordered (paracrystalline) regions of cellulose liberates highly crystalline particles with dimensions in the 50 to 100 pm range. When dissolved in a suitable cellulose solvent, these par-... 

Partial, acid hydrolysis of the recovered polysaccharide, followed by retreatment with lime-water, yields an additional amount (11 g.) of the mixed calcium salts. 

B. Partial Acid Hydrolysis of Neutral Methylated Polysaccharides... 

B. PARTIAL ACID HYDROLYSIS OF NEUTRAL METHYLATED POLYSACCHARIDES... 

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