Methylation Smith degradation

Monosaccharide residues containing vicinal hydroxyl groups are oxidized by periodate, and are subsequently removed in the reduction-hydrolysis step. Therefore, the positions to which such monosaccharide residues are linked can be located by methylation analysis performed before, and after, Smith degradation. Alternatively,59 the oxidized and reduced sample is methylated, the ether hydrolyzed, and the product realkylated with CD3I or CH3CH2I. This kind of procedure can have advantages over that first described. For example, methylation before the hydrolysis step hinders the acetal protection of hydroxyl groups that can occur in acid hydrolysis.7... 

In certain examples where the Smith-degradation fragments have been separated more conveniently by paper chromatography, the structure of these fragments has been demonstrated by examining their methylation products by gas-liquid chromatography. This approach has been used in studying the fine structure of lichenan,644 isolichenan,645 and wheat pentosan.848... 

Often, a polysaccharide gives a polymeric residue after a Smith degradation. Methylation analyses of this material and of the original polysaccharide may nonetheless furnish valuable structural information. It is also possible to subject the material to successive Smith degradations, a notable example being the stepwise degradation of the ovarian-cyst, blood-group H substance (42) by Lloyd and Kabat.100... 

Further examples of modified Smith degradation, in which the polyalcohol is methylated prior to hydrolysis under mild conditions, uronic acid degradation, and /3-elimination preceded by oxidation have been reported in connection with structural studies on the Klebsiella type 28 (Ref. 182), 57 (Ref. 183), 59 (Ref. 142), and 81 (Ref. 184) capsular polysaccharides. 

What products would you expect from cellulose as a result of methylation analysis Periodate oxidation The Smith degradation The action of an alpha amylase ... 

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