Complexes and the Structure of Polysaccharides

The literature contains numerous observations on the properties of polysaccharides in cuprammonium solutions the work on cellulose is especially voluminous. Viscometric measurements in cuprammonium solution are regularly employed to determine the size of cellulosic molecules. However, before the spatial requirements for complexing with cuprammonium became known the properties of the complexes of polysaccharides could not be interpreted in terms of the structure of their monosaccharide units. With the present understanding of cupram-monium-glycol complexing, some of the earlier observations will be reexamined. 

It has been shown that reaction with cuprammonium is greatly influenced by the position of a substituent group on the glucopyranoside ring.28-29 This is illustrated for monosaccharides of known structure 

Me thy 1 2-m eth y 1-jS-D-glucopyranoside Methyl 3-methyl-/3-D-glucopyranoside Methyl 4-methyl-/3-D-glucopyranoside Methyl 6-methyl-/3-D-glucopyranoside Strongly dextrorotatory complex No complex Strongly levorotatory complex Complex of intermediate rotation 

It will be shown that the position of linkage between the glucose units in polysaccharides determines their rotatory behavior in cupram-monium in the same manner that position of substitution does in the monosaccharides. 

Although the problem of the gross structure of cellulose is outside the scope of this review, it is of interest that Lieser32 has interpreted the behavior of cellulose with cuprammonium in support of a micellar theory of cellulose structure Staudinger,33 of a long chain theory Compton,34 of a particulate theory Hess,35 of a theory of secondary valence association between CsHioOs units and Pacsu,36 of a theory of acetal linkages in equidistant open-chain units and the laminated chain structure of cellulose. 

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