Glycols cuprammonium complexes

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. 

The glycosides listed in Table XI have hydroxyl groups at positions 2,3, and 4 unsubstituted (i.e., both 2,3 and 3,4 glycols are free). Complex formation in these substances produces a much smaller shift in optical rotation than it does in those compounds which can react at only one site. The affinities for cuprammonium of the reacting sub-... 

Specific rotations in cuprammonium are based upon the weight of the glycol-containing molecule, not upon the weight of the copper glycol complex. This provision is necessary since the structures and molecular weights of the complexes are unknown. The optical rotations are the result of a reversible reaction, hence they are particularly dependent upon the concentrations of the reactants. The composition of the... 

Specific resistance increments (A,., .) of 20 ohm, cm-4 may be encountered without the actual occurrence of cuprammonium-glycol complexing values above 20 are indicative of a significant amount of complexing. 

Among the best-known nonderivatizing solvent systems is a combination between copper, alkali, and ammonia termed Schweizer s reagent. Solutions of cuprammonium hydroxide have been used for both analytical and industrial cellulose dissolution. Regenerated fibers with silk-like appearance and dialysis membrane have been (and partially continue to be) industrial products on the basis of cellulose dissolution in cuprammonium hydroxide. The success of this solvent is based on the ability of copper and ammonia to complex with the glycol functionality of cellulose as shown inO Fig. 11. Because of the potential side reactions (oxidation and crosslinking, Norman compound formation), alternatives to both ammonia as well as copper have been developed. Cuen and cadoxen are related formulations based on the use of ethylene diamine and cadmium, respectively. The various combinations of alkali, ammonia. 

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