Cuprammonium solution

Cellulose dissolves in strong mineral acids, in NaOH and in cuprammonium solution. It forms a triacetate (tri-ethanoate), a trinitrate... 

The second ceUulosic fiber process to be commercialized was invented by L. H. Despeissis (4) in 1890 and involved the direct dissolution of cotton fiber in ammoniacal copper oxide Uquor. This solvent had been developed by M. E. Schweizer in 1857 (5). The cuprammonium solution of ceUulose was spun into water, with dilute sulfuric acid being used to neutralize the ammonia and precipitate the ceUulose fibers. H. Pauly and co-workers (6) improved on the Despeissis patent, and a German company, Vereinigte Glanstoff Eabriken, was formed to exploit the technology. In 1901, Dr. Thiele at J. P. Bemberg developed an improved stretch-spinning system, the descendants of which survive today. 

Dissolution of the cellulose in cuprammonium solution followed by acid coagulation of extruded fibre ( cuprammonium rayon —no longer of commercial importance). In this case the acid converts the cuprammonium complex back into cellulose. 

Some data for the molecular weight of cellulose of various origins determined by ultra-centrifuging cuprammonium solution, are given in Table 35. 

Polymerization degree of cellulose (determined by measuring the viscosity of cuprammonium solution) 76 186 254 450 720 1540 2550... 

The cuprammonium solution attacks filter paper and hence this solution is best filtered through a fritted glass filter. Two layers of ordinary toweling cloth on a Buchner funnel may also be used. 

WTO MAKE CUPRAMMONIUM SOLUTION, FIRST DISSOLVE 10 g COPPER SULFATE IN 100 ml WATER IN A PINT JAR. ADD 10% NaOH SOLUTION UNTIL NO MORE LIGHT-BLUE CUPRIC HYDROXIDE FORMS. LET STAND. POUR WATER OFF PRECIPITATE. RE-FILL THE JAR WITH WATER. AGAIN LET STAND. AGAIN POUR WATER OFF PRECIPITATE. REPEAT THIS WASHING PROCESS HALF A DOZEN TIMES. 

Kamogawa, and Sekiya (54) studied the graft polymerization of acrylamide onto cotton fabric using ceric ammonium nitrate as the catalyst. Similarly to Kulkarni et al. (35) the authors performed subsequent cross-linking with formaldehyde amd methylol compounds. From precipitation studies by acidification of cuprammonium solutions on mixtures of polyacrylamide and cellulose on the one hand and polyacrylamide-cellulose grafts on the other the authors conclude that chemical bonds must exist between the two polymers in the grafted product. 

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. 

Specific Rotations (436 mfi) in Aqueous and Cuprammonium Solutions (Data from ref. 29 unless otherwise noted)... 

Conformation Glycol Anticipated Behavior in Cuprammonium Solution... 

The preferred conformations of pyranosides in cuprammonium solution have been deduced by Reeves from a study of their cuprammonium-... 

The amorphous or disordered component plays an enormous role in the physicochemical properties of cellulose. Its nature is still poorly defined [66-69] and like crystallites is influenced by physical and chemical treatments as reflected in solubility and reactivity characteristics [14-17]. The alkali solubility of cotton cellulose cannot be correlated entirely with its apparent amorphous content [16]. A regenerated sample prepared from a cuprammonium solution having a 94% amorphous content was totally soluble in 10% NaOH while a powdered cellulose obtained by ball milling to a similar amorphous content (92%) had an alkali solubility of only 58%. 

The position is not so clear for methyl 4,6-0-benzylidene-a-D-idopyrano-side. This was made from the galactoside LVIII under conditions not likely to invert the configuration at the acetal carbon atom, and therefore should also have the 0-inside conformation (LIX), yet the behavior in cuprammonium solution suggests that the pyranose ring has the conformation found in the H-inside conformation LX for the bicyclic system. 

Parallel arguments apply to methyl 4,6-0-benzylidene-/3-D-idopyrano-side the conformation of the pyranose ring observed " in cuprammonium solution is in conflict with that deduced from the observed conformation of methyl 4,6-0-benzylidene-/3-D-galactopyranoside. "... 

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