C-13-NMR spectroscopic studies of cellulose in various solvent systems

In a series of aqeous or water-containing solvent systems, C-13-NMR spectra of cellulose have been recorded and quantitatively evaluated in order to classify these systems into the categories of ''derivatizing'' and ''nonderivatizing'' ones and, if relevant, to elucidate the site of interaction within the anhydroglucose unit. Subject of investigation were some basic systems, some stronger acidic systems, alkaline solutions of cellulose carbamate in comparison to cellulose xanthate and several aqueous metal complex solvents. Concentrated phosphoric acid, formic acid and trifluoro acetic acid can be definitely classified as derivatizing solvents, while an aqueous solution of ''triton B'' is nonderivatizing and exhibits the same cellulose spectrum as the nonderivatizing reference system LiCl/DMAC. In contrast to the xanthate system an exclusive C-2 substitution was observed in the cellulose carbamate system. Cellulose solvent interaction carl be extremely different in well-known aqueous complex solvents, as demonstrated by the spectrum of cellulose in cadoxen, on one hand, and in FeTNa, on the other.