Induced phase separation: a new synthesis concept in cellulose chemistry

摘要

A new synthesis concept in cellulose chemistry is described. Cellulose dissolved in the solvent system N,N-dimethylacetamide/LiCl as well as organo-soluble cellulose derivatives of different hydrolytic stability (dissolved in dimethyl sulfoxide) were converted into cellulose others of unusual substituent patterns after an induced phase separaation with solid NaOH particles. As confirmed by means of HPLC analysis, these cellulose ethers contain a significantly higher amount of both 2,3,6-tri-O-functionalized and unsubstituted units in the polymer chain than those obtained by conventional etherification reactions in cellulose slurries. Moreover, the cellulose ethers show a preferred functionalization of O-6 within the modified anhydroglucose units as revealed by means of ~1H-NMR-spectroscopy.