Homogeneous hydroxyethylation of cellulose in NaOH/urea aqueous solution

The 6 wt.% NaOH/4 wt.% urea aqueous solution was proved to be an aqueous non-derivatizing solvent for cellulose by 13C NMR. O-(2-hydroxyethyl)cellulose (HEC) was prepared by a totally homogeneous hydroxyethylation of cellulose using this new solvent for the first time, and the distribution of substituents within anhydroglucose units (AGU) was examined by 13C NMR. It was found that the relative reactivity of the hydroxyl groups within AGU and the new hydroxyl group was in the order C-x > C-6 > C-2 > C-3, an analogous functionalization pattern as HEC obtained by the heterogeneous slurry process. The ethylene oxide efficiency in this homogeneous etherification reaction was 20 – 30%.