Abstract
Tert-butyldimethylsilyl cellulose with a degree of substitution (DS) of up to 2 could be obtained by homogeneous conversion of the biopolymer with tert-butyldimethylchlorosilane in N,N-dimethyl acetamide/LiCl in the presence of imidazole. The cellulose derivatives were characterized in detail by means of two-dimensional NMR spectroscopic techniques including subsequent derivatization of the original polymer by consecu-tive methylation-desilyation-acetylation. The very well resolved NMR spectra indicate that, dependent on the reaction temperature, 2,6-di-O-tert-butyldimethylsilyl moieties are the main repeating units. 3,6-di-O- and 6-mono-O functionalized repeating units were identified in very small amounts if the reaction is carried out at room temperature. Additionally, 2,3,6-tri-O-silylated functions appear if reaction is carried out at temperature of 100°C. Thus, a novel path for regioselective protection of position 2 and 6 for cellulose was established.Download PDF