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Silylation of cellulose regiocontrolled by bulky reagents and dispersity in the reaction media
Author(s) -
Koschella Andreas,
Klemm Dieter
Publication year - 1997
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19971200113
Subject(s) - silylation , cellulose , dimethylacetamide , polymer , dispersity , reagent , polymer chemistry , chemistry , organic chemistry , methyl cellulose , catalysis , solvent
Reaction of cellulose (1) with the bulky thexyldimethylchlorosilane (TDMSCl) leads to regioselectively functionalized silyl celluloses with degree of substitution (DS) up to 2. Uniform 6‐O‐thexyldimethylsilyl cellulose (2) was obtained in ammonia‐saturated aprotic dipolar media, which was unexpected in a heterogeneous reaction. On the contrary, the 6‐O‐selectivity is low under homogeneous conditions in a N,N‐dimethylacetamide (DMA)/LiCl solution, and with an excess of TDMSCl 2,3‐di‐O‐thexyldimethylsilyl cellulose (3) can be synthesized. The polymer structures were characterized by two dimensional NMR spectroscopy after subsequent methylation (polymers 4 and 5 ), desilylation (polymers 6 and 7 ) and acetylation (polymers 8 and 9 ) as well as by HPLC after chain degradation of 4 and 5 to the complementary methyl glucoses.