U. Schuldt et al., COMPARATIVE INVESTIGATIONS ON THE SILYLAT ION OF CELLULOSE WITH MONOFUNCTIONAL AND MULTIFUNCTIONAL ORGANOSILANES, Das Papier, 48(1), 1994, pp. 3
Cellulose oi DP = 190 dissolved in the LiCl/dimethylacetamide system w
as reacted with different mono and polyfunctional substituted silanes
to silyl ethers of cellulose, and this homogeneous course oi reaction
was compared in some experiments with the corresponding heterogeneous
one. The isolated and purifed reaction products were characterized by
their Si-content, by their solubility or swelling value, resp., and in
some cases by C-13 and Si-29 NMR spectroscopy. The following priority
with regard to the maximal DS obtained was observed by the reaction o
f cellulose with Selected monofunctional silanes under defined reactio
n conditions (Me)(3)SiCl > (Me)(3)SiN(Et)(2) > (Me)(3)SiNHSi(Me)(3) >
(Me)(3)SiOEt > (Me)(3)SiOSi(Me)(3). For preparing highly substituted t
rimethyisilylcellulose of DS = 3,0, the (Me)(3)SiN(Et)(2) was found to
be most suitable. In medium DS-range, a substitution of the C-6 and C
-2 position of the AGU was observed without regioselectivity. With pol
yfunctional silanes gel formation due to covalent crosslinking caused
by an at least bifunctional reaction oi the silane was observed with e
xception of (Me)(2)Sl(OEt)(2) leading to a non-crosslinked organosolub
le silyl cellulose. As revealed by Si-29 NMR spec tra, sell-condensati
ons of the polyfunctional silanes to oligosiloxane structures has to b
e considered besides the substitution of cellulose OH-groups.