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The hemicelluloses of western red cedar (Thuja plicata Donn) : the synthesis of 4-O-β-D-Galactopyranosyl-L-rhamnopyranose

University of British Columbia

PART I The hemicelluloses of western red cedar (Thuja plicata Donn), a member of Family Cupressaceae, were isolated by alkaline extraction. Following purification, methylation and periodate oxidation techniques were employed in the structural studies. The GGM-type hemicelluloses appear to be very similar to those of other softwood species of Family Pinaceae. However, very little arabinose is present in the xylan, which is also moderately branched. These features may prove to be characteristic of Family Cupressaceae. The use of circular dichroism of alditol acetates was developed as a non-destructive technique for ascertaining the configurational series of a sugar. It may also be used to ascertain the composition of a mixture of two sugar derivatives, one being chiral, the other achiral. PART II The disaccharide 4-0-β-D-gaIactopyranosyl-L-rhamnopyranose was synthesized by a Helferich reaction in 60 per cent yield by condensation of 2,3,4,6-tetra-0-acetyl-∝-D-galactopyranosyl bromide with methyl 2, 3-0-isopropylidene-∝-L-rhamnopyranoside. The disaccharide was characterized by its alditol acetate. Methylation and periodate oxidation afforded proof of structure.

Text

2011-03-21

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http://hdl.handle.net/2429/32663

Chemistry

University of British Columbia

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