ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The cationic ring-opening polymerization of 1,6-anhydro-2,3,4-tri-0-benzyl-β-D-altropyranose (TBLAT, M2) failed to give the fourth stereoregular 1,6-α-linked polysaccharide because of its very low homopolymerizability. However, the 1,6-anhydro-altrose monomer was found to copolymerize with 1,6-anhydro-2,3,4-tri-0-(p-methylbenzyl)-β-D-glucopyranose (LGTXE, M1) with PF5 as catalyst at low temperature, giving highly stereoregular copolymers. The monomer reactivity ratios calculated by Kelen-Tüdös method were r1 = 1.52 and r2 = 0.06. The differences in the reactivity between TBLAT monomer and other 1,6-anhydro sugar derivatives are discussed. Moreover, 1,6-anhy-dro-2-0-benzyl-3,4-0-isopropylidene-β-D-galactopyranose (ABIGA, M4), which showed no homopolymerizability under various conditions, was also copolymerized with 1,6-anhydro-2,3,4-tri-0-benzyl-β-D-glucopyranose (LGTBE, M3) at low temperature. The monomer reactivity ratios of r3 = 2.2 and r4 = 0.0 indicate that in the copolymers every galactose unit distributed as a single unit through the main chain. The cause for the lower polymerizability of ABIGA is discussed. Hydrolysis of the copolymer with trifluoroacetic acid gave a copolymer in which only galactose units contained free hydroxyl groups, which were then methylated by methyl iodide. Stereoregular 1,6-α-linked galactoglucan composed of free sugar units was prepared by debenzylation of the ABIGA-LGTBE copolymer followed by hydrolysis.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1982.170200209
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