title: Powder-to-powder polycondensation of natural saccharides. Facile preparation of highly branched polysaccharides.
abstract: Solid-state polycondensation of a natural saccharide was found to take place in the presence of H3PO4(5 mol%) at 110 degrees C under a N2 flow, giving a highly branched polysaccharide (conv. 11-84%, Mw = 1400-19000, Mn = 1200-3700); the reaction mixture was powdery throughout the polymerization. Interestingly, alpha- and beta-anomers showed different polymerization behaviour; the former was polymerized more slowly, however, they gave comparable molecular weight polymers. The polysaccharide product was per-O-methylated and subjected to structure analyses. The acid-hydrolysis products, the partially O-methylated monosaccharides, suggested that the polysaccharide products have highly branched structures. MALDI-TOF mass analysis revealed that intramolecular glycosylation and acetal exchange reactions are involved in the polymerization mechanism.
authors.affiliation: Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kanazawa
authors.forename: Shohei
authors.initials: S
authors.lastname: Okumura
authors.forename: Masato
authors.initials: M
authors.lastname: Suzuki
mesh_terms: D001704:Biopolymers; D002236:Carbohydrate Conformation; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D011134:Polysaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D011208:Powders; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001704:Biopolymers; D011134:Polysaccharides; D011208:Powders