title: Synthesis and Characterization of Periodate-Oxidized Polysaccharides: Dialdehyde Xylan (DAX).
abstract: The cleavage of the C2-C3 bond in the building units of 1 → 4-linked polysaccharides by periodate formally results in two aldehyde units, which are present in several masked forms. The structural elucidation of such polysaccharide dialdehydes remains a big challenge. Since polysaccharide derivatives are increasingly applied in materials technology, unveiling the exact structure is of utmost importance. To address this issue for xylan, dialdehyde xylan (DAX, oxidation degree of 91.5%) has been synthesized as water-soluble polymer. The ATR-FTIR spectrum of DAX showed free aldehyde to be absent and exhibited a characteristic absorption at 858 cm(-1) related to hemiacetal groups. By a combination of 1D and 2D NMR techniques, it was confirmed that oxidized xylan is present as poly(2,6-dihydroxy-3-methoxy-5-methyl-3,5-diyl-1,4-dioxane). Based on GPC analysis, the DAX polymer shows a slightly lower molar mass (6.6 kDa) compared to the starting material (7.7 kDa) right after oxidation, and degraded further after one month of storage in 0.1 M NaCl solution (4.3 kDa). The oxidized xylan demonstrated lower thermal stability upon TGA analysis and a greater amount of residual char (20.6%) compared to the unmodified xylan (13.7%).
authors.affiliation: Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences Vienna , Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.|Department of Natural and Microbial Products Chemistry, National Research Centre , 33 Al Bohous St., Dokki, Giza 12622, Egypt.
authors.forename: Hassan
authors.initials: H
authors.lastname: Amer
authors.affiliation: Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences Vienna , Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.|Institute of Wood Technology and Renewable Materials, Department of Materials Science and Process Engineering, University of Natural Resources and Life Sciences Vienna , Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Tiina
authors.initials: T
authors.lastname: Nypelö
authors.affiliation: Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences Vienna , Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Irina
authors.initials: I
authors.lastname: Sulaeva
authors.affiliation: Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences Vienna , Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Bacher
authors.affiliation: Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences Vienna , Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Ute
authors.initials: U
authors.lastname: Henniges
authors.affiliation: Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences Vienna , Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Antje
authors.initials: A
authors.lastname: Potthast
authors.affiliation: Division of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences Vienna , Konrad-Lorenz-Straße 24, 3430 Tulln, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosenau
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010504:Periodic Acid / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011134:Polysaccharides / Q000138:chemical synthesis*; D014867:Water / Q000737:chemistry*; D014990:Xylans / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D011108:Polymers; D011134:Polysaccharides; D014990:Xylans; D014867:Water; D010504:Periodic Acid; C009288:metaperiodate