title: Homogeneous tosylation of agarose as an approach toward novel functional polysaccharide materials.
abstract: The homogeneous tosylation of agarose was studied with respect to the effects of reaction parameters, such as reaction medium, time, and molar ratio, on the reaction course, the degree of substitution (DS) with tosyl/chloro deoxy groups, and the molecular structure. Tosyl agaroses (TOSA) with DS tosyl ≤ 1 .81 could be obtained in completely homogeneous reactions by using N,N-dimethylacetamide (DMA)/LiCl or 1,3-dimethyl-2-imidazolidinone (DMI) as solvents. The products were characterized by FT-IR and NMR spectroscopy and it was demonstrated that two types of substitution pattern can be achieved: (i) non-preferential substitution at position 6 of the 1 → 3-linked β-d-galactose unit (G-6) and position 2 of the 1 → 4-linked 3,6-anyhdro-α-L-galactose unit (LA-2) and (ii) regioselective tosylation at G-6, depending on whether the reaction is performed with or without LiCl. Finally, the nucleophilic displacement reaction of TOSA was studied using azide and ethylenediamine as representative nucleophiles. Novel deoxy-agarose derivatives were obtained that showed an interesting solubility behavior and will be used for creating functional polysaccharide materials.
authors.affiliation: Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University of Jena, Centre of Excellence for Polysaccharide Research, Humboldtstraße 10, D-07743 Jena, Germany. Electronic address: martin.gericke@uni-jena.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Gericke
authors.affiliation: Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich Schiller University of Jena, Centre of Excellence for Polysaccharide Research, Humboldtstraße 10, D-07743 Jena, Germany; Laboratory of Fibre and Cellulose Technology, Åbo Akademi University, Porthansgatan 3, FI-20500 Turku, Finland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Heinze
mesh_terms: D000081:Acetamides / Q000737:chemistry; D060326:Chemistry Techniques, Synthetic / Q000379:methods; D005690:Galactose / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry; D018021:Lithium Chloride / Q000737:chemistry; D012685:Sepharose / Q000031:analogs & derivatives / Q000737:chemistry*; D014105:Tosyl Compounds / Q000737:chemistry*
chemical_list: D000081:Acetamides; D007093:Imidazoles; D014105:Tosyl Compounds; C583574:1,3-dimethyl-2-imidazolidinone; D012685:Sepharose; D018021:Lithium Chloride; C013959:dimethylacetamide; D005690:Galactose
keywords: Agarose; Homogeneous synthesis; NMR spectroscopy; Polysaccharide derivatives; Substituent distribution pattern; Tosylation