title: Chemical modification of alginates in organic solvent systems.
abstract: Alginates are (1→4)-linked linear copolysaccharides composed of β-D-mannuronic acid (M) and its C-5 epimer, α-l-guluronic acid (G). Several strategies to synthesize organically modified alginate derivatives have been reported, but almost all chemistries are performed in either aqueous or aqueous-organic media. The ability to react alginates homogeneously in organic solvents would open up access to a wide range of new chemistries and derivatives. However, past attempts have been restricted by the absence of methods for alginate dissolution in organic media. We therefore report a strategy to dissolve tetrabutylammonium (TBA) salts of alginic acid in polar aprotic solvents containing tetrabutylammonium fluoride (TBAF). Acylation of TBA-alginate was performed under homogeneous conditions, such that both M and G residues were acetylated up to a total degree of substitution (DS) ≈1.0. Performing the same reaction under heterogeneous conditions resulted in selective acylation of M residues. Regioselectivity in the acylated alginate products was studied, and degradation under basic reaction conditions was probed.
authors: Macromolecules and Interfaces Institute Department of Wood Science and Forest Products Institute for Critical Technology and Applied Science, Virginia Tech, Blacksburg, Virginia 24061, United States.
authors: Siddhesh N
authors: SN
authors: Pawar
authors: Kevin J
authors: KJ
authors: Edgar
mesh_terms: D000081:Acetamides / Q000737:chemistry*; D000215:Acylation; D000464:Alginates / Q000138:chemical synthesis* / Q000737:chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D004126:Dimethylformamide / Q000737:chemistry*; D048289:Imidazolidines / Q000737:chemistry*; D008970:Molecular Weight; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012995:Solubility; D012997:Solvents / Q000737:chemistry*
chemical_list: D000081:Acetamides; D000464:Alginates; D048289:Imidazolidines; D000644:Quaternary Ammonium Compounds; D012997:Solvents; D004126:Dimethylformamide; C009405:tetrabutylammonium; C013959:dimethylacetamide; D004121:Dimethyl Sulfoxide