Specific modifications of galactomannans
Résumé
A sample of galactomannan extracted from the seeds of Leucaema leucocephala is modified on a specific position using the reactant 2,2,6,6-tetramethylpiperidine-l-oxyl (TEMPO). This method allows oxidation at the C-6 position of galactose and free mannose (not connected to a side group). The kinetics of oxidation is followed under well-defined conditions. Different methods are proposed for the characterization of the modified polysaccharides and NMR spectroscopy is shown to give useful information. New polyelectrolytes are produced with different degrees of oxidation. Successive alkylations on the C-6 sites are investigated. The degree of alkylation obtained remains low but it can be increased easily to reinforce the amphiphilic character.