Method for the controlled oxidation of polysaccharides

A method for the controlled oxidation of oligo- and/or polysaccharides containing free —CH2OH primary hydroxyl groups, using an oxidizing agent, characterized in that the oxidation reaction is carried out in a closed system filled with a densified fluid wherein the oligo- and/or polysaccharides are placed, the densified fluid being non reactive with said oxidizing agent and being an inert gas,

• said method being carried out at a temperature of the order of from 20 to 60° C., and under a pressure of the order of from 20 to 400 bar,
• the densified fluid being CO2, the oxidizing agent being NO2, N2O4 dimer or mixtures thereof, and
• said oxidizing agent being solubilized in the densified fluid while the oligo- and/or polysaccharides remain in a non solubilized solid state.