Method for the controlled oxidation of polysaccharides

• US 8,252,921 B2
• Filed: 07/29/2005
• Issued: 08/28/2012
• Est. Priority Date: 07/29/2004
• Status: Active Grant

• Current Assignee: Centre National De La Recherche Scientifique, Institut National Polytechnique de Toulouse
• Original Assignee: Centre National De La Recherche Scientifique, Institut National Polytechnique de Toulouse
• Inventors: Vignon, Michel, Montanari, Suzelei, Samain, Daniel, Condoret, Jean-Stéphane
• Primary Examiner(s): Jiang, Shaojia Anna
• Assistant Examiner(s): Schmidtmann, Bahar
• Application Number:
  US11/658,852
• Publication Number:
  US 20080194805A1
• Time in Patent Office: 2,587 Days
• Field of Search: None
• US Class Current: 536/56
• CPC Class Codes: C08B 15/04 Carboxycellulose, e.g. prepared by oxidation with nitrogen dioxide
• CPC Class Codes: C08B 31/08 Ethers
• CPC Class Codes: C08B 33/08 Oxidised amylose
• CPC Class Codes: C08B 35/08 Oxidised amylopectin
• CPC Class Codes: C08B 37/00 Preparation of polysaccharides not provided for in groups C08B1/00 - C08B35/00; Derivatives thereof cellulose D21; microbiological processes C12P
• CPC Class Codes: D06M 15/03 Polysaccharides or derivatives thereof
• CPC Class Codes: D21H 17/24 Polysaccharides
• CPC Class Codes: D21H 19/54 Starch

Abstract

The invention relates to a method for the controlled oxidation of oligo- and/or polysaccharides containing free —CH₂OH primary hydroxyl groups, using an oxidizing agent. The invention is characterized in that the oxidation reaction is performed in a densified fluid which is inert in relation to the oxidizing agents employed. The invention is suitable for use, for example, in the food, paint, paper, textile, agricultural and pharmaceutical industries, in the medical, biomedical or paramedical fields, in the surgical field, in the cosmetic industry and as agents for the complexing or sequestering of metal ions, heavy metals and radioactive elements in the nuclear industry.

Claims

1. 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.

2. The method as claimed in claim 1, characterized in that said fluid is in the form of a densified gas phase.

3. The method as claimed in claim 1, characterized in that said fluid is in the form of an expanded liquid phase.

4. The method as claimed in claim 3, characterized in that the inert gas(es) is/are used as a mixture with other liquid cosolvents.

5. The method as claimed in claim 1, characterized in that the oxidizing agent is used in excess in relation to the amount of CH₂OH that it is desired to oxidize.

6. The method as claimed in claim 1, characterized by the use of cellulose, starch or glucomannan as polysaccharide.

7. The method of claim 1 wherein the temperature is of the order of from 20 to 40°

C.

8. The method of claim 1 wherein the pressure is of the order of from 60 to 180 bar.

9. The method of claim 1, further comprising eliminating the oxidizing agent after oxidation of said oligo- and/or polysaccharides, by generating a leakage flow rate in the reactor while also maintaining a pressure at least equal to the working pressure in the reactor with introduction of additional densified fluid.