Method For the Controlled Oxidation of Polysaccharides

• US 20080194805A1
• Filed: 07/29/2005
• Published: 08/14/2008
• 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: Samain, Daniel, Condoret, Jean-Stephane, Montanari, Suzelei, Vignon, Michel
• Granted Patent: US 8,252,921 B2
• Time in Patent Office: Days
• 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 oxidising agent. The invention is characterised in that the oxidation reaction is performed in a densified fluid which is inert in relation to the oxidising 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 densified fluid which is inert in relation to the oxidizing agents employed.

2. The method as claimed in claim 1, characterized in that said fluid is an inert gas.

3. The method as claimed in claim 2, characterized in that said inert gas is chosen from the rare gases, CO₂, dinitrogen, perhalogenated gases, and mixtures thereof.

4. The method as claimed in claim 3, characterized in that said inert gas is chosen from CO₂, dinitrogen or argon, or mixtures thereof.

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

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

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

8. The method as claimed in claim 1, characterized in that the oxidizing agent is nitrogen dioxide, i.e. NO₂, the N₂O₄ dimer or mixtures thereof, used, where appropriate, in the presence of oxygen.

9. The method as claimed in claim 1, characterized in that the procedure is carried out in a closed system, under pressure at a temperature of the order of from 20 to 60°

C., in particular from approximately 20 to 40°

C., and under a pressure of the order of from 2 to 40 MPa (20 to 400 bar), in particular from approximately 6 to 18 MPa (60 to 180 bar).

10. The method as claimed in claim 1, characterized in that the polysaccharides are placed in a closed reactor, which is then filled with the inert densified fluid.

11. 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.

12. The method as claimed in claim 1, characterized in that, at the end of the reaction, NO₂ is eliminated by generating a leakage flow rate in the reactor while at the same time maintaining the pressure constantly above or at the same level as the working pressure.

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

14. A carboxylated polysaccharide as obtained by means of the method as claimed in claim 1.

15. The polysaccharide as claimed in claim 14, characterized in that it exhibits a variable mass % carboxylic acid content, ranging up to 25.5% in the case of cellulose.

16. The application of the polysaccharides as claimed in claim 1, in the food industry, in the paint, paper or textile industry, in agriculture, in the pharmaceutical industry, in the medical, biomedical or paramedical field;

in surgery, in the cosmetics industry, and as agents for the complexing or sequestering of metal ions, heavy metals and radioactive elements in the nuclear industry.

17. The application as claimed in claim 16, characterized in that said carboxylated polysaccharides are used as bioresorbable threads and/or fabrics for tissue or organ repair in humans or animals.

18. The application as claimed in claim 16, characterized in that said carboxylated polysaccharides are used as dressings, compresses, fabrics and sponges, having hemostatic and/or bacteriostatic properties.