Patent ID: 8841440

Claim:
A method for preparing chitosan derivative, comprising: i) dispersing chitosan in an aqueous solution to form a first mixture; ii) adding a chitosan salt forming acid to the first mixture; iii) stirring the first mixture containing the chitosan salt forming acid to form a homogenous solution; iv) adding a solvent to the homogenous solution to precipitate an organo-soluble chitosan salt, wherein the organo-soluble chitosan salt is selected from the group consisting of chitosan sulfonate, chitosan methanesulfonate, chitosan toluenesulfonate, chitosan camphorsulfonate, chitosan salicylate, chitosan trifluoromethanesulfonate, chitosan ethanesulfonate, chitosan phenylbenzimidazolesulfonate, chitosan 1-propanesulfonate, (1R)-(−)-10-camphorsulfonate, and chitosan camphorquinone-10-sulfonate; v) recovering the organo-soluble chitosan salt; vi) dissolving the organo-soluble chitosan salt in formamide to form a second mixture; vii) adding a chitosan derivative forming compound to the second mixture; viii) reacting the chitosan derivative forming compound with the organo-soluble chitosan salt to obtain a reaction solution containing the chitosan derivative; ix) stopping the reaction; x) adding a second solvent to the reaction solution to precipitate the chitosan derivative; and xi) recovering the chitosan derivative.