Preparation of chitosan immobilized with β-Cd at C₆ position by a nucleophilic displacement reaction

A novel reaction route to prepare the derivate of chitosan with β-CD immobilized at C₆ position is proposed. It is reliable and of high efficiency. The amino group of the chitosan was protected by reacting with the benzaldehyde, and the schiff base stucture was generated. The hydroxyl group in the schiff base chitosan was tosylated by reacting with p-toluenesulfonyl chloride. Then the mono amino substituted β-cyclodextrin was immobilized onto C₆ position of chitosan by a nucleophilic displacement reaction between the tosylated chitosan and the amino in cyclodextrin derivate. Finally, the schiff base structure was deprotected in the acetic acid solution, and β-CD immobilization derivate of chitosan on C₆-OH (CTS-CD) was prepared. The chemical structure of each resultants was analyzed by FTIR, 13C-NMR, elemental analysis and UV, respectively.The UV absorption peak around 490 nm could be observed for the concentrated sulfuric acid hydrolysis products of CTS-CD. However, the corresponding hydrolysis products of CTS did not show any absorption peak near this range. By drawing the calibration curve of the concentrated sulfuric acid hydrolysis products of β-CD through the UV spectrum, the immobilization amount of β-CD on the C₆ position of chitosan could be quantitative detected. The obtained immobilization amount was 170.81 μmol lg which was by head and shoulders high than the corresponding values reported in literature. The crystallization properties of each resultants were studied through XRD characterization.