亲核取代法制备壳聚糖6-OH固载环糊精衍生物

PREPARATION OF CHITOSAN IMMOBILIZED WITH β-CD AT C_6 POSITION BY A NUCLEOPHILIC DISPLACEMENT REACTION

通过苯甲醛对壳聚糖2-NH2希夫碱化保护后,将壳聚糖C6位—OH与对甲苯磺酰氯反应形成对甲苯磺酰酯;然后用β-环糊精(-βCD)的单—NH2取代衍生物与之发生亲核取代反应,将环糊精固载到壳聚糖分子链上;最后,将得到的固载产物中的希夫碱脱保护后得到壳聚糖6-OH定位固载环糊精衍生物.采用FTIR,13C-NMR,元素分析,UV等表征手段对各步产物的结构进行了表征.紫外光谱法测定表明,-βCD在壳聚糖分子链C6位上的固载率达到了170.81μmol.g-1,远高于文献报道的其它方法制得的固载产物.采用XRD对各步产物的结晶性能进行了研究.

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 sehiff base ehitosan 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 displaeement 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 170.81umol·g^-1, 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.