异相法制备磺酸基取代壳聚糖衍生物

The heterogeneous preparation of N-sulfated chitosan derivatives

用3-氯-2-羟基丙磺酸钠与壳聚糖在较低温度下进行非均相反应制备了一系列取代度,结构新颖的改性壳聚糖。实验表明化学改性能极大的提高壳聚糖在水溶液中的溶解性能。研究了不同的反应条件对壳聚糖取代度的影响并用核磁共振表征了它们的结构。反应可在中性、较为温和的条件下进行,通过改变反应时间和反应物比例能有效的控制改性壳聚糖的取代度。改性后的壳聚糖能溶解于中性的水溶液中,浊度实验表明产物具有明显的两性聚电解质特征,其等电点约在pH=5.7。该方法为制备化学改性壳聚糖的一种有效的方法。

Chemically modified chitosan derivatives with different degree of substitution varying from 0.17 to 0.96 were synthesized by heterogeneous reaction of chitosan with 3-chloro-2-hydroxy propanesulfate. The chemical modification dramatically increases the solubility of chitosan in neutral water. Effects of reaction conditions on the degree of substitution of chitosan were studied and the structure of the modified chitosan was characterized by FTIR and ^1H NMR spectroscopies. The reaction can proceed in mild condition at neutral pH and the degree of substitution can be easily controlled by changing reaction time and the ratio of chitosan to 3-chloro-2-hydroxy propanesulfate. The modified chitosan is soluble in neutral water and potentiometric titration reveals that the product exhibits polyampholyte properties with an isoelectric point at around pH = 5.72. The results showed that the present method is an effective way for the chemical modification of chitosan.