壳聚糖氨基选择性功能化中的空间位阻效应

Influence of Steric Hindrance on Amino-Selective Functionalization of Chitosan

为探索空间位阻效应对壳聚糖的N-酰基化、脲基化和氨基甲酸酯化这3种反应的影响,用不同空间位阻的修饰剂对壳聚糖上的氨基进行衍生化,以~1H NMR确定其取代度。结果表明:当修饰试剂的空间位阻不大时,产物的取代度接近100%;而当空间位阻较大时,用离子液体或者LiCl/DMAc为溶剂进行第2次修饰能提高产物的取代度。

To explore influences of steric hindrance on chitosan acylation,ureidolation and carbamylation,the amino group in chitosan was selectively modified by agents with different steric hindrance,and the degree of substitution(DS)was determined by ~1H nuclear magnetic resonance spectroscopy. The results demonstrate that the DS can approach 100% with low steric hindrance. When the steric hindrance of the agent is high,the DS can increase by the second modification with an ionic liquid or LiCl/DMAc as the solvent.