水溶性甲壳低聚糖的制备与结构表征

Preparation and Characterization of Water-Soluble Chito-Oligosaccharides

以H_2O_2为氧化剂,在中性介质中使壳聚糖氧化降解为水溶性甲壳低聚糖,并研究了H_2O_2用量、反应温度和保温时间对产物收率的影响;用双突跃电位滴定法测定了产物的脱乙酰度,FT-IR和~1H NMR表征了产物结构。实验结果表明,H_2O_2在中性介质中使壳聚糖氧化降解为水溶性甲壳低聚糖的同时,也会使产物进一步降解;产物中含醛基的链式结构组成明显高于壳聚糖,并且过高的反应温度和H_2O_2用量不利于水溶性甲壳低聚糖的生成;适宜的H_2O_2用量为3.0~3.5 m L(30%H_2O_2)/g(CTS),而反应温度和保温时间则分别为60℃和7.0~8 h。

Chitosan was transformed into water- soluble chito -oligosaccharides by oxidizing- degradation method in the neutral medium with H2O2as oxidizing agent. The influence of H2O2dosage, reaction temperature and time on the yields of water - soluble chito - oligosaccharides was investigated respectively. The degree of deaeetylation of product was determined by double - saltation potentiometrie titration and its structure was characterized by FT - IR and ^1 H NMR. Experimental results indicated that the chitosan could be degraded into water - soluble chito - oligosac- charities in the neutral medium using H2O2 as oxidizing agent, and the product could be degraded further. The content of product having chain structure and aldehydyl group in water - soluble chito - oligosaccharides is higher than that in chitosan. The exorbitant dosage of H2OEand reaction temperature are disadvantageous for the formation of water - solu- ble chito - oligosaecharides. The appropriate conditions for preparing water - soluble chito - oligosaceharides were as following： the dosage of H2OEWaS 3.0 ~ 3.5mL（30% H2O2 ）/g（CTS）, the reaction temperature and time were 60 ℃ and 7.0 ~ 8 h, respectively.