离子液体的结构对催化多聚糖水解性能的影响
首发时间:2016-06-27
摘要:本文合成了七种离子液体, 考察了不同结构的离子液体催化菊粉多聚糖的水解性能, 利用紫外可见分光光度计,通过哈米特函数公式计算了所合成离子液体的酸度,分析了离子液体的结构和催化性能之间的关系。实验结果表明:离子液体阴离子的性质, N(1)取代基侧链长度以及N(3)所含功能基团对其酸度和催化性能均有着重要的影响。酸性较强的阴离子更利于糖苷键的断裂。乙基为取代基时,与咪唑阳离子的超共轭作用稍弱于甲基取代基,酸度和水解性能也稍强。咪唑阳离子含功能基团时,酸度增加,催化性能有所提高。所制备的离子液体催化水解菊粉多聚糖,1-甲基-3-丁基羟基咪唑硫酸盐表现出了最佳的水解效果,还原糖收率达71.5%。
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Influence of the ionic liquid structure on its catalytic performance for polysaccharide hydrolysis
Abstract:In the present study, seven kinds of ionic liquids were synthesized. The catalytic performance of ionic liquids with differtent strucutre for inulin polysaccharide were investigated. The acidities of ionic liquids were evaluated from the determination of the Hammett acidity functions, using UV-visible spectroscopy. And the relationship between the chemical structure and catalytic properties of the ionic liquids were analyzed. The experimental results show that the nature of anion, the length of side chain substituent on N(1) and the functional group on N(3) of ionic liquids have significant influence on their catalytic performance. The strong acid anions are more easily to promote the fracture of glycosidic bond. Hyperconjugation effect between imidazole cation and ethyl substituent was slightly weaker than methyl substituent, resulting in the higher acidity and catalytic performance. When imidazole cation contains functional group on N(3), its acidity and catalytic performance could be improved. The prepared ionic liquids were used to catalyze inulin polysaccharide. 1-ethyl-3-(4-hydroxy) imidazole sulfate showed the best hydrolysis performance with reducing sugar yield up to 71.5%.
Keywords: ionic liquid chemical structure polysaccharide hydrolysis acidity
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