【作者】 马淑兰；

【导师】 汪玉庭；

【作者基本信息】 武汉大学 ， 环境科学， 2005， 硕士

【摘要】 壳聚糖是自然界迄今所发现的唯一天然碱性多糖,其结构中包含氨基葡萄糖单元和乙酰氨基葡萄糖单元,对一些金属离子尤其是过渡金属离子有良好的螯合作用,其来源广泛,具有很好的生物可降解性。在自然界中可被壳聚糖酶、溶菌酶和微生物完全生物降解,是一可再生资源和环境友好材料。 催化氢化在有机合成中有着广泛的应用,尤其在化工产品合成中占有重要的地位。目前,以高分子金属配合物作为催化剂的催化氢化反应由于反应条件温和、不污染环境等优势已成为人们研究的热点。冠醚化合物具有独特的分子结构和选择性的配位能力,能与许多金属离子形成主-客体络合物,有较好的选择性,利用壳聚糖与冠醚化合物的协同作用,制备出改性壳聚糖冠醚化合物。 本文概述了壳聚糖的结构及物理化学性质,介绍了壳聚糖金属络合物催化剂的研究进展;简述了冠醚及高分子冠醚金属络合物在催化方面的应用;概述了钯系催化剂在催化氢化中的研究进展。本论文重点研究了三种改性壳聚糖负载氯化钯催化剂的制备及表征,同时还探讨了这三种催化剂对对硝基苯胺的催化性能。 主要研究内容如下: 制备了壳聚糖接枝苯并18-冠-6、交联壳聚糖微球、二苯并18-冠-6交联壳聚糖,并分别负载氯化钯,制成了负载钯非均相催化剂,并分别对三种催化剂用X-射线光电子能谱(XPS)进行了表征,最后分别用这三种催化剂来催化对硝基苯胺生成对苯二胺,用气相色谱仪对产物进行了定量分析。结果表明:在常温常压下,三种催化剂都表现出较好的催化活性,对苯二胺的产率较高,催化剂易从反应体系中分离,同时研究了反应时间及催化剂中钯含量、温度、底物浓度等因素对催化氢化对硝基苯胺的影响,考查了催化剂的稳定性。更多还原

【Abstract】 At present chitosan is only natural alkaline amylase having been founded, which of structure contains both glucosamine units and acetylglucosamine units. Chitosan can chelated metal cations especially transition-metal cations through chelation mechanisms or through electrostatic attraction. Chitosan is abundant and biodegradable in the nature and it is a repro duceible resource and environmental friendly material which can be completely degraded by the chitosan enzyme, bacteriolysis enzyme and animalcule.Catalytic hydrogenation has an important pole in the course of organic synthesis. The catalytic hydrogenation using the macromolecule metal compound as the catalyst has been widely studied due to some advantages, such as the reaction conditions are mild and the reaction doesn’t pollute environment et al. Crown ether compounds can cooperate with metal cations due to the unique molecular structure and selective cooperating ability. We have synthesized crown ether modified chitosan through grafting or crosslinking crown ether onto the chitosan utilizing their cooperating action.The structure and physical-chemical properties of chitosan were summarized, and the progress in studies on the catalyst of chitosan metal compounds was introduced. The application of crown ether metal compounds in the catalysis and the progress in studies on series of catalysts of palladium in the catalytic hydrogenation were reviewed. In the paper, three kinds of catalysts were synthesized and the catalytic performance of catalysts was studied.The main contents are described as follows:Three kinds of novel heterogeneous supported palladium catalysts were synthesized through supporting palladium chloride on three kinds of different macromolecules. These catalysts were confirmed with X-ray photoelectron spectrometry (XPS) respectively. At the same time, the catalytic performance which catalyzes the p-nitroaniline to p-phenylenediamine was studied respectively. The experimental results indicate that three kinds of catalysts show a good activity, and the yield of p-phenylenediamine was high during the course of hydrogenation. The yield of p-phenylenediamine was quantificationallyanalyzed with the gas chromatography. The catalysts can be easily separated from the reaction system. In addition, the influence of experimental parameters on reaction such as the reaction time, the amount of palladium in catalyst, reaction temperature, concentration of substrate was discussed and the catalyst stability was examined respectively.更多还原