【作者】 李秀荣；

【导师】 毛建新；

【作者基本信息】 浙江大学 ， 物理化学， 2005， 硕士

【摘要】 固体酸碱的研究和开发目前已引起催化工作者的重视。水滑石型类阴离子粘土及其复合氧化物具有一定的碱性,对许多碱催化反应如醛酮缩合反应和烯烃氧化物的聚合反应等有较好的活性;另一方面,水滑石类阴离子层柱化合物具有较高的比表面积和良好的水热稳定性及插层性能,可以用作碱性催化剂载体。同时,通过调节层间距,可提高反应的选择性。因此水滑石型类阴离子粘土及其衍生复合氧化物在催化中的应用是近年来的研究热点。 Baeyer-Villiger氧化反应因能生成一系列有价值且很难用其它方法合成的酯和内酯,因而这类氧化反应具有广泛的应用价值。现在Baeyer-Villiger氧化反应已成为酮或环酮转化成酯或内酯的统称,这些反应已成为有机化学反应中的重要基石。因此,有关这一领域的研究引起了化学家们的兴趣。 本论文工作主要分为三部分:一、类水滑石的制备,并结合FT-IR、XRD、TG-DTA、UV-Raman、Vis-UV/DR等来探讨所得类水滑石化合物的结构组成及其催化活性。二、分别考察了在类水滑石碱催化体系和TFP(四氟丙醇)中酸催化体系作用下,6-甲氧基-1-四氢萘酮和四氢萘酮-1的Baeyer-Villiger氧化反应。三、探讨了上述两种不同情况下的可能的反应机理。论文的主要内容如下: 第一章在文献基础上归纳总结了类水滑石常用的制备方法、Baeyer-Villiger氧化反应氧化剂的类型和不同催化体系的作用特点及国内外研究进展,明确了研究的目标及内容。 第二章主要介绍了用低过饱和共沉淀法制备了一系列的类水滑石化合物,并对以其为催化剂,以空气为氧化剂,苯甲醛为助氧化剂的体系中6-甲氧基-1-四氢萘酮和四氢萘酮-1的Baeyer-Villiger重排反应进行了研究,分离出相应的内酯产物,明确了它的分子结构。对所得系列的催化剂的催化活性进行了评价,筛选出了催化活性较高的Zn-Cr系列催化剂。 第三章通过XRD、FT-IR、Vis-UV/DR、UV-Raman、TG-DTA等测试手段对部分合成的水滑石类化合物的结构特征及热稳定性进行了分析,证明了该类化合物的生成。XRD的测试证实了水滑石的晶相结构,Zn-Cr系列的水滑石在450℃灼烧后样品的层状结构被破坏,而且在氮气氛围中用水蒸气处理也很难更多还原

【Abstract】 The investigation and exploitation of acid and base solid catalysts have been recently received much attention by catalysis researchers. Hydrotalcite-like ion clays and their composite oxides with certain basicity have better catalytic activity and selectivity in the aldol condensations, the polymerization of olefin oxide, etc. under environmental friendly conditions. On the other hand, hydrotalcite-like compounds with typical laminated structure have high surface areas, favorable hydro-thermo stability and capability of insertion, so they can be used as catalyst carriers. At the same time, the reaction selectivity can be increased via adjustment of the space between layers. Therefore, the application of hydrotalcite-like compounds and their derivate mixed oxides in catalysis is the research hotspot in recent years.Baeyer-Villiger oxidation is a valuable method to convert ketones into the corresponding esters and lactones, which are with high value and difficulty to be synthesized by other way. At present, Baeyer-Villiger oxidation has been a general designation for converting ketones into esters and lactones, because these reactions are sill very important and fundamental in organic chemistry. The research area of this reaction gives rise to the interests of many chemists.Our research work consists of three parts: Firstly, some hydrotalcite-like compounds (HTLcs) were prepared and characterized by FT-IR, XRD, DTA, UV-Raman, Vis-UV/DR techniques to investigate the relationship between structure composition and catalytic activity. Secondly, the Baeyer-Villiger oxidation of 6-methoxy-l-tetralone and 1-tetralone were examined under the reaction system of basic HTLcs oxidized by air and the reaction system of Bronsted acids oxidized by H2O2. Thirdly, the possible reaction mechanisms above were proposed.The main contents of this paper are as follows:The first chapter is a review based on 67 references. In this chapter, it describes the summarization of the preparation methods of the HTLcs, the type ofoxidants and the different catalytic systems of Baeyer-Villiger oxidation to make the research progress at home and abroad area. At the end of this chapter, the research object and content of this paper are also described concretely.The second chapter mainly introduces the preparation of HTLcs by the technique of coprecipitation at low supersaturation, and the application of HTLcs to the Baeyer-Villiger oxidation of 6-methoxy-l-tetralone and 1-tetralone by using a combination system of molecular oxygen and benzaldehyde. The Zn-Cr hydrotalcites were found to be the best catalyst to give high yields of the corresponding lactones.In the third chapter, it describes characterization of part of the samples as synthesized and their calcined products by bulk chemical analyses, power XRD, FT-IR, Vis-UV/DR, UV-Raman, and TG-DTA. The crystalline hydrotalcite-like structures for the as-synthesized Zn-Cr-HT sample, formation of chromate-like species and mixed oxides for the calcined sample have been confirmed by powder X-ray diffraction. It suggests the structure was destroyed for Zn-Cr-HT calcined at 450°C, and it was very difficult to come back to the original structure even if it was treated with vapor under nitrogen atmosphere. The anion between layers is CO32" namely the carbonate type hydrotalcites is confirmed by FT-IR. The DG-DTA results show hydrotalcite-like compounds have three thermal decomposition courses. The first band at about 100°C is assigned to the removal of water molecules from the interlayer space and the dehydration of the physisorbed water on the surface. The second band is due to removal of water molecules (from condensation of hydroxyl groups from the brucite-like layers) and of carbon dioxide (from interlayer carbonate anions) at about 200°C, thus leading to collapsing of the layered structure. The system changes from out-of-order to in order and forms new species because there is an exothermic band at about 500°C.In the fourth chapter, it gives the results of the Baeyer-Villiger oxidation of 6-methoxy-l-tetralone and 1-tetralone by using hydrogen peroxide as oxidant, Br0nsted acids as catalyst in the solvent of 2,2,3,3-tetrafluoro-l-propanol. The influences at different reaction conditions were discussed. The results indicate thatTFP is the best solvent and HC1 has the best catalytic activity among all the reagents selected.In the final chapter, the possible reaction mechanisms of 6-methoxy-l-tetralone and 1-tetralone mentioned in chapter two and four are discussed. As the reaction was catalyzed by basic hydrotalcite-like compounds, the product was only lactone. But two products were detected as the reaction was carried out in the solvent of 2,2,3,3-tetrafluoro-l-propanol catalyzed by acids with hydrogen peroxide. Lactone structure could not be kept under acid medium and might be hydrolyzed to the corresponding hydroxyphenyl substituted butyric acid. The hydroxyphenyl substituted butyric acid with -OCH3 group in the benzene ring would have higher reactivity and finally be rearranged to be another tetralone. It is interesting to get a dicarbonyl compound by the oxidation of 1-tetralone. The possible reaction pathways are described in detail in this chapter.更多还原