【作者】 王虎群；

【导师】 张智敏；

【作者基本信息】 山西大学 ， 物理化学， 2009， 硕士

【摘要】 芳香胺化合物作为精细化学品在合成方面具有重要的理论意义和应用价值。本论文将非均相光催化反应技术应用于这一反应体系,设计和制备了负载型非金属氮修饰的半导体材料,并对材料的表面组成、晶体结构和光催化反应性能进行了系统的研究,建立了光催化还原芳香硝基物制芳胺的体系并作了进一步发展和创新,形成了催化性能好,易于分离产物并可回收催化剂的新催化体系,使光催化系统在有机合成方面得到广泛的应用。TiO₂在有机合成中的应用一直倍受化学家的关注,它在有机合成中的化学行为主要有以下三个方面:其一,TiO₂利用其空穴进行的氧化反应;其二,TiO₂利用其电子进行的还原反应;其三,TiO₂充分利用电子空穴对在溶液中进行的降解反应。本论文对一些常见硝基化合物在光催化还原体系中的反应进行了较为系统的研究,以芳香族硝基化合物为反应底物,研究了它们在二氧化钛存在的条件下,还原制备重要精细化工原料芳香胺化合物,并对其反应机理进行了初步的探讨和研究。采用溶胶-凝胶法方法,以尿素作为氮源以钛酸丁酯为前驱体在相近条件下制备了纳米TiO₂和N掺杂的TiO₂,并通过红外、电镜以及粉木衍射图谱进行了系统的比较研究。XRD及TEM测试结果显示:溶胶-凝胶法制备方法简单,且样品为锐钛矿相、颗粒均匀细小,并得到了粒径在10nm左右的纳米晶须状N/TiO₂颗粒,并以邻硝基酚的水溶液的光催化降解为模型反应,对催化剂的光催化性能进行评价,结果表明N/TiO₂性能最好。设计光催化体系应用于还原邻硝基酚来合成邻氨基酚,首次在紫外光照射下取得了较好催化效果。并对反应的影响因素以及反应动力学作了详尽的讨论,优化了反应工艺。在此基础上催化体系应用到不同取代基芳胺的合成上,对一些含有卤素,醛基,羧基,氨基等的取代硝基苯实现了硝基的单一选择性还原,同时高产率地获得了相应的芳胺。讨论了取代基对以及空间位阻对产率的影响,这有望为制备各类芳香胺提供一条高效、高选择性、适用面广、环境友好、成本低的新合成方法。结合前人的研究,对新催化体系的还原机理进行了探讨,初探了硝基还原的可能历程。本论文的研究结果既丰富了光催化化学的内容,又提供了较为简便的合成方法,不仅具有一定的理论研究价值,而且具有一定的应用前景。更多还原

【Abstract】 Aromatic amine compounds as fine chemicals have important theoretical significance and application value in the synthesis.In this work,a heterogeneous photocatalytic reaction technology was applied to this reaction. A series of supported non-metal modified coupled semiconductors were designed and prepared.The surface configuration,energy band position, optical absorption property,crystal structure and photocatalytic performance of the materials were systematically investigated.Further development and innovation were made to the original catalytic system reducing nitro aromatics to amines by N/TiO₂ in this thesis,which brought into being new catalytic systems with high efficiency,easy separation of product and facile recycling of catalyst.In chemical behaviors of organic chemistry,TiO₂ that has been paid good attention to the application for organic synthesis by chemist has mainly three characters:First,TiO₂ has been in the oxidation reaction by hole produced.Second,TiO₂ has been in the reducing reaction by electron produced.Third,TiO₂ has been in the deposition reaction by hole-electron produced.In the thesis,we investigated chemical reactivity of some familiar aromatic nitro compounds with TiO₂ reducing system and synthesis of fine chemical,such as aromatic amines by reduction of aromatic nitro compounds in the presence of nanoparticles N/TiO₂.And put forward the tentative reaction mechanism.Nano-TiO₂ and N/TiO₂ powders were prepared by sol-gel method with urea as nitro source and tetrabutyltitanate as a precursor at the same conditions,respectively.The comparative study of the properties was carried out by different technologies,such as FTIR,TEM and XRD.X-ray diffraction（XRD） and transmission electorn microscope（TEM） results showed that the particles（＜10nm） synthesized by a simple sol-gel method were anatase and nano crystal whisker.The photocatalytic activities of catalysts were evaluated by the reation of o-nitrophenol solution degradation as a model performed by photocatalytic technology and results show the properties of N/TiO₂ were the best among the catalysts.The new catalytic systems were used to reduce o-nitrophenol and good results were obtained under UV irridation.Then the influence factor for the reaction and reaction kinetics were discussed detailedly,and the reaction conditions were optimized.Further,we investigated the synthesis of aromatic amines with different substituents basis on the experiments above.For some nitro benzenes substituted by halogen,carbonyl and amino groups,the singly selective reduction of nitro was fulfilled,and corresponding aromatic amines were acquired with high yield,which may offer a new highly efficient and selective versatile,environmentally benign and low cost synthetic method for the preparation of kinds of aromatic amines.And the impact factors of substituents and space steric hindrance for the reaction were discussed. Combined with previous research,the possible reduction mechanism for new catalytic system was discussed primarily.The research results of this thesis not only enriched the content of photocatalytic chemistry and provided a more convenient method of synthesis;not only has a theoretical research value,but also has a certain application.更多还原