【作者】 张强；

【导师】 魏运洋； 罗军；

【作者基本信息】 南京理工大学 ， 应用化学， 2013， 博士

【摘要】 开发负载型催化剂是解决均相催化剂较难分离、回收以及重复使用等问题的主要策略之一。无机载体来源广泛、价廉易得以及具有良好的机械强度和热稳定性,受到广泛关注。其中,硅基材料和硅胶包裹的氧化铁系磁性纳米粒子由于表面(或孔道)具有大量可修饰的羟基存在,对于硅烷功能化的有机分子易于通过缩合反应进行锚定,实现有机分子固载化。此外,磁性纳米粒子独特的磁性能为其固载化的有机分子提供了迅速高效分离的可能。鉴于离子液体和贵金属钯在有机催化领域的重要应用价值及其使用量大、回收困难等缺点,开发新型的具有高催化活性且可重复使用的负载型离子液体和钯催化剂具有十分重要的意义。本论文设计合成了几种新型无机负载催化剂,包括无定形硅胶和磁性纳米粒子负载离子液体催化剂、介孔硅胶负载钯络合物以及磁性纳米粒子负载纳米钯催化剂,考察了这些催化剂在有机合成反应中的应用情况。以廉价的无定形硅胶为载体,通过表面羟基与硅烷化的酸性离子液体进行缩合反应,制备了新型硅胶负载酸性离子液体催化剂,并将其应用于酯化、缩醛化、多组分缩合制备氨烷基萘酚类和4H-吡喃类化合物的反应中,表现出优良的酸催化活性,而且反应条件温和,产率较高。催化剂只需经过简单的过滤、洗涤、干燥即可回收再生,简化了操作过程,并且重复使用多次,仍能保持较高的催化活性。以硅胶包裹的四氧化三铁纳米粒子作载体,制备了磁性纳米粒子负载酸性和碱性离子液体两种新型固体催化剂。考察了无溶剂条件下,磁性纳米粒子负载酸性离子液体催化醛、2-萘酚和环状双甲酮类化合物的三组分缩合,制备相应的氧杂蒽类化合物。在90℃下,催化剂用量为1.5mol%,反应时间为30-60min,产率可达80-94%。将磁性纳米粒子负载碱性离子液体催化剂应用于室温条件下芳醛、乙酰乙酸乙酯、5,5-二甲基-1,3-环己二酮和醋酸铵的非对称Hantzsch反应,催化剂用量为3.6mol%,反应时间为1.5-3.5h,产率可达76-88%。催化剂可经磁分离方便回收,重复使用5次,活性没有明显下降。以介孔硅胶MCM-41为载体,经新型长链硅烷化亚胺吡啶配体化学改性后与钯盐配位,制备了新型负载钯络合物催化剂,并将其应用于Suzuki反应中。在温和的反应条件下,该催化剂可有效地催化多种溴代芳烃和芳基硼酸的Suzuki反应,50℃反应1.0-4.5h,产率可达86-98%。催化剂可通过简单过滤来回收,经洗涤、干燥后,可至少循环使用5次且催化活性没有明显下降。在介孔硅胶负载钯络合物的基础上,制备了磁性纳米粒子负载钯络合物催化剂,并将其应用于Heck反应中。碘代芳烃和含有吸电基的溴代芳烃显示了较高的反应活性,100-120℃反应1-4h,产率可达80-98%。催化剂可在外磁场条件下与反应体系快速分离,方便回收使用,其重复使用性能受到反应用碱的影响,当三乙胺为碱时,催化剂循环使用6次,产率仍可高达92%；而当碳酸钾为碱时,催化剂重复使用3次后,催化活性下降明显。通过点击化学策略制备了一种新型磁性纳米粒子负载纳米钯催化剂,并将其应用于Suzuki反应中,可有效地催化多种卤代芳烃和芳基硼酸的Suzuki反应,60℃反应3-8h,产率可达80-99%。催化剂可在外磁场条件下与反应体系进行快速分离,方便回收使用,其重复使用性能受到反应体系中水含量的显著影响,当以95%EtOH作溶剂时,催化剂可至少循环使用6次且催化活性没有明显下降。更多还原

【Abstract】 The development of supported catalysts is an elegant way to solve the problem of the separation, recovery and reuse of homogeneous catalysts. Inorganic matrixes have many advantages, such as abundant source, low cost, and excellent stability, so the inorganic supported catalysts have attracted wide attention. Among them, the silicon-based materials and silica coated ferric oxide magnetic nanoparticles are often chosen as supports, because there are a lot of hydroxyl groups on their surfaces or pores, some silane functionalized organic molecules can be easily immobilized via condensation reactions with the hydroxyl groups of supports. Moreover, due to the attractive magnetic property, the magnetic nanoparticles supported molecules can be rapidly and efficiently separated from the mixture. Considering the great value of ionic liquids (ILs) and noble metal palladium in the field of organic catalysis, and the disadvantage of high dosage and difficult recovery, it’s very significant to develop some novel supported ionic liquid and palladium catalysts.Herein, some new inorganic supported catalysts were prepared, including amorphous silica and magnetic nanoparticles supported IL catalyst, mesoporous silica supported Pd complex, and magnetic nanoparticles supported nano-Pd catalyst. In addition, their applications in the organic reactions were investigated.An amorphous silica supported acid ionic liquid was prepared via condensation reaction with silane functionalized IL and silica hydroxyl group. It could effectively catalyze the esterification, acetalation, and one-pot synthesis of amidoalkyl naphthols and benzopyrans by multicomponent reactions under mild conditions. The catalyst was simply recovered by filtration, and it could be used several times without significant loss of activity.The silica coated Fe3O4was chosen as the support, and another two supported IL catalyst were then prepared by the similar method. The as-prepared supported acid ionic liquid was found to be an efficient catalyst for the one-pot synthesis of benzoxanthenes by a three-component condensation of dimedone with aldehyde and2-naphthol under solvent-free conditions. The reaction could be well carried out within30-60min at90℃under a low catalyst loading (1.5mol%), and good to excellent yields (80-94%) were obtained. The supported basic IL catalyst prepared in a similar way, could effectively catalyze unsymmetrical Hantzsch reaction of aryl aldehyde, ethyl acetoacetate, dimedone and ammonium acetate at room temperature. The reaction proceeded within1.5-3.5h under3.6mol%catalyst loading to afford the corresponding products in high yields (76-88%). The catalyst could be easily recovered by an external magnet and reused five times without remarkable loss of efficiency.A new mesoporous silica supported palladium imino-pyridine complex was successfully prepared by attaching palladium acetate to a novel imino-pyridine ligand functionalized MCM-41. It was found to be an efficient catalyst for Suzuki reactions under mild conditions, and the reactions of various aryl bromides with arylboronic acids could proceed well within1.0-4.5h at50℃to give excellent yields of coupling products (86-98%). The catalyst was simply recovered by filtration, and it could be used five times without significant loss of activity.A magnetic nanoparticle-supported palladium imino-pyridine complex was prepared by a similar process and was applied for Heck reactions. Aryl iodides and aryl bromides with electron-withdrawing groups could undergo smooth transformation during1-4h at100-120℃to give excellent yields of products (80-98%). The catalyst could be simply recovered by magnetic separation, and its reusability was affected by the base used in the reactions. When triethylamine was used as the base, the yield was still as high as92%after the sixth run. However, the catalytic activity was obviously reduced after three times, when potassium carbonate was chosen as the base.A novel magnetic nanoparticle-supported nano-palladium catalyst was successfully prepared via a "click" route and evaluated in Suzuki reactions. It was found to be highly efficient for the reactions of various aryl halides with arylboronic acids. The reactions proceeded well within3-8h at60℃to give high yields of products (80-99%). The catalyst could be simply recovered by magnetic separation, and its reusability was affected by the water in the solvent. It could be reused six times without significant loss of activity when95%EtOH was used as the solvent.更多还原