BMMs固载联吡啶脯氨酸衍生物及其在Aldol反应中的应用和荧光性能

发布时间：2019-05-23 00:28

【摘要】：非均相不对称催化不仅具有产物易分离纯化、催化剂可回收利用、适用于规模生产等多种优点,还可利用载体与客体分子间特殊的电子效应或空间限域效应等性能提高催化反应的催化活性和立体选择性。介孔二氧化硅纳米粒子因其具有较大的比表面积和孔容积以及可调节的介孔孔径、高的机械强度、较好的热稳定性和易于修饰的内外表面等特点,成为固载均相催化剂的优良载体之一。其中双模型介孔SiO_2(BMMs)是一种新型的介孔材料,它存在双孔道结构:一种是3nm左右的蠕虫状一级孔,另一种是10-30 nm左右的球形颗粒堆积孔。独特的双孔道结构可以使反应物和产物分子在孔道中更好的反应和扩散,从而提高反应效率。为此,本文以双模型介孔SiO_2(BMMs)为无机载体,分别采用氢键和配位键方式实现了联吡啶脯氨酸衍生物在无机多孔载体上的固载,同时制备出一系列非均相催化剂用于催化对硝基苯甲醛和环己酮的不对称Aldol反应。结合多种表征手段,开展了有机-无机杂化材料在多相不对称催化中的性能研究。具体研究内容和相关结果如下:1.以BMMs为无机载体,通过后嫁接法将不同含量的联吡啶脯氨酸衍生物(2S,2’S)-N,N’-([2,2’-bipyridine]-3,3’-diyl)bis(pyrrolidine-2-carboxamide)(Z1)固载于BMMs表面,得到有机-无机纳米复合材料Z1-BMMs-x(x=0.1-30,x代表Z1与BMMs的投入质量比)。采用XRD、SEM、TEM、TG、FT-IR、UV-vis DRS、PL、元素分析等测试手段对样品进行了结构分析和性能表征。同时考察了它们的荧光特性以及在不对称Aldol反应中的催化性能。结果表明有机分子Z1的引入没有破坏介孔的结构和稳定性,且在BMMs表面分散度较高,并获得较好的催化活性(产率高达80%,对映体选择性高达85%),与均相催化剂Z1的催化效果相当。2.为提高活性物种(Z1)在BMMs介孔表面的结构稳定性,将金属离子(Co~(2+),Ni~(2+),Zn~(2+)和Cu~(2+))通过嫁接法负载于BMMs表面,并利用联吡啶与金属的配位络合方式将有机分子(Z1)固载到BMMs介孔表面,从而得到非均相催化剂Z1MBMMs(M=Co,Ni,Zn,Cu)。以对硝基苯甲醛和环己酮的不对称羟醛缩合反应为模型反应,详细考察和分析对比了Z1MBMMs和相对应均相金属配合物(MZ1)的催化性能。结果表明,Z1MBMMs的催化活性和立体选择性均比相应的均相催化剂有所提高。XRD、SEM、TEM、FT-IR、UV-vis DRS等表征结果说明BMMs的双模型介孔结构有利于活性物种(Z1)在介孔内部均匀分布,以及反应分子的吸附和扩散。与氢键固载化方式相比,配位络合作用力对活性物种Z1的固载更稳定。3.上述非均相催化剂(Z1MBMMs)的循环催化效果表明,在进行第一次循环反应时保持了与首次反应相当的产率和立体选择性,但是第二次循环反应的催化活性都有所降低。通过多种表征手段进行初步分析非均相催化剂失活的原因如下:(1)由XRD,SEM,TEM,氮气吸脱附等结果表明BMMs的稳定性在反应过程中受到影响,孔道结构遭到破坏,经过多次循环反应后的催化剂不再保持BMMs独特的双模型孔道结构;(2)TG,UV-Vis DRS等结果表明反应过程中有机物在介孔孔道表面堆积,活性位被覆盖;(3)ICP结果表明反应过程中载体表面金属脱落,伴随着Z1一起流失严重,这是造成催化剂失活的主要原因。
[Abstract]:The heterogeneous asymmetric catalysis not only has the advantages of easy separation and purification of the product, can be recycled by the catalyst, is suitable for large-scale production and the like, but also can improve the catalytic activity and the stereoselectivity of the catalytic reaction by utilizing the special electronic effect or the space limited domain effect between the carrier and the guest molecule. The mesoporous silica nano-particles are one of the excellent carriers of the solid-carrier homogeneous catalyst because of the characteristics of larger specific surface area and pore volume and adjustable mesoporous pore size, high mechanical strength, better thermal stability and easily modified inner and outer surfaces and the like. The two-model mesoporous SiO _ 2 (BMMs) is a novel mesoporous material. It has a double pore structure: a worm-like primary hole of about 3 nm, and the other is a spherical particle accumulation hole of about 10-30 nm. The unique dual-pore structure can enable better reaction and diffusion of reactants and product molecules in the pore canal, thereby improving the reaction efficiency. In this paper, by using double-model mesoporous SiO _ 2 (BMMs) as the inorganic carrier, the solid-loading of the co-dihydro-proline derivative on the inorganic porous carrier was realized by means of hydrogen bonding and coordination, and a series of heterogeneous catalysts were prepared to catalyze the asymmetric dol reaction of p-nitrobenzaldehyde and cyclohexanone. In this paper, the performance of organic-inorganic hybrid materials in heterogeneous asymmetric catalysis is studied by means of a variety of characterization methods. The specific research contents and relevant results are as follows:1. The organic-inorganic nanocomposite Z1-BMMs-x (x = 0.1-30, x represents the input mass ratio of Z1 and BMMs) was obtained by solid-loading BMMs as an inorganic carrier and by post-grafting. The samples were characterized by XRD, SEM, TEM, TG, FT-IR, UV-vis DRS, PL and element analysis. Their fluorescence properties and their catalytic properties in the asymmetric Chol reaction were also investigated. The results show that the introduction of the organic molecules Z1 does not destroy the structure and the stability of the mesopores, and the dispersity of the organic molecules Z1 is higher, and the better catalytic activity is obtained (the yield is as high as 80%, the enantioselectivity is as high as 85%), and the catalytic effect with the homogeneous catalyst Z1 is equivalent to that of the homogeneous catalyst Z1. in order to improve the structural stability of the active species (Z1) on the mesoporous surface of the BMMs, the metal ions (Co ~ (2 +), Ni ~ (2 +), Zn ~ (2 +) and Cu ~ (2 +)) are loaded on the surface of the BMMs by the grafting method, and the organic molecules (Z1) are fixed on the BMMs mesoporous surface by the coordination and complexing method of the coupling agent and the metal, So as to obtain the heterogeneous catalyst Z1MBMMs (M = Co, Ni, Zn, Cu). The catalytic properties of Z1MBMMs and the corresponding homogeneous metal complexes (MZ1) were compared and compared with the asymmetric aldol condensation reaction of p-nitrobenzaldehyde and cyclohexanone. The results show that the catalytic activity and stereoselectivity of Z1MBs are all higher than the corresponding homogeneous catalysts. The results of XRD, SEM, TEM, FT-IR, UV-vis DRS indicate that the two-model mesoporous structure of the BMMs is beneficial to the uniform distribution of the active species (Z1) in the mesoporous and the adsorption and diffusion of the reactive molecules. Compared with the method of hydrogen bonding, the binding force of the coordination complex is more stable to the immobilization of the active species Z1. The cyclic catalytic effect of the above-mentioned heterogeneous catalyst (Z1MBMMs) shows that the yield and the stereoselectivity comparable to the first reaction are maintained at the time of the first cyclic reaction, but the catalytic activity of the second cycle reaction is reduced. The causes of the deactivation of the heterogeneous catalyst by various means of characterization are as follows: (1) The results show that the stability of the BMMs is affected during the reaction, and the pore structure is destroyed. and (2) the TG, the UV-Vis DRS and the like indicate that the organic substances in the reaction process are accumulated on the surface of the mesoporous pore, and the active sites are covered; and (3) the ICP results indicate that the surface metal of the carrier in the reaction process is off, With the loss of Z1 together, this is the main cause of the catalyst deactivation.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O643.36

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