磁性高分子納米粒子負(fù)載型Pd催化劑的制備、應(yīng)用及催化機(jī)理研究
發(fā)布時(shí)間：2019-04-24 22:01
【摘要】：Pd催化的C-C偶聯(lián)反應(yīng)是構(gòu)建有機(jī)化合物中C-C鍵最為有效且溫和的方法。在此類反應(yīng)中,均相Pd催化劑的催化活性很高,但也存在貴金屬難回收和環(huán)境污染等問題。因此,一系列的負(fù)載型Pd催化劑被研究和發(fā)展起來。與均相Pd催化劑相比,負(fù)載型Pd催化劑催化活性較低,催化機(jī)理存在爭議,通過載體結(jié)構(gòu)和實(shí)驗(yàn)研究方法的合理設(shè)計(jì)有望解決這些問題。磁性高分子納米粒子負(fù)載型Pd催化劑不僅催化活性高、穩(wěn)定性好,而且可以通過一個(gè)外加磁場快速分離,操作更加簡易,同時(shí)也為其催化機(jī)理的研究提供了便利的實(shí)驗(yàn)條件,因此被廣泛的應(yīng)用于C-C偶聯(lián)反應(yīng)中。此外,隨著人類社會(huì)的發(fā)展,綠色化學(xué)逐漸成為了化學(xué)發(fā)展的新目標(biāo),開發(fā)能在綠色介質(zhì)里使用的負(fù)載型Pd催化劑具有很大的現(xiàn)實(shí)意義。本課題工作設(shè)計(jì)合成了兩種磁性高分子納米粒子負(fù)載型Pd催化劑Fe_3O_4@SiO_2-Dendrimer-Pd和Pd/Fe_3O_4@PMAA-Met,并通過FT-IR、VSM、TEM、AAS、XPS等表征手段對(duì)其結(jié)構(gòu)和性質(zhì)進(jìn)行了檢測。然后,將這兩種催化劑用于綠色介質(zhì)中的Suzuki反應(yīng)和Heck反應(yīng)中,考察了它們的催化活性、循環(huán)使用性能和催化機(jī)理,具體結(jié)果如下:1.將氨基化修飾的Fe_3O_4@SiO_2-NH_2逐步與丙烯酸甲酯和3,3’-二氨基二丙胺反應(yīng)合成了二代的磁性樹枝狀高分子載體,負(fù)載Pd后得到了納米催化劑Fe_3O_4@SiO_2-Dendrimer-Pd。該催化劑僅以0.009 mol%的Pd用量就可高效催化無溶劑Heck反應(yīng)和EtOH/H_2O中的Suzuki反應(yīng),分離產(chǎn)率分別可達(dá)73%-99%和84%-98%。此催化劑可通過磁鐵快速分離,在無溶劑Heck反應(yīng)中循環(huán)使用5次仍取得88%的產(chǎn)率。熱過濾實(shí)驗(yàn)結(jié)果顯示此催化劑以非均相催化機(jī)理催化Suzuki反應(yīng)進(jìn)行。2.采用二甲雙胍對(duì)聚甲基丙烯酸包覆的磁性納米粒子Fe_3O_4@PMAA修飾,負(fù)載Pd后制備了納米催化劑Pd/Fe_3O_4@PMAA-Met。該催化劑僅以0.01-0.0007mol%的Pd用量就可在Et OH/H_2O中高效催化Suzuki反應(yīng),產(chǎn)率達(dá)74%-99%,TOF值高達(dá)125714 h-1。此催化劑可用磁鐵快速分離,連續(xù)使用12次后分離產(chǎn)率仍可達(dá)到88%。3.過濾實(shí)驗(yàn)結(jié)果顯示Pd/Fe_3O_4@PMAA-Met在EtOH/H_2O、70oC的Suzuki反應(yīng)中存在“釋放與捕捉”現(xiàn)象,結(jié)合不同催化劑用量的動(dòng)力學(xué)曲線、Hg(0)中毒實(shí)驗(yàn)和相軌跡曲線等研究的結(jié)果,證明了該催化劑以均相催化機(jī)理催化Suzuki反應(yīng)進(jìn)行。
[Abstract]:Pd-catalyzed C / C coupling reaction is the most effective and mild method for the construction of C _ (C) bond in organic compounds. In this kind of reaction, homogeneous Pd catalyst has high catalytic activity, but there are also some problems such as difficult recovery of precious metals and environmental pollution. Therefore, a series of supported Pd catalysts have been studied and developed. Compared with homogeneous Pd catalyst, the catalytic activity of supported Pd catalyst is lower and the catalytic mechanism is controversial. The reasonable design of carrier structure and experimental research method is expected to solve these problems. Magnetic polymer nanoparticles supported Pd catalyst not only has high catalytic activity and good stability, but also can be separated quickly by an external magnetic field, which is easier to operate, and also provides a convenient experimental condition for the study of its catalytic mechanism. Therefore, it has been widely used in C / C coupling reaction. In addition, with the development of human society, green chemistry has gradually become a new goal of chemical development. It is of great practical significance to develop supported Pd catalysts which can be used in green media. Two kinds of magnetic polymer nanoparticles supported Pd catalysts Fe_3O_4@SiO_2-Dendrimer-Pd and Pd/Fe_3O_4@PMAA-Met, were designed and synthesized by FT-IR,VSM,TEM,AAS,. Its structure and properties were characterized by XPS and other characterization methods. Then, these two catalysts were used in Suzuki reaction and Heck reaction in green medium, and their catalytic activity, recycling performance and catalytic mechanism were investigated. The specific results are as follows: 1. The second generation magnetic dendrimer was synthesized by the step-by-step reaction of amino modified Fe_3O_4@SiO_2-NH_2 with methyl acrylate and 3,3-diaminodipropylamine. Nano-catalyst Fe_3O_4@SiO_2-Dendrimer-Pd. was prepared by loading Pd. The catalyst can efficiently catalyze solvent-free Heck reaction and Suzuki reaction in EtOH/H_2O at the dosage of Pd of 0.009 mol%, and the separation yields can reach 73% ~ 99% and 84% ~ (98)%, respectively. The catalyst can be separated rapidly by magnet, and 88% yield can be obtained when the catalyst is reused for 5 times in solvent-free Heck reaction. The results of thermal filtration experiments show that the catalyst is catalyzed by heterogeneous catalytic mechanism for Suzuki reaction. 2. The magnetic nanoparticles Fe_3O_4@PMAA coated with poly (methacrylic acid) were modified by metformin, and then loaded with Pd, the nano-catalyst Pd/Fe_3O_4@PMAA-Met. was prepared. The catalyst can efficiently catalyze the Suzuki reaction in Et OH/H_2O at the dosage of 0.01% Pd and 0.0007mol%. The yield is 74% and the TOF value is as high as 125714 h / 1.The yield of the catalyst is 74% ~ 99% and the TOF value is as high as 125714 h / ml. The catalyst can be separated quickly by magnet, and the separation yield can still reach 88% after 12 consecutive use. 3. The results of filtration experiments showed that there was a phenomenon of "release and capture" of Pd/Fe_3O_4@PMAA-Met in Suzuki reaction of EtOH/H_2O,70oC, which combined with the kinetic curves of different amount of catalyst. The results of Hg (0) poisoning experiment and phase trajectory curve show that the catalyst is catalyzed by homogeneous catalytic mechanism for Suzuki reaction.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36
[Abstract]:Pd-catalyzed C / C coupling reaction is the most effective and mild method for the construction of C _ (C) bond in organic compounds. In this kind of reaction, homogeneous Pd catalyst has high catalytic activity, but there are also some problems such as difficult recovery of precious metals and environmental pollution. Therefore, a series of supported Pd catalysts have been studied and developed. Compared with homogeneous Pd catalyst, the catalytic activity of supported Pd catalyst is lower and the catalytic mechanism is controversial. The reasonable design of carrier structure and experimental research method is expected to solve these problems. Magnetic polymer nanoparticles supported Pd catalyst not only has high catalytic activity and good stability, but also can be separated quickly by an external magnetic field, which is easier to operate, and also provides a convenient experimental condition for the study of its catalytic mechanism. Therefore, it has been widely used in C / C coupling reaction. In addition, with the development of human society, green chemistry has gradually become a new goal of chemical development. It is of great practical significance to develop supported Pd catalysts which can be used in green media. Two kinds of magnetic polymer nanoparticles supported Pd catalysts Fe_3O_4@SiO_2-Dendrimer-Pd and Pd/Fe_3O_4@PMAA-Met, were designed and synthesized by FT-IR,VSM,TEM,AAS,. Its structure and properties were characterized by XPS and other characterization methods. Then, these two catalysts were used in Suzuki reaction and Heck reaction in green medium, and their catalytic activity, recycling performance and catalytic mechanism were investigated. The specific results are as follows: 1. The second generation magnetic dendrimer was synthesized by the step-by-step reaction of amino modified Fe_3O_4@SiO_2-NH_2 with methyl acrylate and 3,3-diaminodipropylamine. Nano-catalyst Fe_3O_4@SiO_2-Dendrimer-Pd. was prepared by loading Pd. The catalyst can efficiently catalyze solvent-free Heck reaction and Suzuki reaction in EtOH/H_2O at the dosage of Pd of 0.009 mol%, and the separation yields can reach 73% ~ 99% and 84% ~ (98)%, respectively. The catalyst can be separated rapidly by magnet, and 88% yield can be obtained when the catalyst is reused for 5 times in solvent-free Heck reaction. The results of thermal filtration experiments show that the catalyst is catalyzed by heterogeneous catalytic mechanism for Suzuki reaction. 2. The magnetic nanoparticles Fe_3O_4@PMAA coated with poly (methacrylic acid) were modified by metformin, and then loaded with Pd, the nano-catalyst Pd/Fe_3O_4@PMAA-Met. was prepared. The catalyst can efficiently catalyze the Suzuki reaction in Et OH/H_2O at the dosage of 0.01% Pd and 0.0007mol%. The yield is 74% and the TOF value is as high as 125714 h / 1.The yield of the catalyst is 74% ~ 99% and the TOF value is as high as 125714 h / ml. The catalyst can be separated quickly by magnet, and the separation yield can still reach 88% after 12 consecutive use. 3. The results of filtration experiments showed that there was a phenomenon of "release and capture" of Pd/Fe_3O_4@PMAA-Met in Suzuki reaction of EtOH/H_2O,70oC, which combined with the kinetic curves of different amount of catalyst. The results of Hg (0) poisoning experiment and phase trajectory curve show that the catalyst is catalyzed by homogeneous catalytic mechanism for Suzuki reaction.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36
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