本文選題：光催化 + 二氧化鈦　； 參考：《山東大學(xué)》2017年博士論文

【摘要】：太陽(yáng)光和氧氣是綠色無(wú)污染且取之不盡的寶貴資源,以太陽(yáng)光為光源、氧氣為氧化劑,高選擇性的實(shí)現(xiàn)具有挑戰(zhàn)性的化學(xué)反應(yīng),是科學(xué)家們不懈的追求。然而在有氧條件下,光催化體系中的活潑自由基可能會(huì)優(yōu)先進(jìn)一步失去電子或加氧氧化,從而導(dǎo)致C-C斷裂的降解反應(yīng)發(fā)生和偶聯(lián)反應(yīng)的失敗。利用光催化實(shí)現(xiàn)高選擇性的偶聯(lián)氧化反應(yīng),除了要考慮催化劑的結(jié)構(gòu)、底物的氧化還原電位以及溶劑等因素,還必須考慮光催化劑和底物的作用模式以及底物的反應(yīng)動(dòng)力學(xué)。在本博士論文中,我們構(gòu)建了偶聯(lián)—加氧氧化串聯(lián)反應(yīng)的光催化體系,通過(guò)動(dòng)力學(xué)控制合理地調(diào)控偶聯(lián)反應(yīng)與加氧氧化反應(yīng)的優(yōu)先度,選擇性地使偶聯(lián)反應(yīng)先于加氧氧化發(fā)生,從而避免了導(dǎo)致C-C鍵斷裂的過(guò)度氧化等副反應(yīng)的發(fā)生,實(shí)現(xiàn)了一系列高效的環(huán)化—氧化反應(yīng),從簡(jiǎn)單有機(jī)小分子底物出發(fā),一步合成了四氫萘酮類木質(zhì)素骨架、環(huán)過(guò)氧化合物、VA唑醛、吲哚醛等有機(jī)化合物。論文分為以下幾個(gè)部分:第一章,首先簡(jiǎn)單介紹了光能的吸收和轉(zhuǎn)化,光催化的基本概念和發(fā)展歷程,光催化劑的分類、性質(zhì)及原理;然后,詳細(xì)綜述了異相半導(dǎo)體光催化劑(如二氧化鈦)和均相分子型光催化劑在光照條件下催化的各類有機(jī)反應(yīng);在此基礎(chǔ)上,對(duì)各種光催化體系的優(yōu)勢(shì)和缺點(diǎn)做了總結(jié)和展望;最后對(duì)本博士論文的立題意義進(jìn)行了闡述。第二章,以二氧化鈦為異相光催化劑、O_2作為氧化劑,在不需要添加劑和電子犧牲體的條件下,成功實(shí)現(xiàn)了烯烴的光催化環(huán)化—氧化反應(yīng),合成了一系列四氫萘酮類化合物。該類化合物是天然產(chǎn)物木酚素的重要骨架結(jié)構(gòu)。原料的[2+2]環(huán)加成產(chǎn)物,即1,2—二取代環(huán)丁烷,是該反應(yīng)的穩(wěn)定中間體,結(jié)構(gòu)數(shù)據(jù)表明其全部為反式構(gòu)型。太陽(yáng)光光催化該反應(yīng)取得了很好的產(chǎn)率。對(duì)催化劑結(jié)構(gòu)效應(yīng)、溶劑效應(yīng)、反應(yīng)動(dòng)力學(xué)和光催化機(jī)理做了詳細(xì)研究。機(jī)理研究表明:該反應(yīng)涉及烯烴對(duì)自由基陽(yáng)離子親核進(jìn)攻和加氧氧化兩步反應(yīng);如果生成的自由基陽(yáng)離子具有足夠的化學(xué)穩(wěn)定性以適合另一烯烴分子對(duì)其親核進(jìn)攻,選擇性地使偶聯(lián)反應(yīng)優(yōu)先于加氧氧化發(fā)生,就會(huì)有效的避免導(dǎo)致C-C鍵斷裂的過(guò)度氧化的發(fā)生,從而提高環(huán)化反應(yīng)的效率。第三章,為了克服1,2—二取代烯烴的空間位阻效應(yīng),實(shí)現(xiàn)該類化合物在二氧化鈦光催化中高效轉(zhuǎn)化為四氫萘酮產(chǎn)物,本章中我們采用了兩種策略:(1)考察了 TiO_2光催化的分子內(nèi)的環(huán)化—氧化反應(yīng),利用分子內(nèi)反應(yīng)的動(dòng)力學(xué)優(yōu)勢(shì),克服烯烴β-位取代基的空間位阻效應(yīng);(2)先合成1,2—二取代烯烴的[2+2]環(huán)化產(chǎn)物,然后以此為原料在二氧化鈦光催化條件下進(jìn)行擴(kuò)環(huán)—氧化反應(yīng)�；诖�,以很高的非對(duì)映選擇性合成了一系列四氫萘酮產(chǎn)物,并實(shí)現(xiàn)了從基礎(chǔ)原料出發(fā)的天然木酚素(-)-8'-epi-aristoligone的兩步全合成。第四章,為了進(jìn)一步拓展太陽(yáng)光光催化環(huán)化—氧化串聯(lián)反應(yīng)在有機(jī)合成中的應(yīng)用,我們選擇了既具有可見(jiàn)光活性又具有π路易斯酸性的碘單質(zhì)代替二氧化鈦,催化炔丙基酰胺的環(huán)化—氧化反應(yīng)。在可見(jiàn)光照射下,I_2的π路易斯酸性使其能夠快速地與三鍵加成,然后與含有孤對(duì)電子的氧/氮原子發(fā)生親電環(huán)化反應(yīng),實(shí)現(xiàn)C-O/C-N鍵的構(gòu)筑,進(jìn)一步的光催化加氧氧化實(shí)現(xiàn)產(chǎn)物生成和I_2再生。該可見(jiàn)光催化體系反應(yīng)條件溫和,只需催化量的碘,不需要其他任何犧牲劑和助催化劑,便可在2小時(shí)內(nèi)高產(chǎn)率的生成一系列惡唑醛和吲哚醛衍生物,太陽(yáng)光量子產(chǎn)率接近3%。對(duì)反應(yīng)的中間體、碘物種、活性氧物種、光和I_2各自的作用等等,做了詳細(xì)研究。機(jī)理研究發(fā)現(xiàn),單線態(tài)氧在碘的催化循環(huán)中起了至關(guān)重要的作用。與以往的光敏劑不同,碘作為雙功能光催化劑,一部分與反應(yīng)底物加成并作為反應(yīng)的中間體參與整個(gè)光催化循環(huán)過(guò)程,剩余的碘作為光敏劑。碘的這種新的光催化模式,將光催化和過(guò)渡金屬催化的優(yōu)點(diǎn)結(jié)合起來(lái),拓展了太陽(yáng)光光催化在有機(jī)合成領(lǐng)域的應(yīng)用,有望實(shí)現(xiàn)傳統(tǒng)過(guò)渡金屬催化和光催化難以勝任的催化反應(yīng)類型。
[Abstract]:Solar light and oxygen are green, pollution-free and inexhaustible resources, with solar light as light sources, oxygen as oxidants and highly selective chemical reactions that are challenging. However, under aerobic conditions, the active free radicals in the photocatalytic system may give priority to further loss of electrons or oxygenation. Oxidation, which leads to the degradation of the C-C fracture and the failure of the coupling reaction, uses photocatalytic to realize high selective coupling oxidation. In addition to factors such as the structure of the catalyst, the redox potential of the substrate and the solvent, the mode of action of the photocatalyst and the substrate and the kinetics of the reaction of the substrate must be considered. In this doctoral thesis, we constructed the photocatalytic system of coupling and oxygenation series reaction. Through dynamic control, we reasonably regulate the priority of coupling reaction and oxygenation reaction, and selectively make the coupling reaction precede oxygen oxidation, thus avoiding the over oxidation and other side reactions that lead to the C-C bond fracture. A series of efficient cyclization oxidation reactions, starting from a simple organic small molecule substrate, one step synthesis of four hydrogen naphtha lignin skeleton, cyclo peroxy compounds, VA zolal aldehyde, indolyl aldehyde and other organic compounds. The paper is divided into the following parts: Chapter 1, first briefly introduces the absorption and transformation of light energy, the basic concept and development of photocatalysis. The process, the classification, properties and principles of photocatalyst, and then a detailed overview of the various organic reactions of heterogeneous Semiconductor Photocatalysts (such as titanium dioxide) and homogeneous molecular type photocatalysts catalyzed under light conditions; on this basis, the advantages and disadvantages of various photocatalytic systems are summarized and prospected; finally, the doctoral thesis is established. In the second chapter, the second chapter, using titanium dioxide as a heterogeneous photocatalyst, as an oxidizing agent, successfully realized the photocatalytic epoxidation and oxidation of olefins without the need of additives and electronic sacrificial bodies, and synthesized a series of four naphthyl compounds. This compound is an important skeleton of the natural product of lignin. The [2+2] ring addition product, 1,2 two substituted cyclobutane, is a stable intermediate of the reaction. The structural data show that all of the reactions are trans configuration. The reaction of solar light photocatalyst has obtained good yield. The structure effect, solvent effect, reaction kinetics and photocatalytic mechanism of the catalyst have been studied in detail. The mechanism study shows that: This reaction involves two steps of alkene nucleophilic and oxygenated oxidation of free radical cation; if the free radical cations have sufficient chemical stability to fit the nucleophilic attack by another olefin molecule and selectively make the coupling reaction preferable to oxygen oxidation, the excessive oxygen that causes the C-C bond break is effectively avoided. In order to improve the efficiency of the cyclization reaction, the third chapter, in order to overcome the spatial steric resistance effect of 1,2 - two substituted olefins, realizes the high efficiency conversion of this kind of compound to four hydrogen naphthone products in the photocatalysis of titanium dioxide. In this chapter, we have adopted two strategies: (1) investigation of the intramolecular cyclization oxidation reaction of TiO_2 photocatalyst. The kinetic advantage of intramolecular reaction was used to overcome the spatial steric hindrance effect of the alkene beta substituent. (2) the [2+2] cyclization products of 1,2 - two substituted olefins were synthesized first, and then the reexpansion oxidation reaction was carried out under the photocatalytic condition of titanium dioxide. Based on this, a series of four hydrogen naphthone products were synthesized with high non enantioselectivity. The two step full synthesis of natural lignan (-) -8'-epi-aristoligone from basic raw materials was realized. The fourth chapter, in order to further expand the application of the solar photocatalytic epoxidation series reaction in the organic synthesis, we selected the iodine single substance with both visible light activity and PI Lewis acid instead of titanium dioxide. The cyclization oxidation reaction of propargidamide. Under visible light, I_2's PI Lewis acidity can be added quickly with the three bonds, and then electrophilic ring reaction with the oxygen / nitrogen atom containing the isolated electrons to realize the construction of the C-O/C-N bond and further photocatalytic oxygenation to achieve product generation and I_2 regeneration. The system has a mild reaction condition. A series of oxazole and indoles can be produced in a high yield in 2 hours without any other sacrificial agents and cocatalysts, and the yield of solar light quantum is close to 3%. for the reaction intermediates, iodine species, reactive oxygen species, light and I_2, and so on. The mechanism studies have found that the single state oxygen plays a vital role in the catalytic cycle of iodine. Unlike the previous photosensitizer, iodine is used as a bifunctional photocatalyst, a part of the reaction substrate is added to the reaction substrate and participates in the whole process of photocatalytic cycle. The remaining iodine is used as a photosensitizer. The combination of photocatalysis and transition metal catalysis has expanded the application of solar photocatalysis in the field of organic synthesis, and it is hopeful to realize the type of catalytic reaction which is unqualified for the traditional transition metal catalysis and photocatalysis.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：O621.251;O644.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 Peng Guo;Jun-Hai Huang;Qing-Chun Huang;Xu-Hong Qian;;Synthesis of novel 1,3-oxazole derivatives with insect growth-inhibiting activities[J];Chinese Chemical Letters;2013年11期

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本文編號(hào)：1900606