過(guò)渡金屬催化的若干重要有機(jī)反應(yīng)C-H活化機(jī)理的理論研究
發(fā)布時(shí)間:2018-04-23 05:20
本文選題:過(guò)渡金屬絡(luò)合物 + C-H活化; 參考:《山東大學(xué)》2017年博士論文
【摘要】:金屬有機(jī)化學(xué)是有機(jī)化學(xué)和無(wú)機(jī)化學(xué)的交叉學(xué)科,作為一門新興交叉學(xué)科,金屬有機(jī)化學(xué)的發(fā)展引起了人們廣泛關(guān)注。過(guò)渡金屬有機(jī)化合物作為金屬有機(jī)化學(xué)發(fā)展的核心,因所具有的高度選擇性、高活性、高穩(wěn)定性等特點(diǎn),成為有機(jī)合成領(lǐng)域里一個(gè)新的研究熱點(diǎn)。與實(shí)驗(yàn)研究相比,過(guò)渡金屬有機(jī)化合物的理論研究發(fā)展滯后,實(shí)驗(yàn)過(guò)程中觀察到的某些特別現(xiàn)象無(wú)法用常規(guī)的化學(xué)知識(shí)來(lái)解釋。另外,有關(guān)的分子機(jī)理也不明確,反應(yīng)的中間體無(wú)法用實(shí)驗(yàn)檢測(cè),這些問(wèn)題必然會(huì)限制金屬有機(jī)催化劑的應(yīng)用和新型過(guò)渡金屬有機(jī)催化劑的開(kāi)發(fā)。因此對(duì)有機(jī)反應(yīng)進(jìn)行理論研究,探索宏觀反應(yīng)背后的微觀本質(zhì),對(duì)金屬有機(jī)化學(xué)的發(fā)展具有深遠(yuǎn)意義。C-H活化是有機(jī)合成新目標(biāo)。研究發(fā)現(xiàn)C-H活化所用底物范圍廣,且通常不需要官能團(tuán)預(yù)活化,有高的原子經(jīng)濟(jì)效率,所以通過(guò)底物C-H活化方法可以大大簡(jiǎn)化藥品、天然產(chǎn)品、農(nóng)用化學(xué)品、聚合物等化學(xué)品的合成過(guò)程。盡管C-H活化取得了較大進(jìn)步,但這些反應(yīng)所用催化劑為貴金屬催化劑,如銠、釕、鈀、銥、鉑、鎳,成本較高。另外這類反應(yīng)需加入外部氧化劑,在反應(yīng)過(guò)程中會(huì)導(dǎo)致副產(chǎn)物的形成。為了克服這些弊端,人們開(kāi)始尋找合適的內(nèi)部氧化劑以及C-H活化的新型催化劑。本論文在相關(guān)實(shí)驗(yàn)背景的基礎(chǔ)上,選擇幾種代表性過(guò)渡金屬絡(luò)合物催化的有機(jī)反應(yīng)進(jìn)行研究。通過(guò)理論計(jì)算,探討若干重要有機(jī)反應(yīng)機(jī)理,揭示了催化反應(yīng)的微觀本質(zhì),給出了反應(yīng)的基元步驟和反應(yīng)的熱力學(xué)和動(dòng)力學(xué)性質(zhì)。分析了取代基以及溶劑化對(duì)反應(yīng)的影響,找到反應(yīng)區(qū)域選擇性根源,并給出合理解釋,理論計(jì)算結(jié)果加深了人們對(duì)相關(guān)化學(xué)反應(yīng)及其現(xiàn)象的認(rèn)識(shí)和理解,為新型有機(jī)反應(yīng)的設(shè)計(jì)以及新型有機(jī)反應(yīng)催化劑開(kāi)發(fā)提供了重要理論指導(dǎo)。本論文研究?jī)?nèi)容和創(chuàng)新點(diǎn)概括如下:一、研究了釕原子簇三核釕羰基化合物N-甲基官能團(tuán)上C-H鍵活化反應(yīng)。Cabeza課題組報(bào)道了一類關(guān)于氮雜環(huán)卡賓金屬配合物甲基發(fā)生C-H活化反應(yīng),反應(yīng)在溫和條件下完成。他們提出了 C-H鍵活化的分子機(jī)理,并進(jìn)行了相關(guān)的理論計(jì)算,發(fā)現(xiàn)總能壘超過(guò)80.0kcal/mol,并且反應(yīng)吸熱近40.0kcal/mol,這些結(jié)果與實(shí)驗(yàn)現(xiàn)象(實(shí)驗(yàn)溫度低于100 ℃)明顯不符。為理解這類C-H鍵活化機(jī)理,合理解釋實(shí)驗(yàn)現(xiàn)象,我們對(duì)該反應(yīng)重新進(jìn)行了研究,提出了新的反應(yīng)機(jī)理,反應(yīng)步驟如下:氮雜環(huán)配體重排、脫CO、第一個(gè)C-H活化、脫CO、第二個(gè)C-H活化。反應(yīng)物轉(zhuǎn)化為產(chǎn)物自由能變?yōu)?4.7kcal/mol,總能壘為35.1kcal/mol。計(jì)算結(jié)果驗(yàn)證了 C-H活化反應(yīng)在實(shí)驗(yàn)條件容易發(fā)生,常溫下往反應(yīng)體系通入一氧化碳會(huì)使產(chǎn)物向反應(yīng)物轉(zhuǎn)化。二、研究了三核釕羰基化合物-氮雜環(huán)卡賓絡(luò)合物中N-甲基和亞甲基官能團(tuán)上C-H鍵活化反應(yīng),給出詳細(xì)反應(yīng)機(jī)理,并分析了烴基選擇性活化的原因。(1)理論研究了三核釕羰基化合物與磷相連的N-亞甲基上C-H活化機(jī)理。理論計(jì)算表明該反應(yīng)具有以下特點(diǎn):第一個(gè)C-H活化發(fā)生在磷與金屬重新配位之前,CO消除是第二個(gè)C-H活化必經(jīng)過(guò)程,磷與金屬配位模式在反應(yīng)物和產(chǎn)物中保持不變,第一個(gè)C-H活化為反應(yīng)的決速步,需要克服能壘37.9 kcal/mol。C-H活化涉及兩個(gè)CO配體消除,由于反應(yīng)為敞開(kāi)體系,CO配體消除具有不可逆性,并且實(shí)驗(yàn)中不斷用惰性氣體凈化釋放的CO氣體,因此盡管總能壘相對(duì)高,但是CO不可逆的釋放驅(qū)使反應(yīng)順利進(jìn)行。(2)研究了含有磷配體的釕原子簇羰基化合物氮雜環(huán)N-甲基C-H活化反應(yīng)機(jī)制以及反應(yīng)熱力學(xué)和動(dòng)力學(xué)性質(zhì)。計(jì)算表明磷遷移過(guò)程優(yōu)先于C-H活化過(guò)程發(fā)生,且反應(yīng)過(guò)程中磷配體與金屬配位位置發(fā)生變化,第一個(gè)C-H活化是反應(yīng)決速步,總能壘為39.0kcal/mol。通過(guò)NBO電荷分析發(fā)現(xiàn),與氮雜環(huán)相連甲基上的C1原子電子密度大于亞乙基C2原子電子密度,表明C1具有更強(qiáng)的親核性。因此甲基Cl-H更容易活化。三、研究了輔助酸協(xié)助的甲酸脫氫反應(yīng)。運(yùn)用密度泛函理論分別計(jì)算了一分子輔助酸和兩分子輔助酸條件下,Fe催化甲酸脫氫反應(yīng)可能路徑,結(jié)果表明兩分子輔助酸參與反應(yīng),金屬Fe中心脫氫更有利于甲酸分解。兩分子輔助酸參與反應(yīng)的主要步驟為:H_2脫出、CO_2脫出、催化劑再生。決速步為CO_2脫出,總能壘為23.5 kcal/mol。輔助酸協(xié)助甲酸脫氫的主要原因是其可以有效增加碳酸鹽上的正電荷,使原子重排過(guò)渡態(tài)以及氫鍵合甲酸鹽中間體更加穩(wěn)定,從而有利于CO_2脫出。四、研究了氧化還原中性條件CoⅢ催化N-N鍵斷裂合成吲哚的反應(yīng)機(jī)理。首先計(jì)算了文獻(xiàn)中提出的C-H活化炔烴插入路徑,發(fā)現(xiàn)炔烴插入過(guò)渡態(tài)能量高出反應(yīng)入口55.0 kcal/mol,這一較高能壘無(wú)法合理解釋實(shí)驗(yàn)現(xiàn)象(實(shí)驗(yàn)溫度80 ℃)。通過(guò)計(jì)算提出了新的反應(yīng)機(jī)理,涉及C-H鍵活化、酯基相連N原子脫質(zhì)子、炔烴插入、氮原子質(zhì)子轉(zhuǎn)移、N-C還原消除、N-N氧化加成、質(zhì)子化等過(guò)程。計(jì)算結(jié)果表明,酯基相連N原子脫質(zhì)子形成的穩(wěn)定中間體在反應(yīng)過(guò)程中起著重要作用,可有效降低炔烴插入過(guò)渡態(tài)的能量。理論結(jié)果與同位素標(biāo)記實(shí)驗(yàn)結(jié)果(C-H是決速步驟)吻合較好。理論結(jié)果闡明了詳細(xì)的反應(yīng)機(jī)理,加深了我們對(duì)氧化還原中性條件下鈷催化聯(lián)氨和炔烴合成吲哚反應(yīng)的理解,為相關(guān)實(shí)驗(yàn)提供了一定的理論指導(dǎo)。五、研究了 RhⅢ催化NH-亞砜亞胺和二氮化合物合成1,2-苯并硫氮反應(yīng)。計(jì)算結(jié)果表明,實(shí)驗(yàn)預(yù)測(cè)的反應(yīng)機(jī)理,即先N-H/C-H活化、再脫氮?dú)?不能合理解釋實(shí)驗(yàn)現(xiàn)象。我們提出了新的反應(yīng)機(jī)理:即氮?dú)庀、N-H/C-H活化、卡賓插入、質(zhì)子化、脫水等過(guò)程。反應(yīng)的決速步為C-H活化,總能壘37.2kcal/mol。另外,研究了 NH-亞砜亞胺取代基(甲氧基,硝基)對(duì)反應(yīng)的影響以及反應(yīng)選擇性C-H活化。發(fā)現(xiàn)由電子效應(yīng)是產(chǎn)物產(chǎn)率不同主要原因。反應(yīng)的區(qū)域選擇性主要與電子效應(yīng)以及非鍵相互作用有關(guān),而空間位阻影響較小。理論結(jié)果合理地解釋了實(shí)驗(yàn)觀察現(xiàn)象。
[Abstract]:Organometallic chemistry is an interdisciplinary subject of organic chemistry and inorganic chemistry. As a new interdisciplinary subject, the development of organometallic chemistry has aroused widespread concern. As the core of the development of metal organic chemistry, transition metal organic compounds have become organic synthesis because of their high selectivity, high activity, high stability and so on. A new research hotspot in the field. Compared with experimental research, the theoretical research of transition metal organic compounds is lagging behind. Some special phenomena observed in the experiment can not be explained by conventional chemical knowledge. In addition, the related molecular mechanism is not clear, the intermediates of the reaction can not be tested by experiments. These problems are bound to be inevitable The application of metal organic catalysts and the development of a new type of transition metal organic catalysts. Therefore, the theoretical study of organic reactions and the exploration of the microscopic nature behind the macro reaction have far-reaching significance for the development of the organic chemistry of metals..C-H activation is a new target for organic synthesis. Without the need of functional group pre activation and high atomic economic efficiency, the synthesis process of drugs, natural products, agrochemicals, polymers and other chemicals can be greatly simplified by the activation of substrate C-H. Although great progress has been made in the activation of C-H, these reactions are used as noble metal catalysts, such as rhodium, ruthenium, palladium, iridium, platinum, nickel, and so on. In addition, this kind of reaction needs to be added to the external oxidizer and lead to the formation of the by-products during the reaction. In order to overcome these disadvantages, people began to look for the appropriate internal oxidant and the new catalyst for C-H activation. Based on the relevant experimental background, this paper chooses several representative transition metal complexes to catalyze the catalytic agent. The mechanism of some important organic reactions was discussed by theoretical calculation. The microscopic nature of the catalytic reaction was revealed. The basic steps of the reaction and the thermodynamic and kinetic properties of the reaction were given. The influence of the substituent and solvent on the reaction was analyzed, and the selective root of the reaction was found. The rational explanation was given and the theory was given. The results of the calculation deepen the understanding and understanding of the related chemical reactions and their phenomena, and provide important theoretical guidance for the design of new organic reactions and the development of new organic reaction catalysts. The contents and innovations of this paper are summarized as follows: first, the C-H bond on the ruthenium cluster three nuclear ruthenium carbonyl compound N- methyl functional group is studied. The group of activation reaction.Cabeza reports on a class of nitrogen heterocyclic CABBEEN metal complexes methyl C-H activation reaction. The reaction was completed under mild conditions. They proposed the molecular mechanism of the activation of C-H bonds, and the related theoretical calculations were carried out to find that the total energy barrier was over 80.0kcal/mol and the reaction endothermic was nearly 40.0kcal/mol. In order to understand the activation mechanism of this kind of C-H bonds and explain the experimental phenomena reasonably, we restudied the reaction and proposed a new reaction mechanism. The reaction steps are as follows: nitrogen heterocyclic ligand rearrangement, deactivation of CO, the first C-H activation, deactivation of CO, and activation of C-H. The reactant is transformed into product self. From the energy change to 14.7kcal/mol, the total energy barrier is 35.1kcal/mol. calculation results verifying that the activation reaction of C-H is easy to occur in the experimental conditions. The carbon monoxide in the reaction system at normal temperature can convert the product into the reactant. Two, the activation of the C-H bond on the N- methyl and methylene functional group of the three nuclear ruthenium carbonyl compound nitrogen heterocyclic complex is studied. The reaction mechanism is given and the reasons for the selective activation of alkyl groups are analyzed. (1) the mechanism of C-H activation of N- methylene on the three nuclear ruthenium carbonyl compounds with phosphorus is theoretically studied. The theoretical calculation shows that the reaction has the following characteristics: the first C-H activation occurs before the redistribution of phosphorus and gold, and the elimination of CO is the second C-H activation must. Through the process, the mode of phosphorus and metal coordination remains unchanged in the reactants and products. The first C-H is activated as a quick step of the reaction. It is necessary to overcome the elimination of the energy barrier 37.9 kcal/mol.C-H activation involving two CO ligands, because the reaction is open system, the CO ligand eliminates the irreversibility, and the CO gases released by the inert gas in the experiment are continuously purified. Therefore, although the total energy barrier is relatively high, the CO irreversible release drives the reaction to proceed smoothly. (2) the mechanism of the activation reaction of the Ru atomic cluster carbonyl compound nitrogen heterocyclic N- methyl C-H, which contains phosphorus ligands, and the thermodynamic and kinetic properties are studied. The calculation shows that the phosphorus migration process is preceded by the C-H activation process and the phosphorus is in the process of reaction. The coordination position of ligand and metal is changed, the first C-H activation is the quick step of the reaction. The total energy barrier is 39.0kcal/mol. through the NBO charge analysis. The electron density of the C1 atom on the methylated methyl on the nitrogen heterocycle is greater than the electron density of the ethyl C2 atom, indicating that the C1 has a stronger nucleophilic activity. Therefore, the methyl Cl-H is more easily activated. Three, studies the auxiliary The possible path of dehydrogenation of formic acid catalyzed by Fe is calculated by density functional theory. The results show that the two molecular auxiliary acid is involved in the reaction, and the Fe center dehydrogenation is more favorable for the decomposition of formic acid. The main step of the two molecular auxiliary acid reaction is: H The main reason for dehydrogenation of formic acid with a total barrier of 23.5 kcal/mol. assisted acid to assist the dehydrogenation of formic acid is that it can effectively increase the positive charge on the carbonate, which makes the transition state of the rearrangement of the atom and the intermediate of the hydrogen bond formate more stable, which is beneficial to the release of CO_2. Four, the oxidation reduction is studied. The main reason for the 23.5 kcal/mol. auxiliary acid to assist the dehydrogenation of formic acid is that it can effectively increase the dehydrogenation of formic acid. The neutral condition Co III catalyzes the reaction mechanism of N-N bond breaking into indole. First, the insertion path of C-H activated alkynes proposed in the literature is calculated. It is found that the insertion of the transition state of alkynes into the transition state is 55 kcal/mol. This high energy barrier can not explain the experimental phenomenon reasonably (the experimental temperature is 80 degrees C). The new reaction mechanism is proposed by calculation. C-H bond activation, ester group connecting N atom deprotons, alkyne insertion, nitrogen atom proton transfer, N-C reduction elimination, N-N oxidation addition, and protonation process. The results show that the stable intermediate of ester based N atom deprotonates plays an important role in the reaction process, which can effectively reduce the energy of the insertion of Alkynes into the transition state. The results are in good agreement with the results of the isotope labeling experiment (C-H is a quick step). The theoretical results illustrate the detailed reaction mechanism, which deepens our understanding of the synthesis of indole by cobalt catalyzed hydrazine and alkynes under the oxidation-reduction neutral condition, and provides some theoretical guidance for the related experiments. Five, Rh III catalyzes the catalytic NH- sulfoxide imide and two. The reaction mechanism of 1,2- benzo sulfur nitrogen is synthesized by nitrogen compounds. The results show that the reaction mechanism predicted by the experiment, namely N-H/C-H activation first, and then nitrogen removal, can not explain the experimental phenomena reasonably. We put forward a new reaction mechanism: nitrogen removal, N-H/C-H activation, CABBEEN insertion, protonation, dehydration and so on. The reaction speed step is C-H activation, total energy barrier 37.2 Kcal/mol. also studied the effect of NH- sulfoimide substituent (methoxy, nitro) on the reaction and the activation of selective C-H. It is found that the electron effect is the main reason for the difference in the yield of the products. The regional selectivity of the reaction is mainly related to the electron effect and the non bond interaction, but the effect of the space hindrance is less. The theoretical results are reasonable. The phenomenon of experimental observation was explained.
【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
【參考文獻(xiàn)】
相關(guān)期刊論文 前3條
1 方澤軍;紀(jì)常偉;汪碩峰;;汽油添加劑的現(xiàn)狀與發(fā)展趨勢(shì)[J];小型內(nèi)燃機(jī)與摩托車;2008年01期
2 杜燦屏,唐晉;我國(guó)金屬有機(jī)化學(xué)的研究已進(jìn)入世界前沿[J];化學(xué)進(jìn)展;1999年04期
3 黃耀曾;漫談金屬有機(jī)化學(xué)[J];大學(xué)化學(xué);1990年01期
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