發(fā)布時(shí)間：2018-06-10 20:36

  本文選題：密度泛函理論 + 氨基金卡賓�。� 參考：《曲阜師范大學(xué)》2017年碩士論文

【摘要】：近年來,隨著環(huán)境污染問題的日益加重以及地球資源的不斷消耗枯竭,發(fā)展新型的催化反應(yīng)、實(shí)現(xiàn)物質(zhì)的綠色轉(zhuǎn)換已成為當(dāng)前化學(xué)工作者研究的重點(diǎn)和前沿領(lǐng)域。因此,要完善和發(fā)展新型的催化反應(yīng),必須進(jìn)一步加深對相關(guān)催化反應(yīng)機(jī)理的認(rèn)識和理解。本論文基于量子化學(xué)計(jì)算理論對反應(yīng)能量以及幾何結(jié)構(gòu)的研究,深化了對反應(yīng)機(jī)理的理解,并對相關(guān)反應(yīng)的設(shè)計(jì)提供了理論依據(jù)。本論文的主要工作包括以下三個(gè)方面:(1)利用密度泛函理論研究了通過環(huán)化重排反應(yīng)合成一價(jià)氨基金卡賓化合物的反應(yīng)機(jī)理。計(jì)算結(jié)果表明經(jīng)過[3,3]-σ重排過程的反應(yīng)機(jī)制相對于1,2-烷基遷移的機(jī)理更為有利,這主要是由于1,2-烷基遷移過程會產(chǎn)生很強(qiáng)的空間位阻作用造成的。[3,3]-σ重排過程為整個(gè)反應(yīng)的決速步驟。通過分析不同取代基反應(yīng)決速步驟過渡態(tài)的空間結(jié)構(gòu)發(fā)現(xiàn),影響產(chǎn)率的主要因素在于不同取代基所產(chǎn)生的空間效應(yīng)。(2)基于密度泛函理論研究了氮雜環(huán)卡賓類化合物(NHCs)催化的安息香縮合反應(yīng)詳細(xì)的反應(yīng)機(jī)理。計(jì)算結(jié)果表明第一次的氫遷移過程是在溶劑中水分子的協(xié)助下完成的,第二次的氫遷移經(jīng)歷的是一個(gè)協(xié)同過程而并非分步機(jī)理。此外,我們挖掘了反應(yīng)中產(chǎn)生化學(xué)選擇性的理論根源:不同催化劑結(jié)構(gòu)上的差異所導(dǎo)致的空間位阻作用。(3)運(yùn)用密度泛函理論研究了氮雜環(huán)卡賓類化合物(NHCs)催化二烯醛和偶氮烯烴發(fā)生[4+3]和[4+1]環(huán)化反應(yīng)的機(jī)理。研究發(fā)現(xiàn)添加劑在質(zhì)子轉(zhuǎn)移和脫水過程中起了至關(guān)重要的作用。通過扭曲變形相互作用能分析了催化劑和底物取代基對區(qū)位選擇性的影響。對NHC-A催化、R2’上取代基為Boc的反應(yīng)A而言,導(dǎo)致產(chǎn)生區(qū)位選擇性的主要因素是過渡態(tài)TS3A和TS8A中3與R2’之間的相互作用造成的。對NHC-B催化、R2’上取代基為Boc的反應(yīng)B而言,區(qū)位選擇性的產(chǎn)生主要是由于催化劑NHC-B中不穩(wěn)定的船式構(gòu)象和穩(wěn)定的椅式構(gòu)象的差異而導(dǎo)致的。對NHC-A催化、R2’上取代基為Ts的反應(yīng)C而言,TS3C和TS6C中3與R2’的變形作用是導(dǎo)致區(qū)位選擇性相對于反應(yīng)A增強(qiáng)的主要原因。
[Abstract]:In recent years, with the worsening of environmental pollution and the depletion of the earth's resources, the development of new catalytic reactions to achieve the green conversion of substances has become the focus and frontier of chemical research. Therefore, in order to perfect and develop the new catalytic reaction, we must further understand the mechanism of the catalytic reaction. Based on the quantum chemical calculation theory, the study of the reaction energy and geometric structure has deepened the understanding of the reaction mechanism and provided the theoretical basis for the design of the related reactions. The main work of this thesis includes the following three aspects: 1) the mechanism of the synthesis of monovalent ammonium-fund carbene compounds by cyclization rearrangement reaction is studied by using density functional theory (DFT). The calculated results show that the reaction mechanism of [3N3]-蟽 rearrangement process is more favorable than that of the 1 ~ (2 +) -alkyl migration process. This is mainly due to the strong steric hindrance in the migration process of 1 ~ (2 +) -alkyl group. [3]-蟽 -rearrangement process is the critical step of the whole reaction. By analyzing the spatial structure of the transition states in different substituent reaction, The main factor affecting yield is the spatial effect of different substituents. (2) based on density functional theory, the detailed reaction mechanism of benzoin condensation catalyzed by heterocyclic carbenes was studied. The results show that the first hydrogen migration process is completed with the help of water molecules in the solvent, and the second hydrogen migration is a synergistic process rather than a stepwise mechanism. In addition, We have explored the theoretical origin of chemical selectivity in the reaction: the steric effect caused by the difference in the structure of different catalysts. (3) using density functional theory, we have studied the catalytic properties of dienal and dienal by using the density functional theory (DFT) of nitrogen heterocyclic carbenes (NHCs). Mechanism of [43] and [41] cyclization of azo olefins. It is found that additives play an important role in proton transfer and dehydration. The influence of catalyst and substrate substituent on location selectivity was analyzed by means of distorted deformation interaction energy. For NHC-A catalyzed reaction A with substitution group Boc, the main factor leading to site selectivity is the interaction between 3 and R2'in the transition state TS3A and TS8A. For the reaction B on NHC-B catalyst with substitution group Boc, the location selectivity is mainly due to the difference of unstable ship-type conformation and stable chair conformation in NHC-B catalyst. The deformation of 3 and R2'in TS3C and TS6C is the main reason for the enhancement of location selectivity relative to reaction A.
【學(xué)位授予單位】：曲阜師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.12

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本文編號：2004527