發(fā)布時(shí)間：2018-02-13 10:05

  本文關(guān)鍵詞： β-環(huán)糊精(β-CD) 催化 密度泛函理論(DFT) 包合物　出處：《湘潭大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：本文運(yùn)用密度泛函理論(DFT)研究了β-環(huán)糊精(β-CD)的催化機(jī)理。包括:(1)β-環(huán)糊精催化鄰苯二胺和苯甲醛的反應(yīng);(2)β-環(huán)糊精催化對(duì)硝基苯基乙酸酯與α-丙氨酸的反應(yīng);(3)β-環(huán)糊精催化2-溴苯乙酮與硫代苯甲酰胺的反應(yīng)。第一,在β-CD催化作用下,鄰苯二胺和苯甲醛轉(zhuǎn)化生成2-苯基苯并咪唑的反應(yīng)效率顯著提高,用密度泛函理論對(duì)反應(yīng)機(jī)理進(jìn)行了研究。根據(jù)能量參數(shù)(相互作用能,變形能)和結(jié)構(gòu)變化,判斷各反應(yīng)物進(jìn)入環(huán)糊精包合的先后順序及其反應(yīng)過(guò)程(鄰苯二胺以氨基為首端從環(huán)糊精的大口端進(jìn)入形成包合物,苯甲醛以苯環(huán)為首端從小口端進(jìn)入鄰苯二胺和環(huán)糊精的包合物中)。前線分子軌道理論(HOMO-LUMO)、福井(Fukui)函數(shù)和Mulliken電荷分布,綜合自然鍵軌道理論(NBO)與核磁共振波譜(NMR)揭示反應(yīng)過(guò)程中的電子轉(zhuǎn)移,并由此推測(cè)出可能存在的反應(yīng)機(jī)理。結(jié)果表明,反應(yīng)過(guò)程中在β-CD作用下反應(yīng)的選擇性和活性得到提高。第二,實(shí)驗(yàn)表明,在β-環(huán)糊精參與下,對(duì)硝基苯基乙酸酯和α-丙氨酸的反應(yīng)速率能顯著地提高,環(huán)糊精的催化作用明顯。我們主要用密度泛函理論討論了β-環(huán)糊精與對(duì)硝基苯基乙酸酯之間的相互作用,并推測(cè)了可能的反應(yīng)機(jī)理。根據(jù)能量(相互作用能,變形能)參數(shù)和結(jié)構(gòu)變化,確定客體分子的反應(yīng)模型和反應(yīng)過(guò)程(對(duì)硝基苯基乙酸酯以硝基為首端從β-環(huán)糊精的大口端進(jìn)入空腔),通過(guò)前線分子軌道(HOMO-LUMO),Dual descriptor(DD),氫鍵和核磁共振波譜(NMR)等的分析揭示電子的轉(zhuǎn)移,從而推斷可能的反應(yīng)機(jī)理。計(jì)算結(jié)果表明β-CD在對(duì)硝基苯基乙酸酯與α-丙氨酸的反應(yīng)中起了催化作用,提高了反應(yīng)速率和選擇性。第三,實(shí)驗(yàn)證明在β-環(huán)糊精作用下,溴苯乙酮和硫代酰胺類的反應(yīng)速率和產(chǎn)率有所提高。著重研究了兩個(gè)客體分子與環(huán)糊精分別進(jìn)行包合的可能性,以及包合物性質(zhì)的變化。根據(jù)2-溴苯乙酮和硫代苯甲酰胺分別與環(huán)糊精包合的優(yōu)化分析,確定兩者包合后最穩(wěn)定的構(gòu)型,結(jié)合前線分子軌道,Mulliken電荷,核磁共振波譜等分析包合后兩者的相互作用和結(jié)構(gòu)變化。計(jì)算結(jié)果表明環(huán)糊精在與客體分子包合后兩者的化學(xué)環(huán)境都發(fā)生變化,客體分子中主要基團(tuán)的電荷密度發(fā)生改變。計(jì)算結(jié)果與實(shí)驗(yàn)結(jié)果一致,并推測(cè)了可能存在的反應(yīng)機(jī)理。
[Abstract]:The catalytic mechanism of 尾 -cyclodextrin (尾 -CD) was studied by using density functional theory (DFT), including the reaction between o-phenylenediamine and benzaldehyde catalyzed by 尾 -cyclodextrin and 尾 -cyclodextrin catalyzed by p-nitrophenylacetate and 偽 -alanine. Catalytic reaction of 2-bromoacetophenone with thiobenzamide. First, The conversion efficiency of o-phenylenediamine and benzaldehyde to 2-phenylbenzimidazole was improved significantly under the catalysis of 尾 -CD. The reaction mechanism was studied by density functional theory. Deformation energy) and structural changes were used to determine the order in which the reactants entered cyclodextrin inclusion and the reaction process (o-phenylenediamine entered the inclusion complex from the big mouth of cyclodextrin at the end of amino group). Benzaldehyde leads from the end of benzene ring into the inclusion compound of o-phenylenediamine and cyclodextrin from the small end. The frontier molecular orbital theory of HOMO-LUMOA, Fukui (Fukui) function and Mulliken charge distribution, The electron transfer in the reaction process was revealed by combining the natural bond orbital theory (NBO) with nuclear magnetic resonance spectroscopy (NMR), and the possible reaction mechanism was inferred. The selectivity and activity of the reaction under the action of 尾 -CD were improved. Secondly, the reaction rate of p-nitrophenyl acetate and 偽 -alanine was significantly increased with the participation of 尾 -cyclodextrin. The catalytic effect of cyclodextrin is obvious. We mainly discuss the interaction between 尾 -cyclodextrin and p-nitrophenyl acetate by density functional theory, and speculate the possible reaction mechanism. Deformation energy) parameters and structural changes, The reaction model and reaction process of the guest molecule (p-nitrophenyl acetate entering the cavity from the large mouth of 尾 -cyclodextrin at the nitro-headed end, and the electron transfer revealed by the analysis of the front molecular orbital HOMO-LUMOMOTOR-DUMOTOR DDD, hydrogen bond and nuclear magnetic resonance spectroscopy (NMRs), etc.). The calculated results show that 尾 -CD plays a catalytic role in the reaction of p-nitrophenyl acetate with 偽 -alanine, and improves the reaction rate and selectivity. Thirdly, it is proved that 尾 -CD acts under the action of 尾 -cyclodextrin. The reaction rate and yield of bromoacetophenone and thioamides were improved. The possibility of inclusion of two guest molecules with cyclodextrin was studied. According to the optimized analysis of the inclusion of 2-bromoacetophenone and thiobenzamide with cyclodextrin, the most stable configuration of the inclusion was determined and the Mulliken charge was combined with the frontier molecular orbital. The results show that the chemical environment of cyclodextrin changes after inclusion with guest molecules. The charge density of the main groups in the guest molecule is changed. The calculated results are in agreement with the experimental results and the possible reaction mechanism is deduced.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O636.1;O621.251

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