芳香醛与丙二腈固相反应机理的研究

【作者】 王海燕；

【导师】 刘奉岭；

【作者基本信息】 山东师范大学 ， 有机化学， 2004， 硕士

【摘要】 芳香醛与丙二腈的反应是Knoevenagel缩合反应的一个分支，是形成碳—碳双键的有效途径，可得到活性中间体或良好的配体，被应用于许多有机反应中。芳香醛与丙二腈反应的缩合产物是电荷转移复合物，在现代功能材料方面有很好的应用前景，已引起国内外学者的关注。早在十九世纪末，人们就开始对Knoevenagel缩合反应进行研究。一个世纪来，人们对此类反应的进行了许多研究，采用了许多催化剂。然而，大多数研究都是分散、孤立的，对反应机理和催化剂的研究更是如此。迄今为止，尚缺乏Knoevenagel缩合反应催化规律性及催化效果的系统研究，反应机理也大多停留在推测水平上，尚未见到详细的理论研究。反应机理的研究，对寻找更好的催化剂，寻求更好的合成途径，提高反应效率，具有重要的意义。因此，在本论文中，我们从试验和理论两方面系统研究芳香醛与丙二腈的反应，探讨催化剂的催化作用，采用量子化学理论详细反应机理，为更好得了解反应机理及寻找合适的催化剂提供理论依据。本论文的工作主要包括以下两大方面的内容。 1．香醛与丙二腈固相反应的试验研究 固相合成方法是绿色合成方法，由于没有溶剂参与，反应过程避免了因使用溶剂而造成的能耗高、污染环境、毒害性和爆燃性等缺陷，并且后处理简单。本文芳香醛与丙二腈的缩合反应就是采用固相合成方法进行。 （1）不同催化剂下芳香醛与丙二腈固相缩合反应的试验研究 我们系统比较了芳香醛（以对硝基苯甲醛为例）与丙二腈反应在不同催化剂下的催化效果，探讨催化剂的催化规律。试验工作从两方面展开：一，同一阴离子不同阳离子催化剂的催化效果比较；二，同一阳离子不同阴离子催化剂的催化效果比较。通过对试验结果的分析，得到了不同催化剂催化的规律，并且发现在所有的催化剂中NH₄Ac催化效果最好。 （2）不同芳香醛与丙二腈固相反应的试验研究 从试验上研究对位基团的改变（吸电子基团、共电子基团）对反应速度、反应时间、产率的影响，以及共轭效应和诱导应对芳香醛的性质和缩合反应的影响，以期寻找到最适宜的反应物，有利于合成出所需要的缩合产物。试验结果表明，在同一催化剂（以NH₄Ac为例）催化下的芳香醛与丙二腈缩合反应中，对硝基苯甲醛的产率最高、反应速度最快，对N，N-二甲基氨基苯甲醛次之，对羟基苯甲醛最低。我们对此试验结果作了讨论。山东师范大学硕士论文2.芳香醛与丙二睛反应机理的理论研究 采用半经验的AMI方法和密度泛函DFT方法等，利用Gaussian94程序详细研究了芳香醛与丙二腊缩合反应的机理，找到了反应的过渡态，并用内察反应坐标法（IRC）进行各反应路径的解析，确证了过渡态和反应物及产物的对应关系。在此理论研究的基础上，研究了几种催化剂存在时的反应机理，解释了催化剂对反应的影响问题。本论文的主要理论工作如下。（1）甲醛与丙二睛的枷ev血agel反应机理研究 本文系统研究了无催化剂时，甲醛与丙二睛缩合反应的机理。在此基础上，系统研究了卤化钠及卤化氢催化下，甲醛与丙二睛缩合反应的机理。通过反应机理的对比研究，找出了催化剂加快该缩合反应的原因。理论研究发现，卤化钠作催化剂比卤化氢作催化剂，反应的活化能更低，催化效果也好。（2）芳香醛与丙二睛的K力oevenagel反应机理的研究 芳香醛与丙二睛反应和甲醛与丙二睛反应的反应实质是相同的，都是醛基与丙二腊上的活性亚甲基的脱水缩合反应。但由于取代基的不同，使反应稍有差异。因此，我们对比甲醛与丙二睛Knoevenagel反应机理，尤其是催化剂对反应活化能的影响，进一步探讨芳香醛与丙二睛Knoevenagel反应机理。结果表明，卤化钠作催化剂比卤化氢作催化剂，反应的活化能更低、反应速度更快，这与试验结果相符。更多还原

【Abstract】 The Knoevenagel condensation reaction of aromatic aldehydes with malonotrile is an important method for forming C-C bond, which has been studied extensively and applied in many organic syntheses. The condensation products of the condensation reaction are the charge t ransfer c omplexes t hat c an b e u sed as functional m aterial, a nd t here h as b een a steady growth of interest in this area. A lot of the Knoevenagel condensation reactions have been studied in the 20th century and recently, but the study of reaction is separate and isolated, there are only a few references about the catalysts. To the best of our knowledge, we have not found any report of systemic study about the catalyst-effect in the Knoevenagel condensation and any study of quantum chemistry about mechanism of the reaction. The study of reaction mechanism is important to learn of reaction track and understand the catalyst effect of the reaction. If the reaction mechanism is known, the reaction can be controlled and found the better catalyst. So the Knoevenagel condensation reactions o f a romatic a Idehydes w ith m alonotrile h ave b een s tudied b y experiments a nd quantum chemical computations in this thesis, the major work is as following.l.The experimental studies of the Knoevenagel condensation reaction of aromatic aldehydes with malonotrileThe methods of solid-state synthesis are new green synthetical methods, which are extensively applied in many reactions. There are mang advantage about method of solid-state synthesis, such as free solvent, easy operation, few subsidiary reactions and so on. Solid-state synthesis has been used to the Knoevenagel Condensation reaction of aromatic aldehydes with malonotrile in this thesis, and the experimental work has two major aspects.(1) Using different catalystThe Knoevenagel condensation reaction of 4-NO2-PhCHO with CftyCNh have been studied in details using different catalysts and discussed the rule of catalyst-effect in this thesis.Our work includes two parts. One is the catalyst-effect of different catalysts that have the same anion and different cations; the second is the catalyst-effect of different catalysts that have the same cation and different anions. The experimental result showed that catalyst-effect of catalyst NH4Ac is the best among all catalysts we have studied.(2) The experimental etudies of the Knoevenagel condensation of different aromatic aldehydes with malonotrile using same catalystWe studied the Knoevenagel condensation reaction of different aromatic aldehydes withmalonotrile in details using the same catalyst (NHUAc). The experimental result indicated that reaction activity of 4-NO2-PhCHO is best, 4-OH-PhCHO is worst.2. The theoretical studies of the Rnoevenagel condensation reaction of aromatic aldehydes with malonotrileThe density functional theory (DFT) AT B3LYP/6-31G* level and semi-empirical AMI method have been employed to study mechanism of the Knoevenagel condensation reaction of aromatic aldehydes with malonotrile. The geometries of reactors, products and transition states of the reaction have been optimized, and active energies of the reactions have been obtained. The potential profile for every reaction was studied by using the calculations of IRC. The results are very useful for understanding the mechanism of the Knoevenagel condensation reaction. The major work we have done is as following.(1) Mechanism of the reaction of formaldehyde with malonotrileThe mechanism of the reaction of formaldehyde with malonotrile has been studied under three different conditions, one is the condition of no catalyst, the second is the condition with HX (X=C1, Br) as catalysts and the third is the condition with catalysts of NaX (X=C1, Br). The results of DFT at B3LYP/6-31G* computations indicated that the catalyst-effect of NaBr is the best among the catalysts we studied here.(2) Theoretical studies of the reactions of aromatic aldehydes with malonotrileThe essential of reaction of aromatic aldehydes with malonotrile is the same as the reaction of formald更多还原