Kinetics of Reaction of Bromo-epoxy Resin with Oleic Acid catalyzed by Dimethyl benzyl amine

The kinetics of reaction of bromo-epoxy resin with oleic acid in the presence of dimethylbenzylamine catalyst was studied. The reaction is a zero order reaction with respect to oleic acid, first order with respect to epoxy group and 0. 74 order with respect to dimethylbenzylamine. The reaction rate constants at various temperatures and activation energy were determined. The mechanism of this reaction was discussed. Keywords Tetrabromobisphenol-A, Bromo-epoxy resin, Oleic acid kinetics, Reaction mechanism     

苯甲醛肟与炔丙醇偶极环加成反应的理论研究

用密度泛函理论(DFT)方法在B3LYP/6-31G*水平上研究了苯甲醛肟与炔丙醇加成反应的微观机制和热力学、动力学行为. 结果表明, 在苯甲醛肟与炔丙醇加成反应过程中, 8个可能反应通道的过渡态中均形成非平面五元环结构, 其中苯甲醛肟的Z、E构型特征得到了部分保留, 但主要部分的键长、键角均发生了变化, 电荷也进行了重新分布. 苯甲醛肟以羟基型参与反应的4个反应通道均为吸热反应和热力学非自发过程, 它们均具有较高的反应势垒、较慢的反应速率和较小的平衡常数; 而以离子型参与反应的四个反应通道均为放热反应和热力学自发过程, 它们的反应势垒较低, 反应速度较快, 平衡常数也较大, 故苯甲醛肟应主要以离子型参与反应. 炔丙醇的两种取向对应着加成反应的两种产物, 反应达到平衡后, 3-羟甲基二氢异噁唑为主要产物.     

Kinetics of phenol oxidation with ozone in a thin layer on a solid surface

Ozone has been reacted with phenol in thin supported layers, and the dynamics of this reaction has been investigated. The stoichiometry of this reaction coincides with the stoichiometry of the same reaction in solution. Specific reaction rate (β) has been determined for various phenol conversions. The effective rate constant of the reaction, estimated by extrapolating β to zero reaction time, is significantly higher than the rate constant of the reaction in solution. The reaction between ozone and phenol is diffusion-controlled. The reaction products form a barrier layer, which protects the deeper phenol layers against ozone. The barrier layer is as thick as 8–15 phenol monolayers.     

固体聚合物电解质在肉桂醇电解氧化中的应用(II)——后续化学反应在电催化反应中的地位及其影响因素

对影响肉桂醇电极氧化的各种因素作了进一步的讨论. 实验结果表明固体聚合物电解质内水的含量、pH 以及浸入离子交换膜中的二价锰离子的浓度均对该电极反应的电位以及后续化学反应的速度有很大的影响, 在较高的温度下反应时, 有利手提高生成肉桂醛的电流效率.     

低热固相反应的反应机理研究(Ⅰ)——冷融熔机理和冷溶熔机理的模型

本文提出了低热固相反应的冷融熔机理和冷溶熔机理,其中冷融熔机理主要针对于不含结晶水的反应体系,冷溶熔机理主要针对于含结晶水的反应体系,并对低热固相反应动力学提出冷融熔/冷溶熔、扩散、反应、成核、生长的五步机理。两种机理都避开了分子在固相晶格中的扩散,从而对低热固相反应的扩散问题进行了有效的解释,并给出了低热固相反应的热力学和动力学判据。     

Mechanistic Study on the Ozone‐Mercury Reaction and the Effect of Water and Water Dimer Molecules

The thermodynamics and mechanism of the reaction of elemental mercury with ozone has been studied computationally. The effect of water and water dimer molecules on the reaction has also been investigated. For dry reaction, we obtained two pathways and geometry optimization, atoms in molecules analysis and vibrational frequencies of all component of reaction have been used for confirming of reaction mechanism. Thermodynamic variable of reaction has been calculated. For the reaction in the presence of the water, our studies focus on ozone‐mercury complex reaction with water and water dimer and obtained the mechanism of reactions. Comparison of wet and dry reaction shows the energy profile of reaction decreases with water molecule correspond to experimental prediction. Calculated thermodynamic variable of all reaction shows the Gibbs free energy of reaction decreases with the number of water molecule.     

Investigation of thermal power of reaction of titanium slag with sulphuric acid

Enriched titanium raw materials with high titanium content called titanium slags are received by the electrothermal reduction of ilmenite. Titanium slags are most frequently used in the titanium dioxide industry. The reaction of titanium slags with sulphuric acid is strongly exothermic and creates danger of thermal explosion. Kinetics of this reaction depends on the parameters such as temperature of initiation, sulphuric acid concentration and dimension of particles of titanium slag. The reaction of titanium slag with sulphuric acid was investigated at non-isothermal conditions in a special construction calorimeter. The observed thermal power changes in the calorimeter (“calorimeter run”), are the basis for estimation of reaction kinetics. A proposed model describing the thermal power changes and taking into account the moment of initiation of reaction is presented. The calorimetric investigations showed, that reaction rate of titanium slags with sulphuric acid depends on initial temperature of reaction, size of particles of titanium raw material and sulphuric acid concentration.     

Interaction of dimethyl carbonate with anilines in the presence of potassium methylate: Kinetics and the role of the base

The kinetic patterns of the reaction between dimethyl carbonate and anilines in the presence of a potassium methylate as a catalyst were studied. The mechanism of aminolysis was clarified, which includes the detachment of the proton from the amino group of aniline and the subsequent attack of the resulting anion on the carbonyl group of dimethyl carbonate. It is shown that when the reaction occurs in the dimethyl carbonate-methanol 3:1 system, the process can be described as an irreversible first-order reaction in the aniline though the target reaction is complicated by side interaction between potassium methylate and dimethyl carbonate. The rate constants of the target reaction with substituted anilines and of the side reaction in the temperature range of 70-90°C were determined. It is shown that the influence of the substituent on the reaction rate is described by the Hammett equation, with the constant of the reaction series being positive and the best correlation being achieved for σ-scale. The results obtained are consistent with the proposed mechanism of the reaction and are explained by the facilitation of the aniline deprotonation with increasing acceptor properties of the substituent. Effective activation energies for the reaction of various anilines with dimethyl carbonate are found.     

HCN + OH→CN + H2O反应理论研究

The reaction path of the reaction HCN + OH→ CN + H2O was traced with Fukui's theory of intrinsic reaction coordinate by using ab initio MO method (at UMP4/6-31G** level) with gradient technique. On this basis, the dynamics properties along the reaction path was investigated by reaction path Hamiltonian theory. The rate constants of this reaction at different temperatures were calculated by conventional and variational transition state theory with tunneling correction. The theoretically calculated rate constants are in good agreement with experimental results, this shows that the title reaction is an one step, direct reaction.     

有机磷化合物的研究 XXV: 溶剂性质对烯丙在膦酸酯碳阴离子和芳醛反应区域选择性的影响

本文研究烯丙基膦酸二乙酯碳阴离子和苯甲醛, 对甲基苯甲醛的反应, 考察了溶剂对反应区域选择性的影响.     

Curing of epoxide resins: Model reactions of curing with amines

The reaction of tetrafunctional diamines and bifunctional amines with monoepoxy compounds was investigated by gel-permeation chromatography. At a stoichiometrically equivalent ratio of the functional groups or excess of amine, the consecutive reaction of the epoxide groups with the hydrogen atoms of the amino groups is the only reaction that is taking place; if epoxide is present in excess, the OH groups formed in the reaction are gradually added to the epoxide groups. The ratio of the rate constants of the reaction of the epoxy group with the hydrogen atoms of the primary and secondary amino group was calculated from the concentrations of the reaction products at various excess amounts of amines. The ratio is in good accord with the value calculated from the gel points and limiting stoichiometric ratios in the curing of diepoxides with diamines.     

Effect of Cationic Micelle on the Kinetics of Oxidation of Citric Acid by N-Bromophthalimide in Acidic Medium

Kinetics of the oxidation of citric acid (CA) by N-bromophthalimide (NBP) has been studied in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) at 35°C. The CMC value is lower than those given in the literature for aqueous solutions of CTAB without added electrolyte. The reaction is strongly catalyzed by cationic micelle, CTAB with a progressive increase in CTAB concentration the reaction rate increased, at higher concentration constancy in the rate constant was observed. The reaction follows first and fractional order kinetics in NBP and citric acid, respectively. The reaction follows inverse fractional order with respect to perchloric acid. The Arrhenius equation is found to be valid for the reaction. A detailed mechanism with the associated reaction kinetics is discussed. The catalytic role of CTAB micelles is discussed in terms of the Menger and Portnoy model.     

N溴代丁二酰亚胺氧化醇反应的热动力学研究

氧化反应是有机化学中的一种重要反应类型,也是有机化学、化学工程和生物学家们研究的重点之一.但因其机理复杂,至今未见到用热动力学理论探索氧化反应体系的报道. N溴代丁二酰亚胺(NBS)是良好的溴化试剂,在不同反应条件下,它既可和不饱和键发生加成反应,也可在水溶液中作为次溴酸的来源,还可作为有效的氧化剂和脱氢剂.Reich和Reichstein首先报道了用N溴代乙酰亚胺将仲醇缓慢氧化为酮,Fieser等人报道了NBS的氧化作用.本文用RD-1型热导式自动量热计研究了35℃下NBS氧化异丙醇及环己醇2个反应体系,计算了反应速率常数,对反应的动力学及其机理提出了较合理的解释.     

The photokinetics of phenothiazine dyes with titanium trichloride in different solvents

The kinetic parameters of photoinduced electron transfer reaction of two phenothiazine dyes, methylene blue and methylene green with titanium trichloride, were determined in water and different aqueous-alcoholic solvents at different acidities by using a specially designed optical system. The rate of photoinduced electron transfer reaction was measured by determining the quantum yield of the reaction. The methylene green had a higher reactivity as compared to methylene blue with titanium trichloride. The graphical analysis showed that the reaction of dye with titanium trichloride follows pseudo–first-order kinetics. A reaction mechanism was proposed by considering the different excited states of dye and their possible interaction with the solvent and titanium trichloride. The different steps in the reaction mechanism were taken into consideration for deriving rate equations, which were used to determine the different rate constants in the reaction mechanism in different solvents.     

Kinetics of the metal-exchange reaction of deuteroporphyrin and gematoporphyrin cadmium complexes with cobalt chloride in acetonitrile

The metal-exchange reaction of cadmium deuteroporphyrin (CdDP) and cadmium gematoporphyrin (CdGP) with cobalt chloride in acetonitrile is studied spectrophotometrically. The stoichiometry of the metal-exchange reaction is determined. The results are compared with the exchange reaction of cadmium mesoporphyrin and cadmium protoporphyrin with cobalt acetate in acetonitrile. Substituents in the 2,4-positions of cadmium complexes of protoporphyrins are shown to influence the rate of the metal-exchange reaction. The increasing order of the rates of the metal-exchange reaction between protoporphyrins and cobalt chloride in acetonitrile is established.     

维生素K3电化学反应机理的紫外光谱电化学研究

用薄层池循环伏安法和现场薄层池紫外光谱电化学法研究了维生素Ｋ３（ＶＫ３）在铂电极上的电化学反应机理。薄层池循环伏安实验结果表明：ＶＫ３的电化学反应为二步１ｅ准可逆过程，现场薄层池紫外光谱电化学的实验结果和Ｎｅｒｎｓｔ图解分析表明：电解还原反应的最后产物为２－甲基－１，４－萘酚。该反应偶合有前行化学反应；还原产物经电解氧化的产物为２－甲基－１，４－萘酚。该反应偶合有前行化学反应；还原产物经电解氧化的     

Kinetics of complex formation of 2‐methoxyphenol with ferric ion and hexacyanoferric ion

Complexes containing one molecule of organic ligand have been formed in the reaction of 2 methoxyphenol with ferric ion or hexacyanoferric ion. Kinetic investigations showed that the reaction order with respect to ferric ion or hexacyanoferric ion is close to one. The reaction order with respect to 2‐methoxyphenol is 0.8 in the reaction with ferric ion and close to 0 in the reaction with hexacyanoferric ion. The reaction mechanism, based on kinetic investigations, involves the decomposition of the initial complex, formed with the pentacoordinated complex and water or cyanide ion. In a second stage of the reaction, the pentacoordinated complex adds 2‐methoxyphenol; and one molecule of initial ligand, water, or cyanide ion, comes off. Some ratios of rate constants of elementary reactions have been calculated. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 184–191, 2000     

纳米TiO_2光催化芳香醛的缩醛反应研究

本文以纳米TiO2为催化剂,UV-LED（=365 nm）为紫外光源,在自制的恒温石英玻璃光催化反应器中成功实现了芳香醛的非均相光催化缩醛反应.以乙醇等作为溶剂和反应物,快速高效和高选择性地合成了苯甲醛二乙基缩醛（BDA）.在光强为0.6 mw/cm2,苯甲醛初始浓度为0.05 mol/L,催化剂TiO2（P25）用量为5.0 g/L,反应时间为15 min的条件下,苯甲醛二乙缩醛的产率可达99.86%.研究表明,氧气的存在是顺利发生光催化缩醛反应的重要条件.反应液pH值、醇溶剂种类及苯环对位取代基等因素都会对光催化缩醛反应速率和产率产生影响.pH值及醇溶剂的pKa越小,缩醛反应速率越快.苯环上对位取代基会抑制缩醛反应的进行,其中供电子取代基相对吸电子取代基更有利于缩醛反应进行.结合实验,提出了光催化缩醛反应的机理.     

芴的9位羟甲基化反应产物的影响因素

以聚甲醛为羟甲基化试剂,研究了碱的种类、反应温度和反应时间等因素对芴与聚甲醛发生羟甲基化反应产物类型的影响。 结果表明,提高碱的强度有利于生成9,9-双羟甲基芴,升高温度和延长反应时间则有利于生成9,9′-亚甲基双芴。 通过控制反应条件,有可能优先生成9-芴甲醇或9,9-双羟甲基芴或联产这2个化合物。     

Kinetics of the isomerization reaction of cholest-5-en-3-one catalyzed by trichloroacetic acid in aprotic solvents of low dielectric constant

The isomerization reaction of cholest-5-en-3-one has been studied in a solution of cyclohexane using trichloroacetic acid as catalyst. At the same time a general reaction scheme is proposed to be valid for all the cases assayed in which the monomer form of the acid is considered as the only effective catalyst. The experimental results agree with these hypotheses and with the calculation of the individual rate constant together with the reaction order with respect to the catalyst. Semiquantitative studies have been carried out with other catalysts and solvents, confirming the validity of the reaction scheme. The thermodynamic activation parameters have also been calculated, and a comparative study was made with the results of the evaluation of the reaction when it takes place in amphiprotic solvents. A reaction mechanism is proposed based on all the kinetic information obtained.