(4-溴甲基双环[4.4.1]-1,3,5,7,9-十一碳五烯基-3-)甲醇环氧化反应机理的理论研究

A reaction mechanism of epoxidation reaction of the 4-(bromomethyl)bicyclo4.4.1undeca-1,3,5,7,9-pentaen-3-ylmethanol has been studied by using the density functional theory(DFT) method at B3LYP level with 6 31G* basis set. The geometric structures of reactant, product and transition state have been optimized. The transition state is found by the QST2 method and characterized by the vibration frequency analysis. The intrinsic reaction coordinate(IRC) for this reaction is traced and confirms the reaction mechanism. The changes and the nature of related chemical bonds along the IRC path have been analyzed by the theory of electronic charge density. The result shows that the elimination reaction and ring closing reaction are synergistic, and the hydrogen in the elimination reaction derives from hydroxyl. In addition, the activation energy of the reaction is 139.2 kJ/mol.     

MINDO/3研究胞嘧啶异构体间异构化反应——Ⅰ. N1-氢-4-氨基-2-羰基胞嘧啶与4-亚氨基-2-羰基胞嘧啶异构反应

本文报导用半经验方法研究N_1-氢-4-氨基-2-羰基胞嘧啶与4-亚氨基-2-羰基胞嘧啶异构化反应。用MINDO/3能量梯度法优化了孤立体系的全部自由度, 计算结果表明氨型比亚氨型稳定, △E=33.85 kJ mol~(-1); 限定分子体系在同一平面, 用Powell法优化过渡态几何构型, 计算所得正反应活化势垒为168.87 kJ mol~(-1), 逆反应活化势垒为135.02 kJ mol~(-1)。从IRC途径分析了该异构化反应的物理实质。     

N-硬脂酰基亮氨酸的合成

采用酰氯化反应与缩合反应两步法合成N -硬脂酰基亮氨酸。以硬脂酸和亚硫酰氯为原料 ,n(硬脂酸 )∶n(亚硫酰氯 ) =1∶1 .5 ,在 80℃下冷凝回流 6h酰氯化反应合成硬脂酰氯 ,硬脂酰氯经减压蒸馏收集 1 70～2 0 0℃的馏分得到。硬脂酰氯收率为 65 %。硬脂酰氯再与亮氨酸的氢氧化钠溶液在冰水浴中进行Schotten -Baumann缩合反应制得N -硬脂酰基亮氨酸。缩合反应最佳工艺条件是反应溶液pH值控制为 9.0。反应后滴加1mol/L盐酸至pH =5 .0～ 6.0 ,加入正己烷使N -硬脂酰基亮氨酸处于水层中 ,分离并蒸干水层溶液得含NaCl的混合物。用无水乙醇萃取混合物 ,萃取液蒸干得产物。N -硬脂酰基亮氨酸收率为 75 %     

Poly(vinyl chloride) stabilization with organo-tin compounds: Part VII—Dibutyl tin maleate: Model compound studies

The reaction between dibutyl tin maleate or dibutyl tin bisbutylmaleate and chlorohexene as a model compound for allylic chloride in PVC was studied at 80°C in dichlorobutane solution. From kinetic studies by gas chromatographic analysis of the reaction medium, and also spectroscopic data (infra-red and ¹H NMR) it may be concluded that the main reaction is the substitution reaction which produces mono- and dihexenyl esters, as well as mixed diesters of maleic acid. The elimination reaction plays a minor rôle. Both activities are related to their Lewis acidities. The Diels-Alder condensation between maleates and hexadiene is not observed as a side reaction in these conditions; the main side reaction is the decomposition of monoesters of maleic acid (which is produced by the elimination reaction after one or two steps) into an alcohol and maleic anhydride—a reaction which can be catalysed by organo-tin chlorides. A Diels-Alder reaction between maleic anhydride and hexadiene takes place. The alcohol produced in the side reaction mentioned above may take part in a transesterification reaction with the organo-tin maleate and that reaction probably provides the best explanation of the earlier observation of Frye et al.,¹ according to which there is at least temporary retention of reactivity of tin labelled organo-tin maleate by PVC.     

Organocatalytic Formation of Chiral Trisubstituted Allenes and Chiral Furan Derivatives

A novel reaction that provides chiral allenes by amino catalytic activation of either aldehydes or α,β‐unsaturated aldehydes for reaction with alkynyl‐substituted enones is presented. The reaction forms a variety of trisubstituted allenes in high yields and with excellent stereoselectivities. The utility of the reaction concept is demonstrated by the synthesis of chiral furan derivatives in high yields and stereoselectivities.     

中度气化煤焦异相还原NO机理

采用量子化学密度泛函理论结合热力学和动力学研究了中度气化的锯齿形煤焦异相还原NO的反应机理。分析了中度气化煤焦异相还原NO的反应路径、异相还原过程中的能量变化以及热力学和动力学分析。结果表明,中度气化煤焦更易于NO的吸附,IM2→IM3的开环过程为整个反应的决速步,所需克服能垒最大（398.03 kJ/mol）。中度气化煤焦异相还原NO的反应在煤燃烧系统中为可自发的放热反应,且为单向反应。根据决速步理论,反应的进行需克服较大活化能（389.83 kJ/mol）,同时根据阿伦尼乌斯公式,总体反应速率受温度影响较大,温度越高反应速率越快,越利于NO还原。     

Copper-catalyzed enantioselective Henry reactions of alpha-keto esters: an easy entry to optically active beta-nitro-alpha-hydroxy esters and beta-amino-alpha-hydroxy esters

The catalytic enantioselective Henry reaction of alpha-keto esters with nitromethane has been developed. The reaction conditions have been optimized by the screening of different chiral Lewis acids, solvents, and bases, and it was found that the copper(II)-tert-butyl bisoxazoline complex in combination with triethylamine catalyzed a highly enantioselective reaction giving optically active beta-nitro-alpha-hydroxy esters in high yields and with excellent enantiomeric excesses. The scope of the reaction is demonstrated by the reaction of a variety of different alpha-keto esters. The catalytic enantioselective Henry reaction of beta,gamma-unsaturated-alpha-keto esters proceeds as a 1,2-addition reaction exclusively, in contrast to the uncatalyzed reaction where both the 1,2- and 1,4-addition products are formed. It is demonstrated that the beta-nitro-alpha-hydroxy esters can be converted into, e.g., Boc-protected beta-amino-alpha-hydroxy esters in high yields and without loss of optical purity. The mechanism for the reaction is discussed, and it is postulated that both the alpha-keto ester and nitromethane/nitronate is coordinated to the metal center during the reaction course.     

焦炭溶损反应动力学及其模型研究

利用未反应核收缩模型对高炉焦炭与CO2的反应动力学进行了研究，建立了以可测参数（R）表达的焦炭与CO2的反应动力学关系式。并对反应速率常数和有效扩散系数、表观反应活化能和有效扩散活化能及反应过程中各步骤阻力进行了分析。结果表明，（1）焦炭与CO2的反应符合未反应核收缩模型。（2）反应的表观活化能Ea=124.5kJ/mol，有效扩散活化能ED=642.4 kJ/mol；界面化学反应的阻力随反应温度升高而增加；残余灰层内的内扩散传质阻力相对比例随温度升高而下降。（3）焦炭溶损反应在低温区主要受内扩散控制，随着温度升高，反应由外扩散、化学反应和内扩散三步控制；当进入高温区，反应进行一段时间后主要受内扩散控制。     

Mechanism of transesterification and cyclization of epoxy–polycarbonate blends catalyzed by quarternary ammonium salt

The reaction of oxirane with carbonate using quarternary ammonium salts as catalyst has been studied. Curing is caused by the transesterification reaction of the oxirane cycle with the carbonate group that proceeds by an “insertion” mechanism in the stoichiometric system. The ratio of the reactants is two oxirane groups to one carbonate group. In the nonstoichiometric system, the epoxide content is more than the stoichiometric quantity required. A cyclization reaction is followed by the transesterification reaction. To identify the finished products, a model reaction was proposed using diphenyl carbonate and phenyl glycidyl ether which results in the formation of 4-phenoxymethyl-1,3-dioxolane-2-one (PMD). The mechanism of forming the cyclic structure is assumed to proceed through the chain scission of the network in which the molecular chain crosslinked with carbonate group by a transesterification reaction. © 1996 John Wiley & Sons, Inc.     

The photo-dehydro-Diels-Alder (PDDA) reaction

The photo-dehydro-Diels-Alder (PDDA) reaction is a valuable extension of the classical Diels-Alder (DA) reaction. The PDDA reaction differs from the DA reaction by the replacement of one of the C-C-double bonds of the diene moiety by a C-C triple bond and by the photochemical triggering of the reaction. This entails that, in contrast to the DA reaction, the PDDA reaction proceeds according to a multistage mechanism with biradicals and cycloallenes as intermediates. The PDDA reaction provides access to a considerable variety of compound classes. For example, 1-phenylnaphthlenes, 1,1'-binaphthyls, N-heterocyclic biaryls, and naphthalenophanes could be obtained by this reaction.     

两相流中煤粉的燃烧机理及动力学特征

利用微型流化床动力学分析仪研究了两相流条件下无烟煤粉的燃烧反应机理和动力学特征,并与热重法所得结果进行比较分析。结果表明,当温度大于850℃时,煤粉燃烧机理发生了变化,燃烧气态产物的生成比例也随之改变;当气速大于0.10 m/s时,气体扩散限制基本被消除,煤粉燃烧反应速率主要受界面化学反应控制;煤粉燃烧反应速率随着氧气分压的增大呈幂函数形式增长,且氧气分压对煤粉静置燃烧的影响更加显著。煤氧两相流燃烧的表观活化能与静置燃烧相比降低了49 kJ/mol,相同温度条件下两相流燃烧的界面化学反应阻力也明显小于热重法测试结果。     

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.     

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.     

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.     

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.     

烷基自由基β位裂解反应类反应势垒与速率常数的精确计算

提出反应类等键方法并用于高温燃烧机理中一类重要反应——烷基自由基β位裂解反应的反应势垒和速率常数的精确校正计算. 通过10种不同从头算水平对类反应中5个代表反应的反应势垒的计算发现, 用反应类等键反应方法和直接从头算方法获得的5 个代表反应的反应势垒最大绝对偏差的平均值分别为5.32 和16.16 kJ·mol^-1, 表明反应类等键反应方法计算的反应势垒对不同水平从头算方法的依赖性小, 可在较低从头算水平计算得到精确的反应势垒, 解决大分子体系反应势垒的精确计算问题. 此外应用反应类等键反应方法在BHandHLYP/cc-pVDZ 从头算水平计算了3 个代表反应的速率常数, 并与文献报道的实验值进行了比较, 其在500-2000 K温度区间内计算速率常数与实验速率常数中较大值与较小值的比值k_max/k_min的平均值为1.67, 最大值也仅有2.49. 表明应用反应类等键反应方法在较低从头算水平即可对同类反应的速率常数进行精确计算.最后在BHandHLYP/cc-pVDZ从头算水平用反应类等键反应方法计算了13个烷基自由基β位裂解反应的速率常数.     

Regioselective palladium-catalyzed electrophilic allylic substitution in the presence of hexamethylditin

[reaction: see text]. Palladium-catalyzed electrophilic allylic substitution of functionalized allyl chlorides and allyl acetates can be achieved in the presence of hexamethylditin under mild reaction conditions. The substitution reaction occurs with very high regioselectivity at the branched allylic terminus. Regioselective tandem bisallylation reaction could be performed by employing benzylidenemalonitrile as substrate. The reaction mechanism can be explained by involvement of a bisallylpalladium intermediate. A particularly interesting mechanistic feature of this reaction is that palladium catalyzes up to three different transformations in the same catalytic cycle. DFT calculations indicate that the regioselectivity is determined by the location of the allylic substituent in the eta1-allyl moiety of the reaction intermediate.     

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.     

柠檬酸铝/聚丙烯酰胺胶态分散凝胶反应动力学和机理的研究

采用粘度法研究了柠檬酸铝（AlCit)与部分水解取丙烯酰胺（HPAM）胶态分散凝胶体系的反应动力学。结果表明，胶态分散凝胶体系的交联反应是一级反应。并推导出胶态分散凝胶体系的反应动力学方程。     

气相中La催化乙烯脱氢及C-C键耦合的理论研究

采用密度泛函理论中的B3LYP方法研究了气相中过渡金属La在二、四重态势能面上催化C2H4的反应机理。全参数优化了二、四重态势能面上各个驻点的几何构型,同时对过渡态进行了频率分析,使用内禀反应坐标（IRC）方法验证了过渡态的准确性,通过AIM理论和NBO分析方法对主要的驻点进行了键分析,并对2IM1、2IM3进行了态密度分析。结果表明：La与C2H4的反应存在两种可能的路径,反应在二重态势能面上进行且均为放热反应。键分析表明初始复合物中La与C2H4分子之间为共价作用。