2-硅萘与乙炔和苯乙炔杂Diels-Alder反应的理论研究

采用密度泛函理论(DFT)方法在B3LYP/6-311G(d,p)水平上研究了2-硅萘与乙炔和苯乙炔的杂Diels-Alder反应的微观机理和势能剖面,考察了反应的取代基效应和溶剂效应,并与硅苯参与的类似反应进行了比较.计算结果表明,所研究反应均以协同非同步的方式进行.乙炔分子中碳原子上的苯基取代基对反应活化能垒的影响与产物中苯基所处的位置有关.2-硅萘分子中硅原子上的C(CH3)3或NH2取代基对反应势能剖面的影响一般都比较小,而其上的CCl3取代基对反应势能剖面的影响则比较复杂.苯溶剂对所研究反应的势能剖面影响不大.2-硅萘参与的杂Diels-Alder反应在热力学和动力学上均不如涉及硅苯的相应反应容易进行.     

硅杂苯与甲醛和二苯甲酮的Diels-Alder反应的理论研究

采用密度泛函理论(DFT)方法在B3LYP/6-311G(d,P)水平上研究了硅杂苯与甲醛和二苯甲酮的Diels-Alder反应的微观机理、势能剖面和取代基效应.计算结果表明,所研究反应均为协同的基元反应,形成1个Si-O键的反应中2个新键的形成具有较大的非同步性,而其他反应的非同步性相对较小.羰基碳原子上的苯基取代基不利于反应的进行,而硅杂苯分子中硅原子上的C(CH3)3与CCl3取代基有利于反应的进行.硅原子参与的反应在热力学和动力学上均远比不涉及硅原子的反应容易进行,而形成1个Si-O键的反应比形成1个Si-C键的反应容易进行,此结果与实验一致.     

9-硅蒽和9-锗蒽与烯烃杂Diels-Alder反应的理论研究

采用密度泛函理论方法在B3LYP/6-311G**水平研究了9-硅蒽和9-锗蒽与烯烃的杂Diels-Alder反应的微观机理、势能剖面,考察取代基对反应势能剖面的影响.计算结果表明,所研究反应均以协同非同步的方式进行,且Si(Ge)—C键总是先于C—C键形成.乙烯分子中C原子上的苯基取代基在热力学上对反应不利,但在动力学上的影响取决于产物中苯基与Si(Ge)原子之间的相对位置.9-硅(锗)蒽分子中Si(Ge)原子上的2,4,6-三甲基苯基取代基在热力学和动力学上均对反应不利.     

硅苯-Cr(CO)_3配合物与H_2O的加成反应的计算研究

采用密度泛函理论方法,研究了硅苯-Cr(CO)_3配合物(R)与H_2O的1,2-及1,4-加成反应的微观机理和势能剖面,考察了H_2O分子数目、Si原子上的2,4,6-三甲基苯基(Mes)取代基及四氢呋喃溶剂对反应势能剖面的影响.结果表明,R可分别与H_2O的单聚体、二聚体及三聚体发生加成反应.R与H_2O二聚体的加成反应在动力学上比其与H_2O单聚体及三聚体的相应反应有利.Cr(CO)_3与硅苯形成配合物对硅苯与H_2O的加成反应的动力学性质影响较小,但在热力学上对反应非常不利,特别是对1,4-加成反应的影响更为显著.当Cr(CO)_3与硅苯形成配合物后,实验观察到的完全的位置选择性主要由热力学因素控制.Si原子上具有较大体积的Mes取代基对反应不利.四氢呋喃溶剂在热力学和动力学上均不利于R与H_2O的加成反应.     

乙烯氧基在苯乙烯醚亲电取代反应中的定位效应

从理论上研究了苯乙烯醚的电子结构,结果表明,苯乙烯醚的乙烯氧基在空间的位置影响苯乙烯醚的原子电荷分布和能量,从而影响苯乙烯醚的亲电取代反应.苯乙烯醚的O-Ph键旋转,形成不同构象之间的最大与最小体系能量值之差ΔE仅0.005 402 a.u..当O₁₂-C₁C₁₃与苯环垂直时,体系能量最低,为稳定的优势构象.苯乙烯醚中乙烯氧基表现为吸电基,它的作用使邻位碳原子的负电荷比苯环碳原子多,邻位亲电取代反应中间体最稳定,反应的途径最有利,乙烯氧基主要表现为邻、对位定位基.     

三环硅芳香化合物二聚反应的理论研究

采用密度泛函理论方法在B3LYP/6-31G*水平研究了一些三环硅芳香化合物(1-硅蒽、2-硅蒽及9-硅菲)的可能的[2+2]、[4+2]及[4+4]二聚反应的微观机理和势能剖面,并与硅苯、1-硅萘及2-硅萘的类似反应进行了比较.计算结果表明,[2+2]和[4+4]反应为同步的协同过程,而[4+2]反应为非同步的协同过程.无论从热力学还是从动力学来看,1-硅蒽的[2+2]和[4+2]反应都远比[4+4]反应容易进行.两种不同的进攻方式(endo进攻与exo进攻)在热力学和动力学上的差别不大.1-硅蒽(2-硅蒽)的反应性高于硅苯和1-硅萘(2-硅萘),因此其稳定性低于硅苯和1-硅萘(2-硅萘).     

锡烯与一些亲核试剂加成反应的理论研究

采用密度泛函理论(DFT)方法研究了锡烯与一些亲核试剂(H_2O、MeOH及PhOH)间的加成反应的微观机理和势能剖面,考察了Sn=C双键中Sn原子和C原子上的取代基对反应势能剖面的影响.计算结果表明,H_2O及MeOH的单聚体、二聚体及三聚体均可作为亲核试剂与锡烯发生加成反应,但只有PhOH的单聚体才能与锡烯发生加成反应.Sn=C双键中Sn原子上的吸电子基团和给电子基团分别能使加成反应的活化Gibbs自由能降低或升高,而C原子上的取代基则有相反的效应.所涉及的三种亲核试剂的反应活性从高到低的顺序为:MeOHH_2OPhOH.     

沸石催化剂上苯与乙烯液相烷基化反应的研究

采用微型等温积分反应器,对改性β沸石催化剂上苯与乙烯液相烷基化反应进行了实验研究。通过考察反应温度、苯烯摩尔比和乙烯质量空速对催化剂性能的影响,获得了如下适宜工艺条件:反应温度190～220℃ ,苯烯摩尔比6～8,乙烯质量空速≤2h^-1。在此条件下,乙烯转化率在99.0%以上,乙苯选择性可达93%,乙基化选择性不低于99.0%。苯与乙烯液相烷基化稳定性实验表明,乙烯转化率和乙苯选择性未出现随反应时间延长而降低的现象,表明该沸石催化剂具有良好的活性稳定性.在所考察实验范围内,基本上检测不到二甲苯,其它烷基化副产物的含量也处于极低水平。     

Negishi试剂与铜或镍化合物促进含硅基六取代苯的合成

分别采用苯或噻吩和三甲基硅烷基(TMS)取代炔烃,在Negishi试剂诱导下生成三甲基硅烷基取代锆杂环戊二烯,加入氯化亚铜(CuCl)促进该锆环与乙炔二甲酸二甲酯(DMAD)反应,能够以较高的区域选择性得到苯或噻吩、TMS以及酯基取代的新型六取代苯衍生物.将TMS、甲基取代的锆杂环戊二烯在镍配合物NiBr2(PPh3)2作用下分别与N,N-二甲基-3-苯基-丙炔酰胺、对甲氧基苯乙炔苯甲酮反应,得到2个新型含多种基团、不对称的六取代苯衍生物.上述过程均为一锅法反应,能够由不同种类不对称内部炔烃通过分子间偶联生成六取代苯衍生物,选择性较高.     

OxoMn(Salen)与取代乙烯的环氧化反应机理的理论研究

使用B3LYP方法研究了OxoMn(Salen)与取代乙烯CH2=CHR(R=H,Me,NO2,CF3)的环氧化反应机理.结果表明:OxoMn(Salen)与取代乙烯的反应不可能经由协同反应通道完成;由于第一过渡态的相对Gibbs自由能太高,单重态OxoMn(Salen)与取代乙烯的反应也不可能经由分步反应通道完成;三重态和五重态OxoMn(Salen)与取代乙烯的反应可以经由分步反应通道2步完成,并且第1步是反应的决速步骤.研究结果还表明,取代基对第一过渡态的相对Gibbs自由能影响不大.     

Modeling of Solid-state Polycondensation of Poly (ethylene terephthalate)

A mathematical model has been developed to handle the reactions in Poly(ethylene terephthalate) (PET) undergoing polycondensation reactions in the solid state. The effect of temperature on chain mobility was considered to estimate the rate constants of chemical reactions. The polymer crystalline fraction is modeled as containing only repeat units, thus concentrating end groups and conden-sates in the amorphous fraction. This model is compared with PET reaction data with good results.     

ON THE OPTIIMAL REACTIONS ASSEMBLAGE OF COMPLEX REACTION SYSTEMS

In this paper, the author analyzes distinguishing features of complex reaction systems and single reversible reaction, and optimizes complex reaction systems starting from set theory.The method of constructing the optimal reactions assemblage and calculating the potential maximum equilibrium yield (PMEY) of objective products is proposed here. This paper points out clearly that the euqilibrium yield of objective products calculated by means of conventional method is the global equilibrium yield (GEY).It is not the thermodynamic constraint, and could be exceeded by observed yield of objective products; only PMEY is the thermodynamic constraint. It gives information on potential and possible optimal yield and thereby improving production. This paper also points out the way in which the real complex reaction system approached the optimal reactions assemblage. The new concept of PMEY and optimal reaction assemblage proposed by this Paper is universally applicable for the important complex reaction systems, such as the pyrolysis of alkane to produce ethylene, steam reforming of methane to produce syngas, production of formaldehyde from methanol, epoxidation of ethylene to produce ethylene oxide, hydrogenation of benzene to produce cyclohexane.     

二氯锗烯与乙烯环加成反应的DFT计算研究

用密度泛函理论的B3LYP方法．以6-311G^ 为基组．研究了Cl2Ge(^1A1)与C2H4环加成反应的机理。并用经典过渡态理论计算了该反应在不同温度下的反应速率常数和平衡常数，讨论了取代基对该加成反应的影响．     

STUDIES ON COPOLYCONDENSATION MECHANISMS FROM m-METHOXY-p-ACETOXYBENZOIC ACID,p-ACETOXYBENZOIC ACID AND POLY(ETHYLENE TEREPHTHALATE)

Copolycondensation mechanisms for the terpolyester system from m-methoxy-p-acetoxybenzoic acid,p-acetoxybenzoic acid and poly(ethylene terephthalate)are first investigatedby high resolution proton NMR spectroscopy at 400 MHz.A series of reactivity ratios of thecopolycondensation reactions are given.The results shown that the m-methoxy-p-acetoxybenzoicacid tends to homopolymerize,while the p-acetoxybenzoic acid,and the ethylene terephthalate unitespecially,tend to copolymerize with the m-methoxy-p-acetoxybenzoic acid.     

烯酮与乙烯或乙炔的[2+2]环加成反应机理的从头计算研究

用从头计算法研究了乙烯酮与乙烯(或乙炔)环加成反应机理.所有的几何构型优化都采用能量梯度法(在STO-3G水平上).对过渡态结构都用分析力常数矩阵计算进行了确证。为了得到较好的反应位垒和生成热,在HF/STO-3G结构参数基础上。采用MP2/6-31G和MP3/6-31G作了单点能量计算。计算结果表明,这2个反应都按协同、非同步的方式进行。乙烯酮与乙烯和乙炔环加成反应的活化位垒分别为244.2和294.5kJ/mol。     

CA型环氧树脂固化剂的研究

采用氯磺化聚乙烯与乙二胺、二氨基二苯基甲烷的混合物反应,合成一种新型固化剂;研究了混合多元胺的组成对合成反应的影响,以及所制固化剂的固化性能及其固化环氧树脂的物理－机械性能。实验结果表明该固化剂能使环氧树脂涂料在潮湿表面和水中良好成膜,所固化的环氧树脂涂膜具有良好的附着力、柔韧性、冲击强度等物理机械性能和良好的耐蚀性。     

Salicylic acid and ethylene signaling pathways are involved in production of rice trypsin proteinase inhibitors induced by the leaf folder Cnaphalocrocis medinalis （Guenee）

The roles of signaling pathways in the production of trypsin proteinase inhibitors (TrypPIs) in rice infested by the leaf folder (LF) Cnaphalocrocis medinalis were studied. Infestation by LF increased TrypPI levels in the leaves of rice plants at the tillering, booting and flowering stages but decreased TrypPI levels at the ripening stage; TrypPI levels in rice stems did not increase at any developmental stage. Infestation by LF at the tillering stage systemically increased TrypPI levels in leaves but not in stems; it also enhanced salicylic acid (SA) levels in leaves and stems, and the ethylene level released from plants. However, LF infestation did not increase JA concentrations. Exogenous application of SA or ethylene enhanced TrypPI levels in the leaves and stems of plants at the tillering stage, whereas treatment with both SA and ethylene induced lower levels of TrypPIs than treatment with SA or ethylene alone, suggesting an antagonistic effect of SA and ethylene on TrypPIs induction. The results suggest that both SA and ethylene signaling pathways are involved in the production of TrypPIs in rice induced by LF; moreover, the antagonistic effect of SA and ethylene may explain the changes in TrypPI levels seen at different plant developmental stages and in different organs.     

The dual effects of ethylene on the negative gravicurvature of arabidopsis inflorescence, an intriguing action model for the plant hormone ethylene

Ethylene was found to alter the shoot gravitropic response a century ago. However, its actual effects remained controversial over the century. In the present study, we investigated the effects of ethylene on the gravitropic response of Arabidopsis inflorescence and discovered that although the intact Arabidopsis inflorescence bent upward at the rate of 43°±3°/h in the first 1.5 h under the given control growth conditions, it bent upward at a rate of 20°±3° and 64°±14°/h in the presence of exogenous ethylene if the plants were pretreated for 0.5 and 12 h, respectively, before the initiation of gravistimulation. The increase in gravicurvature rate is proportional to the length of ethylene pretreatment. The minimum ethylene pretreatment time required for achieving the maximum curvature rate is 10—11 h with removal of exogenous ethylene. The stimulatory effect of ethylene on the inflorescence gravicurvature requires a latent period of time (1 h) to become measurable. In contrast, the inhibitory effect of ethylene becomes measurable shortly after application of ethylene. The stimulatory effect remained nearly unchanged when the applied ethylene concentration increased from 0.1 to 10 ml/L. However, the inhibitory effect increased substantially as ethylene concentration increased to 10 mL/L. These results suggest that ethylene simultaneously exerts both stimulatory and inhibitory effects on the gravitropic response of the inflorescence, and the stimulatory effect dominates over the inhibitory effect during the interplay between the two in the inflorescence. A “Yin and Yang” action model is hereby proposed to address the interplay between the two effects of ethylene. They may act through distinct signaling pathways.     

二氟锗烯与乙烯环加成反应的DFT计算研究

用密度泛函理论的B3LYP方法,以6-311 G**为基组,研究了F2Ge(1A1)与C2H4环加成反应的机理,并用经典过渡态理论计算了该反应在不同温度下的反应速率常数和平衡常数,讨论了取代基对该反应的影响.