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1.
研究了含汞三金属化合物「η-RC5H4(CO)3M2「Hg(M=Mo,W;R=Me,Et,CO2Me,CO2Et)与锌粉的置换反应,发现当取代基R为给电子的Me和Et时底物不发生反应,而取代基R为拉电子的CO2Me和CO2Et时,则底物中的汞可被锌置我。  相似文献   

2.
研究了含汞三金属化合物[η_5-RC_5H_4(CO)_3M]_2Hg(M=Mo,W;R=Me,Et,CO_2Me,CO_2Et)与锌粉的置换反应,发现当取代基R为给电子的Me和Et时底物不发生反应,而取代基R为拉电子的CO_2Me和CO_2Et时,则底物中的汞可被锌置换,生成带有机官能团的三金属化合物[η_5-RC_5H_4(CO)_3M]_2Zn;另外,还发现R为CO_2Et,M为Mo的产物[η_5-RC_5H_4(CO)_3M]_2Zn可在室温下被分解为相应的氯代物η_5-EtO_2CC_5H_4MoCl.  相似文献   

3.
三羰基全甲基硅基环戊二烯基钼衍生物的合成与表征   总被引:2,自引:0,他引:2  
通过三羰基(五甲基二硅基)环戊二烯基钼负离子盐与卤代烃(EtI,PhCH2Cl,ClCH2COOEt,I(CH2)4I)进行基化反应合成其烷基钼化合物。用六甲基三硅二氧烷桥联双(三羰基环戊二烯基钼)负离子经冰醋酸处理,硫酸铁氧化偶联成钼-钼键双核化合物,经碘裂解后钼-钼键生成六甲基三硅二氧烷桥联双(三羰基环戊二烯基碘钼)化合物。以元素分析,IR和1HNMR谱表征了化合物的结构。  相似文献   

4.
N,N’双(2羟基苯亚甲基)邻苯二亚胺合钴(Ⅱ)具有可逆加合分子氧的性质[1],因此可作为烃类氧化反应的催化剂[2],但有关这类络合催化剂的取代基效应,尤其是二胺芳环上的取代基对其稳定性和催化活性的影响则未见报道。为此,我们设计合成了在不同芳环上含不同电负性取代基的双水杨醛缩邻苯二胺新配体L1H2~L8H2及其钴(Ⅱ)配合物CoL1~CoL8,以期研究其取代基对CoL的载氧性能和催化活性的影响。R1HHHHOHOCH3OCH3OCH3R2HHHHHOCH3OCH3OCH3R35CH35NO23NO25OCH3HH5NO24OHLL1L2L3L…  相似文献   

5.
研究了Cu(OAc)2.H2O与两个Schiff碱[水杨醛缩邻氨基吡啶(HSPy),水杨醛缩邻氨,基苯酚(H2SAP)]在室温下的固相化学反应,用元素分析、XRD、DTA、UV漫反射和磁化率测定等方法表征的固相产物,其组成分别为Cu(SAPy)2和Cu(SAP),后者为双核结构,通过等温电导法得到固相反应的活化能为:H2SAP(35.25kJ/mol<HSAPy82.31kJ/mol,并初步讨论了  相似文献   

6.
用BOC-MP方法及Monte Carlo模拟技术,对H2S导致Cu基催化剂失活的原因进行了计算分析。研究结果表明,当原料气中存在H2S时,WGS反应的活化能明显高于无H2S时的活化能,随着表面H2S浓度的增大(θ=0,0.10,0.25),反应的活化能也逐渐变大(其大小比为1:1.34:3.3),究其原因可归结为H2S的存在使得反应物分子的吸附热减小,从而使H2O的解离吸附(WGS反应的速控步骤  相似文献   

7.
氧经铝基COS,CS2水解催化剂表面碱性和催化作用   总被引:3,自引:0,他引:3  
上官炬  郭汉贤 《分子催化》1997,11(5):337-342
进行了3种氧化铝基催化剂上CO2的TPD和COS,CS2的水解活尾研究。结果表明,催化剂表面碱性中心类型,强度和数目是不相同的;K2O和Pt的负载能提高弱碱性中心的数目和强度,同时能显著提高COS,CS2的水解转化率。关联第一类CO2脱附活化能和峰面积与COS水解反应活化能和速率常数,发现呈线性关系,说明弱碱性中心是COS催化水解的活性中心。  相似文献   

8.
通过Fe3(CO)12、硫醇(硫酚)和EtMgBr所形成的络盐[(μ-CO)(μ-RS)Fe2(CO6)》-Mg^+Br与氯代芳酰氯的原位反应,合成了通式为(μ-RS)(μ-o-ClC6H4CO)Fe2(CO6)和(μ-RS)(μ-m-ClC6H4CO)Fe2(CO)6(R=n-Bu,t-Bu,Ph)的6个新桥芳酰基铁硫配合物,并用C/H分析、IR和^1HNMR表征了它们的结构。  相似文献   

9.
用BOCMP方法及MonteCarlo模拟技术,对H2S导致Cu基催化剂失活的原因进行了计算分析。研究结果表明,当原料气中存在H2S时,WGS反应的活化能明显高于无H2S时的活化能,随着表面H2S浓度的增大(θ=0,0.10,0.25),反应的活化能也逐渐变大(其大小比为1∶1.34∶3.3),究其原因可归结为H2S的存在使得反应物分子的吸附热减小,从而使H2O的解离吸附(WGS反应的速控步骤)活化能增大。  相似文献   

10.
本文通过二茂基镧系金属氯化物Cp2LnCl(CP=C5H5;Ln=Dy,Ho,Yb)与等摩尔的NaOAc(Ac=CH3CO)及烷基醇HOR(R=-CH2CH2CH3,-CH2CH=CH2)在四氢呋喃溶剂中混合一步反应,合成了六种新的含三种不同配位基的镧系金属有机化合物。化合物的元素分析结果符合通式CpLn(OR)(OAc),红外光谱显示了η^5-Cp、OR及OAc基团的特征吸收峰,质谱显示了化合物  相似文献   

11.
用MINDO/3方法研究SCRCR′CO的热重排反应的机理,给出了活化能和IRC途径,讨论了活化能与取代基R′和迁移基R的性质之间的内在联系.  相似文献   

12.
与四唑相同,对位取代苯基四唑有两种异构体(见图1).几十年来,实验工作者对这类化合物在医药和农业等方面的应用研究表现出浓厚兴趣[‘-‘1.最近,我们用从头计算和PM3等方法研究了四唑两种异构体间异构化反应的机理问.为了探明这类反应的取代基效应,本文报导用PM3方法[6]  相似文献   

13.
The mechanism of the liberation reaction of the N-oxide group has been studied and compared with the methylation reaction using a semi-empirical molecular orbital PM3 method. By comparing the calculated values of Gibbs free energy of activation, we can determine whether a liberation reaction or methylation reaction occurs.  相似文献   

14.
The activation energy is the minimum amount of energy required to initiate a reaction. It is one of the important indexes for appraising a reaction. The chemical reaction rate is closely related to the value of activation energy, and reducing activation energy is propitious to promoting a chemical reaction. In the present paper, the relationship between the activation energy in Si-KOH reaction system and the ultrasound frequency and power has been discussed for the first time. The range of ultrasound frequency and power is 40-100kHz (interval by 20kHz) and 10-50W (interval by 10W), respectively. The experimental clata indicate that the activation energy decreases with the increasing ultrasound power. Comparing with the activation energy without ultrasound irradiation, the results in our paper indicate that ultrasound irradiation could reduce the activation energy in Si-KOH reaction system and increase the reaction rate.  相似文献   

15.
选取海萤类似物6-芳基-2-甲基咪唑[1,2-α]吡嗪-3(7H)酮环的C6位取代物(命名为MIPa~MIPd)进行理论研究. 采用密度泛涵理论B3LYP方法在气相和二甲亚砜(DMSO)及二甘醇二甲醚(DG)两种溶剂中, 对这些类似物在脱去二氧化碳反应过程中所涉及的2个反应路径的反应活化能和产物激发态的荧光寿命进行了计算, 结果表明, 取代吡嗪酮的过氧化四元环在DMSO溶剂中的反应活化能较低, 给电子基团作为取代基时反应更快. 在DMSO溶剂中, 路径Ⅱ的荧光量子效率比路径Ⅰ的高, 但在DG溶剂中, 路径Ⅰ的荧光效率高于路径Ⅱ的荧光效率.  相似文献   

16.
The enthalpy change of formation of the reaction of hydrous dysprosium chloride with ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phen·H2O) in absolute ethanol at 298.15 K has been determined as (-16.12±0.05) kJ·mol-1 by a microcalor-meter. Thermodynamic parameters (the activation enthalpy, the activation entropy and the activation free energy), rate constant and kinetics parameters (the apparent activation energy, the pre-exponential constant and the reaction order) of the reaction have also been calculated. The enthalpy change of the solid-phase reaction at 298.15 K has been obtained as (53.59±0.29) kJ·mol-1 by a thermochemistry cycle. The values of the enthalpy change of formation both in liquid-phase and solid-phase reaction indicated that the complex could only be synthesized in liquid-phase reaction.  相似文献   

17.
A series of dimolybdenum metal catalysts with different ligand have been successfully synthesized and used to catalyze the epoxidation of alkenes to generate epoxides by using tert-butyl-hydroperoxide (TBHP) as oxidant. The reaction condition was optimized by the adjustment of some key parameters, such as, temperature, to target high catalytic performance. The oxidation of cyclooctene gave 95.00% conversion and almost 100.00% selectivity. Kinetic study of the oxidation of cyclooctene under different temperature was taken out, indicating the reaction have good catalytic performance. Furthermore, it is calculated from the Arrhenius equation that different functional groups affect the activation energy of the reaction. The electron donor group substituent on the liagnd increases the catalytic activity by reducing the activation energy, and vice versa. Finally, a possible catalytic mechanism has been proposed by measuring the electronic absorption spectrum of the reaction.  相似文献   

18.
粒度对多相反应动力学参数的影响   总被引:1,自引:0,他引:1  
以纳米氧化锌与硫酸氢钠溶液为反应体系, 研究反应物粒度对动力学参数的影响规律. 讨论了表观活化能降低的原因. 结果表明:当反应物粒径、反应温度和搅拌速率一定时, 纳米氧化锌与硫酸氢钠溶液的反应速率仅与反应物的浓度有关;反应物粒度对多相反应的反应级数、速率常数、表观活化能和指前因子均有较大的影响;随着反应物粒径的减小, 表观活化能和指前因子减小, 而反应级数和速率常数增大, 并且速率常数和表观活化能与反应物粒径的倒数呈线性关系;反应物粒度是通过摩尔表面积、摩尔表面能和摩尔表面熵三个方面影响多相反应的动力学参数的.  相似文献   

19.
A recently developed ab initio MO theory including solvent effects has been applied to a typical cation-anion reaction, the SN2 reaction of the trimethylsulfonium cation with the chloride anion. In the gas phase, the trimethylsulfonium and chloride ions are unstabilized, and the reaction is expected to proceed rapidly. In aqueous solution, the reactant ions are largely stabilized, and the reaction has been predicted to be endothermic, with an activation energy of 30–40 kcal/mol. This potential energy profile, which agrees with experimental results, has been well elucidated by differential solvation at several stages of the reaction path. At the transition state of this reaction, the C and H atoms in the transferring CH3 group are almost in a plane that is perpendicular to the Cl(SINGLE BOND)C(SINGLE BOND)S line, reflecting the concerted nature of the reaction. The population analysis has shown that the electrons in the C(SINGLE BOND)S bond are mostly withdrawn by the sulfur atom at the transition state and that the electron transfer from Cl to CH3 occurs after the transition state. The calculated activation energy for the reaction in ethanol is smaller than that in water. This agrees with experiments. © 1996 John Wiley & Sons, Inc.  相似文献   

20.
The kinetics of the imidazole-catalyzed decomposition of bis(2,4,6-trichlorophenyl) oxalate (TCPO) and bis(2,4-dinitrophenyl) oxalate (DNPO) was investigated by the stopped-flow technique. Pseudo-first-order rate constants were determined as a function imidazole concentration in the temperature range 6-45 degrees C by fitting the temporal changes in absorbance throughout the 245 to 345 nm wavelength range for TCPO and at 420 nm for DNPO. The reaction proceeds by release of two molecules of substituted phenol and formation of 1,1'-oxalyldiimidazole (ODI) for both esters. The identity of ODI was confirmed in the reaction of imidazole with TCPO by its UV absorbance spectrum and (13)C-NMR spectrum. The reaction of imidazole with TCPO has a second-order dependence on imidazole concentration and an observed negative activation energy of -6.2 +/- 0.3 kJ/mol, whereas the DNPO reaction has a first-order dependence on imidazole concentration and an observed positive activation energy of 12.0 +/- 0.6 kJ/mol. The differences in the temperature dependence and order of the reaction with respect to imidazole for the two oxalate esters are explained by a shift in the rate-determining step from addition to the acyl group for DNPO to imidazole-catalyzed release of the phenol leaving group for TCPO. These kinetics results are useful in interpreting the initial reaction steps in peroxyoxalate chemiluminescence.  相似文献   

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