Some aspects of cis–trans-isomerization mechanisms

1968 ◽  
Vol 46 (6) ◽  
pp. 973-978 ◽  
Author(s):  
M. C. Lin ◽  
K. J. Laidler
Keyword(s):  
Activation Energy ◽  
Linear Relationship ◽  
Bond Energy ◽  
Reaction Mechanisms ◽  
Compensation Effect ◽  
Trans Isomerization ◽  
Entropy Of Activation ◽  
Partial Compensation

It is shown that there is a linear relationship between the activation energy for a thermal cis–trans isomerization and the heat of hydrogenation of the C=C bond. There is also a linear relationship between the entropy of activation and the heat of activation, there being a partial compensation effect. It is pointed out that the activation energy for these processes is very close to the π-bond energy of the C=C bond. The significance of these relationships is discussed in terms of the reaction mechanisms.

Aromatic oxidation by cobaltic acetate in acetic acid

1969 ◽  
Vol 47 (3) ◽  
pp. 387-392 ◽  
Author(s):  
Koichiro Sakota ◽  
Yoshio Kamiya ◽  
Nobuto Ohta
Keyword(s):  
Activation Energy ◽  
Electron Transfer ◽  
Acetic Acid ◽  
Bond Energy ◽  
Hydrogen Abstraction ◽  
Steric Factor ◽  
Benzyl Acetate ◽  
Kcal Mole ◽  
First Order ◽  
Reversible Electron Transfer

A detailed kinetic study of oxidation of toluene and its derivatives by cobaltic acetate in 95 vol% acetic acid is reported. The reaction was found to be profoundly affected by a steric factor and rather insensitive to the C—H bond energy. The order of reactivities of various alkylbenzenes is quite reversal to that of hydrogen abstraction reactions. The reaction was of first-order with respect to toluene, of second-order with respect to cobaltic ion and of inverse first-order with respect to cobaltous ion. The oxidation by cobaltic ion seems to proceed via an initial reversible electron transfer from toluene to cobaltic ion, yielding [Formula: see text] which is oxidized into benzyl acetate by another cobaltic ion. The apparent activation energy for toluene was found to be 25.3 kcal mole−1, and the same activation energy was found for ethylbenzene, cumene, diphenylmethane, and triphenylmethane.

On the Possibility to Observe a Compensation Effect around the Glass Transition Temperature

2006 ◽  
Vol 514-516 ◽  
pp. 1462-1466
Author(s):  
Rodica M. Neagu ◽  
José N. Marat-Mendes ◽  
Eugen R. Neagu
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Compensation Effect ◽  
Depolarization Current ◽  
Exponential Factor ◽  
Relaxation Parameters ◽  
Maximum Current ◽  
Thermally Stimulated Depolarization

Compensation has been reported for the relaxation parameters: the activation energy W and the pre-exponential factor τ0, determined from the Thermal Sampling of Thermally Stimulated Depolarization Current technique. Below the glass transition it is assumed that the relaxation time follows an Arrhenius equation. In the vicinity of glass transition temperature an experimental thermogram may be analyzed using the Vogel-Fulcher-Tamman-Hesse (VFTH) or the Williams- Landel -Ferry equation. In this article we use the VFTH relationship to study the compensation effect in the range of glass transition. For an elementary peak obtained by TS there is a relationship between the activation energy W, the temperature of the maximum current Tm, the VFTH temperature, the compensation temperature Tc and the compensation time τ c. We employ this relationship for a basic analysis of the compensation effect in the temperature range around Tg. By numerical simulations, and assuming parameters similar to those measured experimentally, we show that it is possible to observe a compensation point in some well defined conditions

Correlation between the acid–base properties of the La2O3 catalyst and its methane reactivity

2016 ◽  
Vol 18 (24) ◽  
pp. 16509-16517 ◽  
Author(s):  
Changqing Chu ◽  
Yonghui Zhao ◽  
Shenggang Li ◽  
Yuhan Sun
Keyword(s):  
Activation Energy ◽  
Linear Relationship ◽  
Acid Base ◽  
Chemisorption Energy ◽  
Base Properties

The linear relationship between CH4 activation energy and CO2 chemisorption energy illuminates the high OCM activity of strongly basic La2O3 catalysts.

scholarly journals Thermodynamic model and kinetic compensation effect of oil sludge pyrolysis based on thermogravimetric analysis

2020 ◽  
pp. 350-350
Author(s):  
Hui Liu ◽  
Chenglang Xiang ◽  
Jie Mu ◽  
Jieyu Yao ◽  
Dong Ye ◽  
...  
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Compensation Effect ◽  
Thermodynamic Characteristics ◽  
Oil Sludge ◽  
High Heating Rate ◽  
Thermodynamic Models ◽  
Heating Rates ◽  
Kinetic Compensation Effect ◽  
Exponential Factor

Oil sludge (OS) is an organic solid waste in the petrochemical industry and improper treatment of OS will cause environmental pollution. Pyrolysis is an effective way to realize its resource reuse. In order to understand the pyrolysis behavior and thermodynamic characteristics of OS, four OS samples from storage tanks were used as the research object, and pyrolysis experiments were carried out at heating rates of 5, 10, and 15?/min under a nitrogen atmosphere. The kinetic parameters of pyrolysis of OS are calculated by three equal conversion methods (Friedman method (FR), Flynn-Wall-Ozawa method (FWO) and Distributed activation energy model (DAEM)), and the most possible thermodynamic models for the main pyrolysis phase were analyzed and discussed by introducing the Malek method. The results show: High heating rate can promote the pyrolysis of OS; In the pyrolysis stage, the apparent activation energy increases with the increase of the conversion rate. The apparent activation energy calculated by the FR method is more reliable. The average apparent activation energies of the four OS are 221.23, 84.71, 94.67 and 116.56 kJ/mol, respectively. The apparent activation energy and the pre-exponential factor are positively correlated, indicating that there is a kinetic compensation effect in the pyrolysis process. The thermodynamic models of the four OS samples are all three-dimensional diffusion models, but their integral functions are different. The research results can provide theoretical support for the industrialization, harmlessness and resource utilization of OS pyrolysis.

scholarly journals On the nature of crystallization water using thermal analysis. - The application to some hydrates with different cations

1999 ◽  
Vol 64 (12) ◽  
pp. 737-744
Author(s):  
Lucia Odochian ◽  
Magdelena Pantea ◽  
Irina Calugareanu ◽  
Dana Ionescu ◽  
Olga Vicol
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Kinetic Parameters ◽  
Compensation Effect ◽  
Crystallization Water ◽  
Water Elimination ◽  
Thermogravimetric Data ◽  
Dta Analysis ◽  
Derivative Thermogravimetry

The nature of the crystallization water in some hydrates with different cations, namely: MnSO4?H2O; FeSO4?7H2O; CoSO4?7H2O; NiSO4?7H2O, has been studied by the application of the following non-isothermal techniques: thermogravimetry (TG), derivative thermogravimetry (DTG), and differential thermal analysis (DTA). Analysis of the characteristic thermogravimetric data (Tm, W ) and of the kinetic parameters (n, Ea) calculated from DTG and DTA data - with CuSO4?5H2O as a reference - demonstrated the existence of crystallization and anionwater in the studiedhydrates. The activation energy of the process of anion water elimination does not depend on the nature of the cation. This conclusion was confirmed by the absence of the compensation effect in this process.

Topological Unraveling the [3+2] Cycloaddition (32CA) Reaction between N-Methylphenylnitrone and Styrene Catalyzed by Chromium Tricarbonyl Complex from Electron Localization Function and Catastrophe Theory.

2021 ◽  
Author(s):  
Abel Idrice I ADJIEUFACK ◽  
Jean Moto Ongagna ◽  
Joseline Flore KENMOGNE KENMOGNE ◽  
Ibrahim M. Mbouombouo Ndassa
Keyword(s):  
Activation Energy ◽  
Catastrophe Theory ◽  
Reaction Mechanisms ◽  
Energy Analysis ◽  
Electron Localization Function ◽  
Electron Localization ◽  
Tricarbonyl Complex ◽  
Chromium Tricarbonyl ◽  
Localization Function

We have investigated the reaction mechanisms of [3+2] cycloaddition (32CA) between N-methylphenylnitrone and styrene catalyzed by chromium tricarbonyl complex at the MPWB1K/6-311G(d,p) level of approximation. Activation energy analysis reveals that...

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