scholarly journals On the strong difference in reactivity of acyclic and cyclic diazodiketones with thioketones: experimental results and quantum-chemical interpretation

2015 ◽  
Vol 11 ◽  
pp. 504-513 ◽  
Author(s):  
Andrey S Mereshchenko ◽  
Alexey V Ivanov ◽  
Viktor I Baranovskii ◽  
Grzegorz Mloston ◽  
Ludmila L Rodina ◽  
...  
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Quantum Chemical ◽  
Experimental Results ◽  
Free Energy Change ◽  
Energy Change ◽  
Dipolar Cycloaddition ◽  
Cyclic Structure ◽  
Gibbs Free Energy Change ◽  
Two Stages

The 1,3-dipolar cycloaddition of acyclic 2-diazo-1,3-dicarbonyl compounds (DDC) and thioketones preferably occurs with Z,E-conformers and leads to the formation of transient thiocarbonyl ylides in two stages. The thermodynamically favorable further transformation of C=S ylides bearing at least one acyl group is identified as the 1,5-electrocyclization into 1,3-oxathioles. However, in the case of diazomalonates, the dominating process is 1,3-cyclization into thiiranes followed by their spontaneous desulfurization yielding the corresponding alkenes. Finally, carbocyclic diazodiketones are much less reactive under similar conditions due to the locked cyclic structure and are unfavorable for the 1,3-dipolar cycloaddition due to the Z,Z-conformation of the diazo molecule. This structure results in high, positive values of the Gibbs free energy change for the first stage of the cycloaddition process.

Theoretical Thermodynamic Analysis and Phase Analysis of AZ91D/Flyash Composites

2014 ◽  
Vol 788 ◽  
pp. 604-607
Author(s):  
Hong Chao Chu ◽  
Si Rong Yu ◽  
Cui Xiang Wang ◽  
Qi Lou
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Minimum Principle ◽  
Solution Treatment ◽  
Entropy Change ◽  
Treatment Temperature ◽  
Free Energy Change ◽  
Energy Change ◽  
Solution Treatment Temperature ◽  
Gibbs Free Energy Change

The thermodynamic calculation is valuable for judging the feasibility of a reaction. In the present paper, the enthalpy change (∆HR), entropy change (∆SR) and Gibbs free energy change (∆GR) among various components in AZ91D Mg alloy-Cenosphere composites (FAC/AZ91D) were calculated. Through the calculation, we obtained the relationships between the Gibbs free energy changes and temperatures. The difficulty degree of every potential reaction could be directly reflected by the correlation curve between the temperature and the Gibbs free energy change. The analysis result provided the theoretical basis for the reaction temperature and the solution treatment temperature of the FAC/AZ91D system. At the same time, the analysis based on the minimum principle of the reaction free energy revealed the final components (MgO, Mg2Si and MgAl2O4), which was partially similar to the result of XRD analysis (MgO, Mg2Si and Mg17Al12).

Gibbs free energy change of a discrete chemical reaction event

2020 ◽  
Vol 152 (8) ◽  
pp. 084116
Author(s):  
Carlos Floyd ◽  
Garegin A. Papoian ◽  
Christopher Jarzynski
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Chemical Reaction ◽  
Free Energy Change ◽  
Energy Change ◽  
Gibbs Free Energy Change ◽  
Reaction Event

Behavior of Intermediate CaTiO3 in Reduction Process of TiO2 by Calcium Vapor

2013 ◽  
Vol 551 ◽  
pp. 25-31 ◽  
Author(s):  
Jin Gang Jia ◽  
Bao Qiang Xu ◽  
Bin Yang ◽  
Dong Sheng Wang ◽  
Heng Xiong ◽  
...  
Keyword(s):  
Free Energy ◽  
Titanium Oxide ◽  
Gibbs Free Energy ◽  
Reduction Process ◽  
Free Energy Change ◽  
Energy Change ◽  
Flow Sheet ◽  
Gibbs Free Energy Change ◽  
Crystal Water ◽  
Calcium Vapor

Preparing titanium powders by calcium vapor reduction of titanium oxide directly is a new way with short flow sheet and CaTiO3 is the very important intermediate compound in this process. In this paper, the behavior of intermediate CaTiO3 in the reduction process of TiO2 was investigated. The thermodynamic calculation indicated that the Gibbs free energy change of the reaction to produce CaTiO3 by CaO and TiO2 was always negative below 1000 °C; The reaction Gibbs free energy change of the calciothermic reduction of CaTiO3 was lower than that of TiO, which would be the most predominant step from TiO2 to Ti. The experimental results showed that CaTiO3 phase derived from the reaction between TiO2 and the reduction by-product CaO, and the reaction between TiO2 and the decomposition product CaO from the additive of CaCl2 with crystal water as well in the calcium vapor reduction process of titanium oxide. But CaTiO3 could be reduced to Ti much easier than that of TiO2 by calcium vapor.

Blinking Suppression in Highly Excited CdSe/ZnS Quantum Dots by Electron Transfer under Large Positive Gibbs (Free) Energy Change

ACS Nano ◽  
2018 ◽  
Vol 12 (9) ◽  
pp. 9060-9069 ◽  
Author(s):  
Elizabeth Mariam Thomas ◽  
Sushant Ghimire ◽  
Reiko Kohara ◽  
Ajith Nair Anil ◽  
Ken-ichi Yuyama ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Electron Transfer ◽  
Free Energy ◽  
Gibbs Free Energy ◽  
Free Energy Change ◽  
Energy Change ◽  
Gibbs Free Energy Change
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