Calculation of the enthalpies of formation of free radicals and the energies of dissociation of chemical bonds by the group contribution method. Communication 3. Compounds with electronegative substituents

1984 ◽  
Vol 33 (7) ◽  
pp. 1424-1428
Author(s):  
Yu. D. Orlov ◽  
Yu. A. Lebedev ◽  
B. L. Korsunskii
Keyword(s):  
Free Radicals ◽  
Group Contribution ◽  
Enthalpies Of Formation ◽  
Chemical Bonds ◽  
Group Contribution Method

scholarly journals Temperature-dependent estimation of Gibbs energies using an updated group contribution method

2018 ◽  
Author(s):  
Bin Du ◽  
Zhen Zhang ◽  
Sharon Gruber ◽  
James T. Yurkovich ◽  
Bernhard O. Palsson ◽  
...  
Keyword(s):  
Metal Ion ◽  
Equilibrium Constants ◽  
Binding Constants ◽  
Entropy Change ◽  
Group Contribution ◽  
Mass Action ◽  
Enthalpies Of Formation ◽  
Standard Entropy ◽  
Group Contribution Method ◽  
Reaction Equilibrium

AbstractReaction equilibrium constants determine the mass action ratios necessary to drive flux through metabolic pathways. Group contribution methods offer a way to estimate reaction equilibrium constants at wide coverage across the metabolic network. Here, we present an updated group contribution method with: 1) additional curated thermodynamic data used in fitting; and 2) capabilities to calculate equilibrium constants as a function of temperature. We first collected and curated aqueous thermo-dynamic data, including reaction equilibrium constants, enthalpies of reaction, Gibbs free energies of formation, enthalpies of formation, entropies change of formation of compounds, and proton and metal ion binding constants. We further estimated magnesium binding constants for 618 compounds using a linear regression model validated against measured data. Next, we formulated the calculation of equilibrium constants as a function of temperature and calculated necessary parameters, including standard entropy change of formation (ΔfS∘) and standard entropy change of reaction (ΔrS∘), using a model based on molecular properties. The median absolute errors in estimating ΔfS∘ and ΔrS∘ were 0.010 kJ/K/mol and 0.018 kJ/K/mol, respectively. The efforts here fill in gaps for thermodynamic calculations under various conditions, specifically different temperatures and metal ion concentrations. These results support the study of thermodynamic driving forces underlying the metabolic function of organisms living under diverse conditions.

Mechanochemical Phenomena in Polymers. II. The Effects of Initiators and Inhibitors of Chain Processes

1963 ◽  
Vol 36 (2) ◽  
pp. 480-487
Author(s):  
E. V. Reztsova ◽  
B. T. Kipkina ◽  
G. L. Slonimskii
Keyword(s):  
Free Radicals ◽  
Fatigue Resistance ◽  
Substantial Effect ◽  
Chemical Bonds ◽  
Chain Processes ◽  
Radical Processes ◽  
Effect Of Inhibitors ◽  
Dynamic Fatigue

Abstract 1. The substantial effect of inhibitors and initiators of chain radical processes on the change in the properties of rubbers in milling, as well as on the resistance of vulcanizates to fatigue, has been shown. This indicates a mechanochemical mechanism for processing of polymers and in the fatigue of elastomers. The act of mechanical scission of chemical bonds, with the formation of free radicals which initiate the secondary chain processes, rests on these processes. 2. The possibility has been shown of regulating the properties of polymers during processing, and also of increasing the dynamic fatigue resistance of vulcanizates by incorporating small quantities of additives active in regard to free radicals.

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