Dramatic reduction in the activation barrier for dinitrogen splitting using amine–borane as a hydrogen carrier: insights from the DFT study

2014 ◽  
Vol 50 (17) ◽  
pp. 2187 ◽  
Author(s):  
Tanmay Malakar ◽  
Ankan Paul
Keyword(s):  
Activation Barrier ◽  
Dft Study ◽  
Dramatic Reduction ◽  
Hydrogen Carrier

A single-atom catalyst of cobalt supported on a defective two-dimensional boron nitride material as a promising electrocatalyst for the oxygen reduction reaction: a DFT study

2019 ◽  
Vol 21 (13) ◽  
pp. 6900-6907 ◽  
Author(s):  
Chaofang Deng ◽  
Rongxing He ◽  
Wei Shen ◽  
Ming Li ◽  
Tao Zhang
Keyword(s):  
Boron Nitride ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Activation Barrier ◽  
Reduction Reaction ◽  
Dft Study ◽  
Single Atom ◽  
Two Dimensional ◽  
Nitride Material

Single cobalt atoms supported by a defective two-dimensional boron nitride material catalyze the ORR via a direct 4e− pathway with a largest activation barrier of 0.3 eV.

DFT study of phenol alkylation with propylene on H-BEA in the absence and presence of water

2021 ◽  
Author(s):  
Sajal Kanti Dutta ◽  
Vishal Agarwal
Keyword(s):  
Transition State ◽  
Transition State Theory ◽  
Rate Coefficient ◽  
Activation Barrier ◽  
State Theory ◽  
Dft Study ◽  
Phenol Alkylation ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

Water reduces the activation barrier of the rate-limiting step of phenol alkylation with propylene in H-BEA. This, in turn, increases the transition-state theory rate coefficient by two orders-of-magnitude, suggesting much faster alkylation.

Comparison of Progressive Antithrombin Activity and the Concentration of Three Thrombin Inhibitors in Nephrotic Syndrome

1981 ◽  
Vol 46 (03) ◽  
pp. 623-625 ◽  
Author(s):  
B Boneu ◽  
F Bouissou ◽  
M Abbal ◽  
P Sie ◽  
C Caranobe ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Antithrombin Iii ◽  
Heparin Therapy ◽  
Thrombin Inhibitors ◽  
Compensatory Mechanism ◽  
Dramatic Reduction ◽  
Antithrombin Activity ◽  
Α2 Macroglobulin ◽  
At Iii ◽  
A Prospective Study

SummaryIn order to compare the plasmatic progressive antithrombin activity to the concentration of three thrombin inhibitors, antithrombin III (AT III), α2 macroglobulin (α2, M), α1 anti-trypsin (α1 AT) in nephrotic syndrome, a prospective study was carried out on a group of 28 children affected with the disease. A dramatic reduction of the level of AT III and of α1 AT, two inhibitors of molecular weight close to that of albumin, was observed. The decreased level of AT III was counterbalanced by an increase in α2 M. This phenomenon accounts for the increased progressive antithrombin activity observed in all the affected children. It is suggested that the above compensatory mechanism explains the absence of thrombotic accidents in this series and that the benefit of heparin therapy is doubtful in these conditions.

DFT study of the effect of hidrocarbonated chains on the electronic properties of some oligothiophene derivatives

2009 ◽  
Author(s):  
Manuel Fernández-Gómez ◽  
Amparo Navarro ◽  
MªPaz Fernández-Liencres ◽  
Mónica Moral ◽  
José Manuel Granadino-Roldán ◽  
...  
Keyword(s):  
Electronic Properties ◽  
Dft Study

Hydrostibination of Alkynes: A Radical Mechanism

2020 ◽  
Author(s):  
Josh MacMillan ◽  
Katherine Marczenko ◽  
Erin Johnson ◽  
Saurabh Chitnis
Keyword(s):  
Density Functional ◽  
Activation Barrier ◽  
Closed Shell ◽  
Reaction Rates ◽  
Radical Mechanism ◽  
Neutral Radical ◽  
Kinetic Isotope ◽  
Rate Limiting Step ◽  
Ionic Mechanisms ◽  
Terminal Acetylenes

The addition of Sb-H bonds to alkynes was reported recently as a new hydroelementation reaction that exclusively yields anti-Markovnikov <i>Z</i>-olefins from terminal acetylenes. We examine four possible mechanisms that are consistent with the observed stereochemical and regiochemical outcomes. A comprehensive analysis of solvent, substituent, isotope, additive, and temperature effects on hydrostibination reaction rates definitively refutes three ionic mechanisms involving closed-shell charged intermediates. Instead the data support a fourth pathway featuring neutral radical Sb<sup>II</sup> and Sb<sup>III</sup> intermediates. Density Functional Theory (DFT) calculations are consistent this model, predicting an activation barrier that is within 1 kcal mol<sup>-1</sup> of the experimental value (Eyring analysis) and a rate limiting step that is congruent with experimental kinetic isotope effect. We therefore conclude that hydrostibination of arylacetylenes is initiated by the generation of stibinyl radicals, which then participate in a cycle featuring Sb<sup>II</sup> and Sb<sup>III</sup> intermediates to yield the observed <i>Z</i>-olefins as products. This mechanistic understanding will enable rational evolution of hydrostibination as a methodology for accessing challenging products such as <i>E</i>-olefins.

Sign in / Sign up

Export Citation Format

Share Document