First principle simulation on oxidation mechanism of diethyl ether by nitrogen dioxide

2015 ◽  
Vol 14 (03) ◽  
pp. 1550020 ◽  
Author(s):  
Yuan Yuan ◽  
Wei Hu ◽  
Xuhui Chi ◽  
Cuihua Li ◽  
Dayong Gui ◽  
...  
Keyword(s):  
Diethyl Ether ◽  
Energy Barrier ◽  
Density Functional ◽  
Oxidation Process ◽  
Oxidation Mechanism ◽  
High Energy ◽  
First Principle ◽  
Functional Theory ◽  
The Third ◽  
High Energy Barrier

The oxidation mechanism of diethyl ethers by NO2was carried out using density functional theory (DFT) at the B3LYP/6-31+G (d, p) level. The oxidation process of ether follows four steps. First, the diethyl ether reacts with NO2to produce HNO2and diethyl ether radical with an energy barrier of 20.62 kcal ⋅ mol-1. Then, the diethyl ether radical formed in the first step directly combines with NO2to form CH3CH ( ONO ) OCH2CH3. In the third step, the CH3CH ( ONO ) OCH2CH3was further decomposed into the CH3CH2ONO and CH3CHO with a moderately high energy barrier of 32.87 kcal ⋅ mol-1. Finally, the CH3CH2ONO continues to react with NO2to yield CH3CHO , HNO2and NO with an energy barrier of 28.13 kcal ⋅ mol-1. The calculated oxidation mechanism agrees well with Nishiguchi and Okamoto's experiment and proposal.

A THEORETICAL STUDY OF UNSATURATED OLEFIN HYDROGENATION AND ISOMERIZATION ON Pd(111)

2008 ◽  
Vol 15 (03) ◽  
pp. 249-259 ◽  
Author(s):  
PATRICIA G. BELELLI ◽  
NORBERTO J. CASTELLANI
Keyword(s):  
Energy Barrier ◽  
Density Functional ◽  
Theoretical Study ◽  
High Energy ◽  
Slab Model ◽  
Functional Theory ◽  
Hydrogen Addition ◽  
High Energy Barrier ◽  
The Density Functional Theory ◽  
Cis And Trans

The addition of hydrogen to the carbon–carbon double bond of 2-butenes adsorbed on Pd (111) was studied within the density functional theory (DFT) and using a periodic slab model. For that purpose, the Horiuti–Polanyi mechanisms for both complete hydrogenation and isomerization were considered. The hydrogenation of cis and trans-2-butene to produce butane proceeds via the formation of eclipsed and staggered-2-butyl intermediates, respectively. In both cases, a relatively high energy barrier to produce the half-hydrogenated intermediate makes the first hydrogen addition the slowest step of the reaction. The competitive production of trans-2-butene from cis-2-butene requires the conversion from the eclipsed-2-butyl to the staggered-2-butyl isomer. As the corresponding energy barrier is relatively small and because the first of these isomers is less stable than the second, an easy conversion is predicted.

scholarly journals Revisiting the reactivity between HCO and CH3 on interstellar grain surfaces

2020 ◽  
Vol 493 (2) ◽  
pp. 2523-2527 ◽  
Author(s):  
J Enrique-Romero ◽  
S Álvarez-Barcia ◽  
F J Kolb ◽  
A Rimola ◽  
C Ceccarelli ◽  
...  
Keyword(s):  
Water Molecule ◽  
Energy Barrier ◽  
Density Functional ◽  
High Energy ◽  
Functional Theory ◽  
Radical Coupling ◽  
High Energy Barrier ◽  
Single Water Molecule ◽  
Complex Organic

ABSTRACT The formation of interstellar complex organic molecules is currently thought to be dominated by the barrierless coupling between radicals on the interstellar icy grain surfaces. Previous standard density functional theory (DFT) results on the reactivity between CH3 and HCO on amorphous water surfaces showed that the formation of CH4 + CO by H transfer from HCO to CH3 assisted by water molecules of the ice was the dominant channel. However, the adopted description of the electronic structure of the biradical (i.e. CH3/HCO) system was inadequate [without the broken-symmetry (BS) approach]. In this work, we revisit the original results by means of BS-DFT both in gas phase and with one water molecule simulating the role of the ice. Results indicate that the adoption of BS-DFT is mandatory to describe properly biradical systems. In the presence of the single water molecule, the water-assisted H transfer exhibits a high energy barrier. In contrast, CH3CHO formation is found to be barrierless. However, direct H transfer from HCO to CH3 to give CO and CH4 presents a very low energy barrier, hence being a potential competitive channel to the radical coupling and indicating, moreover, that the physical insights of the original work remain valid.

scholarly journals High Throughput Virtual Screening of 230 Billion Molecular Solar Heat Battery Candidates

2020 ◽  
Author(s):  
Mads Koerstz ◽  
Anders S. Christensen ◽  
Kurt V. Mikkelsen ◽  
Mogens Brøndsted Nielsen ◽  
Jan H. Jensen
Keyword(s):  
Free Energy ◽  
Energy Barrier ◽  
Density Functional ◽  
Parent Compound ◽  
High Energy ◽  
Back Reaction ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Practical Applications ◽  
Quantum Chemical Methods

<div>The dihydroazulene/vinylheptafulvene (DHA/VHF) thermocouple is a promising can- didate for thermal heat batteries that absorb and store solar energy as chemical energy without the need for insulation. However, in order to be viable the energy storage capacity and lifetime of the high energy form (i.e. the free energy barrier to the back reaction) of the canonical parent compound must be increased significantly to be of practical use. We use semiempirical quantum chemical methods, machine learning, and density functional theory to virtually screen over 230 billion substituted DHA molecules to identify promis- ing candidates. We identify a molecule with a predicted energy density of 0.38 kJ/g, which is significantly larger than the 0.14 kJ/g computed for the parent compound. The free energy barrier to the back reaction is 11 kJ/mol higher than the parent compound, which should correspond to a half-life of about 10 days - 4 months. This is considerably longer than the 3-39 hours (depending on solvent) observed for the parent compound and sufficiently long for many practical applications. However, the main conclusion of this study is that there are no molecules among the 230 billion with a storage density approaching 1 kJ/g.<br></div>

scholarly journals High Throughput Virtual Screening of 230 Billion Molecular Solar Heat Battery Candidates

2020 ◽  
Author(s):  
Mads Koerstz ◽  
Anders S. Christensen ◽  
Kurt V. Mikkelsen ◽  
Mogens Brøndsted Nielsen ◽  
Jan H. Jensen
Keyword(s):  
Free Energy ◽  
Energy Barrier ◽  
Density Functional ◽  
Parent Compound ◽  
High Energy ◽  
Back Reaction ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Practical Applications ◽  
Quantum Chemical Methods

<div>The dihydroazulene/vinylheptafulvene (DHA/VHF) thermocouple is a promising can- didate for thermal heat batteries that absorb and store solar energy as chemical energy without the need for insulation. However, in order to be viable the energy storage capacity and lifetime of the high energy form (i.e. the free energy barrier to the back reaction) of the canonical parent compound must be increased significantly to be of practical use. We use semiempirical quantum chemical methods, machine learning, and density functional theory to virtually screen over 230 billion substituted DHA molecules to identify promis- ing candidates. We identify a molecule with a predicted energy density of 0.38 kJ/g, which is significantly larger than the 0.14 kJ/g computed for the parent compound. The free energy barrier to the back reaction is 11 kJ/mol higher than the parent compound, which should correspond to a half-life of about 10 days - 4 months. This is considerably longer than the 3-39 hours (depending on solvent) observed for the parent compound and sufficiently long for many practical applications. However, the main conclusion of this study is that there are no molecules among the 230 billion with a storage density approaching 1 kJ/g.<br></div>

DFT study on the hydrolysis of metsulfuron-methyl: A sulfonylurea herbicide

2018 ◽  
Vol 17 (08) ◽  
pp. 1850050 ◽  
Author(s):  
Qiuhan Luo ◽  
Gang Li ◽  
Junping Xiao ◽  
Chunhui Yin ◽  
Yahui He ◽  
...  
Keyword(s):  
Free Energy ◽  
Water Molecule ◽  
Carbonyl Group ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Metsulfuron Methyl ◽  
Catalytic Role ◽  
Hydrolysis Of

Sulfonylureas are an important group of herbicides widely used for a range of weeds and grasses control particularly in cereals. However, some of them tend to persist for years in environments. Hydrolysis is the primary pathway for their degradation. To understand the hydrolysis behavior of sulfonylurea herbicides, the hydrolysis mechanism of metsulfuron-methyl, a typical sulfonylurea, was investigated using density functional theory (DFT) at the B3LYP/6-31[Formula: see text]G(d,p) level. The hydrolysis of metsulfuron-methyl resembles nucleophilic substitution by a water molecule attacking the carbonyl group from aryl side (pathway a) or from heterocycle side (pathway b). In the direct hydrolysis, the carbonyl group is directly attacked by one water molecule to form benzene sulfonamide or heterocyclic amine; the free energy barrier is about 52–58[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. In the autocatalytic hydrolysis, with the second water molecule acting as a catalyst, the free energy barrier, which is about 43–45[Formula: see text]kcal[Formula: see text]mol[Formula: see text], is remarkably reduced by about 11[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is obvious that water molecules play a significant catalytic role during the hydrolysis of sulfonylureas.

Enhancing the energy barrier and hysteresis temperature in two benchtop-stable Ho(III) single-ion magnets

2021 ◽  
Author(s):  
Kexin Jia ◽  
Xixi Meng ◽  
Mengmeng Wang ◽  
Xiaoshuang Gou ◽  
Yu-Xia Wang ◽  
...  
Keyword(s):  
Energy Barrier ◽  
High Energy ◽  
Halogen Anion ◽  
High Energy Barrier

The energy barrier and hysteresis temperature in two benchtop-stable D5h-symmetry HoIII single-ion magnets were significantly enhanced via the variation of halogen anion. The coexistence of high energy barrier of 418...

scholarly journals Insights on forming N,O-coordinated Cu single-atom catalysts for electrochemical reduction CO2 to methane

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yanming Cai ◽  
Jiaju Fu ◽  
Yang Zhou ◽  
Yu-Chung Chang ◽  
Qianhao Min ◽  
...  
Keyword(s):  
Energy Barrier ◽  
Active Sites ◽  
Theoretical Calculations ◽  
High Energy ◽  
Single Atom ◽  
Faradaic Efficiency ◽  
High Energy Barrier ◽  
Catalytic Sites ◽  
Electron Reduction ◽  
First Time

AbstractSingle-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO2 reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN2O2 sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO2 to CH4 with current density of 40 mA·cm-2 in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN2O2 active sites are due to the proper elevated CH4 and H2 energy barrier and fine-tuned electronic structure of Cu active sites.

Slow magnetic relaxation in dinuclear dysprosium and holmium phenoxide bridged complexes: a Dy2 single molecule magnet with a high energy barrier

2021 ◽  
Author(s):  
Matilde Fondo ◽  
Julio Corredoira-Vázquez ◽  
Ana M. Garcia-Deibe ◽  
Jesus Sanmartin Matalobos ◽  
Silvia Gómez-Coca ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Single Molecule ◽  
Energy Barrier ◽  
Magnetic Relaxation ◽  
High Energy ◽  
Single Molecule Magnet ◽  
High Energy Barrier ◽  
Slow Magnetic Relaxation

Dinuclear [M(H3L1,2,4)]2 (M = Dy, Dy2; M = Ho, Ho2) complexes were isolated from an heptadentate aminophenol ligand. The crystal structures of Dy2·2THF, and the pyridine adducts Dy2·2Py and Ho2·2Py,...

Estimating the adsorption energy of element 113 on a gold surface

Open Physics ◽  
2013 ◽  
Vol 11 (11) ◽  
Author(s):  
Alexander Rusakov ◽  
Yuriy Demidov ◽  
Andréi Zaitsevskii
Keyword(s):  
Adsorption Energy ◽  
Cluster Size ◽  
Density Functional ◽  
Gold Surface ◽  
Gold Clusters ◽  
Basis Sets ◽  
Energy Estimates ◽  
First Principle ◽  
Gaussian Basis Sets ◽  
Functional Theory

AbstractWe report first-principle based studies of element 113 (E113) interactions with gold aimed primarily at estimating the adsorption energy in thermochromatographic experiments. The electronic structure of E113-Aun systems was treated within the accurate shape-consistent small core relativistic pseudopotential framework at the level of non-collinear relativistic density functional theory (RDFT) with specially optimised Gaussian basis sets. We used gold clusters with up to 58 atoms to simulate the adsorption site on the stable Au(111) surface. Stabilization of the E113-Aun binding energy and the net Bader charge of E113 and the neighboring Au atoms with respect to n indicated the cluster size used was appropriate. The resulting adsorption energy estimates lie within the 1.0–1.2 eV range, substantially lower than previously reported values.

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