scholarly journals Application of β-Phosphorylated Nitroethenes in [3+2] Cycloaddition Reactions Involving Benzonitrile N-Oxide in the Light of a DFT Computational Study

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 26-37
Author(s):  
Karolina Zawadzińska ◽  
Karolina Kula
Keyword(s):  
Density Functional ◽  
Reaction Path ◽  
Computational Study ◽  
Cyano Group ◽  
Cycloaddition Reactions ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Reaction Channels ◽  
One Step ◽  
Step Mechanism

The regiochemistry of [3+2] cycloaddition (32CA) processes between benzonitrile N-oxide 1 and β-phosphorylated analogues of nitroethenes 2a–c has been studied using the Density Functional Theory (DFT) at the M062X/6-31+G(d) theory level. The obtained results of reactivity indices show that benzonitrile N-oxide 1 can be classified both as a moderate electrophile and moderate nucleophile, while β-phosphorylated analogues of nitroethenes 2a–c can be classified as strong electrophiles and marginal nucleophiles. Moreover, the analysis of CDFT shows that for [3+2] cycloadditions with the participation of β-phosphorylatednitroethene 2a and β-phosphorylated α-cyanonitroethene 2b, the more favored reaction path forms 4-nitro-substituted Δ2-isoxazolines 3a–b, while for a reaction with β-phosphorylated β-cyanonitroethene 2c, the more favored path forms 5-nitro-substituted Δ2-isoxazoline 4c. This is due to the presence of a cyano group in the alkene. The CDFT study correlates well with the analysis of the kinetic description of the considered reaction channels. Moreover, DFT calculations have proven the clearly polar nature of all analyzed [3+2] cycloaddition reactions according to the polar one-step mechanism.

Mechanism and regioselectivity of 1,3-dipolar cycloaddition reactions of bicyclic monoterpenes with aryl and heteroaryl nitrile oxides: a DFT study

2015 ◽  
Vol 93 (7) ◽  
pp. 749-753 ◽  
Author(s):  
Hossein Eshghi ◽  
Amir Khojastehnezhad ◽  
Farid Moeinpour ◽  
Mehdi Bakavoli
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Energy Surface ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Functional Theory ◽  
Nitrile Oxides ◽  
Reactivity Indices ◽  
One Step ◽  
Step Mechanism

The reactivity and regioselectivity of 1,3-dipolar cycloaddition reactions of aryl and heteroaryl nitrile oxides (1a–1c) with bicyclic monoterpenes (R)-(+)-a-pinene (2a) and (S)-(–)-b-pinene (2b) have been investigated by using density functional theory based on reactivity indices and activation energy calculations at the B3LYP/6-31G(d) level of theory in the gas phase. The potential energy surface analyses for both reactions are in agreement with the experimental observations. Moreover, our calculations on the geometries, bond orders, and global electron density transfers at the transition state structures shows that these 1,3- dipolar cycloaddition reactions occur via an asynchronous one-step mechanism.

scholarly journals MNDO and DFT Computational Study on the Mechanism of the Oxidation of 1,2-Diphenylhydrazine by Iodine

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Gideon A. Shallangwa ◽  
Adamu Uzairu ◽  
Victor O. Ajibola ◽  
Hamza Abba
Keyword(s):  
Reaction Mechanisms ◽  
Density Functional ◽  
Computational Study ◽  
The Other ◽  
Complex Mechanism ◽  
Functional Theory ◽  
One Step ◽  
The One ◽  
Activated Complex ◽  
Step Mechanism

The reaction mechanisms of the oxidation of 1,2-diphenylhydrazine by iodine have been examined using semiempirical and density functional theory methods, the oxidation proceeded via two independent pathways that can be separately monitored. One pathway involved the chain multistep mechanism. The other pathway occurred via a one-step mechanism in which a “cyclic” activated complex was formed which on disproportionation gave the products. The one-step “cyclic” activated complex mechanism proceeds more rapidly than the chain multistep mechanism. The results were explained by analyses based on computational energetics of the optimised reactants, intermediates, transition states, and products of the reaction of iodine with 1,2-diphenylhydrazine.

scholarly journals Insights Into The Origin of Selectivity For [2+2] Cycloaddition Step Reaction Involved In The Mechanism of Enantioselective Reduction of Ketones With Borane Catalyzed By A B-Methoxy Oxazaborolidine Catalyst Derived From (–)-β-Pinene. A DFT And Combined Topological ELF, NCI And QTAIM Study

2021 ◽  
Author(s):  
Hichem Sadrik Kettouche
Keyword(s):  
Density Functional ◽  
Topological Analysis ◽  
Density Functional Theory Method ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Enantioselective Reduction ◽  
The Density Functional Theory ◽  
One Step ◽  
Step Mechanism ◽  
Reduction Of Ketones

Abstract Theoretical studies on [2+2] cycloaddition step involved in the Enantioselective Reduction of ketones with borane catalyzed by a B-MethoxyOxazaborolidine Catalyst Derived from Pinene has been performed by means of the Density Functional Theory method (DFT) at MPWB1K /6-31G (d,p). The formation of the M5a(S) complexes via transition state TSa(S) was the more favorable pathway among other [2+2]cycloaddition competing steps. The explanation of the formation of O-B and N-B through two-stage one-step mechanism was allowed by means of the electron localization function (ELF) topological analysis. NCI and QTAIM analysis of the two computed transition states TSa(S) and TSa(R) indicate that the difference between both in term of stability comes mainly from the orientation of the methanediyl group inside the pinene skeleton, which implies that CH-H…O interaction found at TSa(S) is the great factor that makes it more stable than TSa(R).

scholarly journals Perfluorobicyclo[2.2.0]hex-1(4)-ene as unique partner for Diels–Alder reactions with benzene: a density functional theory study

2021 ◽  
Vol 140 (2) ◽  
Author(s):  
Agnieszka Kącka-Zych ◽  
Patricia Pérez
Keyword(s):  
Density Functional Theory ◽  
Electron Density ◽  
Density Functional ◽  
Diels Alder ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
One Step ◽  
Step Mechanism ◽  
Single Bonds ◽  
Reactivity Order

AbstractThe mechanism of the Diels–Alder reactions between perfluorobicyclo[2.2.0]hex-1(4)-ene (1a) and bicyclo[2.2.0]hex-1(4)-ene (1b) with benzene (2a) and naphthalene (2b) has been studied within the density functional theory at the MPWB1K/6-311G(d,p) level. The bonding pattern in these reactions is analyzed in the topology of the electron localization function within the bonding evolution theory perspective. The bonding electron density changes along the reaction paths reveal that the C–C bond formation takes place through a synchronous and non-concerted one-step mechanism and proceeds with a moderate activation energy. The reactivity order with 1a is 2a–2b. The reactions begin by the rupture of the double bond in the strained 1a-b molecules, and then two pseudoradical centers at the 1a-b fragments are created. Finally, at the same time, two new single bonds are formed in the cycloaddition products. The TSs proceed with high global electron density transfer providing a polar character at these reactions.

Mechanistic insight into the selective trans-1,4-polymerization of butadiene by terpyridine–iron(II) complexes — A computational study

2009 ◽  
Vol 87 (10) ◽  
pp. 1392-1405 ◽  
Author(s):  
Sven Tobisch
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Dft Method ◽  
Chain Growth ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Insertion Mechanism ◽  
Trans Regulation ◽  
Insight Into

The density functional theory (DFT) method has been employed to unravel mechanistic intricacies of the 1,4-polymerization of 1,3-butadiene mediated by the [(η3-RC3H4)FeII(C15H11N3)(η2-C4H6)]+ terpyridine–iron(II) active catalyst species. The π-allyl-insertion mechanism is operative for chain growth, whilst the alternative σ-allyl-insertion mechanism has been explicitly demonstrated as being inoperable. This study elucidates the mechanism of cis–trans regulation and unveils the factors that govern the observed high trans-1,4 stereoselectivity, in particular, the discriminative role of allylic isomerization. An atactic trans-1,4-polydiene is expected from polymerization of a terminally monosubstituted butadiene, the experimental results of which have not been reported thus far.

scholarly journals Structural characterization of kaempferol: a spectroscopic and computational study

2019 ◽  
Vol 38 (1) ◽  
pp. 49 ◽  
Author(s):  
Dejan Milenković ◽  
Jasmina M Dimitrić Marković ◽  
Dušan Dimić ◽  
Svetlana Jeremić ◽  
Dragan Amić ◽  
...  
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Chemical Shifts ◽  
Absolute Error ◽  
Nbo Analysis ◽  
Basis Set ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Spectroscopic Characteristics

Calculations based on the density functional theory, with the B3LYP functional and the 6-311++G(d,p) basis set, were performed with the aim of confirming the molecular structure and spectroscopic characteristics of kaempferol, a naturally occurring flavonoid molecule. The electronic structure of kaempferol was examined using NBO analysis. The assigning of the experimentally obtained IR and Raman spectra was performed after the best-fit-based comparison with theoretical spectra. The 13C and 1H NMR experimental spectra were related to the theoretically obtained values of the chemical shifts determined by the GIAO method. The correlation coefficient and the average absolute error values proved B3LYP-D3 to be an adequate method in describing the NMR parameters of kaempferol. Molecular docking analysis was carried out in order to identify the potency of inhibition of the title molecule against human procalcitonin. The inhibition activity was obtained for 10 conformations of ligand inside the protein.

scholarly journals Mechanism of Reactions of 1-Substituted Silatranes and Germatranes, 2,2-Disubstituted Silocanes and Germocanes, 1,1,1-Trisubstituted Hyposilatranes and Hypogermatranes with Alcohols (Methanol, Ethanol): DFT Study

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2803 ◽  
Author(s):  
Denis Chachkov ◽  
Rezeda Ismagilova ◽  
Yana Vereshchagina
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical ◽  
Density Functional ◽  
Activation Energies ◽  
Functional Theory ◽  
Gibbs Energies ◽  
The Density Functional Theory ◽  
Lower Activation ◽  
One Step ◽  
Intramolecular Hydrogen

The mechanism of reactions of silatranes and germatranes, and their bicyclic and monocyclic analogues with one molecule of methanol or ethanol, was studied at the Density Functional Theory (DFT) B3PW91/6-311++G(df,p) level of theory. Reactions of 1-substituted sil(germ)atranes, 2,2-disubstituted sil(germ)ocanes, and 1,1,1-trisubstituted hyposil(germ)atranes with alcohol (methanol, ethanol) proceed in one step through four-center transition states followed by the opening of a silicon or germanium skeleton and the formation of products. According to quantum chemical calculations, the activation energies and Gibbs energies of activation of reactions with methanol and ethanol are close, their values decrease in the series of atranes–ocanes–hypoatranes for interactions with both methanol and ethanol. The reactions of germanium-containing derivatives are characterized by lower activation energies in comparison with the reactions of corresponding silicon-containing compounds. The annular configurations of the product molecules with electronegative substituents are stabilized by the transannular N→X (X = Si, Ge) bond and different intramolecular hydrogen contacts with the participation of heteroatoms of substituents at the silicon or germanium.

Tritium adsorption in the lithium vacancy of Li2ZrO3: A first principles study

2018 ◽  
Vol 29 (10) ◽  
pp. 1850103
Author(s):  
Kun Li ◽  
Wen Yang ◽  
Wei-Hua Wang ◽  
Yong-Tang Li
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Fundamental Problem ◽  
Density Functional Theory Calculations ◽  
Intrinsic Defect ◽  
Release Process ◽  
Functional Theory ◽  
Theoretical Support ◽  
The Density Functional Theory ◽  
Lithium Vacancy

Tritium adsorption in the irradiation defects of the Li2ZrO3 is a fundamental problem to understand the tritium behavior during the release process. A comprehensive computational study of tritium/helium adsorption in the lithium vacancy of bulk Li2ZrO3 is presented by the density functional theory calculations. The most stable tritium adsorption position has been found and it is determined by the neighboring lithium–oxygen interactions. The results reveal that the intrinsic defect is the lithium vacancy with one electron and it transforms to be the neutral state after a tritium atom is adsorbed. Moreover, helium is adsorbed almost in the center of lithium vacancy without bonding with surrounding oxygen atoms, which could diffuse easily in the bulk Li2ZrO3. Therefore, we predict that the intrinsic Li vacancy tends to adsorb a positive ion T[Formula: see text] other than a neutral T atom. Our results provide theoretical support to understand the T behavior in the Li2ZrO3 crystal.

DECOMPOSITION OF SiH4 ON THE SA TYPE STEPPED Si(100) SURFACE

2002 ◽  
Vol 09 (03n04) ◽  
pp. 1401-1407 ◽  
Author(s):  
ŞENAY KATIRCIOĞlu ◽  
ŞAKIR ERKOÇ
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Atom ◽  
Density Functional ◽  
Reaction Path ◽  
Density Functional Theory Method ◽  
Dissociative Adsorption ◽  
Theory Method ◽  
Functional Theory ◽  
Initial Stage ◽  
The Density Functional Theory

The density functional theory method is used to explore the mechanism of dissociative adsorption of silane (SiH4) on the SA type stepped Si(100) surface. Two reaction paths are described that produce silyl (SiH3) and hydrogen atom fragments adsorbed on the dimer bonds present on each terrace. It has been found that the initial stage of the dissociation of SiH4 on the SA type stepped Si(100) surface shows similarity to the dissociation of SiH4 on the flat Si(100) surface; SiH3 and hydrogen fragments bond to the Si dimer atoms by following the first reaction path.

scholarly journals Understanding the Molecular Mechanism of the Rearrangement of Internal Nitronic Ester into Nitronorbornene in Light of the MEDT Study

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 462 ◽  
Author(s):  
Agnieszka Kącka-Zych
Keyword(s):  
Density Functional ◽  
Functional Theory ◽  
Molecular Electron ◽  
Bet Analysis ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Step Mechanism ◽  
Nitronic Ester ◽  
Computational Level

The characterization of the structure of nitronic esters and their rearrangement into nitronorbornene reactions has been analyzed within the Molecular Electron Density Theory (MEDT) using Density Functional Theory (DFT) calculations at the B3LYP/6-31G(d) computational level. Quantum-chemical calculations indicate that this rearrangement takes place according to a one-step mechanism. The sequential bonding changes received from the Bonding Evolution Theory (BET) analysis of the rearrangement of internal nitronic ester to nitronorbornene allowed us to distinguish seven different phases. This fact clearly contradicts the formerly-proposed concerted pericyclic mechanism.

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