Computational study on NHC-catalyzed enantioselective and chemoselective fluorination of aliphatic aldehydes

2017 ◽  
Vol 4 (10) ◽  
pp. 1987-1998 ◽  
Author(s):  
Yang Wang ◽  
Yan Qiao ◽  
Donghui Wei ◽  
Mingsheng Tang
Keyword(s):  
Computational Study ◽  
Mechanistic Study ◽  
Aliphatic Aldehydes ◽  
First Time

A mechanistic study on NHC-catalyzed enantioselective and chemoselective fluorination of aliphatic aldehydes has been performed for the first time.

Nitrenium ions and trivalent boron ligands as analogues of N-heterocyclic carbenes in olefin metathesis: a computational study

2015 ◽  
Vol 44 (46) ◽  
pp. 20021-20026 ◽  
Author(s):  
A. Pazio ◽  
K. Woźniak ◽  
K. Grela ◽  
B. Trzaskowski
Keyword(s):  
Olefin Metathesis ◽  
Computational Study ◽  
Heterocyclic Carbenes ◽  
Mechanistic Study ◽  
Nitrenium Ions ◽  
Nitrenium Ion ◽  
Metathesis Catalysts

A DFT mechanistic study reveals that nitrenium ion-modified Hoveyda-like complexes are good candidates for latent metathesis catalysts, while boron-modified systems are candidates for very fast metathesis catalysts.

scholarly journals Comparison of ±σ-hole and ±R˙-hole interactions formed by tetrel-containing complexes: a computational study

RSC Advances ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 4011-4021
Author(s):  
Mahmoud A. A. Ibrahim ◽  
Ebtisam M. Z. Telb
Keyword(s):  
Computational Study ◽  
First Time

The characteristics and nature of ±R˙-hole interactions were uncovered for the first time and compared to their ±σ-hole analogs in ˙TF3⋯ and W–T–F3⋯B/R˙/A complexes.

Effect of soya phosphatidylcholine and possible underlying mechanism on ischemia/reperfusion injury in isolated perfused rat heart: an experimental and computational study

2022 ◽  
pp. 1-7
Author(s):  
Anita A. Mehta ◽  
Purav Patel ◽  
Vandana R. Thakur ◽  
Jayesh V. Beladiya
Keyword(s):  
Ischemia Reperfusion Injury ◽  
Computational Study ◽  
Ischemia Reperfusion ◽  
Underlying Mechanism ◽  
Left Ventricular ◽  
Global Ischemia ◽  
Mechanistic Study ◽  
Cardiac Damage ◽  
Nitric Oxide Synthase Inhibitor ◽  
Triton X

This study was designed to assess the effect of soya phosphatidylcholine (SPC) against ischemia/reperfusion (I/R) injury and the possible underlying mechanism using experimental and computational studies. I/R injury was induced by global ischemia for 30 min followed by reperfusion for 120 min. The perfusion of the SPC was performed for 10 min before inducing global ischemia. In the mechanistic study, the involvement of specific cellular pathways was identified using various inhibitors such as ATP-dependent potassium channel (KATP) inhibitor (glibenclamide), protein kinase C (PKC) inhibitor (chelerythrine), non-selective nitric oxide synthase inhibitor (L-NAME), and endothelium remover (Triton X-100). The computational study of various ligands was performed on toll-like receptor 4 (TLR4) protein using AutoDock version 4.0. SPC (100 μM) significantly decreased the levels of cardiac damage markers and %infarction compared with the vehicle control (VC). Furthermore, cardiodynamics (indices of left ventricular contraction (dp/dtmax), indices of left ventricular relaxation (dp/dtmin), coronary flow, and antioxidant enzyme levels were significantly improved as compared with VC. This protective effect was attenuated by glibenclamide, chelerythrine, and Triton X-100, but it was not attenuated by L-NAME. The computational study showed a significant bonding affinity of SPC to the TLR4-MD2 complex. Thus, SPC reduced myocardial I/R injury in isolated perfused rat hearts, which might be governed by the KATP channel, PKC, endothelium response, and TLR4-MyD88 signaling pathway.

scholarly journals A practical way to synthesize chiral fluoro-containing polyhydro-2H-chromenes from monoterpenoids

2016 ◽  
Vol 12 ◽  
pp. 648-653 ◽  
Author(s):  
Oksana S Mikhalchenko ◽  
Dina V Korchagina ◽  
Konstantin P Volcho ◽  
Nariman F Salakhutdinov
Keyword(s):  
Aromatic Aldehydes ◽  
Single Step ◽  
Preparative Synthesis ◽  
Aliphatic Aldehydes ◽  
First Time

Conditions enabling the single-step preparative synthesis of chiral 4-fluoropolyhydro-2H-chromenes in good yields through a reaction between monoterpenoid alcohols with para-menthane skeleton and aldehydes were developed for the first time. The BF3·Et2O/H2O system is used both as a catalyst and as a fluorine source. The reaction can involve aliphatic aldehydes as well as aromatic aldehydes containing various acceptor and donor substituents. 4-Hydroxyhexahydro-2H-chromenes were demonstrated to be capable of converting to 4-fluorohexahydro-2H-chromenes under the developed conditions, the reaction occurs with inversion of configuration.

Computational Design and Analysis of Nitinol-Based Arch Wedge Support

2018 ◽  
Author(s):  
Tyler Stranburg ◽  
Yucheng Liu ◽  
Harish Chander ◽  
Adam Knight
Keyword(s):  
Boundary Conditions ◽  
Mechanical Response ◽  
Computational Study ◽  
Experimental Testing ◽  
Permanent Deformation ◽  
Computational Design ◽  
Element Analysis ◽  
Human Movements ◽  
First Time ◽  
Human Motions

A nitinol-based arch wedge support (AWS) was designed using computational approach. Finite element analysis (FEA) was performed to on this design to assess the influence of loading, boundary conditions, and thickness on the mechanical response of the computer-aid design (CAD) model. Five loading conditions caused by different human movements, two boundary conditions, and three thicknesses are involved in this computational study. FEA results showed that the presented AWS design can resist forces caused by different human motions without generating any permanent deformation. The study features the first time to design and evaluate a thin-walled nitinol AWS model. The results of this study form the background of prototyping and experimental testing of the design in the next phase.

The effect of the aliphatic carboxylate linkers on the electronic structures, chemical bonding and optical properties of the uranium-based metal–organic frameworks

RSC Advances ◽  
2015 ◽  
Vol 5 (34) ◽  
pp. 26735-26748 ◽  
Author(s):  
Saumitra Saha ◽  
Udo Becker
Keyword(s):  
Optical Properties ◽  
Detailed Analysis ◽  
Computational Methods ◽  
Chemical Bonding ◽  
Electronic Structures ◽  
Computational Study ◽  
Metal Organic Frameworks ◽  
Metal Organic ◽  
First Time

A series of uranyl containing aliphatic dicarboxylate structures is studied using computational methods. Our computational study provides a detailed analysis of these MOFs and explores the effect of linkers on their properties for the first time.

scholarly journals Computational mechanistic study of the unimolecular dissociation of ethyl hydroperoxide and its bimolecular reactions with atmospheric species

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mansour H. Almatarneh ◽  
Asmaa Alnajajrah ◽  
Mohammednoor Altarawneh ◽  
Yuming Zhao ◽  
Mohammad A. Halim
Keyword(s):  
Activation Energy ◽  
Density Functional ◽  
Computational Study ◽  
Basis Sets ◽  
Mechanistic Study ◽  
Intrinsic Reaction Coordinate ◽  
Unimolecular Dissociation ◽  
Phase Reaction ◽  
Atmospheric Species ◽  
Solvation Models

Abstract A detailed computational study of the atmospheric reaction of the simplest Criegee intermediate CH2OO with methane has been performed using the density functional theory (DFT) method and high-level calculations. Solvation models were utilized to address the effect of water molecules on prominent reaction steps and their associated energies. The structures of all proposed mechanisms were optimized using B3LYP functional with several basis sets: 6-31G(d), 6-31G (2df,p), 6-311++G(3df,3pd) and at M06-2X/6-31G(d) and APFD/6-31G(d) levels of theory. Furthermore, all structures were optimized at the B3LYP/6-311++G(3df,3pd) level of theory. The intrinsic reaction coordinate (IRC) analysis was performed for characterizing the transition states on the potential energy surfaces. Fifteen different mechanistic pathways were studied for the reaction of Criegee intermediate with methane. Both thermodynamic functions (ΔH and ΔG), and activation parameters (activation energies Ea, enthalpies of activation ΔHǂ, and Gibbs energies of activation ΔGǂ) were calculated for all pathways investigated. The individual mechanisms for pathways A1, A2, B1, and B2, comprise two key steps: (i) the formation of ethyl hydroperoxide (EHP) accompanying with the hydrogen transfer from the alkanes to the terminal oxygen atom of CIs, and (ii) a following unimolecular dissociation of EHP. Pathways from C1 → H1 involve the bimolecular reaction of EHP with different atmospheric species. The photochemical reaction of methane with EHP (pathway E1) was found to be the most plausible reaction mechanism, exhibiting an overall activation energy of 7 kJ mol−1, which was estimated in vacuum at the B3LYP/6-311++G(3df,3pd) level of theory. All of the reactions were found to be strongly exothermic, expect the case of the sulfur dioxide-involved pathway that is predicted to be endothermic. The solvent effect plays an important role in the reaction of EHP with ammonia (pathway F1). Compared with the gas phase reaction, the overall activation energy for the solution phase reaction is decreased by 162 and 140 kJ mol−1 according to calculations done with the SMD and PCM solvation models, respectively.

Novel catalytic and mechanistic studies on wastewater denitrification with hydrogen

2013 ◽  
Vol 69 (3) ◽  
pp. 680-686 ◽  
Author(s):  
C. P. Theologides ◽  
G. G. Olympiou ◽  
P. G. Savva ◽  
N. A. Pantelidou ◽  
B. K. Constantinou ◽  
...  
Keyword(s):  
Active Sites ◽  
Ex Situ ◽  
Mechanistic Study ◽  
Feed Composition ◽  
Water Media ◽  
Active Intermediate ◽  
Cu Catalysts ◽  
Diffuse Reflectance Infrared ◽  
Isotopic Transient Kinetic Analysis ◽  
First Time

The present work reports up-to-date information regarding the reaction mechanism of the catalytic hydrogenation of nitrates in water media. In the present mechanistic study, an attempt is made, for the first time, to elucidate the crucial role of several catalysts and reaction parameters in the mechanism of the NO3−/H2 reaction. Steady-state isotopic transient kinetic analysis (SSITKA) experiments coupled with ex situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) were performed on supported Pd-Cu catalysts for the NO3−/H2 and NO3−/H2/O2 reactions. The latter experiments revealed that the formation and surface coverage of various adsorbed active intermediate N-species on the support or Pd/Cu metal surface is significantly favored in the presence of TiO2 in the support mixture and in the presence of oxygen in the reaction's gaseous feed stream. The differences in the reactivity of these adsorbed N-species, found in the present work, adequately explain the large effect of the chemical composition of the support and the gas feed composition on catalyst behaviour (activity and selectivity). The present study leads to solid mechanistic evidence concerning the presence of a hydrogen spillover process from the metal to the support. Moreover, this study shows that Cu clusters are active sites for the reduction of nitrates to nitrites.

Oxido-molybdenum complexes obtained by Cl/O interchange between MoCl5 and carboxylic acids: a crystallographic, spectroscopic and computational study

2014 ◽  
Vol 43 (43) ◽  
pp. 16416-16423 ◽  
Author(s):  
Marco Bortoluzzi ◽  
Fabio Marchetti ◽  
Guido Pampaloni ◽  
Stefano Zacchini
Keyword(s):  
Carboxylic Acids ◽  
Computational Study ◽  
Molybdenum Complexes ◽  
First Time

The reactivity of MoCl5 with carboxylic acids has been elucidated for the first time. The reactions are featured by the chlorinating behaviour of MoCl5, rather than affording the respective carboxylato complexes.

RADICAL-MOLECULE REACTIONS HCO/HOC + C2H4: A MECHANISTIC STUDY

2005 ◽  
Vol 04 (04) ◽  
pp. 1029-1055 ◽  
Author(s):  
HONG-BIN XIE ◽  
YI-HONG DING ◽  
CHIA-CHUNG SUN
Keyword(s):  
Kinetic Study ◽  
Kinetic Data ◽  
Computational Study ◽  
The Other ◽  
Mechanistic Study ◽  
Potential Importance ◽  
Donation Process ◽  
Combustion Processes ◽  
Extrusion Product ◽  
Orbital Analysis

A detailed computational study is performed on the radical-molecule reactions between HCO/HOC and ethylene ( C 2 H 4) at the Gaussian-3//B3LYP/6-31G(d) level. For the HCO + C 2 H 4 reaction, the most favorable pathway is the direct C -addition forming the intermediate H 2 CCH 2 CHO , followed by a 1,2- H -shift leading to H 3 CCHCHO . Subsequently, there are two highly competitive dissociation pathways for H 3 CCHCHO : one is the formation of the direct H -extrusion product H 2 CCHCHO + H , and the other is the formation of C 2 H 5 + CO via the intermediate H 3 CCH 2 CO . The overall reaction barrier is 14.1 and 14.6 kcal/mol respectively, at the G3B3 level. The quasi-direct H -donation process to produce C 2 H 5 + CO with the barrier 16.5 kcal/mol is less competitive. Thus, only at higher temperatures, the HCO + C 2 H 4 reaction could play a role. In contrast, the HOC + C 2 H 4 reaction just need to overcome a small barrier 2.0 kcal/mol to generate C 2 H 5 + CO via the quasi-direct H -donation mechanism. This is suggestive of the potential importance of the HOC + C 2 H 4 reaction in combustion processes. However, the direct C -addition channel is much less competitive. The present kinetic data and orbital analysis show that the HCO radical has much higher reactivity than HOC , although the latter is more energetic. Till now, no kinetic study on the HOC radical has been reported, the present study can provide useful information on understanding the reactivity and depletion mechanism of the energetic HOC radical.

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