Computational Study on the Reaction Pathway of α-Bromoacetophenones with Hydroxide Ion: Possible Path Bifurcation in the Addition/Substitution Mechanism

2011 ◽  
Vol 76 (20) ◽  
pp. 8294-8299 ◽  
Author(s):  
Shuhei Itoh ◽  
Nobuyoshi Yoshimura ◽  
Makoto Sato ◽  
Hiroshi Yamataka
Keyword(s):  
Computational Study ◽  
Reaction Pathway ◽  
Hydroxide Ion ◽  
Substitution Mechanism ◽  
Path Bifurcation

Synthesis of novel N-functionalized 4-aryl-tetrahydrobiquinoline-2,5-(1H,3H)-diones via one-pot three-component reaction: a joint experimental and computational study

2018 ◽  
Vol 96 (12) ◽  
pp. 1071-1078
Author(s):  
Vahideh Zadsirjan ◽  
Sayyed Jalil Mahdizadeh ◽  
Majid M. Heravi ◽  
Masumeh Heydari
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Computational Study ◽  
Reaction Pathway ◽  
Deep Insight ◽  
One Pot ◽  
Functional Theory ◽  
Three Component Reaction ◽  
High Yields ◽  
Mechanism Of The Reaction

A novel series of N-functionalized 4-aryl-tetrahydrobiquinoline-2,5-(1H,3H)-diones were synthesized in high yields by a one-pot three-component reaction involving 2-chloroquinoline-3-carbaldehydes, Meldrum’s acid, and enaminones (dimedone-based enaminones) in the presence of K2CO3 in CH3CN under reflux condition. To gain a deep insight on the mechanism of the reaction, an extensive series of quantum mechanics calculations in the framework of density functional theory (DFT) were carried out for supporting the suggested reaction pathway.

Reaction kinetics of 1,2-diaminobenzene with ethyl 2-oxopropanoate and 2,3-butanedione

1988 ◽  
Vol 53 (12) ◽  
pp. 3154-3163 ◽  
Author(s):  
Jiří Klicnar ◽  
Jaromír Mindl ◽  
Ivana Obořilová ◽  
Jaroslav Petříček ◽  
Vojeslav Štěrba
Keyword(s):  
Reaction Kinetics ◽  
Acid Catalysis ◽  
Reaction Pathway ◽  
Hydroxide Ion ◽  
Tetrahedral Intermediate ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
General Acid ◽  
Rate Limiting ◽  
Kinetics Of

The reaction of 1,2-diaminobenzene with 2,3-butanedione is subject to general acid catalysis in acetate and phosphate buffers (pH 4-7). The rate-limiting step of formation of 2,3-dimethylquinoxaline consists in the protonation of dipolar tetrahedral intermediate. In the case of the reaction of 1,2-diaminobenzene with ethyl 2-oxopropanoate, the dehydration of carbinolamine gradually becomes rate-limiting with increasing pH in acetate buffers, whereas in phosphate buffers a new reaction pathway makes itself felt, viz. the formation of amide catalyzed by the basic buffer component and by hydroxide ion.

Inhibition of Premixed Methane-Air Flames with CF3I

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
Caimao Luo ◽  
Bogdan Dlugogorski ◽  
Eric Kennedy ◽  
Behdad Moghtaderi
Keyword(s):  
Sensitivity Analysis ◽  
Pathway Analysis ◽  
Laminar Flame ◽  
Computational Study ◽  
Reaction Pathway ◽  
Burning Velocity ◽  
Flame Velocity ◽  
Promoting Effect ◽  
Elementary Reactions ◽  
Reaction Pathway Analysis

This paper presents a systematic computational study of the inhibition of premixed flames of short chain hydrocarbons with CF3I, focusing on sensitivity analysis of the (normalized) burning velocity and reaction pathway analysis using the "iodine-flux" approach. A comprehensive kinetic mechanism was obtained by combining the GRI, hydrofluorocarbon and CF3I sub-mechanisms, and updating the rates of some of the elementary reactions. Calculations were performed using the PREMIX computer code in the CHEMKIN suite of computer codes. The updated mechanism yielded estimates of the normalized laminar burning velocities which concurs closely with published measurements. The sensitivity analysis resulted in a positive coefficient for CF3I + M ? CF3 + I + M, confirming the promoting effect of CF3I on the laminar flame velocity and is consistent with previous studies. Reaction pathways were drawn for stoichiometric, fuel-lean and fuel-rich flames doped with 1 and 2% of CF3I at atmospheric pressure. The reaction pathway analysis served to identify four major inhibition cycles, denoted as HI ? I ? HI, HI ? I ? I2 ? HI, HI ? I ? CH3I ? HI and HI ? I ? C2H5I ? HI. Furthermore, the paper developed a linear expression linking the normalized rate of heat release with the ratio of laminar burning velocities of mitigated and non-mitigated flames, and verified the efficacy of this expression for flames inhibited with CF3I.

scholarly journals Computational Study of the Dissociation Reactions of Secondary Ozonide

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 100 ◽  
Author(s):  
Mansour H. Almatarneh ◽  
Shefa’ F. Alrebei ◽  
Mohammednoor Altarawneh ◽  
Yuming Zhao ◽  
Abd Al-Aziz Abu-Saleh
Keyword(s):  
Barrier Height ◽  
Computational Study ◽  
Reaction Pathway ◽  
Single Point ◽  
Water Dimer ◽  
Basis Set ◽  
Basis Sets ◽  
Water Molecules ◽  
Point Energy ◽  
Secondary Ozonide

This contribution presents a comprehensive computational study on the reactions of secondary ozonide (SOZ) with ammonia and water molecules. The mechanisms were studied in both a vacuum and the aqueous medium. All the molecular geometries were optimized using the B3LYP functional in conjunction with several basis sets. M06-2X, APFD, and ωB97XD functionals with the full basis set were also used. In addition, single-point energy calculations were performed with the G4MP2 and G3MP2 methods. Five different mechanistic pathways were studied for the reaction of SOZ with ammonia and water molecules. The most plausible mechanism for the reaction of SOZ with ammonia yields HC(O)OH, NH3, and HCHO as products, with ammonia herein acting as a mediator. This pathway is exothermic and exergonic, with an overall barrier height of only 157 kJ mol−1 using the G3MP2 method. All the reaction pathways between SOZ and water molecules are endothermic and endergonic reactions. The most likely reaction pathway for the reaction of SOZ with water involves a water dimer, in which the second water molecule acts as a mediator, with an overall barrier height of only 135 kJ mol−1 using the G3MP2 method. Solvent effects were found to incur a significant reduction in activation energies. When the second H2O molecule acts as a mediator in the reaction of SOZ with water, the barrier height of the rate-determining step state decreases significantly.

Rate and equilibrium constants for formation and hydrolysis of 9-formylfluorene oxime: diffusion-controlled trapping of a protonated aldehyde by hydroxylamine

2000 ◽  
Vol 78 (12) ◽  
pp. 1594-1612 ◽  
Author(s):  
RA More O'Ferrall ◽  
D M O'Brien ◽  
D G Murphy
Keyword(s):  
Aqueous Solution ◽  
Acetic Acid ◽  
Reaction Pathway ◽  
Equilibrium Constants ◽  
Diffusion Control ◽  
General Measure ◽  
Hydroxide Ion ◽  
Diffusion Controlled ◽  
Enol Tautomer ◽  
Hydrolysis Of

Equilibrium constants Kadd = 440 and Kox = 3.0 × 108 for formation of a carbinolamine adduct and oxime, respectively from 9-formylfluorene and hydroxylamine, and pKa = –1.62 for protonation of the oxime, have been evaluated at 25°C in aqueous solution, based on measurements in hydroxylamine buffers, acetic acid buffers, and dilute HCl. Rate constants for hydrolysis of the oxime have been measured in the acidity range pH 4–12 M HClO4. At the highest acidities, a reaction pathway via protonated carbinolamine has been identified: evidence is presented that the reverse of this reaction involves rate-determining attack of hydroxylamine upon protonated 9-formylfluorene. By assuming that the attack of hydroxylamine is diffusion-controlled, with rate constant 3 × 109 M –1 s–1, a pKa for O-protonation of the aldehyde (–4.5) is derived. Taking account of the equilibrium constant for enolization of 9-formylfluorene (KE = 16.6), a pKa for for C-protonation of the enol tautomer ((–5.7) may also be obtained. Comparison of this pKa with that of the enol of acetophenone shows that the enol of 9-formylfluorene is less basic by a factor of 1010. By combining pKas for protonation of the aldehyde and oxime with measured or estimated equilibrium constants for addition of water, hydroxide ion, and hydroxylamine to 9-formylfluorene, it is also possible to obtain values of pKR = –5.3, 4.1, and 12.25 for the protonated 9-formylfluorene, protonated oxime, and 9-formylfluorene, respectively. The usefulness of pKR in providing a general measure of equilibrium constants for electrophile-nucleophile combination reactions is discussed.Key words: oxime, formyfluorene, hydrolysis, protonation, diffusion-control.

Computational study of reverse water gas shift reaction on Cu38 cluster model and Cu slab model

2020 ◽  
Vol 19 (02) ◽  
pp. 2050008
Author(s):  
Dabin Qi ◽  
Xudong Luo ◽  
Jun Yao ◽  
Xiaojun Lu ◽  
Zhan Zhang
Keyword(s):  
Density Functional ◽  
Surface Defects ◽  
Computational Study ◽  
Reaction Pathway ◽  
Water Gas Shift ◽  
Slab Model ◽  
Slab Surface ◽  
Reverse Water Gas Shift ◽  
Rwgs Reaction ◽  
Water Gas

Density functional theory (DFT) calculation has been applied to investigate the adsorption behaviors of reactive adsorbate and the reaction pathway of reverse water gas shift (RWGS) reaction on Cu[Formula: see text] cluster and Cu slab surface. The possible adsorption configuration, sites and energies of reactive intermediates on Cu[Formula: see text] cluster and Cu slab surface have been calculated to reveal the effects between Cu[Formula: see text] cluster and Cu slab surface. In addition, transition states, reaction energies and activation barriers were calculated to RWGS mechanism on Cu[Formula: see text] cluster and Cu slab model. Compared to the mechanism of RWGS on different surfaces, it was found the Cu[Formula: see text] cluster facilitates the RWGS reaction. The intrinsic differences between Cu cluster and Cu slab model suggest that surface defects play a pivotal role in RWGS reaction.

scholarly journals Valence tautomerism and recyclisation of type B mesoionic tetrazoles: a computational study

2021 ◽  
Author(s):  
Wojciech Piotr Oziminski ◽  
Christopher Antony Ramsden
Keyword(s):  
Solvent Effect ◽  
Ring Opening ◽  
Continuum Model ◽  
Computational Study ◽  
Reaction Pathway ◽  
Type B ◽  
Valence Tautomerism ◽  
Energy Profiles ◽  
Aqueous Solvation ◽  
Influence Of Solvent

AbstractThe energy profiles for ring opening of representative type B mesoionic 2,3-diphenyl-1,2,3,4-tetrazolium-5-olates, -thiolates, -aminides and –methylides and for alternative recyclisation pathways are investigated using ab initio MP2 calculations. The energetics of initial ring opening are found to be comparable for all systems, but the tetrazolium-5-olates are anomalous in that no alternative reaction pathway is accessible. The influence of solvent is explored using the polarised continuum model (PCM) method to simulate aqueous solvation. The only significant solvent effect is found to be solvation of the mesoionic precursors. This solvent effect correlates with dipole moment and disfavours initial valence tautomerism both kinetically and thermodynamically.

Potential energy surface of the cation–neutral hydroamination reaction: a computational study on the role of an ion–molecule complex in the reaction pathway

Tetrahedron ◽  
2014 ◽  
Vol 70 (43) ◽  
pp. 7906-7911
Author(s):  
Sanyasi Sitha ◽  
Linda L. Jewell ◽  
Priya Bhasi ◽  
Zanele P. Nhlabatsi ◽  
Vijay M. Miriyala
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Computational Study ◽  
Reaction Pathway

A computational study and valence bond approach to the intramolecular electrophilic aromatic substitution mechanism of ortho-allyl-N-benzylanilines

Tetrahedron ◽  
2008 ◽  
Vol 64 (30-31) ◽  
pp. 7407-7418 ◽  
Author(s):  
Elena E. Stashenko ◽  
Jairo R. Martínez ◽  
Geovanna Tafurt-García ◽  
Alirio Palma ◽  
Josep Maria Bofill
Keyword(s):  
Computational Study ◽  
Valence Bond ◽  
Electrophilic Aromatic Substitution ◽  
Aromatic Substitution ◽  
Substitution Mechanism
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