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Analysis of 12 three-atom-components (TACs) participating in [3+2] cycloaddition (32CA) reactions towards ethylene and acetylene allows establishing good correlations between the pseudodiradical character, the hardness η, and the nucleophilicity N index of the TAC with the feasibility of these non-polar reaction. These results allow the introduction of the pr index, which comprises the two aforementioned DFT reactivity indices. The increase of the pr index for an allylic-type TAC goes accompanied by a linear decrease of the activation enthalpy of the reaction. The present study makes it possible to establish a useful classification of 32CA reactions into zw-type reactions involving TACs with a high zwitterionic character, and pr-type reactions involving TACs with a high pseudodiradical character. 相似文献
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Hosseini S. J. Emamian S. Hassani H. Hamzehzadeh N. D. 《Russian Journal of Organic Chemistry》2020,56(12):2171-2178
Russian Journal of Organic Chemistry - The present work explores the highly trans-stereoselective reaction of a pyridinum ylide (PY1) with 2-(4-chlorobenzylidene)malononitrile (4-CBM) in... 相似文献
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Structural and electronic properties of a bistable redox-responsive molecular switch based on dibenzo[1,2]dithiine (PSBH) were studied using the DFT-B3LYP/6-31G* method. The results confirmed that the electrical conductivity of the closed form of considered molecular switch is higher than that of the open form. NBO electric charges on heavy atoms of biphenyl unit revealed that the positive charge on sulfur atoms reinforced, which caused the collapse of disulfide bond. 相似文献
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Mehdi Bidabadi Saeedreza Zadsirjan Seyed Alireza Mostafavi 《Heat and Mass Transfer》2014,50(6):759-767
In the present paper, combustion of dust clouds from the discrete point heat source method has been addressed. Time-place temperature profile generated by single particle burning has been obtained to study the dust combustion. The summation of the temperature profiles of burned and burning particles predict the temperature in the preheating zone so that the ignition time of layer in flame front can be determined. Consequently the flame propagating speed was obtained based on the dust concentration corresponding to particles spacing and particle diameter. This method has been validated with aluminum dust cloud combustion. Decrease in the dust concentration leads to the lean limit of dust combustion. Increase in particles diameter or reduction in the dust concentration causes higher lean limit and also reduction in the flame propagating speed. Adding the ignition energy as igniter to this system, provides the path to study the effects of ignition energy in the dust combustion. 相似文献
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Fatemeh Ghodsi Sayyed Mostafa Habibi-Khorassani Mehdi Shahraki Saeedreza Emamian Mar Ríos-Gutiérrez Luis R. Domingo 《Tetrahedron》2019,75(19):2807-2816
The domino reactions of alkyne-tethered N-mesylhydrazones yielding fused polycyclic pyrazoles have been studied within the Molecular Electron Density Theory (MEDT). Analysis of the Gibbs free energies indicates that the more favourable reactive path is the one in which the elimination of mesylate anion takes place before the intramolecular [3 + 2] cycloaddition (IM32CA) reaction, which corresponds with the rate-determining step of these domino processes. ELF topological analysis of the bond formation along the IM32CA reaction indicates that in spite of the high activation energy associated to this intramolecular reaction, it shows a pmr-type mechanism characterised by the presence of a pseudoradical carbon at the phenyldiazomethane framework. 相似文献
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Structural Chemistry - In the present work, a molecular electron density theory (MEDT) study is carried out to shed light on the regio- and stereochemistry in two Diels–Alder (DA) reactions... 相似文献
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Structural Chemistry - The [3+2] cycloaddition (32CA) reaction between furoxancarbonitrile oxide (FNO 2) and electron-deficient 2,2,2-trichloroacetonitrile (TCAN 3) in the presence of chloroform... 相似文献
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Understanding the molecular mechanism of the [3 + 2] cycloaddition reaction of benzonitrile oxide toward electron‐rich N‐vinylpyrrole: a DFT study
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Luis R. Domingo Saeedreza Emamian Majid Salami Mar Ríos‐Gutiérrez 《Journal of Physical Organic Chemistry》2016,29(7):368-376
The [3 + 2] cycloaddition (32CA) reaction of benzonitrile oxide, BNO 2 , with an electron‐rich N‐vinylpyrrole derivative, NVP 3a , in the presence of dichloromethane, has been theoretically studied using density functional theory (DFT) methods at the B3LYP/6‐31G(d) level. This 32CA reaction presents a relatively high activation Gibbs free energy as a result of the low polar character of this zwitterionic‐type (zw‐type) reaction. Analyses of the calculated relative Gibbs free energies and transition state geometries indicate that the studied 32CA reaction, in excellent agreement with experimental outcomes, takes place in a complete regioselective manner as a consequence of the steric repulsions that appear at the most unfavorable transition state. An electron localization function (ELF) topological analysis of the bonding changes along this 32CA reaction supports a non‐concerted two‐stage one‐step molecular mechanism in which the formation of the O3‐ C5 single bond takes place at the end of the reaction after the complete formation of the C1‐C4 one. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Amiri Delouei Amin Emamian Amin Karimnejad Sajjad Sajjadi Hasan Jing Dengwei 《Journal of Thermal Analysis and Calorimetry》2021,144(3):611-621
Journal of Thermal Analysis and Calorimetry - This study aimed at presenting a steady-state analytical solution for the two-dimensional heat conduction in a cylindrical segment made of functionally... 相似文献