Search results for "molecular electron density theory"
showing 10 items of 19 documents
Applications of the Conceptual Density Functional Theory Indices to Organic Chemistry Reactivity.
2016
Indexación: Web of Science Theoretical reactivity indices based on the conceptual Density Functional Theory (DFT) have become a powerful tool for the semiquantitative study of organic reactivity. A large number of reactivity indices have been proposed in the literature. Herein, global quantities like the electronic chemical potential μ, the electrophilicity ω and the nucleophilicity N indices, and local condensed indices like the electrophilic and nucleophilic Parr functions, as the most relevant indices for the study of organic reactivity, are discussed. http://www.mdpi.com/1420-3049/21/6/748
Understanding the Origin of the Regioselectivity in Non-polar [3+2] Cycloaddition Reactions through the Molecular Electron Density Theory
2020
The regioselectivity in non-polar [3+2] cycloaddition (32CA) reactions has been studied within the Molecular Electron Density Theory (MEDT) at the B3LYP/6-311G(d,p) level. To this end, the 32CA reactions of nine simplest three-atom-components (TACs) with 2-methylpropene were selected. The electronic structure of the reagents has been characterized through the Electron Localisation Function (ELF) and the Conceptual DFT. The energy profiles of the two regioisomeric reaction paths and ELF topology of the transition state structures are studied to understand the origin of the regioselectivity in these 32CA reactions. This MEDT study permits to conclude that the least electronegative X1 end atom…
The structural aspects of the transformation of 3-nitroisoxazoline-2-oxide to 1-aza-2,8-dioxabicyclo[3.3.0]octane derivatives: Experimental and MEDT …
2019
Abstract Reaction of 3-nitroisoxazoline-2-oxide with monosubstituted ethenes, first time documented fifty years ago, have been reviewed. Structures of phenyl and cyano derivatives of 1-aza-2,8-dioxabicyclo[3.3.0]octane produced in [3 + 2] cycloaddition (32CA) between styrene and acrylonitrile with 3-nitroisoxazoline-2-oxide were determined through single crystal XRD analysis. The molecular mechanism of the title 32CA has been also analyzed within the Molecular Electron Density Theory (MEDT) based on the M06-2X(PCM)/6-311 + G(d,p) calculations.
Molecular Electron Density Theory: A Modern View of Reactivity in Organic Chemistry
2016
A new theory for the study of the reactivity in Organic Chemistry, named Molecular Electron Density Theory (MEDT), is proposed herein. MEDT is based on the idea that while the electron density distribution at the ground state is responsible for physical and chemical molecular properties, as proposed by the Density Functional Theory (DFT), the capability for changes in electron density is responsible for molecular reactivity. Within MEDT, the reactivity in Organic Chemistry is studied through a rigorous quantum chemical analysis of the changes of the electron density as well as the energies associated with these changes along the reaction path in order to understand experimental outcomes. St…
Unveiling the Intramolecular Ionic Diels–Alder Reactions within Molecular Electron Density Theory
2021
The intramolecular ionic Diels–Alder (IIDA) reactions of two dieniminiums were studied within the Molecular Electron Density Theory (MEDT) at the ωB97XD/6-311G(d,p) computational level. Topological analysis of the electron localization function (ELF) of dieniminiums showed that their electronic structures can been seen as the sum of those of butadiene and ethaniminium. The superelectrophilic character of dieniminiums accounts for the high intramolecular global electron density transfer taking place from the diene framework to the iminium one at the transition state structures (TSs) of these IIDA reactions, which are classified as the forward electro density flux. The activation enthalpy ass…
Unveiling the Chemistry of Higher-Order Cycloaddition Reactions within the Molecular Electron Density Theory
2022
The higher-order cycloaddition (HOCA) reaction of tropone with cyclopentadiene (Cp) has been studied within the Molecular Electron Density Theory. The Electron Localization Function (ELF) analysis of the electronic structure of tropone and Cp characterizes the structural behaviors of the two conjugated unsaturated systems, while the conceptual DFT reactivity indices classify tropone as a strong electrophile and Cp as a strong nucleophile participating in polar cycloaddition reactions of reverse electron density flux. Eight competitive reaction paths have been characterized for this cycloaddition reaction. The most favorable one allowing the formation of the formal out [6 + 4] cycloadduct ha…
Nitropyrroles, Diels-Alder reactions assisted by microwave irradiation and solvent effect. An experimental and theoretical study
2017
The behaviors of N-tosylnitropyrroles acting as electrophilic dienophiles in polar Diels-Alder reactions joint to different dienes of increeased nucleophilicity are analyzed. The reactions were developed under microwave irradiation using toluene or protic ionic liquids (PILs) as solvents and in free solvent conditions. In all the cases explored we observed good yields in short reaction times. For these reactions, the free solvent condition and the use of protic ionic liquids as solvents offer similar results. However, the free solvent conditions favor environmental sustainability. The role of PILs in these polar Diels-Alder reactions has been theoretically studied within the Molecular Elect…
A Molecular Electron Density Theory Study of the Competitiveness of Polar Diels–Alder and Polar Alder-ene Reactions
2018
Indexación: Scopus. Funding: Ministry of Economy and Competitiveness (MINECO) of the Spanish Government, project CTQ2016-78669-P (AEI/FEDER, UE) and Fondecyt (Chile) grant 1180348. Acknowledgments: This research was supported by the Ministry of Economy and Competitiveness (MINECO) of the Spanish Government, project CTQ2016-78669-P (AEI/FEDER, UE) and Fondecyt (Chile) grant 1180348. L.R.D. thanks Fondecyt for continuous support through Cooperación Internacional. M.R.-G. also thanks MINECO for a post-doctoral contract cofinanced by the European Social Fund (BES-2014-068258). The competitiveness of the BF3 Lewis acid (LA) catalyzed polar Diels–Alder (P-DA) and polar Alder-ene (P-AE) reactions …
Unveiling the Different Chemical Reactivity of Diphenyl Nitrilimine and Phenyl Nitrile Oxide in [3+2] Cycloaddition Reactions with (R)-Carvone throug…
2020
The [3+2] cycloaddition (32CA) reactions of diphenyl nitrilimine and phenyl nitrile oxide with (R)-carvone have been studied within the Molecular Electron Density Theory (MEDT). Electron localisation function (ELF) analysis of these three-atom-components (TACs) permits its characterisation as carbenoid and zwitterionic TACs, thus having a different reactivity. The analysis of the conceptual Density Functional Theory (DFT) indices accounts for the very low polar character of these 32CA reactions, while analysis of the DFT energies accounts for the opposite chemoselectivity experimentally observed. Topological analysis of the ELF along the single bond formation makes it possible to characteri…
Unveiling the Lewis Acid Catalyzed Diels–Alder Reactions Through the Molecular Electron Density Theory
2020
The effects of metal-based Lewis acid (LA) catalysts on the reaction rate and regioselectivity in polar Diels&ndash