scholarly journals Experimental and Theoretical Mechanistic Study on the Thermal Decomposition of 3,3-Diphenyl-4-(trichloromethyl)-5-nitropyrazoline

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1364
Author(s):  
Karolina Kula ◽  
Agnieszka Kącka-Zych ◽  
Agnieszka Łapczuk-Krygier ◽  
Zbigniew Wzorek ◽  
Anna K. Nowak ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Molecular Mechanisms ◽  
Single Step ◽  
Mechanistic Study ◽  
Molecular Electron ◽  
Molecular Electron Density Theory ◽  
Experimental And Theoretical Studies ◽  
Step Mechanism ◽  
Computational Level ◽  
Comprehensive Study

The present paper is a continuation of comprehensive study regarding to synthesis and properties of pyrazoles and their derivatives. In its framework an experimental and theoretical studies of thermal decomposition of the 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline were performed. It was found, that the decompositions of the mentioned pyrazoline system in the solution and at the melted state proceed via completely different molecular mechanisms. These mechanisms have been explained in the framework of the Molecular Electron Density Theory (MEDT) with the computational level of B3LYP/6-31G(d). A Bonding Evolution Theory (BET) examination of dehydrochlorination of the 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline permits elucidation of the molecular mechanism. It was found, that on the contrary for most known HCl extrusion processes in solution, this reaction is realised via single-step mechanism.

scholarly journals Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory

2020 ◽  
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
Nivedita Acharjee
Keyword(s):  
Electron Density ◽  
Complete Agreement ◽  
Slowing Down ◽  
Molecular Electron ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Electrophilic Character ◽  
Step Mechanism ◽  
Computational Level ◽  
Density Transfer

The [3+2] cycloaddition (32CA) reactions of strongly nucleophilic norbornadiene (NBD) with simplest diazoalkane (DAA) and three DAAs of increased electrophilicity have been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G(d,p) computational level. These pmr-type 32CA reactions follow an asynchronous one-step mechanism with activation enthalpies ranging from 17.7 to 27.9 kcal·mol-1 in acetonitrile. The high exergonic character of these reactions makes them irreversible. The presence of electron-withdrawing (EW) substituents in the DAA increases the activation enthalpies, in complete agreement with the experimental slowing-down of the reactions, but contrary to the Conceptual DFT prediction. Despite the nucleophilic and electrophilic character of the reagents, the global electron density transfer at the TSs indicates rather non-polar 32CA reactions. The present MEDT study allows establishing that the depopulation of the NNC core in this series of DAAs with the increase of the EW character of the substituents present at the carbon center is responsible for the experimentally found deceleration.

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.

scholarly journals Mpro-SARS-CoV-2 Inhibitors and Various Chemical Reactivity of 1-Bromo- and 1-Chloro-4-vinylbenzene in [3 + 2] Cycloaddition Reactions

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 1-16
Author(s):  
Mohammed El Idrissi ◽  
Mohamed El Ghozlani ◽  
Asli Eşme ◽  
Mar Ríos-Gutiérrez ◽  
Anas Ouled Aitouna ◽  
...  
Keyword(s):  
Electron Density ◽  
Chemical Reactivity ◽  
Cycloaddition Reactions ◽  
Two Stage ◽  
Docking Analysis ◽  
Molecular Electron ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Step Mechanism ◽  
Computational Level

The regioselectvity and the mechanism of the (32CA) cycloadditions reactions of 1-bromo-4-vinylbenzene 1 and 1-chloro-4-vinylbenzene 2 with benzonitrile oxide 3 were investigated under the molecular electron density theory (MEDT) at the B3LYP/6-311++G(d,p) computational level. Evaluation of the ELF reveals that these zwitterionic type (zw-type) 32CA reactions take place in a two-stage one-step mechanism. This MEDT study shows that the meta isoxazolines are kinetically and thermodynamically favored over the ortho ones, these 32CA reactions being completely regioselective, in agreement with experimental outcomes. In addition, the efficiency of isoxazolines against SARS-CoV-2 have been also investigated. According to the docking analysis, the present study concludes that 5-(p-bromophenyl)-3-phenyl-2-isoxazoline (B-m) shows better interactions for the inhibition of SARS-CoV-2 in comparison to chloroquine.

scholarly journals Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 74-93
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
Nivedita Acharjee
Keyword(s):  
Electron Density ◽  
Complete Agreement ◽  
Slowing Down ◽  
Molecular Electron ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Electrophilic Character ◽  
Step Mechanism ◽  
Computational Level ◽  
Density Transfer

The [3+2] cycloaddition (32CA) reactions of strongly nucleophilic norbornadiene (NBD), with simplest diazoalkane (DAA) and three DAAs of increased electrophilicity, have been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G (d,p) computational level. These pmr-type 32CA reactions follow an asynchronous one-step mechanism with activation enthalpies ranging from 17.7 to 27.9 kcal·mol−1 in acetonitrile. The high exergonic character of these reactions makes them irreversible. The presence of electron-withdrawing (EW) substituents in the DAA increases the activation enthalpies, in complete agreement with the experimental slowing-down of the reactions, but contrary to the Conceptual DFT prediction. Despite the nucleophilic and electrophilic character of the reagents, the global electron density transfer at the TSs indicates rather non-polar 32CA reactions. The present MEDT study establishes the depopulation of the N–N–C core in this series of DAAs with the increase of the EW character of the substituents present at the carbon center is responsible for the experimentally found deceleration.

scholarly journals Understanding the Reactivity of Trimethylsilyldiazoalkanes Participating in [3+2] Cycloaddition Reactions towards Diethylfumarate with a Molecular Electron Density Theory Perspective

Organics ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 3-18
Author(s):  
Luis R. Domingo ◽  
Nivedita Acharjee ◽  
Haydar A. Mohammad-Salim
Keyword(s):  
Electron Density ◽  
Energy Cost ◽  
Trimethylsilyl Group ◽  
Gibbs Energies ◽  
Molecular Electron ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Non Covalent Interactions ◽  
Covalent Interactions ◽  
Step Mechanism

A Molecular Electron Density Theory (MEDT) study is presented here for [3+2] cycloaddition (32CA) reactions of three trimethylsilyldiazoalkanes with diethyl fumarate. The presence of silicon bonded to the carbon of these silyldiazoalkanes changes its structure and reactivity from a pseudomonoradical to that of a zwitterionic one. A one-step mechanism is predicted for these polar zw-type 32CA reactions with activation enthalpies in CCl4 between 8.0 and 19.7 kcal·mol−1 at the MPWB1K (PCM)/6-311G(d,p) level of theory. The negative reaction Gibbs energies between −3.1 and −13.2 kcal·mole−1 in CCl4 suggests exergonic character, making the reactions irreversible. Analysis of the sequential changes in the bonding pattern along the reaction paths characterizes these zw-type 32CA reactions. The increase in nucleophilic character of the trimethylsilyldiazoalkanes makes these 32CA reactions more polar. Consequently, the activation enthalpies are decreased and the TSs require less energy cost. Non-covalent interactions at the TSs account for the stereoselectivity found in these 32CA reactions involving the bulky trimethylsilyl group.

scholarly journals Unveiling the Intramolecular Ionic Diels–Alder Reactions within Molecular Electron Density Theory

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 834-853
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
María José Aurell
Keyword(s):  
Electron Density ◽  
Electronic Structures ◽  
Activation Enthalpy ◽  
Topological Analysis ◽  
Chair Conformation ◽  
Diels Alder ◽  
Molecular Electron ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Step Mechanism

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 associated with the IIDA reaction of the experimental dieniminium, 8.7 kcal·mol−1, was closer to that of the ionic Diels–Alder (I-DA) reaction between butadiene and ethaniminium, 9.3 kcal·mol−1. However, the activation Gibbs free energy of the IIDA reaction was 12.7 kcal·mol−1 lower than that of the intermolecular I-DA reaction. The strong exergonic character of the IIDA reaction, higher than 20.5 kcal·mol−1, makes the reaction irreversible. These IIDA reactions present a total re/exo and si/endo diastereo selectivity, which is controlled by the most favorable chair conformation of the tetramethylene chain. ELF topological analysis of the single bond formation indicated that these IIDA reactions take place through a non-concerted two-stage one-step mechanism. Finally, ELF and atoms-in-molecules (AIM) topological analyses of the TS associated with the inter and intramolecular processes showed the great similarity between them.

scholarly journals Participation of Phosphorylated Analogues of Nitroethene in Diels–Alder Reactions with Anthracene: A Molecular Electron Density Theory Study and Mechanistic Aspect

Organics ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 36-48
Author(s):  
Agnieszka Kącka-Zych
Keyword(s):  
Electron Density ◽  
Density Functional ◽  
Diels Alder ◽  
Single Bond ◽  
Conceptual Density Functional Theory ◽  
Molecular Electron ◽  
Bet Analysis ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Step Mechanism

The structure and the contribution of the bis(2-chloroethyl) 2-nitro 1a and 2-bromo-2-nitroethenylphosphonates 1b with anthracene 2 in the Diels–Alder (DA) reactions have been studied within the Molecular Electron Density Theory (MEDT) at the B3LYP functional together with 6-31G(d), 6-31+G(d) and 6-31+G(d,p) basic sets. Analysis of the Conceptual Density Functional Theory (CDFT) reactivity indices indicates that 1a and 1b can be classified as a strong electrophile and marginal nucleophile, while 2 is classified as a strong electrophile and strong nucleophile. The studied DA reactions take place through a one-step mechanism. A Bonding Evolution Theory (BET) of the one path associated with the DA reaction of 1a with 2 indicates that it is associated with non-concerted two-stage one-step mechanism. BET analysis shows that the first C2-C3 single bond is formed in Phase VI, while the second C1-C6 single bond is formed in the Phase VIII. The formation of both single bonds occurs through the merging of two C2 and C3, C1 and C6 pseudoradical centers, respectively.

scholarly journals A molecular electron density theory study of the mechanism, chemo- and stereoselectivity of the epoxidation reaction of R-carvone with peracetic acid

RSC Advances ◽  
2019 ◽  
Vol 9 (49) ◽  
pp. 28500-28509 ◽  
Author(s):  
Abdellah Zeroual ◽  
Mar Ríos-Gutiérrez ◽  
Ouafa Amiri ◽  
Mohammed El Idrissi ◽  
Luis R. Domingo
Keyword(s):  
Electron Density ◽  
Peracetic Acid ◽  
Epoxidation Reaction ◽  
Molecular Electron ◽  
Molecular Electron Density Theory ◽  
Computational Level

The epoxidation reaction of R-carvone 8 with peracetic acid 9 has been studied within the molecular electron density theory at the B3LYP/6-311(d,p) computational level.

scholarly journals A Molecular Electron Density Theory Study of the Synthesis of Spirobipyrazolines through the Domino Reaction of Nitrilimines with Allenoates

Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4159
Author(s):  
Luis R. Domingo ◽  
Fatemeh Ghodsi ◽  
Mar Ríos-Gutiérrez
Keyword(s):  
Electron Density ◽  
Energy Cost ◽  
Reaction Path ◽  
Bond Formation ◽  
Domino Reaction ◽  
Formation Processes ◽  
Free Energies ◽  
Molecular Electron ◽  
Molecular Electron Density Theory ◽  
Computational Level

The reaction of diphenyl nitrilimine (NI) with methyl 1-methyl-allenoate yielding a spirobipyrazoline has been studied within molecular electron density theory (MEDT) at the MPWB1K/6-311G(d) computational level in dichloromethane. This reaction is a domino process that comprises two consecutive 32CA reactions with the formation of a pyrazoline intermediate. Analysis of the relative Gibbs free energies indicates that both 32CA reactions are highly regioselective, the first one being also completely chemoselective, in agreement with the experimental outcomes. The geometries of the TSs indicate that they are associated to asynchronous bond formation processes in which the shorter distance involves the C1 carbon of diphenyl NI. Despite the zwitterionic structure of diphenyl NI, the appearance of a pseudoradical structure at the beginning of the reaction path, with a very low energy cost, suggests that the 32CA reaction between diphenyl NI, a strong nucleophile, and the allenoate, a moderate electrophile, should be mechanistically considered on the borderline between pmr-type and cb-type 32CA reactions, somewhat closer to the latter.

scholarly journals Synthesis, characterization and thermal decomposition of ethyl-2’-amino-5’-cyano-6’-(1H-indole-3yl)-2-oxospiro[indoline-3,4’-pyran]-3’-carboxylate under non‐isothermal condition in nitrogen atmosphere

2019 ◽  
Vol 10 (1) ◽  
pp. 72-81
Author(s):  
Ganesan Nalini ◽  
Natesan Jayachandramani ◽  
Radhakrishnan Suresh ◽  
Prakasam Thirumurugan ◽  
Venugopal Thanikachalam ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Model Fitting ◽  
Isothermal Condition ◽  
Nitrogen Atmosphere ◽  
Single Step ◽  
Heating Rates ◽  
Model Free ◽  
Ft Ir ◽  
Step Mechanism

A new compound, spiro-oxindole derivative compound namely ethyl-2ʹ-amino-5ʹ-cyano-6ʹ-(1H-indole-3yl)-2-oxospiro[indoline-3,4ʹ-pyran]-3ʹ-carboxylate (EACIOIPC) has been synthesized and characterized by microanalysis, FT-IR, mass spectrum and NMR (1H and 13C) techniques. The thermal decomposition of the compound was studied by thermogravimetric analysis under dynamic nitrogen atmosphere at different heating rates of 10, 15, 20 and 30 K/min. The kinetic parameters were calculated using model-free (Friedman’s, Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods) and model-fitting (Coats and Redfern (CR)) methods. The decomposition process of EACIOIPC followed a single step mechanism as evidenced from the data. Existence of compensation effect is noticed for the decomposition of EACIOIPC. Invariant kinetic parameters are consistent with the average values obtained by Friedman and KAS in conversional methods.

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