Theoretical Studies on the Reactions of Aryl and Hetaryl Thioketones with Nitrilimines

10.26434/chemrxiv.14012888.v1 ◽

2021 ◽

Author(s):

George Baffour Pipim ◽

Ernest Opoku

Keyword(s):

Density Functional ◽

Biologically Active ◽

Functional Theory ◽

Atomic Spin ◽

One Step ◽

Synthetic Routes ◽

The One ◽

Total Agreement ◽

Ethylene Derivative ◽

Spin Densities

Many synthetic routes to constructing biologically-active heterocyclic compounds are made feasible through the (3 + 2) cycloaddition 32CA reactions. Due to a large number of possible combinations of several heteroatoms from either the three-atom components (TACs) or the ethylene derivatives, the potential of the 32CA reactions in heterocyclic syntheses is versatile. Herein, the 32CA of thiophene-2-carbothialdehyde derivatives and C,N-disubstituted nitrilimines have been studied through density functional theory (DFT) calculations at the B3LYP/6-311G(d,p) level of theory. In the present study, one-step (3 + 2) and two-step (4 + 3) mechanisms of the addition of the TAC and ethylene derivative have been investigated. In all reactions considered, the one-step (3 + 2) cycloaddition is preferred over the two-step (4 + 3) cycloaddition. The TAC chemoselectively adds across the thiocarbonyl group present in the ethylene derivative in a (3 + 2) fashion to form the corresponding cycloadduct. Analysis of the electrophilic ( and nucleophilic ( Parr functions at the various reaction centers in the ethylene derivative show that the TAC adds across the atomic centers with the largest Mulliken atomic spin densities, which is in total agreement with the experimental observation. The selectivities observed in the title reaction are kinetically controlled.

Download Full-text

[3 + 2] versus [2 + 2] Addition: A Density Functional Theory Study on the Mechanistic Aspects of Transition Metal-Assisted Formation of 1,2-Dinitrosoalkanes

Journal of Chemistry ◽

10.1155/2016/4538696 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 6

Author(s):

Ernest Opoku ◽

Richard Tia ◽

Evans Adei

Keyword(s):

Transition Metal ◽

Density Functional ◽

Basis Set ◽

Functional Theory ◽

Activation Barriers ◽

One Step ◽

The One ◽

Electron Donating Groups ◽

Very High ◽

Addition Pathway

The pathways for the transition metal-assisted formation of 1,2-dinitrosoalkane complexes of cobalt and its congeners, have been studied using DFT/M06 with theLACVP*basis set. The activation barriers for the one-step [3 + 2] addition pathway for the formation of 1,2-dinitrosoalkanes, proposed by Bergman and Becker, are generally low compared to the activation barriers for the [2 + 2] addition to form an intermediate, which is the first of the two-step pathway proposed by Rappé and Upton, which are very high. The barriers of the rearrangement of the Rappé intermediates to the final products by reductive elimination involving the second metal-nitrogenπ-bond are also very high. The reactions of the Co complexes have lower activation barriers than Rh and Ir complexes. The barriers of the reactions involving olefins with electron-donating groups are generally lower compared to the reactions of the parent (unsubstituted) ethylene while the activation barriers for reactions of olefins with electron-withdrawing groups are generally higher compared to the parent (unsubstituted) ethylene. The one-step [3 + 2] pathway remains the most favoured irrespective of the metal centre or the nature of the olefin. The mechanism of the reaction is therefore settled in favour of the [3 + 2] addition pathway.

Download Full-text

MNDO and DFT Computational Study on the Mechanism of the Oxidation of 1,2-Diphenylhydrazine by Iodine

ISRN Physical Chemistry ◽

10.1155/2014/592850 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Gideon A. Shallangwa ◽

Adamu Uzairu ◽

Victor O. Ajibola ◽

Hamza Abba

Keyword(s):

Reaction Mechanisms ◽

Density Functional ◽

Computational Study ◽

The Other ◽

Complex Mechanism ◽

Functional Theory ◽

One Step ◽

The One ◽

Activated Complex ◽

Step Mechanism

The reaction mechanisms of the oxidation of 1,2-diphenylhydrazine by iodine have been examined using semiempirical and density functional theory methods, the oxidation proceeded via two independent pathways that can be separately monitored. One pathway involved the chain multistep mechanism. The other pathway occurred via a one-step mechanism in which a “cyclic” activated complex was formed which on disproportionation gave the products. The one-step “cyclic” activated complex mechanism proceeds more rapidly than the chain multistep mechanism. The results were explained by analyses based on computational energetics of the optimised reactants, intermediates, transition states, and products of the reaction of iodine with 1,2-diphenylhydrazine.

Download Full-text

Phenanthro[9,10-a]corannulene by one-step annulative π-extension of corannulene

Canadian Journal of Chemistry ◽

10.1139/cjc-2016-0467 ◽

2017 ◽

Vol 95 (3) ◽

pp. 329-333 ◽

Cited By ~ 35

Author(s):

Kenta Kato ◽

Yasutomo Segawa ◽

Kenichiro Itami

Keyword(s):

Crystal Structure ◽

Density Functional ◽

Photophysical Properties ◽

Coupling Reaction ◽

Density Functional Theory Calculations ◽

Functional Theory ◽

X Ray ◽

Palladium Catalyzed ◽

One Step ◽

The One

The one-step π-extension of corannulene was achieved using a palladium-catalyzed C–H coupling reaction. The X-ray crystal structure and photophysical properties of the thus formed phenanthro[9,10-a]corannulene (1) were investigated, and the structural properties of 1 were examined by density functional theory calculations. In contrast to dibenzo[g,p]chrysene, the most stable structure of 1 was a butterfly-shaped structure, resulting from the bowl-shaped distortion of the corannulene moiety.

Download Full-text

Mechanistic investigation in the [1,4] and [1,2] Wittig rearrangement reactions: a DFT study

Physical Chemistry Chemical Physics ◽

10.1039/c8cp01045e ◽

2018 ◽

Vol 20 (33) ◽

pp. 21457-21473

Author(s):

Shilpa R. Nath ◽

Kaustubh A. Joshi

Keyword(s):

Density Functional Theory ◽

Density Functional ◽

Natural Bond Orbital ◽

Functional Theory ◽

Wittig Rearrangement ◽

Mechanistic Investigation ◽

One Step ◽

Rearrangement Reactions ◽

Reaction Barriers ◽

The One

Mechanistic pathways associated with the sigmatropic Wittig rearrangement reactions along different routes have been investigated using density functional theory. The reaction barriers for the one-step as well as two-step pathways have been calculated and the [1,4]-Wittig rearrangement is predicted to occur via a two-step mode. Detailed natural bond orbital calculations have been carried out to get deeper insights into these mechanistic pathways.

Download Full-text

Synthesis, Conformational Analysis and Crystal Structure of New Thioxo, Oxo, Seleno Diastereomeric Cyclophosphamides Containing 1,3,2-dioxaphosphorinane

Current Organic Chemistry ◽

10.2174/1385272823666190213142748 ◽

2019 ◽

Vol 23 (2) ◽

pp. 205-213

Author(s):

Dorra Kanzari-Mnallah ◽

Med L. Efrit ◽

Jiří Pavlíček ◽

Frédéric Vellieux ◽

Habib Boughzala ◽

...

Keyword(s):

Molecular Structure ◽

Crystal Structure ◽

Density Functional ◽

Chemical Shifts ◽

Structural Determination ◽

Conformational Study ◽

Functional Theory ◽

One Step ◽

High Resolution Mass Spectroscopy ◽

Resolution Mass

Thioxo, Oxo and Seleno diastereomeric cyclophosphamides containing 1,3,2- dioxaphosphorinane are prepared by a one-step chemical reaction. Their structural determination is carried out by means of Nuclear Magnetic Resonance NMR (31P, 1 H, 13C) and High-Resolution Mass Spectroscopy (HRMS). The conformational study of diastereomeric products is described. Density Functional Theory (DFT) calculations allowed the identification of preferred conformations. Experimental and calculated 31P, 13C, 1H NMR chemical shifts are compared. The molecular structure of the 2-Benzylamino-5-methyl-5- propyl-2-oxo-1,3,2-dioxaphosphorinane (3d) has been determined by means of crystal Xray diffraction methods.

Download Full-text

Application of β-Phosphorylated Nitroethenes in [3+2] Cycloaddition Reactions Involving Benzonitrile N-Oxide in the Light of a DFT Computational Study

Organics ◽

10.3390/org2010003 ◽

2021 ◽

Vol 2 (1) ◽

pp. 26-37

Author(s):

Karolina Zawadzińska ◽

Karolina Kula

Keyword(s):

Density Functional ◽

Reaction Path ◽

Computational Study ◽

Cyano Group ◽

Cycloaddition Reactions ◽

Functional Theory ◽

The Density Functional Theory ◽

Reaction Channels ◽

One Step ◽

Step Mechanism

The regiochemistry of [3+2] cycloaddition (32CA) processes between benzonitrile N-oxide 1 and β-phosphorylated analogues of nitroethenes 2a–c has been studied using the Density Functional Theory (DFT) at the M062X/6-31+G(d) theory level. The obtained results of reactivity indices show that benzonitrile N-oxide 1 can be classified both as a moderate electrophile and moderate nucleophile, while β-phosphorylated analogues of nitroethenes 2a–c can be classified as strong electrophiles and marginal nucleophiles. Moreover, the analysis of CDFT shows that for [3+2] cycloadditions with the participation of β-phosphorylatednitroethene 2a and β-phosphorylated α-cyanonitroethene 2b, the more favored reaction path forms 4-nitro-substituted Δ2-isoxazolines 3a–b, while for a reaction with β-phosphorylated β-cyanonitroethene 2c, the more favored path forms 5-nitro-substituted Δ2-isoxazoline 4c. This is due to the presence of a cyano group in the alkene. The CDFT study correlates well with the analysis of the kinetic description of the considered reaction channels. Moreover, DFT calculations have proven the clearly polar nature of all analyzed [3+2] cycloaddition reactions according to the polar one-step mechanism.

Download Full-text

Developing orbital-free quantum crystallography: the local potentials and associated partial charge densities

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s2052520621005540 ◽

2021 ◽

Vol 77 (4) ◽

Author(s):

Vladimir Tsirelson ◽

Adam Stash

Keyword(s):

Density Functional Theory ◽

Electron Density ◽

Density Functional ◽

Electronic Energy ◽

Physical Content ◽

Functional Theory ◽

Orbital Free ◽

The One ◽

Physical And Chemical ◽

Quantum Crystallography

This work extends the orbital-free density functional theory to the field of quantum crystallography. The total electronic energy is decomposed into electrostatic, exchange, Weizsacker and Pauli components on the basis of physically grounded arguments. Then, the one-electron Euler equation is re-written through corresponding potentials, which have clear physical and chemical meaning. Partial electron densities related with these potentials by the Poisson equation are also defined. All these functions were analyzed from viewpoint of their physical content and limits of applicability. Then, they were expressed in terms of experimental electron density and its derivatives using the orbital-free density functional theory approximations, and applied to the study of chemical bonding in a heteromolecular crystal of ammonium hydrooxalate oxalic acid dihydrate. It is demonstrated that this approach allows the electron density to be decomposed into physically meaningful components associated with electrostatics, exchange, and spin-independent wave properties of electrons or with their combinations in a crystal. Therefore, the bonding information about a crystal that was previously unavailable for X-ray diffraction analysis can be now obtained.

Download Full-text

Computational Evidence Suggests That 1-chloroethanol May Be an Intermediate in the Thermal Decomposition of 2-chloroethanol into Acetaldehyde and HCl

10.26434/chemrxiv.7608857.v1 ◽

2019 ◽

Author(s):

Zoi Salta ◽

Agnie M. Kosmas ◽

Oscar Ventura ◽

Vincenzo Barone

Keyword(s):

Aqueous Solution ◽

Water Molecule ◽

Gas Phase ◽

Density Functional ◽

Water Molecules ◽

Functional Theory ◽

Direct Transformation ◽

The Density Functional Theory ◽

Successive Step ◽

The One

The dehalogenation of 2-chloroethanol (2ClEtOH) in gas phase with and without participation of catalytic water molecules has been investigated using methods rooted into the density functional theory. The well-known HCl elimination leading to vinyl alcohol (VA) was compared to the alternative elimination route towards oxirane and shown to be kinetically and thermodynamically more favorable. However, the isomerization of VA to acetaldehyde in the gas phase, in the absence of water, was shown to be kinetically and thermodynamically less favorable than the recombination of VA and HCl to form the isomeric 1-chloroethanol (1ClEtOH) species. This species is more stable than 2ClEtOH by about 6 kcal mol-1, and the reaction barrier is 22 kcal mol-1 vs 55 kcal mol-1 for the direct transformation of VA to acetaldehyde. In a successive step, 1ClEtOH can decompose directly to acetaldehyde and HCl with a lower barrier (29 kcal mol-1) than that of VA to the same products (55 kcal mol-1). The calculations were repeated using a single ancillary water molecule (W) in the complexes 2ClEtOH_W and 1ClEtOH_W. The latter adduct is now more stable than 2ClEtOH_W by about 8 kcal mol-1, implying that the water molecule increased the already higher stability of 1ClEtOH in the gas phase. However, this catalytic water molecule lowers dramatically the barrier for the interconversion of VA to acetaldehyde (from 55 to 6 kcal mol-1). This barrier is now smaller than the one for the conversion to 1ClEtOH (which also decreases, but not so much, from 22 to 12 kcal mol-1). Thus, it is concluded that while 1ClEtOH may be a plausible intermediate in the gas phase dehalogenation of 2ClEtOH, it is unlikely that it plays a major role in water complexes (or, by inference, aqueous solution). It is also shown that neither in the gas phase nor in the cluster with one water molecule, the oxirane path is competitive with the VA alcohol path.

Download Full-text