scholarly journals THEORETICAL STUDY OF THE INTERACTION OF 1,2-Ethanedithiol With 1,3-Dichloropropene in the Hydrazrazine Hydrate System

2018 ◽  
Vol 1 (12) ◽  
pp. 114-120
Author(s):  
Elena Chirkina
Keyword(s):  
Carbon Atom ◽  
Chlorine Atom ◽  
Density Functional ◽  
Thiol Group ◽  
Nucleophilic Attack ◽  
Substitution Product ◽  
Chemical Studies ◽  
Allyl Rearrangement ◽  
Quantum Chemical Studies ◽  
Theoretical Mechanism

According to the results of quantum chemical studies in the framework of the electron density functional theory, the B3LYP / 6-311 ++ G (d, p) method proposed a theoretical mechanism for the interaction of 1,3-dichloropropene with 1,2-ethanedithiol in the hydrazine-hydrateKOH system. It was shown that the reaction proceeds sequentially in several stages, including the nucleophilic substitution of the chlorine atom of the sp3 hybridized carbon atom to the sulfur atom with the formation of the mono-substitution product, which undergoes prototropic allyl rearrangement, providing the double bond to the atom sulfur. Next, the dithiolan ring closes due to the nucleophilic attack of the sulfide anion of the second thiol group of the reagent on the carbon atom, which is in the γ position relative to the second chlorine atom. The resulting vinyldithiolan is isomerized to a more stable ethylidene-dithiolan as a result of prototropic allyl rearrangement

scholarly journals THEORETICAL STUDY OF THE REACTION MECHANISM 1,2-ETHANEDIIOL WITH 1,3-DICHLOROPROPENE

2020 ◽  
Vol 2018 (1) ◽  
pp. 68-77
Author(s):  
Elena Chirkina ◽  
Leonid Krivdin ◽  
Nikolay Korchevin
Keyword(s):  
Carbon Atom ◽  
Chlorine Atom ◽  
Sulfur Atom ◽  
Density Functional ◽  
Theoretical Study ◽  
Thiol Group ◽  
Nucleophilic Attack ◽  
Substitution Product ◽  
Reaction Proceeds ◽  
Theoretical Mechanism

The theoretical mechanism of the interaction of 1,3-dichloropropene with 1,2-ethanedithiol in the system "hydrazine hydrate-KOH" has been proposed by the method of B3LYP / 6-311 ++ G (d, p) in the framework of the theory of the electron-density functional according to which the reaction proceeds successively in several stages, including the nucleophilic substitution of the chlorine atom present in the sp3-hybridized carbon atom with a sulfur atom to form a mono-substitution product that undergoes a prototropic allylic rearrangement that migrates the double bond to the sulfur atom, followed by closure in the dithiolane cycle due to the nucleophilic attack of the sulfide anion of the second thiol group of the reagent per carbon atom located in the γ-position with respect to the second chlorine atom.

scholarly journals QUANTUM-CHEMICAL STUDY OF THE REACTION MECHANISM 1,2-ETHANEDIIOL WITH 1,3-DICHLOROPROPENE

2020 ◽  
Vol 2018 (1) ◽  
pp. 56-57
Author(s):  
Elena Chirkina ◽  
Leonid Krivdin ◽  
Nikolay Korchevin
Keyword(s):  
Carbon Atom ◽  
Sulfur Atom ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Thiol Group ◽  
Chemical Study ◽  
Nucleophilic Attack ◽  
Substitution Product ◽  
Reaction Proceeds ◽  
Theoretical Mechanism

The theoretical mechanism of the interaction of 1,3-dichloropropene with 1,2- ethanedithiol in the system "hydrazine hydrate-KOH" has been proposed by the method of B3LYP / 6- 311 ++ G (d, p) in the framework of the theory of the electron-density functional according to which the reaction proceeds successively in several stages, including the nucleophilic substitution of the chlorine atom present in the sp3-hybridized carbon atom with a sulfur atom to form a mono-substitution product that undergoes a prototropic allylic rearrangement that migrates the double bond to the sulfur atom, followed by closure in the dithiolane cycle due to the nucleophilic attack of the sulfide anion of the second thiol group of the reagent per carbon atom located in the γ-position with respect to the second chlorine atom.

scholarly journals QUANTUM-CHEMICAL STUDY OF INTERACTION 1,2-ETHANEDITHIOL WITH 1,3-DICHLOROBUTENE-2 IN THE SYSTEM HYDRASINEHYDRATEKOH

2018 ◽  
Vol 1 (12) ◽  
pp. 121-127
Author(s):  
Elena Chirkina
Keyword(s):  
Carbon Atom ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Nucleophilic Attack ◽  
Central Carbon ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Methylene Group ◽  
Mechanism Of The Reaction

According to the results of quantum-chemical studies in the framework of the theory of functional density of the electron density using the B3LYP / 6-311 ++ G (d, p) method, a theoretical mechanism of the reaction of 1,3-dichlorobutene-2 with 1,2-ethanedithiol in the hydrazine hydrateKOH system has been proposed. It has been shown that this interaction proceeds sequentially in several stages, including the nucleophilic substitution of the chlorine atom of the sp3 hybridized carbon atom to the sulfur atom with the formation of a monosubstitution product (SN2 mechanism), which under the action of alkali undergoes deprotonation of the methylene group to form an allyl carbanion . The resulting carbanion, due to the migration of hydrogen and the removal of chlorine, is converted into an allene derivative, which as a result of the intramolecular nucleophilic attack of the free thiolate group on the central carbon atom of the allene fragment closes into the final dithian cycle.

scholarly journals Understanding the reaction mechanism of the regioselective piperidinolysis of aryl 1-(2,4-dinitronaphthyl) ethers in DMSO: Kinetic and DFT studies

2021 ◽  
Vol 46 ◽  
pp. 146867832110274
Author(s):  
Yasmen M Moghazy ◽  
Nagwa MM Hamada ◽  
Magda F Fathalla ◽  
Yasser R Elmarassi ◽  
Ezzat A Hamed ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Density Functional ◽  
Function Analysis ◽  
Density Functional Theory Method ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Nucleophilic Attack ◽  
Common Mechanism ◽  
Slow Step ◽  
Rate Determining Step

Reactions of aryl 1-(2,4-dinitronaphthyl) ethers with piperidine in dimethyl sulfoxide at 25oC resulted in substitution of the aryloxy group at the ipso carbon atom. The reaction was measured spectrophotochemically and the kinetic studies suggested that the titled reaction is accurately third order. The mechanism is began by fast nucleophilic attack of piperidine on C1 to form zwitterion intermediate (I) followed by deprotonation of zwitterion intermediate (I) to the Meisenheimer ion (II) in a slow step, that is, SB catalysis. The regular variation of activation parameters suggested that the reaction proceeded through a common mechanism. The Hammett equation using reaction constant σo values and Brønsted coefficient value showed that the reaction is poorly dependent on aryloxy substituent and the reaction was significantly associative and Meisenheimer intermediate-like. The mechanism of piperidinolysis has been theoretically investigated using density functional theory method using B3LYP/6-311G(d,p) computational level. The combination between experimental and computational studies predicts what mechanism is followed either through uncatalyzed or catalyzed reaction pathways, that is, SB and SB-GA. The global parameters of the reactants, the proposed activated complexes, and the local Fukui function analysis explained that C1 carbon atom is the most electrophilic center of ether. Also, kinetics and theoretical calculation of activation energies indicated that the mechanism of the piperidinolysis passed through a two-step mechanism and the proton transfer process was the rate determining step.

scholarly journals Molecular bending as a vital step toward transforming planar PAHs to fullerenes and tubular structures

2020 ◽  
Vol 644 ◽  
pp. A146
Author(s):  
Tao Chen ◽  
Yang Wang
Keyword(s):  
Density Functional ◽  
Intermolecular Forces ◽  
Molecular Structures ◽  
Intrinsic Reaction Coordinate ◽  
Functional Theory ◽  
B3lyp Method ◽  
Polycyclic Aromatic ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Hybrid Density Functional

Context. Polycyclic aromatic hydrocarbons (PAHs) and fullerenes are the largest molecules found in the interstellar medium (ISM). They are abundant and widespread in various astronomical environments. However, the detailed connection between these two species is unknown; in particular, no quantum chemical studies have been performed. Aims. In this work, we investigate a vital step in transforming planar PAHs to fullerenes, that is, the tubulation processes of PAHs. Methods. We used density functional theory for this study. The molecular structures and vibrational frequencies were calculated using the hybrid density functional B3LYP method. To better describe intermolecular forces, we considered Grimme’s dispersion correction in the calculations for this work. Intrinsic reaction coordinate calculations were also performed to confirm that the transition state structures are connected to their corresponding local potential energy surface minima. Results. As expected, we find that it is easier to bend a molecule as it gets longer, whereas it is harder to bend the molecule if it gets “wider” (i.e., with more rows of benzene rings). The change of multiplicity slightly alters the bending energies, while (a complete) dehydrogenation alleviates the bending barrier significantly and facilitates the formation of pentagons, which may act as an indispensable step in the formation of fullerenes in the ISM.

scholarly journals Inhibition Effect of Atenolol on Copper Corrosion in 1M HNO3: Experimental Study and DFT

2021 ◽  
pp. 1-13
Author(s):  
Ehouman Ahissan Donatien ◽  
Bamba Kafoumba ◽  
Kogbi Guy Roland ◽  
Bamba Amara ◽  
Kouakou Adjoumani Rodrigue ◽  
...  
Keyword(s):  
Molecular Orbital ◽  
Quantum Chemical ◽  
Density Functional ◽  
Energy Gap ◽  
Copper Surface ◽  
Thermodynamic Quantities ◽  
Copper Corrosion ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Lowest Unoccupied Molecular Orbital

Atenolol was examined as a copper corrosion inhibitor in 1M nitric acid solution using the mass loss technique and quantum chemical studies, based on density functional theory (DFT) at the B3LYP level with the base 6-311G (d,p). The inhibitory efficiency of the molecule increases with increasing concentration and temperature. The adsorption of the molecule on the copper surface follows the modified Langmuir model. The thermodynamic quantities of adsorption and activation were determined and discussed. The calculated quantum chemical parameters related to the inhibition efficiency are the energy of the highest occupied molecular orbital E(HOMO), the energy of the lowest unoccupied molecular orbital E(LUMO), the HOMO-LUMO energy gap, the hardness (η), softness (S), dipole moment (μ), electron affinity (A), ionization energy (I), absolute electronegativity (χ),absolute electronegativity (χ), fraction (ΔN) of electrons transferred from Atenolol to copper and electrophilicity index(ω). The local reactivity was analyzed through the condensed Fukui function and condensed softness indices to determine the nucleophilic and electrophilic attack sites. There is good agreement between the experimental and theoretical results.

Methods and models for studying mechanisms of redox-active enzymes

2005 ◽  
Vol 363 (1829) ◽  
pp. 847-860 ◽  
Author(s):  
Per E.M Siegbahn ◽  
Margareta R.A Blomberg
Keyword(s):  
Density Functional ◽  
Hybrid Methods ◽  
Proton Pumping ◽  
X Ray ◽  
Functional Methods ◽  
Redox Active ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Exact Exchange ◽  
Stable Structures

Methods and models used in recent quantum chemical studies of redox-active enzymes are described. Only density functional methods are able to treat these systems with sufficient accuracy. For the most accurate of these methods, the so-called hybrid methods, a fraction of exact exchange is included and the deviation from experimental energies is usually not higher than 5 kcal mol −1 . The size of the models depends on the problem studied, but is usually in the range 60–100 atoms. To keep the optimized structures sufficiently close to the experimental ones, one atom in each amino acid residue is kept frozen to its position in the X-ray structure. Examples from different recent studies are given with emphasis on dioxygen evolution in photosystem II and proton pumping in cytochrome oxidase. The main advantage of using theoretical methods to study these systems is that short-lived intermediates and transition states can be investigated as easily as stable structures.

Divalent carbon(0) compounds

2009 ◽  
Vol 81 (4) ◽  
pp. 597-614 ◽  
Author(s):  
Gernot Frenking ◽  
Ralf Tonner
Keyword(s):  
Carbon Atom ◽  
Lewis Acids ◽  
Binding Energies ◽  
Bond Dissociation Energies ◽  
Dissociation Energies ◽  
Carbon Compounds ◽  
Valence Electrons ◽  
Chemical Studies ◽  
Donor Acceptor ◽  
Quantum Chemical Studies

Quantum chemical studies show that there is a class of carbon compounds with the general formular CL2 where the carbon atom retains its four valence electrons as two lone pairs. The C-L bonds come from L → C donor-acceptor interactions where L is a strong σ-donor. Divalent C(0) compounds (carbones) are conceptually different from divalent C(II) compounds (carbenes) and tetravalent carbon compounds, but the bonding situation in a real molecule may be intermediate between the three archetypes. There are molecules like tetraaminoallenes which may be described in terms of two double bonds (R2N)2C=C=C(NR2)2 where the extraordinary donor strength of the dicoordinated carbon atom comes only to the fore through the interactions with protons and Lewis acids. They may be considered as "hidden divalent C(0) compounds". The donor strength of divalent C(0) molecules has been investigated by calculations of the binding energies with protons and with main-group Lewis acids and the bond dissociation energies (BDEs) of transition-metal complexes.

scholarly journals Inhibition of Aluminium Corrosion in 1M HCl by Pyridoxine Hydrochloride: Thermodynamic and Quantum Chemical Studies

2020 ◽  
pp. 20-38
Author(s):  
Mamadou Yeo ◽  
Mougo André Tigori ◽  
Amadou Kouyaté ◽  
Paulin Marius Niamien ◽  
Albert Trokourey
Keyword(s):  
Density Functional ◽  
Activation Parameters ◽  
Structure Property ◽  
Pyridoxine Hydrochloride ◽  
Functional Theory ◽  
Structure Property Relationship ◽  
Chemical Studies ◽  
Quantum Chemical Studies ◽  
Increasing Temperature ◽  
Green Corrosion Inhibitors

Currently, research in the area of corrosion inhibition is focussed on the development of green corrosion inhibitors. It is with this in mind that pyridoxine hydrochloride, which is vitamin B6, has been tested as a corrosion inhibitor of aluminium in 1M HCl by mass loss, Density Functional Theory (DFT) and Quantitative Structure-Property Relationship (QSPR) methods. The results obtained show that the inhibition efficiency increases with concentration but decreases with increasing temperature. This vitamin is adsorbed on aluminium according to the modified Langmuir isotherm and occurs in two modes: physisorption and chemisorption. Thermodynamic adsorption and activation parameters have been determined and discussed. Finally, QSPR approach was used to find the best set of parameters in order to determine the theoretical inhibition efficiencies from the experimental data. Experimental measurements were found in good collaboration with the theoretical results.

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