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 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 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 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 QUANTUM-CHEMICAL STUDY OF THE MECHANISM OF REACTION OF DIFORMYLHYDRAZINE WITH p-AMINOPHENOL

2021 ◽  
Vol 1 (1) ◽  
pp. 86-87
Author(s):  
Elena Chirkina
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Functional Theory ◽  
Mechanism Of Reaction ◽  
Theoretical Mechanism

Based on the results of a quantum chemical study within the framework of the elec tron density functional theory by the B3LYP/6-311++G(d, p) method, a theoretical mechanism for the reaction of diformylhydrazine with p-aminophenol is proposed

scholarly journals QUANTUM-CHEMICAL STUDY OF THE MECHANISM OF REACTION OF BENZOELACETHYLENE WITH DISELENOMALONAMIDE

2020 ◽  
Vol 2020 (1) ◽  
pp. 89-90
Author(s):  
Elena Chirkina
Keyword(s):  
Nucleophilic Addition ◽  
Quantum Chemical ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Selenium Atom ◽  
Functional Theory ◽  
Mechanism Of Reaction ◽  
Theoretical Mechanism ◽  
Mechanism Of The Reaction

According to the results of a quantum chemical study in the framework of the electron density functional theory using the В3LYP/6-311++G (d, p) method, a theoretical mechanism of the reaction of benzoylacetylene with dyselenomalonamide is proposed. It was shown that the reaction includes the following stages: nucleophilic addition of the selenoamide fragment to the electrondeficient -carbon atom of benzoylacetylene with the formation of ketovinyl selenide and further intramolecular cyclization of the mono-derivative due to nucleophilic addition of the second selenium atom of the selenol group of the reagent via the same -carbon with the formation of a heterocyclic product.

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.

Studies on the structure and conformational flexibility of secondary structures in amyloid beta — A quantum chemical study

2020 ◽  
Vol 19 (06) ◽  
pp. 2050014
Author(s):  
Mahendiraprabu Ganesan ◽  
Selvarengan Paranthaman
Keyword(s):  
Gas Phase ◽  
Amyloid Beta ◽  
Density Functional ◽  
Conformational Transition ◽  
Intermolecular Hydrogen Bond ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Secondary Structures ◽  
Conformational Flexibility ◽  
Solution Phase

Density functional theory (DFT) calculations are performed to study the conformational flexibility of secondary structures in amyloid beta (A[Formula: see text]) polypeptide. In DFT, M06-2X/6-31[Formula: see text]G(d, p) method is used to optimize the secondary structures of 2LFM and 2BEG in gas phase and in solution phase. Our calculations show that the secondary structures are energetically more stable in solution phase than in gas phase. This is due to the presence of strong solvent interaction with the secondary structures considered in this study. Among the backbone [Formula: see text] and [Formula: see text] dihedral angles, [Formula: see text] varies significantly in sheet structure. This is due to the absence of intermolecular hydrogen bond (H-bond) interactions in sheets considered in this study. Our calculations show that the conformational transition of helix/coil to sheet or vice-versa is due to the floppiness of the amino acid residues. This is observed from the Ramachandran map of the studied secondary structures. Further, it is noted that the intramolecular H-bond interactions play a significant role in the conformational transition of secondary structures of A[Formula: see text].

Quantum chemical study on the formation of isopropyl cyanide and its linear isomer in the interstellar medium

2020 ◽  
pp. 1-11
Author(s):  
Keshav Kumar Singh ◽  
Poonam Tandon ◽  
Alka Misra ◽  
Shivani ◽  
Manisha Yadav ◽  
...  
Keyword(s):  
Amino Acids ◽  
Interstellar Medium ◽  
Gas Phase ◽  
Quantum Chemical ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Dark Cloud ◽  
Water Ice ◽  
Hydrocarbon Radicals

Abstract The formation mechanism of linear and isopropyl cyanide (hereafter n-PrCN and i-PrCN, respectively) in the interstellar medium (ISM) has been proposed from the reaction between some previously detected small cyanides/cyanide radicals and hydrocarbons/hydrocarbon radicals. n-PrCN and i-PrCN are nitriles therefore, they can be precursors of amino acids via Strecker synthesis. The chemistry of i-PrCN is especially important since it is the first and only branched molecule in ISM, hence, it could be a precursor of branched amino acids such as leucine, isoleucine, etc. Therefore, both n-PrCN and i-PrCN have significant astrobiological importance. To study the formation of n-PrCN and i-PrCN in ISM, quantum chemical calculations have been performed using density functional theory at the MP2/6-311++G(2d,p)//M062X/6-311+G(2d,p) level. All the proposed reactions have been studied in the gas phase and the interstellar water ice. It is found that reactions of small cyanide with hydrocarbon radicals result in the formation of either large cyanide radicals or ethyl and vinyl cyanide, both of which are very important prebiotic interstellar species. They subsequently react with the radicals CH2 and CH3 to yield n-PrCN and i-PrCN. The proposed reactions are efficient in the hot cores of SgrB2 (N) (where both n-PrCN and i-PrCN were detected) due to either being barrierless or due to the presence of a permeable entrance barrier. However, the formation of n-PrCN and i-PrCN from the ethyl and vinyl cyanide always has an entrance barrier impermeable in the dark cloud; therefore, our proposed pathways are inefficient in the deep regions of molecular clouds. It is also observed that ethyl and vinyl cyanide serve as direct precursors to n-PrCN and i-PrCN and their abundance in ISM is directly related to the abundance of both isomers of propyl cyanide in ISM. In all the cases, reactions in the ice have smaller barriers compared to their gas-phase counterparts.

scholarly journals Quantum Chemical Study of Mixed-Ligand Monometallic Ruthenium(II) Complex of Composition [(bpy)2Ru(H3Imbzim)](ClO4)2·2H2O

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Mohsin Yousuf Lone ◽  
Prakash Chandra Jha
Keyword(s):  
Absorption Spectra ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Mixed Ligand ◽  
Excitation Energies ◽  
Functional Theory ◽  
Effect Of Solvent ◽  
The Density Functional Theory ◽  
Metal Ligand

On the basis of density functional theoretical approach, we have assessed the ground state geometries and absorption spectra of recently synthesized monometallic ruthenium (II) complex of composition [(bpy)2Ru(H3Imbzim)](ClO4)2·2H2O where bpy = 2,2′-bypyridine and H3Imbzim = 4,5-bis(benzimidazol-2-yl)imidazole. The all different kinds of charge transfers such as ligand-ligand, and metal-ligand have been quantified, compared, and contrasted with the experimental results. In addition, the effect of solvent on excitation energies has been evaluated. In spite of some digital discrepancies in calculated and observed geometries, as well as in absorption spectra, the density functional theory (DFT) seems to explain the main features of this complex.

scholarly journals Structural, Electronic, and Vibrational Properties of Isoniazid and Its Derivative N-Cyclopentylidenepyridine-4-carbohydrazide: A Quantum Chemical Study

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Anoop kumar Pandey ◽  
Abhishek Bajpai ◽  
Vikas Baboo ◽  
Apoorva Dwivedi
Keyword(s):  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Basis Sets ◽  
Ground State Structure ◽  
Vibrational Modes ◽  
Functional Theory ◽  
Complete Assignment ◽  
Experimental Values ◽  
Homo Lumo

Isoniazid (Laniazid, Nydrazid), also known as isonicotinylhydrazine (INH), is an organic compound that is the first-line medication in prevention and treatment of tuberculosis. The optimized geometry of the isoniazid and its derivative N-cyclopentylidenepyridine-4-carbohydrazide molecule has been determined by the method of density functional theory (DFT). For both geometry and total energy, it has been combined with B3LYP functionals having LANL2DZ and 6-311 G (d, p) as the basis sets. Using this optimized structure, we have calculated the infrared wavenumbers and compared them with the experimental data. The calculated wavenumbers by LANL2DZ are in an excellent agreement with the experimental values. On the basis of fully optimized ground-state structure, TDDFT//B3LYP/LANL2DZ calculations have been used to determine the low-lying excited states of isoniazid and its derivative. Based on these results, we have discussed the correlation between the vibrational modes and the crystalline structure of isoniazid and its derivative. A complete assignment is provided for the observed FTIR spectra. The molecular HOMO, LUMO composition, their respective energy gaps, and MESP contours/surfaces have also been drawn to explain the activity of isoniazid and its derivative.

Sign in / Sign up

Export Citation Format

Share Document