Alkyl versus hydrogen substitution: an abinitio study of the addition of hydroxide to formaldehyde and to acetone

1989 ◽  
Vol 67 (1) ◽  
pp. 176-182 ◽  
Author(s):  
C. I. Bayly ◽  
F. Grein
Keyword(s):  
Quantum Chemical Study ◽  
Chemical Study ◽  
Energy Difference ◽  
Basis Set ◽  
Secondary Minimum ◽  
Energy Curve ◽  
Co Addition ◽  
Hydrogen Substitution ◽  
Acetone System ◽  
Reaction Profile

The reaction profiles of the anionic nucleophilic addition of hydroxide to formaldehyde (system I) and to acetone (system II) were studied using theoretical abinitio methods. Calculations were carried out using the 4-31G basis set augmented with polarization and diffuse functions on some atoms. Electron correlation calculations were performed at the MP2 (frozen core), MP2, and MP4 levels for system I and at the MP2 (frozen core) level for system II. For both systems a local energy maximum was found at a C—OH distance of 2.5 Å. The barrier maximum was at lower energy than the separated reactants (−17.2 kcal/mol for system I and −5.6 kcal/mol for system II). This type of reaction profile is in accordance with a previous study on a prototype reaction. The energy difference between the barrier maximum and the secondary minimum (towards the reactants) was very small for system I (0.7 kcal/mol), but higher for system II (5.4 kcal/mol). The geometries of the two systems differed significantly in the region of the reaction coordinate containing the barrier and the secondary minimum. Keywords: quantum chemical study, addition of OH− to H2CO, addition of OH− to (CH3)2CO, alkyl versus hydrogen substitution, potential energy curve.

scholarly journals Energy maxima in anionic nucleophilic additions to carbonyl groups: The location of a saddle point for the addition of hydride to formaldehyde

1988 ◽  
Vol 66 (1) ◽  
pp. 149-154 ◽  
Author(s):  
C. I. Bayly ◽  
F. Grein
Keyword(s):  
Electron Correlation ◽  
Nucleophilic Addition ◽  
Major Change ◽  
Energy Difference ◽  
Basis Set ◽  
Basis Sets ◽  
Attractive Potential ◽  
Energy Curve ◽  
Energy Maximum ◽  
Reaction Profile

The reaction profile of the anionic nucleophilic addition of hydride to formaldehyde giving methanolate was re-investigated using theoretical ab initio methods. A variety of basis sets (including 4-31G and 6-31G with and without polarization and diffuse functions) were used, and electron correlation calculations were performed at the MP2, MP3, and MP4 levels with geometry optimizations at the MP2 level. Upon the addition of diffuse functions to the basis set, a local energy maximum was introduced into the SCF reaction profile, a major change in the character of the profile compared to the entirely attractive potential energy curve found in previous studies. On the reactants side of the barrier a local minimum 4.56 kcal/mol lower in energy was found, corresponding to an ion–dipole complex. With the inclusion of electron correlation, the local barrier almost disappeared, with the energy difference between the ion–dipole complex and the barrier maximum decreasing to less than 1 kcal/mol. Furthermore, the location of the energy maximum along the reaction coordinate changed by 0.4 Å. These results are used to critically re-evaluate some prevalent viewpoints on the nature of the reaction profiles of this type of anionic nucleophilic addition.

scholarly journals Fukui Function Analysis and Optical, Electronic, and Vibrational Properties of Tetrahydrofuran and Its Derivatives: A Complete Quantum Chemical Study

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Apoorva Dwivedi ◽  
Vikas Baboo ◽  
Abhishek Bajpai
Keyword(s):  
Molecular Electrostatic Potential ◽  
Function Analysis ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Basis Set ◽  
Potential Surfaces ◽  
Vibrational Assignments ◽  
Optical And Electronic Properties ◽  
Homo Lumo ◽  
Complete Quantum

The spectroscopic, optical, and electronic properties of tetrahydrofuran and its derivatives were investigated by FTIR techniques. We have done a comparative study of tetrahydrofuran and its derivatives with B3LYP with 6-311 G (d, p) as the basis set. Here we have done a relative study of their structures, vibrational assignments, and thermal, electronic, and optical properties of ttetrahydrofuran and its derivatives. We have plotted frontier orbital HOMO-LUMO surfaces and molecular electrostatic potential surfaces to explain the reactive nature of tetrahydrofuran and its derivatives.

Studies of intramolecular H-bond interactions and solvent effects in the conformers of glycolic acid — A quantum chemical study

2018 ◽  
Vol 17 (01) ◽  
pp. 1850009 ◽  
Author(s):  
Mahendiraprabu Ganesan ◽  
Nirmala Vedamanickam ◽  
Selvarengan Paranthaman
Keyword(s):  
Solvent Effects ◽  
Density Functional ◽  
Glycolic Acid ◽  
Chemical Potential ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Basis Set ◽  
Chemical Hardness ◽  
Geometrical Parameters ◽  
Water Media

In this work, density functional theory is applied to understand the conformational stability and solvent effects on glycolic acid conformers in different solvents. In addition, the role of intramolecular hydrogen bond (H-bond) interactions in the stability of conformers are investigated. The molecular geometries of selected conformers are optimized using B3LYP and PBE0 functionals with 6-311[Formula: see text]G(d,p) basis set. The effects of solvent on the geometrical parameters, relative stability, dipole moment, chemical hardness, chemical potential, etc. are studied for the conformers of glycolic acid. Our calculations show that the order of stability of the SSC and AAT conformers does not change in liquid phase. However, the energy of SSC and AAT conformers is very close to each other in water media. In water media, strong intramolecular H-bond interaction is present in AAT conformer which causes the energy of AAT conformer to be very close to that of SSC conformer. This may be due to the influence of water media.

Efficient Synthesis, Spectroscopic and Quantum Chemical Study of 2,3-Dihydrobenzofuran Labelled Two Novel Arylidene Indanones: A Comparative Theoretical Exploration

2020 ◽  
Vol 17 (2) ◽  
pp. 146-161
Author(s):  
Rahul Ashok Shinde ◽  
Vishnu Ashok Adole ◽  
Bapu Sonu Jagdale ◽  
Thansing Bhavsing Pawar ◽  
Bhatu Shivaji Desale
Keyword(s):  
Magnetic Resonance ◽  
Density Functional ◽  
Computational Study ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Reactivity Descriptors ◽  
B3lyp Method ◽  
The Density Functional Theory

Indanone and 2,3-dihydrobenzofuran scaffolds are considered as special structures in therapeutic science and explicitly associated with various biologically potent compounds. In the present disclosure, we report the synthesis of two new 2,3-dihydrobenzofuran tethered arylidene indanones via an environmentally adequate and viable protocol. The two compounds revealed in this have been characterized well by analytical methods; proton magnetic resonance (PMR), carbon magnetic resonance (CMR). The Density Functional Theory (DFT) study has been presented for the spectroscopic, structural and quantum correlation between (E)-2-((2,3-dihydrobenzofuran-5-yl)methylene)-2,3-dihydro-1H-inden-1-one (DBDI) and (E)-7-((2,3-dihydrobenzofuran-5-yl)methylene)-1,2,6,7-tetrahydro-8H-indeno[5,4-b]furan-8-one (DBTI). Optimized geometry, frontier molecular orbital, global reactivity descriptors, and thermodynamic parameters have been computed for DBDI and DBTI. DFT/B3LYP method using basis set 6-311++G (d,p) has been employed for the computational study. Mulliken atomic charges are established by using 6-311G (d,p) basis set. Besides, molecular electrostatic potential for DBDI and DBTI is also explored to locate the electrophilic and nucleophilic centres.

CH3 and H2 Quantum Chemical Study of Reaction Mechanisms

2011 ◽  
Vol 142 ◽  
pp. 225-228
Author(s):  
Rui Li ◽  
Xiang Yu Liu
Keyword(s):  
Vibration Mode ◽  
Quantum Chemical Study ◽  
Geometry Optimization ◽  
Chemical Study ◽  
Basis Set ◽  
B3lyp Method ◽  
Selection Mode ◽  
Mode Vibration ◽  
Experimental Values ◽  
Base Group

Using DFT (B3LYP) method, the 6-31G * ,6-311G ** ,6-311 + + G ** and cc-pvtz basis set level, through the CH3+ H2→ CH4+ H reaction of the reactants, transition state and product geometry optimization show that: the base group selection mode on the stationary geometry has little effect; by B3LYP/6-31G * calculated barrier 39.61kJ/mol only difference with the experimental values ​​39.41kJ/mol 0.20 kJ / mol; analysis along the IRC that the HH bond breaking and CH bond formation is a coordinated manner, and in response there is a guide on ways to respond to the vibration mode, vibration mode, the range to guide reaction is s =- 0.57 ~ 0.60 (amu) 1 / 2 • bohr.

scholarly journals Silicon-Doped Nanotube (Si-CNT) as Drug Delivery Nanocarrier for Osteoporosis Drug: Quantum Chemical Study

2021 ◽  
Author(s):  
Zaid Al-Sawaff ◽  
Fatma Kandemirli ◽  
Serap Senturk Dalgic
Keyword(s):  
Drug Delivery ◽  
Quantum Chemical ◽  
Active Sites ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Basis Set ◽  
Drug Molecules ◽  
Spontaneous Interaction ◽  
Silicon Doped ◽  
Molecular Orbital Analysis

Abstract The aim of this study is to investigate the potential and capability of Si-CNT to detect and adsorb BMSF-BENZ ((4-bromo-7-methoxy-1-(2-methoxyethyl)-5-{[3-(methylsulfonyl)phenyl]methyl}-2-[4-(propane-2-))yl) phenyl]-1H-1,3-benzothiazole) molecular. For this purpose, we considered different configurations for adsorbing BMSF-BENZ drug on the surface of the Si-CNT nanocluster. All considered configurations are optimized using DFT theory at the 6-31G** basis set and B3LYP level of theory, and then from optimized structures, for each nanoparticle, we selected four stable models for the adsorption of BMSF-BENZ from (Br, N8, N9, N58, O35, O41 and S) active sites on the surface the selected nanoparticle. and Quantum theory of atoms in Molecular Analysis (QTAIM), and Molecular Orbital Analysis (MO) was also established. The calculated results indicate that the distance between nanocluster and drug from the N8 site is lower than from all other locations sites for all investigated nanoparticles, and adsorption of BMSF-BENZ from the N8 site is more favorable especially for the Si-CNT nanotube. The adsorption energy, hardness, softness, and fermi energy results reveal that the interaction of BMSF-BENZ with Si-CNT, is an encouraging adsorbent for this drug as Eads of BMSF-BENZ/Si-CNT complexes are (-5.15, -24.21, -8.22, -17.03, -13.16, -2.22, -12.70) kcal/mol in the gas phase. As well, the appropriate and spontaneous interaction between the BMSF-BENZ drug and Si-CNT nanoparticle was confirmed by investigating the quantum chemical molecular descriptors and solvation Gibbs free energies of all atoms. Si-CNT can be used as an amperometric sensor to detect the BMSF-BENZ drug molecule. Thus, we propose that the Si-CNT can be a promising candidate as a drug delivery vehicle for BMSF-BENZ drug molecules.

scholarly journals Hyperpolarizability of 6-vertex carboranes quantum chemical study

2003 ◽  
Vol 1 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Kyrill Suponitsky ◽  
Tatiana Timofeeva
Keyword(s):  
Dft Calculations ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Calculated Data ◽  
Chemical Study ◽  
Relative Orientation ◽  
Basis Set ◽  
Basis Sets ◽  
First Hyperpolarizability ◽  
Bond Lengths

AbstractStructure and molecular first hyperpolarizability (β) of nitro-amino-substituted 6-vertex 1,6-carboranes are investigated by means of DFT calculations. The results obtained have revealed that the relative orientation of substituents with respect to the carborane cage influences bond lengths distribution in the cage, which leads to significant changes in the values of hyperpolarizabilities. Calculations with different basis sets have demonstrated that the value of β is not significantly affected by the choice of basis set. The calculated data shows that hyperpolarizability of carborane molecules substituted for carbon atoms is lower than when substituted for boron atoms. For latter molecule, the value of β is of the same order as that of para-nitroaniline molecule.

scholarly journals QUANTUM-CHEMICAL STUDY OF THE MECHANISM OF REACTION OF BENZOELACETHYLENE WITH DITIO- AND DISELENOMALONAMIDES

2020 ◽  
Vol 2020 (1) ◽  
pp. 127-135
Author(s):  
Elena Chirkina
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Quantum Chemical Study ◽  
Chemical Study ◽  
Polarizable Continuum Model ◽  
Basis Set ◽  
Mechanism Of Reaction ◽  
The Density Functional Theory ◽  
Two Stages ◽  
Polarizable Continuum

A mechanism of the interaction of benzoylacetylene with dithio- and diselenomalonamides has been proposed on the basis of quantum-chemical calculations in the framework of the density functional theory using the B3LYP/6-311++G(d,p) basis set taking into account solvent effects (AcOH) within the polarizable continuum model, PCM, with inclusion of the HCl molecule in the calculated space. It is shown that the reaction involves two stages to afford heterocyclic compounds of the dithiine and diselenine type

scholarly journals Quantum-chemical study of molecular structure and relative stability of trans and cis isomers of model anilide derivatives

2017 ◽  
Vol 10 (2) ◽  
pp. 144-151
Author(s):  
Denisa Cagardová ◽  
Peter Poliak ◽  
Vladimír Lukeš
Keyword(s):  
Density Functional ◽  
Quantum Chemical Study ◽  
Theoretical Data ◽  
Chemical Study ◽  
Basis Set ◽  
Ortho Position ◽  
Hybrid Functional ◽  
Trans Conformation ◽  
Length Changes ◽  
Cis And Trans

AbstractDerivatives of anilide were studied systematically by the density functional theory (DFT) using the B3LYP hybrid functional and the 6-311+G(3df,2p) basis set. Characteristic frequencies of N-H and C=O stretching modes for cis and trans conformers distinguishing were compared with available experimental and theoretical data. Effect of substitution in ortho position and acidic residue group is discussed with respect to the bond length changes in the aromatic ring and aromaticity indexes. Energy differences between cis and trans conformations allow estimating the effect of intramolecular hydrogen bonds stabilizing the studied conformations. The trans conformation of parent formanilide is stabilized via the C(aromatic)-H∙∙∙O=C interaction with the energy of around 4 kJ・mol-1. The selected anilide series represent model compounds for drug design.

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