scholarly journals Study on the Product Formation of the Reaction between Criegee Compound and Propargyl Radical

2021 ◽  
Vol 31 (4) ◽  
pp. 80-84
Keyword(s):  
Density Functional ◽  
Single Point ◽  
Product Formation ◽  
Basis Set ◽  
Functional Theory ◽  
Point Energy ◽  
Propargyl Radical ◽  
The Density Functional Theory ◽  
Stable Product ◽  
Mechanism Of The Reaction

Mechanism of the reaction between Criegee compound (CH2OO) and Propargyl radical (C3H3) has been studied by using the density functional theory DFT/M06-2X in conjunction with the 6-311++G(3df,2p) basis set for both optimization and single-point energy calculations. The calculated results indicate that mechanism of the C3H3 + CH2OO reaction can occur in two different directions: H-atom abstraction and/or addition. As a result, 11 various products have been created from this reaction; in which, P10 (OCHCHCHCHO + H) is the most thermodynamically stable product and the reaction path leading to the P7 (CH2-[cyc-CCHCHOO] + H) product is the most energetically and kinetically favorable channel.

scholarly journals Theoretical investigation of the Anti-Parkinson drug rasagiline and its salts: conformations and infrared spectra

2012 ◽  
Vol 10 (2) ◽  
pp. 395-406 ◽  
Author(s):  
U. Başköse ◽  
Sevgi Bayarı ◽  
Semran Sağlam ◽  
Hacı Özışık
Keyword(s):  
Density Functional ◽  
Single Point ◽  
Normal Modes ◽  
Basis Set ◽  
Stable Conformer ◽  
Functional Theory ◽  
Point Energy ◽  
Vibrational Assignments ◽  
B3lyp Method ◽  
The Density Functional Theory

AbstractThe conformational analysis of rasagiline [N-propargyl-1(R)-aminoindan] was performed by the density functional theory (DFT) B3LYP method using the 6–31++G (d,p) basis set. A single point energy calculations based on the B3LYP optimized geometries were also performed at MP2/6-31++G (d, p) level. The vibrational frequencies of the most stable conformer of rasagiline was calculated at the B3LYP level and vibrational assignments were made for normal modes on the basis of scaled quantum mechanical force field (SQM) method. The influence of mesylate and ethanedisulfonate salts on the geometry of rasagiline free base and its normal modes are also discussed.

scholarly journals Quantum Mechanical Investigations into Thermochemistry Properties and Electronic, Structural of Nanocrystals

2019 ◽  
Vol 29 (3) ◽  
pp. 133
Author(s):  
Huda M. Jawad
Keyword(s):  
Density Functional ◽  
Gallium Phosphide ◽  
Zero Point ◽  
Basis Set ◽  
Quantum Mechanical ◽  
Generalized Gradient ◽  
Actual System ◽  
Functional Theory ◽  
Point Energy ◽  
The Density Functional Theory

This paper presents quantum mechanical investigations that is into electronic and thermochemistry properties of Gallium phosphide. It also investigates diamondoids and nanocrystals using the density functional theory. This is done at the generalized gradient approximation of Perdew et al basis set. This has been used to create Gaussian 09 program auxiliary by Gaussian view. In order to full investigate the ionization potential, affinity, valance bond, conduction bond, zero point energy and thermochemistry properties. The result GaP diamondoids. Electron affinity and conduction band, decreases as a function of the total number of Ga and P atoms in most of the investigated range. Ionization energies zero point and valance bands increased with the number of Ga and P atoms but there are fluctuations in tetramantane and hexamantane In fact, since the present diamondoids are built from nearly cubic cages. Thermochemistry entails calculation of frequency which also includes thermochemical analysis of actual system comprising of thermal energy correction, heat capacity and entropy.

THEORETICAL STUDY OF MECHANISM FOR THE ATMOSPHERIC REACTION CF3CHFO2 + NO

2013 ◽  
Vol 12 (01) ◽  
pp. 1250101 ◽  
Author(s):  
YA-NA WENG ◽  
XIAO-JUAN YAN ◽  
SHU-JIN LI
Keyword(s):  
Density Functional ◽  
Energy Surface ◽  
Single Point ◽  
Basis Set ◽  
Stationary Points ◽  
Cluster Method ◽  
Radical Pairs ◽  
Functional Theory ◽  
Point Energy ◽  
Optimized Geometries

The mechanism of the reaction CF3CHFO2 + NO was investigated using ab initio and density functional theory (DFT). The optimized geometries for all stationary points on the reaction energy surface were calculated using MP2 and B3LYP methods with the aug-cc-pVDZ basis set. Single-point energy calculations were performed using the coupled cluster method with single, double and perturbative triple configurations, CCSD(T). The most important energy minima on the potential energy surface (PES) were found corresponding to two conformers of the peroxynitrite association adducts, cis- CF3CHFOONO and trans- CF3CHFOONO , and the nitrate, CF3CHFONO2 . The radical pairs ( CF3CHFO + NO2 ) and the nitrate are formed through the breaking of the peroxy bond of trans- CF3CHFOONO and the rearrangement of cis- CF3CHFOONO , respectively. The nitrate can be decomposed to carbonylated species ( CF3CHO or CF3CFO ), nitryl fluoride (NO2F), nitrous acid (HONO), and radical pairs ( CF3CHFO + NO2 ), which are of potential atmospheric importance.

Formation of a vanillic Mannich base – theoretical study

2015 ◽  
Vol 69 (9) ◽  
Author(s):  
Vladimir P. Petrović ◽  
Dušica Simijonović ◽  
Zorica D. Petrović ◽  
Svetlana Marković
Keyword(s):  
Mannich Reaction ◽  
Density Functional ◽  
Room Temperature ◽  
Mannich Base ◽  
Nucleophilic Attack ◽  
One Pot ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Stable Product ◽  
Mechanism Of The Reaction

AbstractOne-pot anti-Mannich reaction of vanillin, aniline and cyclohexanone was successfully catalyzed by ionic liquid triethanolammonium chloroacetate, at room temperature. Yield of the obtained Mannich base was very good and excellent diastereoselectivity was achieved. Mechanism of the reaction was investigated using the density functional theory. The reaction started with a nucleophilic attack of aniline nitrogen at the carbonyl group of vanillin. The intermediate α-amino alcohol formed in this way was further subjected to protonation by the triethanolammonium ion yielding the imminium ion. Theoretically, the obtained imminium ion and the enol form of cyclohexanone can build the protonated Mannich base via the anti and syn pathways. The chloroacetic anion spontaneously abstracts the proton yielding the final product of the reaction anti 2-[1-(N-phenylamino)-1-(4-hydroxy- 3-methoxyphenyl)]methylcyclohexanone (MB-H). The syn pathway requires lower activation energy but the anti pathway yields a thermodynamically more stable product, which implies that the examined Mannich reaction is thermodynamically controlled

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

2021 ◽  
Vol 43 (1) ◽  
pp. 25-25
Author(s):  
Said Abdelqadar Said Said Abdelqadar Said ◽  
Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ring Closure ◽  
Basis Set ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Electronic And Structural Properties ◽  
Maximum Hardness Principle

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

scholarly journals Analysis of vibratinal spectra of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,7-dinitro derivatives based on density functional theory calculations

2007 ◽  
Vol 5 (1) ◽  
pp. 201-220 ◽  
Author(s):  
Khaled Bahgat ◽  
Abdel Ragheb
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Basis Set ◽  
Normal Coordinate ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Vibrational Bands ◽  
Good Agreement

AbstractThe geometry, frequency and intensity of the vibrational bands of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,7-dinitro derivatives were obtained by the density functional theory (DFT) calculations with Becke3-Lee-Parr (B3LYP) functional and 6-31G* basis set. The effects of chloride, bromide, iodide and nitro substituent on the vibrational frequencies of 8-hydroxyquinoline have been investigated. The assignments have been proposed with aid of the results of normal coordinate analysis. The observed and calculated spectra are found to be in good agreement.

Atmospheric oxidation mechanism of polyfluorinated sulfonamides — A quantum chemical and kinetic study

2013 ◽  
Vol 91 (6) ◽  
pp. 472-478 ◽  
Author(s):  
Xiaoyan Sun ◽  
Lei Ding ◽  
Qingzhu Zhang ◽  
Wenxing Wang
Keyword(s):  
Rate Constants ◽  
Density Functional ◽  
Single Point ◽  
Oxidation Mechanism ◽  
Basis Set ◽  
Atmospheric Oxidation ◽  
Oh Radicals ◽  
Oh Radical ◽  
Orbital Theory ◽  
Point Energy

Polyfluorinated sulfonamides (FSAs, F(CF2)nSO2NR1R2) are present in the atmosphere and may serve as the source of perfluorocarboxylates (PFCAs, CF3(CF2)nCOO–) in remote locations through long-range atmospheric transport and oxidation. Density functional theory (DFT) molecular orbital theory calculations were carried out to investigate OH radical-initiated atmospheric oxidation of a series of sulfonamides, F(CF2)nSO2NR1R2 (n = 4, 6, 8). Geometry optimizations of the reactants as well as the intermediates, transition states, and products were performed at the MPWB1K level with the 6-31G+(d,p) basis set. Single-point energy calculations were carried out at the MPWB1K/6-311+G(3df,2p) level of theory. The OH radical-initiated reaction mechanism is given and confirms that the OH addition to the sulfone double bond producing perfluoroalkanesulfonic acid directly cannot occur in the general atmosphere. Canonical variational transition-state (CVT) theory with small curvature tunneling (SCT) contribution was used to predict the rate constants. The overall rate constants were determined, k(T) (N-EtFBSA + OH) = (3.21 × 10−12) exp(–584.19/T), k(T) (N-EtFHxSA + OH) = (3.21 × 10−12) exp(–543.24/T), and k(T) (N-EtFOSA + OH) = (2.17 × 10−12) exp(–504.96/T) cm3 molecule−1 s−1, over the possible atmospheric temperature range of 180–370 K, indicating that the length of the F(CF2)n group has no large effect on the reactivity of FSAs. Results show that the atmospheric lifetime of FSAs determined by OH radicals will be 20–40 days, which agrees well with the experimental values (20–50 days), 20 thus they may contribute to the burden of perfluorinated pollution in remote regions.

scholarly journals The difference in stability between 5′R and 5′S diastereomers of 5′,8-cyclopurine-2′-deoxynucleosides. DFT study in gaseous and aqueous phase

2010 ◽  
Vol 8 (1) ◽  
pp. 134-141 ◽  
Author(s):  
Boleslaw Karwowski
Keyword(s):  
Density Functional ◽  
Bond Cleavage ◽  
Basis Set ◽  
Small Range ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Formic Acid Hydrolysis ◽  
The Difference ◽  
The Stability ◽  
First Time

AbstractOxidatively generated damage to DNA frequently appears in the human genome as an effect of aerobic metabolism or as the result of exposure to exogenous oxidizing agents. Due to these facts it has been decided to calculate the stability of 5′,8-cyclo-2′-deoxyadenosine/guanosine (cdA, cdG) in their 5′R and 5′S diastereomeric forms. For all points of quantum mechanics studies presented, the density functional theory (DFT) with B3LYP parameters on 6-311++G** basis set level was used. The calculations showed a significant negative enthalpy for glycosidic bond cleavage reaction for cationic forms and slightly negative for neutral ones. The preliminary study of the discussed process has shown the nature of stepwise nucleophilic substitution DN*AD type mechanism. Surprisingly, the different values in free energy, between short-lived oxacarbenium ion intermediates, have been found to lie over a relatively small range, around 1 and 2.8 kcal mol−1. For anions, the decomposition enthalpies were found as positive in aqueous phases. These theoretical results are supported by the formic acid hydrolysis experiments of both diastereomers of cdA, for the first time. (5′S)cdA exhibited higher stability than (5′R)cdA.

scholarly journals Structural characterization of kaempferol: a spectroscopic and computational study

2019 ◽  
Vol 38 (1) ◽  
pp. 49 ◽  
Author(s):  
Dejan Milenković ◽  
Jasmina M Dimitrić Marković ◽  
Dušan Dimić ◽  
Svetlana Jeremić ◽  
Dragan Amić ◽  
...  
Keyword(s):  
Density Functional ◽  
Computational Study ◽  
Chemical Shifts ◽  
Absolute Error ◽  
Nbo Analysis ◽  
Basis Set ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Spectroscopic Characteristics

Calculations based on the density functional theory, with the B3LYP functional and the 6-311++G(d,p) basis set, were performed with the aim of confirming the molecular structure and spectroscopic characteristics of kaempferol, a naturally occurring flavonoid molecule. The electronic structure of kaempferol was examined using NBO analysis. The assigning of the experimentally obtained IR and Raman spectra was performed after the best-fit-based comparison with theoretical spectra. The 13C and 1H NMR experimental spectra were related to the theoretically obtained values of the chemical shifts determined by the GIAO method. The correlation coefficient and the average absolute error values proved B3LYP-D3 to be an adequate method in describing the NMR parameters of kaempferol. Molecular docking analysis was carried out in order to identify the potency of inhibition of the title molecule against human procalcitonin. The inhibition activity was obtained for 10 conformations of ligand inside the protein.

A Density Functional Theory Study of the Isomerization of Substituted 2and#39;-hydroxychalcones to the Corresponding Flavanones

2021 ◽  
Vol 43 (1) ◽  
pp. 25-25
Author(s):  
Said Abdelqadar Said Said Abdelqadar Said ◽  
Omar A Shareef and Abdulkhalik S Alkazzaz Omar A Shareef and Abdulkhalik S Alkazzaz
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Ring Closure ◽  
Basis Set ◽  
Functional Theory ◽  
Rate Determining Step ◽  
The Density Functional Theory ◽  
Electronic And Structural Properties ◽  
Maximum Hardness Principle

The transformation of 2and#39;-hydroxychalcones to their corresponding flavanones was studied theoretically by the use of the density functional theory (DFT) with B3-LYP/ 6-311G basis set to get important information about the role of both of electronic and structural properties in this process. The obtained energies were found to be in agreement with our previous results that obtained from HPLC studies. The estimated hardness, polarizability, and electrophilicity profiles were found to obey the maximum hardness principle (MHP), minimum polarizability principle (MPP), and the minimum electrophilicity principle (MEP) respectively. Flavanone ring closure was found to be the rate-determining step.

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