Theoretical calculations of rate of NDMA formation from gramine

2013 ◽  
Vol 91 (4) ◽  
pp. 275-282
Author(s):  
F. Shojaie ◽  
M. Dehestani
Keyword(s):  
Reaction Mechanism ◽  
Transition State ◽  
Density Functional ◽  
Transition State Theory ◽  
Theoretical Calculations ◽  
State Theory ◽  
Stationary Points ◽  
Functional Theory ◽  
Molecule Reaction ◽  
Good Agreement

The first ab initio theoretical study is performed on the ion–molecule reaction of gramine (C11H14N2) with NO+ for the formation of N-nitrosodimethylamine (NDMA). The reaction mechanism is investigated using the B3LYP density functional theory level. The stationary points along the reaction energy profile have been calculated at the B3LYP/6-311+G(d,p) level of the theory in the gas phase and solution phase. In this work, an attempt is made to elucidate the mechanism and so is proposed the efficient reactive pathway for the reaction of gramine with NO+ step by step. A complete reaction mechanism has been established, and the temperature dependence of all rate constants between 23 and 65 °C are reported and analyzed in terms of transition state theory. The percentages of NDMA formation in the 23–65 °C temperature range have been calculated in aqueous solution by transition state theory. The results are in good agreement with experimental results.

Density functional theoretical study on the reaction mechanism of SiHF radical with HNCO

2014 ◽  
Vol 13 (07) ◽  
pp. 1450054 ◽  
Author(s):  
Li-Jie Hou ◽  
Bo-Wan Wu ◽  
Yan-Xia Han ◽  
Chao Kong ◽  
Dong-Ping Chen ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Density Functional ◽  
Transition State Theory ◽  
Main Product ◽  
Theoretical Study ◽  
State Theory ◽  
Functional Theory ◽  
B3lyp Method ◽  
Reaction Channels ◽  
Thermodynamic And Kinetic Characters

The reaction mechanism of SiHF radical with HNCO has been investigated by the B3LYP method of density functional theory (DFT), while the geometries and harmonic vibration frequencies of reactants, intermediates, transition states and products have been calculated at the B3LYP/6-311++G** level. To obtain more precise energy result, stationary point energies were calculated at the CCSD(T)/6-311++G**//B3LYP/6-311++G** level. In temperature range of 100 K to 1900 K, the statistical thermodynamics and Eyring transition state theory with Winger correction are used to study the thermodynamic and kinetic characters of the channel with low energy barrier at 1.0 Atm. SiHF + HNCO → IM 8 → TS 8 → SiFNHCHO ( P 3) was the main channel with low potential energy in the singlet state, SiFNHCHO was the main product. The analyses for the combining interaction between SiHF radical and HNCO with the atom-in-molecules (AIM) theory have been performed. There are three reaction channels in the triplet.

Surface Structure Sensitivity of Hydrodeoxygenation of Biomass-derived Organic Acids over Palladium Catalysts: A Microkinetic Modeling Approach

2021 ◽  
Author(s):  
Subrata K. Kundu ◽  
Vijay Solomon Rajadurai ◽  
Wenqiang Yang ◽  
Eric Walker ◽  
Osman Mamun ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Transition State ◽  
Organic Acids ◽  
Organic Acid ◽  
Palladium Catalysts ◽  
Density Functional ◽  
Transition State Theory ◽  
State Theory ◽  
Propanoic Acid ◽  
Functional Theory

Microkinetic models based on parameters obtained from density functional theory and transition state theory have been developed for the hydrodeoxygenation (HDO) of propanoic acid, a model lignocellulosic biomass-derived organic acid,...

Resonance Raman and absorption infrared with density functional theory studies of Fe(III)/Fe(II) and Ni(II) complexes of modified 21-oxaporphyrins

2013 ◽  
Vol 17 (04) ◽  
pp. 289-308 ◽  
Author(s):  
Mateusz Fościak ◽  
Edyta Proniewicz ◽  
Krzysztof Zborowski ◽  
Younkyoo Kim ◽  
Leonard M. Proniewicz
Keyword(s):  
Density Functional ◽  
Theoretical Calculations ◽  
Resonance Raman ◽  
Vibrational Analysis ◽  
Basis Set ◽  
Functional Theory ◽  
B3lyp Level ◽  
Ft Ir ◽  
Optimized Geometries ◽  
Good Agreement

This work presents a complete vibrational analysis of iron [ Fe (II) and Fe (III)] and nickel [ Ni (II)] complexes with 5,10,15,20-tetraphenyl-21-oxaporphyrin [OTPPH] and 5,20-bis(p-tolyl)-10,15-diphenyl-21-oxaporphyrin [ODTDPPH]. In these porphyrins, a furan ring replaces one of the pyrrole rings. The six-coordinate (OTPP) FeIIICl2 and (ODTDPP) FeIIICl2 as well as the five-coordinate (OTPP) FeIICl and (OTPP) NiIICl complexes were investigated using experimental and theoretical methods. The experimental part of this work involved Fourier-transform absorption infrared (FT-IR), resonance Raman (RR), and electron absorption (UV-vis) measurements for all of the investigated complexes. In the theoretical section, optimized geometries and vibrational frequencies for model compounds are provided. The theoretical calculations were performed at the B3LYP level with the LANL2DZ basis set. Good agreement was achieved between the experimental and theoretical vibrational spectra. In addition, charge distributions (GAPT) and geometrical aromaticity indices (Bird's I5 and HOMA) were calculated and discussed.

DIRECT DENSITY FUNCTIONAL THEORY DYNAMICS STUDY FOR THE CH3OCF2CF2OCH3 + OH REACTION

2011 ◽  
Vol 10 (02) ◽  
pp. 231-244 ◽  
Author(s):  
HONG-BO YU ◽  
FENG-CHAO CUI ◽  
YONG-XIA WANG ◽  
HONG-XIA LIU ◽  
JING-YAO LIU
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Theoretical Data ◽  
State Theory ◽  
Stationary Points ◽  
Enthalpies Of Formation ◽  
Oh Radicals ◽  
Isodesmic Reactions ◽  
Functional Theory ◽  
Barrier Heights

The mechanism and kinetics of the reaction of CH3OCF2CF2OCH3 with OH radicals have been studied theoretically by a direct density functional theory dynamics method. All possible H -abstraction channels and displacement processes taking place on two different conformers of CH3OCF2CF2OCH3 have been taken into consideration. The potential energy surface information including the optimized geometries and harmonic vibrational frequencies of all the stationary points and barrier heights involved in these channels were obtained at the BB1K/6-31+G(d,p) level of theory. The rate constants were calculated using improved canonical variational transition state theory (ICVT) with the small-curvature tunneling correction (SCT) over the temperature range of 200–2000 K. The overall rate constant for the title reaction, which was obtained by considering the weight factor of each conformer from the Boltzman distribution function, is in reasonable agreement with the available experimental value. Three-term Arrhenius expression is fitted to be k T = 1.56 × 10-20 T 2.47 exp (-124.64/ T ) cm 3 molecule-1 s-1 (200–2000 K). Also, the enthalpies of formation of the reactant CH3OCF2CF2OCH3 and product radicals CH3OCF2CF2OCH2 and CH3OCF2CF2O , which lack experimental or theoretical data, were evaluated via applying isodesmic reactions.

Computational study on the reaction of atomic chlorine with 1,2-dibromoethane (CH2BrCH2Br)

2013 ◽  
Vol 91 (11) ◽  
pp. 1123-1129 ◽  
Author(s):  
Ang-yang Yu
Keyword(s):  
Transition State ◽  
Rate Constants ◽  
Transition State Theory ◽  
Computational Study ◽  
Minimum Energy ◽  
State Theory ◽  
Basis Set ◽  
Stationary Points ◽  
Variational Transition State Theory ◽  
Variational Transition State

In this work, the reaction mechanism and kinetics of Cl + CH2BrCH2Br → products are theoretically investigated for the first time. The optimized geometries and frequencies of all of the stationary points and selected points along the minimum-energy path for the three hydrogen abstraction channels and two bromine abstraction channels are calculated at the BH&H-LYP level with the 6-311G** basis set and the energy profiles are further calculated at the CCSD(T) level of theory. The rate constants are evaluated using the conventional transition-state theory, the canonical variational transition-state theory, and the canonical variational transition-state theory with a small-curvature tunneling correction over the temperature range 200–1000 K. The results show that reaction channel 3 is the primary channel and the calculated rate constants are in good agreement with available experimental values. The three-parameter Arrhenius expression for the total rate constants over 200–1000 K is provided.

Theoretical calculations of stability, mechanical and thermodynamic properties of IVA group Willemite-II nitrides

2015 ◽  
Vol 14 (04) ◽  
pp. 1550024 ◽  
Author(s):  
Ying-Chun Ding ◽  
Min Chen ◽  
Wen-Juan Wu
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
First Principles ◽  
Density Functional ◽  
Theoretical Calculations ◽  
Mechanical Anisotropy ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Good Agreement

The structural stability and mechanical and thermodynamic properties of WII- A 3 N 4 ( A=C , Si , Ge and Sn ) are calculated by first-principles calculations based on the density functional theory. The calculated lattice parameters and elastic constants of WII- A 3 N 4 ( A=C , Si , Ge and Sn ) are in good agreement with the experimental data and previously calculated values. WII- A 3 N 4 ( A=C , Si , Ge and Sn ) compounds are also found to be thermodynamically and mechanically stable. The results suggest that hardness of WII- C 3 N 4 is the hardest of these C 3 N 4 polymorphs. The hardness of WII- Sn 3 N 4 is the smallest among WII- A 3 N 4 ( A=C , Si , Ge and Sn ). Furthermore, the mechanical anisotropy, Debye temperature, the minimum thermal conductivity and thermodynamic properties of WII- A 3 N 4 ( A=C , Si , Ge and Sn ) compounds can be investigated.

scholarly journals Post-transition state bifurcations induce dynamical detours in Pummerer-like reactions

2018 ◽  
Vol 9 (48) ◽  
pp. 8937-8945 ◽  
Author(s):  
Stephanie R. Hare ◽  
Ang Li ◽  
Dean J. Tantillo
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Dft Calculations ◽  
Transition State ◽  
Density Functional ◽  
Stationary Points ◽  
Functional Theory ◽  
Direct Dynamics ◽  
Dynamics Simulations

A post-transition state bifurcation (PTSB) involved in a Pummerer-type rearrangement is characterized using density functional theory (DFT) calculations on potential energy stationary points and direct dynamics simulations.

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