Effect of Substitution for Insertion of CO2 into Epoxides and Aziridines: An Ab Initio Study

2020 ◽  
Vol 73 (1) ◽  
pp. 30
Author(s):  
Yunhan Yang ◽  
Fenji Li ◽  
Cuicui Yang ◽  
Lijuan Jia ◽  
Lijuan Yang ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Free Energy ◽  
Reaction Mechanism ◽  
Ab Initio ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Concerted Mechanism

The insertion of CO2 into epoxides and aziridines has been studied using density functional theory (B3LYP) and ab initio (MP2) methods, and the effect of substitution for the two reactions are further explored. It is found that the reactivity of epoxides and aziridines are similar, and insertion of CO2 proceeds through a concerted mechanism. The substitutions of methyl and phenyl does not change the reaction mechanism, but the transition state for the substitution on the attacking position becomes loose with a lower free energy barrier. The substitutions of methyl and phenyl decrease the free energy barrier, with phenyl substitution having a greater affect. The results also show that the free energy barriers for the insertions of CO2 into aziridines are ~10kcalmol−1 lower than the corresponding reactions of CO2 with epoxides.

scholarly journals Ab Initio Study of Geminal Steric Hindrance Effects on the Stability of Conformations of Cyclohexane Derivatives

2005 ◽  
Vol 2005 (8) ◽  
pp. 508-515 ◽  
Author(s):  
Davood Nori-Shargh ◽  
Mostafa Mohamadpour Amini ◽  
Maryam Jafari ◽  
Farzad Deyhimi ◽  
Saeed Jameh-Bozorghi
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Energy Barrier ◽  
Density Functional ◽  
Energy Difference ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Conformational Properties ◽  
The Stability ◽  
Twist Boat

Ab initio and density functional theory methods (HF/3-21G*//HF/3-21G*, MP2/3-21G*//HF/3-21G*, B3LYP/3-21G*//HF/3-21G*, B3LYP/LANL2DZ*//HF/LANL2DZ*, MP2/LANL2DZ*//HF/LANL2DZ* and HF/LANL2DZ*//HF/LANL2DZ*) used to investigate the conformational properties of cyclohexane, 1,1-dimethylcyclohexane, 1,1-di-tert-butylcyclohexane, 1,1-bis(trimethylsilanyl)cyclohexane, 1,1-bis(trimethylgermanyl)cyclohexane and 1,1-bis(trimethylstannyl)cyclohex ane showed that the energy difference between the chair and twist-boat conformations and also the ring flipping energy barrier decreases from cyclohexane, 1,1-dimethylcyclohexane to 1,1-di-tert-butylcyclohexane, and increases from 1,1-bis(trimethylsilanyl)cyclohexane, 1,1-bis(trimethylgermanyl)cyclohexane to 1,1-bis(trimethylstannyl)cyclohexane.

DFT study on the hydrolysis of metsulfuron-methyl: A sulfonylurea herbicide

2018 ◽  
Vol 17 (08) ◽  
pp. 1850050 ◽  
Author(s):  
Qiuhan Luo ◽  
Gang Li ◽  
Junping Xiao ◽  
Chunhui Yin ◽  
Yahui He ◽  
...  
Keyword(s):  
Free Energy ◽  
Water Molecule ◽  
Carbonyl Group ◽  
Energy Barrier ◽  
Density Functional ◽  
Free Energy Barrier ◽  
Functional Theory ◽  
Metsulfuron Methyl ◽  
Catalytic Role ◽  
Hydrolysis Of

Sulfonylureas are an important group of herbicides widely used for a range of weeds and grasses control particularly in cereals. However, some of them tend to persist for years in environments. Hydrolysis is the primary pathway for their degradation. To understand the hydrolysis behavior of sulfonylurea herbicides, the hydrolysis mechanism of metsulfuron-methyl, a typical sulfonylurea, was investigated using density functional theory (DFT) at the B3LYP/6-31[Formula: see text]G(d,p) level. The hydrolysis of metsulfuron-methyl resembles nucleophilic substitution by a water molecule attacking the carbonyl group from aryl side (pathway a) or from heterocycle side (pathway b). In the direct hydrolysis, the carbonyl group is directly attacked by one water molecule to form benzene sulfonamide or heterocyclic amine; the free energy barrier is about 52–58[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. In the autocatalytic hydrolysis, with the second water molecule acting as a catalyst, the free energy barrier, which is about 43–45[Formula: see text]kcal[Formula: see text]mol[Formula: see text], is remarkably reduced by about 11[Formula: see text]kcal[Formula: see text]mol[Formula: see text]. It is obvious that water molecules play a significant catalytic role during the hydrolysis of sulfonylureas.

scholarly journals STRUCTURAL AND ELECTRONIC PROPERTIES OF BRIDGED BITHIOPHENE S-OXIDES (BTO) WITH S, S=O, O, SiH2 and BH2 BRIDGE: SEMI-EMPIRICAL AND AB INITIO STUDY

2010 ◽  
Vol 18 (18) ◽  
pp. 1-10
Author(s):  
Banjo Semire ◽  
Isaiah Ajibade Adejoro ◽  
Olusegun Ayobami Odunola
Keyword(s):  
Density Functional Theory ◽  
Thermodynamic Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Ab Initio Study ◽  
Empirical Methods ◽  
Functional Theory ◽  
Structural And Electronic Properties ◽  
Semi Empirical ◽  
Good Agreement

In this paper, we theoretically studied the geometries, stabilities, electronic and thermodynamic properties of bridged bithiophene S-oxide (BTO-X) derivates (with X = BH2, SiH2, S, S=O, and O) by using semi-empirical methods, ab-initio, and Density functional theory. The geometries and thermodynamic parameters calculated by PM3 were in good agreement with that of B3LYP/6-31G(d). The bandgap calculated by B3LYP/6-31G(d) ranged from 3.94eV (BTO-O)-3.16eV (BTO-BH2). The absorption λmax calculated suing B3LYP/6-31G(d) shifted to longer wavelength with X=BH2, SiH2, and S=O due to enhancement of π-conjugated system whereas, BTO-S and BTO-O shifted to shorter wavelengths as compared to dimmer thiophene S-oxide (2TO).

scholarly journals Ab initio study of elastic anisotropies and thermal conductivities of rhenium diborides in different crystal structures

RSC Advances ◽  
2020 ◽  
Vol 10 (61) ◽  
pp. 37142-37152
Author(s):  
Yi X. Wang ◽  
Ying Y. Liu ◽  
Zheng X. Yan ◽  
W. Liu ◽  
Jian B. Gu
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Crystal Structures ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Ab Initio Study ◽  
Ambient Conditions ◽  
Functional Theory ◽  
Thermal Conductivities

The phase stabilities, elastic anisotropies, and thermal conductivities of ReB2 diborides under ambient conditions have been investigated by using density functional theory calculations.

Catalytic polymerization of naphthalene by HF/BF3 super acid: an ab initio density functional theory study

2018 ◽  
Vol 20 (36) ◽  
pp. 23311-23319 ◽  
Author(s):  
Po-Yu Yang ◽  
Hsing-Yin Chen ◽  
Shin-Pon Ju ◽  
Chia-Lin Chang ◽  
Gao-Shee Leu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Reaction Mechanism ◽  
Dft Calculations ◽  
Ab Initio ◽  
Density Functional ◽  
Catalytic Polymerization ◽  
Density Functional Theory Study ◽  
Functional Theory ◽  
Detailed Reaction Mechanism ◽  
Super Acid

The detailed reaction mechanism of naphthalene catalytic polymerization by HF/BF3 has been investigated by DFT calculations and the directionality of the naphthalene-derived mesophase molecule has been explained.

Optical and dielectric properties of lead perovskite and iodoplumbate complexes: an ab initio study

2020 ◽  
Vol 22 (33) ◽  
pp. 18423-18434
Author(s):  
Malladi Srikanth ◽  
Mailde S. Ozório ◽  
Juarez L. F. Da Silva
Keyword(s):  
Density Functional Theory ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Ab Initio ◽  
Density Functional ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Optical Dielectric Constant ◽  
Energetic Stability ◽  
Optical Dielectric

Optical and dielectric properties, and energetic stability orders of black phase of perovskites and yellow phase of iodoplumbates have been studied using density functional theory; where the optical dielectric constant varies with the polymorphic phase and nature of cation.

scholarly journals Ab initio study of aspirin adsorption on single-walled carbon and carbon nitride nanotubes

2017 ◽  
Vol 19 (11) ◽  
pp. 8076-8081 ◽  
Author(s):  
Yongju Lee ◽  
Dae-Gyeon Kwon ◽  
Gunn Kim ◽  
Young-Kyun Kwon
Keyword(s):  
Density Functional Theory ◽  
Carbon Nanotube ◽  
Acetylsalicylic Acid ◽  
Ab Initio ◽  
Density Functional ◽  
Carbon Nitride ◽  
Adsorption Properties ◽  
Graphitic Carbon Nitride ◽  
Ab Initio Study ◽  
Functional Theory

Using density functional theory, we investigate the adsorption properties of acetylsalicylic acid (aspirin) on the outer surfaces of a (10,0) carbon nanotube (CNT) and a (8,0) triazine-based graphitic carbon nitride nanotube (CNNT).

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