scholarly journals DFT study on the gold(I)-catalyzed cycloaddition and rearrangement reactions of allene-containing allylic silyl ether

2021 ◽  
Author(s):  
Yamei Zhao ◽  
MengDan Huo ◽  
HongJi Zhou
Keyword(s):  
Single Point ◽  
Membered Ring ◽  
Silyl Ether ◽  
Experimental Conditions ◽  
Point Energy ◽  
Intramolecular Cycloaddition ◽  
Activation Free Energy ◽  
Rearrangement Process ◽  
Calculation Results ◽  
Group Carbon

Abstract The DFT calculation of the B3LYP level was carried out to explore the reaction mechanism of the synthesis of spirocyclo[4, 5]decane skeleton by gold-catalyzed allenyl compounds. The more accurate energy under the CH3CN solvent in the experiment is calculated by the single point energy of the SMD model. Computational studies have shown that the reaction consists of three main steps: intramolecular cycloaddition of the end group carbon atoms of allenyl and vinyl groups, the semipinacol rearrangement process in which the four-membered ring is reconstructed into the five-membered ring, the elimination reaction releases the catalyst and obtains the product. The calculation results show that Zheng et al. reported that the gold-catalyzed synthesis reaction can easily occur under the experimental conditions due to its low activation free energy (12.42–16.79 kcal/mol). Furthermore, it was found that the MOMO(CH2)2 substituent has higher reactivity than the corresponding reactant of the phenyl substituent.

Theoretical study on NO3-initiated oxidation of acenaphthene in the atmosphere

2008 ◽  
Vol 86 (2) ◽  
pp. 129-137 ◽  
Author(s):  
Xiaohui Qu ◽  
Qingzhu Zhang ◽  
Wenxing Wang
Keyword(s):  
Product Information ◽  
Environmental Concern ◽  
Single Point ◽  
Basis Set ◽  
Orbital Theory ◽  
Night Time ◽  
Point Energy ◽  
Secondary Reactions ◽  
Favorable Reaction ◽  
High Level

Acenaphthene is widespread and toxic, and thus of substantial environmental concern. The reaction with NO3 radicals is an important atmospheric loss process of acenaphthene at night time. In this work, the mechanism for the NO3-initiated atmospheric oxidation reaction of acenaphthene has been studied using high level molecular orbital theory. Geometries of all the related species have been optimized at the MPWB1K level with the 6–31G(d,p) basis set. The single-point energy calculations have been carried out at the MPWB1K/6–311+G(3df,2p) level. The possible secondary reactions were also studied. Several energetically favorable reaction pathways were revealed for the first time.Key words: acenaphthene, NO3 radicals, reaction mechanism, product information, oxidation degradation.

scholarly journals Trans Influence of Boryl Ligands in CO2 Hydrogenation on Ruthenium Complexes: Theoretical Prediction of Highly Active Catalysts for CO2 Reduction

Catalysts ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1356
Author(s):  
Tian Liu ◽  
Zhangyong Liu ◽  
Lipeng Tang ◽  
Jun Li ◽  
Zhuhong Yang
Keyword(s):  
Active Catalyst ◽  
Co2 Reduction ◽  
Nbo Analysis ◽  
Activation Free Energy ◽  
Highly Active ◽  
Trans Influence ◽  
Bond Property ◽  
Hydride Ligand ◽  
Calculation Results ◽  
Ruthenium Dihydride

In this work, we study the trans influence of boryl ligands and other commonly used non-boryl ligands in order to search for a more active catalyst than the ruthenium dihydride complex Ru(PNP)(CO)H2 for the hydrogenation of CO2. The theoretical calculation results show that only the B ligands exhibit a stronger trans influence than the hydride ligand and are along increasing order of trans influence as follows: –H < –BBr2 < –BCl2 ≈ –B(OCH)2 < –Bcat < –B(OCH2)2 ≈ –B(OH)2 < –Bpin < –B(NHCH2)2 < –B(OCH3)2 < –B(CH3)2 < –BH2. The computed activation free energy for the direct hydride addition to CO2 and the NBO analysis of the property of the Ru–H bond indicate that the activity of the hydride can be enhanced by the strong trans influence of the B ligands through the change in the Ru–H bond property. The function of the strong trans influence of B ligands is to decrease the d orbital component of Ru in the Ru–H bond. The design of a more active catalyst than the Ru(PNP)(CO)H2 complex is possible.

DFT STUDY ON SECOND-ORDER NONLINEAR OPTICAL PROPERTIES OF THE DERIVATIVES OF DISUBSTITUTED SEVEN-VERTEX COBALTACARBORANE METALLOCENYL

2010 ◽  
Vol 09 (01) ◽  
pp. 219-231 ◽  
Author(s):  
XIAODONG LIU ◽  
YONGQING QIU ◽  
SHILING SUN ◽  
CHUNGUANG LIU ◽  
ZHONGMIN SU
Keyword(s):  
Nonlinear Optical ◽  
Membered Ring ◽  
Second Order ◽  
Meta Position ◽  
Nlo Response ◽  
B3lyp Method ◽  
Acceptor Group ◽  
Calculation Results ◽  
Optimum Model ◽  
Derivatives Of

DFT B3LYP method was employed to calculate the second-order nonlinear optical (NLO) responses of the derivatives of disubstituted seven-vertex cobaltacarborane metallocenyl. The results show that cobaltacarborane metallocenyl plays a pushing/pulling role and a bridge role to transfer electron in these molecules. The five-membered ring of cyclopentadiene is more beneficial to increase second-order NLO response than the five-membered ring composed of two C atoms and three B atoms in cobaltacarborane. Moreover, the second-order NLO response is more powerful when one substituent containing electron donor group and one substituent containing electron acceptor group are located at meta position. Accordingly, among the nine models, model c2 is the optimum model with largest value of βtot. The calculation results also show that cobaltacarborane metallocenyl and ferrocene parts play the same roles to increase second-order NLO response. Thus, cobaltacarborane metallocenyl can be a promising second-order NLO material.

INVESTIGATION OF SINGLE-POINT DRESSING OVERLAP RATIO AND DIAMOND-ROLL DRESSING INTERFERENCE ANGLE ON SURFACE ROUGHNESS IN GRINDING

2010 ◽  
Vol 34 (2) ◽  
pp. 295-308 ◽  
Author(s):  
Akram Saad ◽  
Robert Bauer ◽  
Andrew Warkentin
Keyword(s):  
Surface Roughness ◽  
Material Removal Rate ◽  
Empirical Model ◽  
Material Removal ◽  
Removal Rate ◽  
Single Point ◽  
Experimental Conditions ◽  
Workpiece Surface ◽  
Different Depths ◽  
Overlap Ratio

This paper investigates the effect of both single-point and diamond-roll dressing techniques on the workpiece surface roughness in grinding. Two empirical surface roughness models are studied – one that incorporates single-point dressing parameters, and another that incorporates diamond-roll dressing parameters. For the experimental conditions used in this research, the corresponding empirical model coefficients are found to have a linear relationship with the inverse of the overlap ratio for single-point dressing and the interference angle for diamond-roll dressing. The resulting workpiece surface roughness models are then experimentally validated for different depths of cut, workpiece speeds and dressing conditions. In addition, the models are used to derive a relationship between overlap ratio for single-point dressing, and interference angle for diamond-roll dressing such that both dressing techniques produce a similar surface finish for a given material removal rate.

LDA Measurements in Rough Surface ZPG Turbulent Boundary layers

2006 ◽  
Author(s):  
Brian Brzek ◽  
Rau´l Bayoa´n Cal ◽  
Gunnar Johansson ◽  
Luciano Castillo
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Laser Doppler Anemometry ◽  
Single Point ◽  
Roughness Parameter ◽  
Reynolds Stresses ◽  
Experimental Conditions ◽  
Boundary Layer Equations ◽  
Entire Boundary ◽  
Boundary Layer Development

A new set of experiments have been performed in order to study the effects of the upstream conditions and the surface roughness on a zero pressure gradient turbulent boundary layer. In order to properly capture the x-dependence of the single point statistics, consecutive measurements of 11 streamwise locations were performed. These 2-D Laser Doppler Anemometry (LDA) measurements enable us to use the full boundary layer equations in order to calculate the skin friction and determine the boundary layer development which is not possible in the majority of experiments on rough surfaces. It will be shown that for fixed experimental conditions (i.e., fixed upstream wind tunnel speed, trip wire, etc), the velocity deficit profiles collapse for each of the scalings investigated but only the Zagarola/Smits scaling (1998) could collapse all the different experimental conditions into a single curve. In addition, the Reynolds stresses were increasingly affected by the surface roughness as the roughness parameter, k+, increased. Moreover, it was found that the shape of the Reynolds stress profiles was very different throughout the entire boundary layer, particularly the < u2 > component. This is likely the result of the flow becoming more isotropic for increased k+, and will be seen in the anisotropy coefficients. Moreover, increased production of < u2 > and < uv > due to roughness is also seen throughout the entire boundary layer although its overall role in the changing shape of the < u2 > profiles still needs to be determined. The effect of roughness on the boundary layer parameters is also evident and their x-dependence is also shown.

Novel, intramolecular hydrogen-transfer and cyclo-addition photochemistry of cyclic 1,3-dienes

1991 ◽  
Vol 69 (10) ◽  
pp. 1554-1562 ◽  
Author(s):  
Franciscus W. A. M. Miesen ◽  
Hans C. M. Baeten ◽  
Harm A. Langermans ◽  
Leo H. Koole ◽  
Henk A. Claessens
Keyword(s):  
Hydrogen Transfer ◽  
Membered Ring ◽  
Unsaturated Ketone ◽  
Triplet Excited State ◽  
Hydroxyl Proton ◽  
Conformational Studies ◽  
Rigid System ◽  
H Nmr ◽  
Rearrangement Process ◽  
Intramolecular Hydrogen

With use of one- and two-dimensional NMR spectroscopy and deuterium labelling, the photochemistry of 9-endo-hydroxy-9-exo-vinyl-bicyclo[4.2.1]nonadiene (1) and the 9-exo-(11-dimethylvinyl)- (2) and 9-exo-ethyl- (3) analogues has been studied. Irradiation of 1–3 gave novel 8-membered ring systems 4–6 by a light-induced rearrangement process, in which the hydroxyl proton is transferred on one side of the molecule toward one of the termini of the endocyclic diene. This rearrangement process thus involves a formal hydrogen transfer, during which either H+ or H• may be transferred to a reactive diene intermediate. Replacement of the hydroxyl proton by deuterium in 1–3, and 2H NMR of the corresponding photoproducts, confirmed that the hydrogen translocation occurs intramolecularly. Prolonged irradiation of 4 and 5 results in the formation of pyran products 10 and 11 by an intramolecular photocycloaddition of the triplet excited state of the α,β-unsaturated ketone to 1,3-cis,cis-cyclooctadiene, via a stabilized bisallylic biradical intermediate. Conformational studies of the structurally more rigid system 10, which is derived from 4, revealed that the hydroxyl proton was transferred on the endo side of the molecule. Key words: intramolecular hydrogen transfer, photochemistry of hydroxy-alkyl-bicyclononadienes, intramolecular photocycloaddition, conformational studies.

scholarly journals Computational Modeling and Theoretical Calculations on the Interactions between Spermidine and Functional Monomer (Methacrylic Acid) in a Molecularly Imprinted Polymer

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Yujie Huang ◽  
Qiujin Zhu
Keyword(s):  
Binding Energy ◽  
Methacrylic Acid ◽  
Molecularly Imprinted Polymer ◽  
Single Point ◽  
Basis Set ◽  
Stable Complex ◽  
Functional Monomer ◽  
Imprinted Polymer ◽  
Point Energy ◽  
Molecularly Imprinted

This paper theoretically investigates interactions between a template and functional monomer required for synthesizing an efficient molecularly imprinted polymer (MIP). We employed density functional theory (DFT) to compute geometry, single-point energy, and binding energy (ΔE) of an MIP system, where spermidine (SPD) and methacrylic acid (MAA) were selected as template and functional monomer, respectively. The geometry was calculated by using B3LYP method with 6-31+(d) basis set. Furthermore, 6-311++(d, p) basis set was used to compute the single-point energy of the above geometry. The optimized geometries at different template to functional monomer molar ratios, mode of bonding between template and functional monomer, changes in charge on natural bond orbital (NBO), and binding energy were analyzed. The simulation results show that SPD and MAA form a stable complex via hydrogen bonding. At 1 : 5 SPD to MAA ratio, the binding energy is minimum, while the amount of transferred charge between the molecules is maximum; SPD and MAA form a stable complex at 1 : 5 molar ratio through six hydrogen bonds. Optimizing structure of template-functional monomer complex, through computational modeling prior synthesis, significantly contributes towards choosing a suitable pair of template-functional monomer that yields an efficient MIP with high specificity and selectivity.

Theoretical study on the OH-initiated atmospheric reaction of N-methyl perfluorobutane sulfonamidoethanol (C4F9SO2N(CH3)CH2CH2OH)

2013 ◽  
Vol 91 (12) ◽  
pp. 1161-1167
Author(s):  
Juan Dang ◽  
Lei Ding ◽  
Xiaoyan Sun ◽  
Qingzhu Zhang ◽  
Wenxing Wang
Keyword(s):  
Reaction Mechanism ◽  
Degradation Products ◽  
Single Point ◽  
Basis Set ◽  
Stationary Points ◽  
Geometrical Parameters ◽  
Chemical Transformations ◽  
Point Energy ◽  
Range Transport ◽  
Perfluorinated Carboxylic Acids

N-methyl perfluorobutane sulfonamidoethanol (NMeFBSE), a new product of the 3M Company, is currently widely used in many countries and territories. It is prone to volatilize to the atmosphere where it can undergo long-range transport and chemical transformations. In this work, the reaction mechanism for the OH-initiated atmospheric oxidation of NMeFBSE was investigated. The geometrical parameters and vibrational frequencies of all of the stationary points were calculated 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. The results indicate that the channel of the formation of C4F9 and HSO3N(CH3)CH2CH2OH resulting from OH addition to NMeFBSE and hydrogen abstractions from the −CH3 group in NMeFBSE are energetically favorable. The main degradation products include perfluorinated carboxylic acids (C3F7COOH, C2F5COOH, CF3COOH), HSO3N(CH3)CH2CH2OH, NMeFBSA (C4F9SO2NH(CH3)), C4F9SO2N(CH3)CH2CHO, and C4F9SO2N(CH3)CH2COOH. The reaction mechanism for the formation of NMeFBSA is reported for the first time. Using the atmospheric fate of NMeFBSE as a guide, it seems that N-methyl perfluorooctane sulfonamidoethanol (NMeFOSE) contributes to the ubiquity of perfluoroalkyl sulfonate and carboxylate compounds in the atmosphere.

ONIOM:  A Multilayered Integrated MO + MM Method for Geometry Optimizations and Single Point Energy Predictions. A Test for Diels−Alder Reactions and Pt(P(t-Bu)3)2+ H2Oxidative Addition

1996 ◽  
Vol 100 (50) ◽  
pp. 19357-19363 ◽  
Author(s):  
Mats Svensson ◽  
Stéphane Humbel ◽  
Robert D. J. Froese ◽  
Toshiaki Matsubara ◽  
Stefan Sieber ◽  
...  
Keyword(s):  
Single Point ◽  
Diels Alder ◽  
Point Energy

The Direct Oxidizing Mechanism for the Reaction of Ozone and Phenol: A DFT Study

2012 ◽  
Vol 554-556 ◽  
pp. 1632-1636
Author(s):  
Shuang Kou Chen ◽  
Jian Fang Zhu ◽  
Wen Zhang Huang ◽  
Bai He ◽  
Li Jun Xiang ◽  
...  
Keyword(s):  
Global Optimization ◽  
Transition State ◽  
Calculation Result ◽  
Substitution Reaction ◽  
Single Point ◽  
Vibrational Analysis ◽  
Ortho Position ◽  
Free Energies ◽  
Point Energy ◽  
Exothermic Reactions

Using DFT/6-31+G (d, p) method, the structure of phenol are gained in the global optimization and properties were theoretically studied. The atomic electric charges, activation of reaction and thermodynamics parameters are obtained. The calculation shows that benzene ring in phenol tends to have electrophonic attacking substitution reaction O3 directly and form catechol and hydroquinol. The calculation of thermodynamics properties indicate that two pathways are exothermic reactions, and the Gibbs free energies (ΔG) are always less than zero, two reactions are easily occurred spontaneously. Dynamics calculations show that there is only one transition state in each reaction; through vibrational analysis we confirm the transition state. After corrected single point energy, we find that the reaction activation energies of the two reactions are small (Ea1=4.48kcal/mol and Ea2=2.87kal/mol), indicating that ortho-position and para-position products exist simultaneously, which is in accordance with the thermodynamics calculation result.

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