Oxidative [4+2] Annulation of 1-Naphthols with Alkynes Accelerated by an Electron-Deficient Rhodium(III) Catalysts

2022 ◽  
Author(s):  
Antônio Junio Araujo Dias ◽  
Hiroto Takahashi ◽  
Juntaro Nogami ◽  
Yuki Nagashima ◽  
Ken Tanaka
Keyword(s):  
Dft Calculations ◽  
Activation Energies ◽  
High Efficacy ◽  
Mild Conditions ◽  
Internal Alkynes ◽  
Lower Activation

The 1,3-diethoxycarbonyl-2,4,5-trimethylcyclopentadienyl (CpE) rhodium(III) complex displayed high efficacy in the catalytic oxidative annulation of 1-naphthols with internal alkynes under mild conditions. DFT calculations revealed that lower activation energies for the...

Pt-Pd Nanoalloy for the Unprecedented Activation of Carbon-Fluorine Bond at Low Temperature

2019 ◽  
Author(s):  
Raghu Nath Dhital ◽  
keigo nomura ◽  
Yoshinori Sato ◽  
Setsiri Haesuwannakij ◽  
Masahiro Ehara ◽  
...  
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Dft Calculations ◽  
Bond Activation ◽  
Mild Conditions ◽  
Selective Transformation ◽  
Rate Determining Step ◽  
Highly Active ◽  
Harsh Conditions ◽  
Reaction Profile

Carbon-Fluorine (C-F) bonds are considered the most inert organic functionality and their selective transformation under mild conditions remains challenging. Herein, we report a highly active Pt-Pd nanoalloy as a robust catalyst for the transformation of C-F bonds into C-H bonds at low temperature, a reaction that often required harsh conditions. The alloying of Pt with Pd is crucial to activate C-F bond. The reaction profile kinetics revealed that the major source of hydrogen in the defluorinated product is the alcoholic proton of 2-propanol, and the rate-determining step is the reduction of the metal upon transfer of the <i>beta</i>-H from 2-propanol. DFT calculations elucidated that the key step is the selective oxidative addition of the O-H bond of 2-propanol to a Pd center prior to C-F bond activation at a Pt site, which crucially reduces the activation energy of the C-F bond. Therefore, both Pt and Pd work independently but synergistically to promote the overall reaction

Design and synthesis of dichromeno[2,3-b;3′,2′-e]pyridine-12,14-dione to evaluate its optical properties

2017 ◽  
Vol 41 (10) ◽  
pp. 3887-3893 ◽  
Author(s):  
Pritam Biswas ◽  
Jaydip Ghosh ◽  
Tapas Sarkar ◽  
Debabrata Jana ◽  
Chandrakanta Bandyopadhyay
Keyword(s):  
Cyclic Voltammetry ◽  
Optical Properties ◽  
Thermogravimetric Analysis ◽  
Dft Calculations ◽  
Design And Synthesis ◽  
Mild Conditions ◽  
Cv Measurements

An unambiguous synthesis of dichromeno[2,3-b;3′,2′-e]pyridine-12,14-diones has been developed under mild conditions and their optical properties have been evaluated by studying UV-vis absorption and photoluminescence (PL) spectroscopy, cyclic voltammetry (CV) measurements, DFT calculations and thermogravimetric analysis.

1,3-Dipolar cycloaddition of nitrones to oxa(aza)bicyclic alkenes

2019 ◽  
Vol 6 (19) ◽  
pp. 3360-3364 ◽  
Author(s):  
Yongqi Yao ◽  
Wen Yang ◽  
Qifu Lin ◽  
Weitao Yang ◽  
Huanyong Li ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Reaction Pathways ◽  
Dipolar Cycloaddition ◽  
Concerted Mechanism ◽  
Mild Conditions

A new 1,3-dipolar cycloaddition of oxa(aza)bicyclic alkenes with nitrones has been developed without any catalyst and additive under mild conditions. The proposed concerted mechanism is investigated by DFT calculations of the reaction pathways.

Growth Properties of the Si(100) Steps: A Molecular Dynamics Study

1991 ◽  
Vol 237 ◽  
Author(s):  
Christopher Roland ◽  
George H. Gilmer
Keyword(s):  
Molecular Dynamics ◽  
Surface Diffusion ◽  
Binding Sites ◽  
Activation Energies ◽  
Step Edge ◽  
Lower Activation ◽  
Growth Properties ◽  
Molecular Dynamics Methods ◽  
Energy Surfaces

ABSTRACTWe have mapped out the energy surfaces seen by a single silicon adatom over the Si(100) surface and Si(100) steps, using Molecular Dynamics methods. This identifies the most likely binding sites as well as the activation energies for diffusion over the terraces and steps. We find that only the 5e step with no rebonded atoms is a good sink for adatoms - the SA, rebonded Sb and Db steps are weak sinks. Because of a higher density of binding sites and lower activation energies for surface diffusion along die step edge, we expect mat growth at the Sb and Db steps take place much more readily man at the SA step.

scholarly journals Mechanism of Reactions of 1-Substituted Silatranes and Germatranes, 2,2-Disubstituted Silocanes and Germocanes, 1,1,1-Trisubstituted Hyposilatranes and Hypogermatranes with Alcohols (Methanol, Ethanol): DFT Study

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2803 ◽  
Author(s):  
Denis Chachkov ◽  
Rezeda Ismagilova ◽  
Yana Vereshchagina
Keyword(s):  
Density Functional Theory ◽  
Quantum Chemical ◽  
Density Functional ◽  
Activation Energies ◽  
Functional Theory ◽  
Gibbs Energies ◽  
The Density Functional Theory ◽  
Lower Activation ◽  
One Step ◽  
Intramolecular Hydrogen

The mechanism of reactions of silatranes and germatranes, and their bicyclic and monocyclic analogues with one molecule of methanol or ethanol, was studied at the Density Functional Theory (DFT) B3PW91/6-311++G(df,p) level of theory. Reactions of 1-substituted sil(germ)atranes, 2,2-disubstituted sil(germ)ocanes, and 1,1,1-trisubstituted hyposil(germ)atranes with alcohol (methanol, ethanol) proceed in one step through four-center transition states followed by the opening of a silicon or germanium skeleton and the formation of products. According to quantum chemical calculations, the activation energies and Gibbs energies of activation of reactions with methanol and ethanol are close, their values decrease in the series of atranes–ocanes–hypoatranes for interactions with both methanol and ethanol. The reactions of germanium-containing derivatives are characterized by lower activation energies in comparison with the reactions of corresponding silicon-containing compounds. The annular configurations of the product molecules with electronegative substituents are stabilized by the transannular N→X (X = Si, Ge) bond and different intramolecular hydrogen contacts with the participation of heteroatoms of substituents at the silicon or germanium.

10-Membered Azaenediyne Fused to a Benzothiophene through the Nicholas Macrocyclization: Synthesis and DNA Cleavage Ability

Synlett ◽  
2018 ◽  
Vol 30 (02) ◽  
pp. 161-166 ◽  
Author(s):  
Irina Balova ◽  
Natalia Danilkina ◽  
Andrey Rumyantsev ◽  
Anna Lyapunova ◽  
Alexander D’yachenko ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Dna Cleavage ◽  
Functional Group ◽  
Analysis Data ◽  
Activation Energies ◽  
Efficient Technique ◽  
Bergman Cyclization ◽  
Dsc Analysis ◽  
Cleavage Assay ◽  
Pbr322 Plasmid

The Nicholas-type macrocyclization through NH-tosyl functional group has been found to be an efficient technique for the synthesis of a 10-membered azaenediyne system annulated with a benzothiophene. To compare the activity of azaenediyne synthesized with similar oxa- and carbocyclic enediynes the Bergman cyclization activation energies and the ability of enediynes to cleave DNA (pBR322 plasmid) were investigated. The order of reactivity predicted by DFT calculations (N-enediyne < C-enediyne < O-enediyne) was confirmed by DSC analysis data. Surprisingly azaenediyne was found to be more active in the DNA cleavage assay than the C-analogue.

Rhodium-Catalyzed [6 + 2] Cycloaddition of Internal Alkynes with Cycloheptatriene: Catalytic Study and DFT Calculations of the Reaction Mechanism

2013 ◽  
Vol 32 (12) ◽  
pp. 3529-3536 ◽  
Author(s):  
Xinrui Zhang ◽  
Jingjing Wang ◽  
Hui Zhao ◽  
Haitao Zhao ◽  
Jianhui Wang
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Internal Alkynes

Voc Saturation Effect in High-temperature Hydrogenated Polycrystalline Silicon Thin-film Solar Cells

2011 ◽  
Vol 1321 ◽  
Author(s):  
Hidayat Hidayat ◽  
Per I. Widenborg ◽  
Armin G. Aberle
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Polycrystalline Silicon ◽  
Hydrogen Plasma ◽  
Activation Energies ◽  
Open Circuit ◽  
Thin Film Solar Cells ◽  
Silicon Thin Film ◽  
Lower Activation ◽  
Hydrogenation Temperature

ABSTRACTHydrogenation of polycrystalline silicon thin-film solar cells is performed to improve the one-sun open-circuit voltage (Voc) of the device. Voc is found to increase linearly with increasing hydrogenation temperature and then saturates. For planar and textured samples, the Voc saturates at about 340 ºC and 307 ºC respectively. The low hydrogenation temperature helps to lower thermal budget during industrial process. Arrhenius plot of Voc prior to the saturation shows that the textured samples have lower activation energies than the planar sample. The activation energies of samples 188 (planar), 788 (textured) and 888 (textured) are 1.31 eV, 0.86 eV and 0.92 eV, respectively. The lower activation energies of the textured samples could be due to the shorter diffusion thickness and the increased surface area that is exposed to the hydrogen plasma.

Gold(i)-catalyzed addition of carboxylic acids to internal alkynes in aqueous medium

2017 ◽  
Vol 15 (7) ◽  
pp. 1670-1679 ◽  
Author(s):  
Pedro J. González-Liste ◽  
Sergio E. García-Garrido ◽  
Victorio Cadierno
Keyword(s):  
Aqueous Medium ◽  
Carboxylic Acids ◽  
Catalytic System ◽  
Mild Conditions ◽  
Broad Scope ◽  
Internal Alkynes

A broad scope catalytic system for the intermolecular addition of carboxylic acids to internal alkynes, in water under mild conditions, has been developed.

scholarly journals An aniline dication-like transition state in the Bamberger rearrangement

2013 ◽  
Vol 9 ◽  
pp. 1073-1082 ◽  
Author(s):  
Shinichi Yamabe ◽  
Guixiang Zeng ◽  
Wei Guan ◽  
Shigeyoshi Sakaki
Keyword(s):  
Activation Energy ◽  
Dft Calculations ◽  
Transition State ◽  
Water Cluster ◽  
Transition States ◽  
Activation Energies ◽  
Nitrenium Ion ◽  
Proton Transfers ◽  
First Time

A Bamberger rearrangement of N-phenylhydroxylamine, Ph–N(OH)H, to p-aminophenol was investigated by DFT calculations for the first time. The nitrenium ion, C6H5–NH+, suggested and seemingly established as an intermediate was calculated to be absent owing to the high nucleophilicity of the water cluster around it. First, a reaction of the monoprotonated system, Ph–N(OH)H + H3O+(H2O) n (n = 4 and 14) was examined. However, the rate-determining transition states involving proton transfers were calculated to have much larger activation energies than the experimental one. Second, a reaction of the diprotonated system, Ph–N(OH)H + (H3O+)2(H2O)13, was traced. An activation energy similar to the experimental one was obtained. A new mechanism of the rearrangement including the aniline dication-like transition state was proposed.

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