scholarly journals Investigations on non-classical silylium ions leading to a cyclobutenyl cation

2019 ◽  
Vol 10 (9) ◽  
pp. 2821-2829 ◽  
Author(s):  
Arthur Martens ◽  
Marvin Kreuzer ◽  
Alexander Ripp ◽  
Marius Schneider ◽  
Daniel Himmel ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Room Temperature ◽  
The Way

The formation of simple non-classical silylium ions from [Me3Si]+ sources and alkenes or alkynes was investigated, but mainly oligomerization was observed. Yet, the reaction with MeCCMe led to a room temperature stable cyclobutenyl cation. DFT calculations suggest that a non-classical silylium ion intermediate was formed on the way to this product.

Atomistic prediction on the configuration- and temperature-dependent dielectric constant of Be0.25Mg0.75O superlattice as a high-κ dielectric layer

2021 ◽  
Author(s):  
Gyuseung Han ◽  
In Won Yeu ◽  
Kun Hee Ye ◽  
Seung-Cheol Lee ◽  
Cheol Seong Hwang ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dft Calculations ◽  
Bond Length ◽  
Dielectric Layer ◽  
Room Temperature ◽  
High Dielectric Constant ◽  
Temperature Dependent ◽  
High Dielectric

Through DFT calculations, a Be0.25Mg0.75O superlattice having long apical Be–O bond length is proposed to have a high bandgap (>7.3 eV) and high dielectric constant (∼18) at room temperature and above.

Surface-assisted cis–trans isomerization of an alkene molecule on Cu(110)

2014 ◽  
Vol 50 (14) ◽  
pp. 1728-1730 ◽  
Author(s):  
Qiang Sun ◽  
Chi Zhang ◽  
Likun Wang ◽  
Zhiwen Li ◽  
Aiguo Hu ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Room Temperature ◽  
Ultrahigh Vacuum ◽  
Trans Isomerization ◽  
Isomerization Process

Interplay of STM imaging and DFT calculations demonstrates the isomerization of an alkene molecule on Cu(110) under ultrahigh vacuum conditions. We show that the on-surfacecis–transisomerization could efficiently occur well below room temperature, in which the surface is speculated to play a key role in assisting this isomerization process.

scholarly journals Recovery of ancestral knowledge for production of traditional Manabí cocoa paste

2019 ◽  
Vol 3 (1) ◽  
pp. 71-78
Author(s):  
Telly Yarita Macias Zambrano ◽  
Ingri Catherine Garcia Castro ◽  
Carmen Liliana Mera Plaza ◽  
Ricardo Munoz Farfan
Keyword(s):  
Experimental Method ◽  
Rural Area ◽  
Room Temperature ◽  
Ancestral Knowledge ◽  
Saturated Fats ◽  
Useful Life ◽  
Family Consumption ◽  
Peasant Women ◽  
Clay Pots ◽  
The Way

The high family consumption of chocolates and cocoa powders with a high content of sugars and saturated fats, and on the contrary a very low content of cocoa paste is a problem. The objective was to recover the ancestral knowledge in the elaboration and conservation of the traditional Manabi cocoa paste. The experimental method was used for the elaboration and conservation of cocoa paste in clay pots with dried guineo leaves, in glass jars, at room temperature, and in refrigeration. Through the technique of interviewing 10 peasant women from the rural area of Chone, the way of elaboration and conservation of the cocoa ball was known. The main results: increase of the useful life of the cocoa ball wrapped in dried guinean leaves and stored in clay pots at room temperature, due to the decrease in humidity up to 180 days. As conclusions: little use of ancestral knowledge in the elaboration and conservation of traditional Manabí cocoa paste, unlike the consumption of refined chocolates with low cocoa content.

scholarly journals Synthesis of 5-arylacetylene 1,2,4-oxadiazoles and their transformations under superelectrophilic activation conditions

2021 ◽  
Author(s):  
Andrey I Puzanov ◽  
Dmitry S Ryabukhin ◽  
Anna S Zalivatskaya ◽  
Dmitriy N Zakusilo ◽  
Darya S Mikson ◽  
...  
Keyword(s):  
Double Bond ◽  
Dft Calculations ◽  
Reaction Mechanisms ◽  
Room Temperature ◽  
Triflic Acid ◽  
Activation Conditions ◽  
First Time ◽  
Vinyl Triflates ◽  
Derivatives Of ◽  
Acetylene Derivatives

Acetylene derivatives of 1,2,4-oxadiazoles, 5-(2-arylethynyl)-3-aryl-1,2,4-oxadiazoles, have been obtained, for the first time, from 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles by their bromination at the carbon-carbon double bond followed by di-dehydrobromination with NaNH2 in liquid NH3.  Reaction of the acetylene 1,2,4-oxadiazoles with arenes in neat triflic acid TfOH (CF3SO3H) at room temperature for 1 h result in the formation of E-/Z-5-(2,2-diarylethenyl)-3-aryl-1,2,4-oxadiazoles as products of regioselective hydroarylation of the acetylene bond. Addition of TfOH to acetylene bond of these oxadiazoles gives rise quantitatively to E-/Z-vinyl triflates. Reaction cationic intermediates have been studied by DFT calculations. The reaction mechanisms have been discussed.

Hydroarylation of olefins catalysed by a dimeric ytterbium(II) alkyl

2021 ◽  
Author(s):  
GM Richardson ◽  
I Douair ◽  
Scott Cameron ◽  
Joe Bracegirdle ◽  
Robert Keyzers ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Dft Calculations ◽  
Density Functional ◽  
Room Temperature ◽  
Main Group ◽  
Functional Theory

Although the nucleophilic alkylation of aromatics has recently been achieved with a variety of potent main group reagents, all of this reactivity is limited to a stoichiometric regime. We now report that the ytterbium(II) hydride, [BDI YbH] (BDI = CH[C(CH )NDipp] , Dipp = 2,6-diisopropylphenyl), reacts with ethene and propene to provide the ytterbium(II) n-alkyls, [BDI YbR] (R = Et or Pr), both of which alkylate benzene at room temperature. Density functional theory (DFT) calculations indicate that this latter process operates through the nucleophilic (S 2) displacement of hydride, while the resultant regeneration of [BDI YbH] facilitates further reaction with ethene or propene and enables the direct catalytic (anti-Markovnikov) hydroarylation of both alkenes with a benzene C-H bond. Dipp Dipp Dipp Dipp 2 3 2 2 N 2

On-surface construction of a metal–organic Sierpiński triangle

2015 ◽  
Vol 51 (75) ◽  
pp. 14164-14166 ◽  
Author(s):  
Qiang Sun ◽  
Liangliang Cai ◽  
Honghong Ma ◽  
Chunxue Yuan ◽  
Wei Xu
Keyword(s):  
High Resolution ◽  
Dft Calculations ◽  
Room Temperature ◽  
Sierpinski Triangle ◽  
Metal Organic ◽  
Surface Construction

From the interplay of high-resolution STM imaging and DFT calculations we demonstrate the first example of a metal–organic fractal (Sierpiński triangle) on the surface, and also the first room-temperature stable 2D supramolecular Sierpiński triangle.

scholarly journals Dipolar addition to cyclic vinyl sulfones leading to dual conformation tricycles

2013 ◽  
Vol 9 ◽  
pp. 1419-1425 ◽  
Author(s):  
Steven S Y Wong ◽  
Michael G Brant ◽  
Christopher Barr ◽  
Allen G Oliver ◽  
Jeremy E Wulff
Keyword(s):  
Dft Calculations ◽  
Nmr Spectra ◽  
Room Temperature ◽  
Synthetic Methodology ◽  
Nitrogen Center ◽  
Azomethine Imines ◽  
Nmr Methods

Dipolar addition of cyclic azomethine imines with cyclic vinyl sulfones gave rise to functionalized tricycles that exhibited fluxional behavior in solution at room temperature. The scope of the synthetic methodology was explored, and the origin of the fluxional behavior was probed by NMR methods together with DFT calculations. This behavior was ultimately attributed to stereochemical inversion at one of two nitrogen centers embedded in the tricyclic framework. Two tetracycles were also synthesized, and the degree of signal-broadening in the NMR spectra was found to depend on the presence of substitution next to the inverting nitrogen center.

scholarly journals Superelectrophilic activation of 5-hydroxymethylfurfural and 2,5-diformylfuran: organic synthesis based on biomass-derived products

2016 ◽  
Vol 12 ◽  
pp. 2125-2135 ◽  
Author(s):  
Dmitry S Ryabukhin ◽  
Dmitry N Zakusilo ◽  
Mikhail O Kompanets ◽  
Anton A.Tarakanov ◽  
Irina A Boyarskaya ◽  
...  
Keyword(s):  
High Pressure ◽  
Nmr Spectroscopy ◽  
Dft Calculations ◽  
Organic Synthesis ◽  
Room Temperature ◽  
Trifluoromethanesulfonic Acid ◽  
Reaction Products ◽  
Triflic Acid ◽  
Pressure Tubes ◽  
Acidic Zeolites

The reaction of 5-hydroxymethylfurfural (5-HMF) with arenes in superacidic trifluoromethanesulfonic acid (triflic acid, TfOH) as the solvent at room temperature for 1–24 h gives rise to 5-arylmethylfurfurals (yields of 17–91%) and 2-arylmethyl-5-(diarylmethyl)furans (yields of 10–37%). The formation of these two types of reaction products depends on the nucleophilicity of the arene. The same reactions under the action of acidic zeolites H-USY in high pressure tubes at 130 °C for 1 h result in the formation of only 5-arylmethylfurfurals (yields of 45–79%). 2,5-Diformylfuran (2,5-DFF) in the reaction with arenes under the action of AlBr3 at room temperature for 1 h leads to 5-(diarylmethyl)furfurals (yields of 51–90%). The reactive protonated species of 5-HMF and 2,5-DFF were characterized by NMR spectroscopy in TfOH and studied by DFT calculations. These reactions show possibilities of organic synthesis based on biomass-derived 5-HMF and 2,5-DFF.

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