scholarly journals Teaching an old carbocation new tricks: Intermolecular C–H insertion reactions of vinyl cations

Science ◽  
2018 ◽  
Vol 361 (6400) ◽  
pp. 381-387 ◽  
Author(s):  
Stasik Popov ◽  
Brian Shao ◽  
Alex L. Bagdasarian ◽  
Tyler R. Benton ◽  
Luyi Zou ◽  
...  
Keyword(s):  
Theoretical Studies ◽  
Computational Studies ◽  
Mechanistic Studies ◽  
Insertion Reactions ◽  
Bond Forming ◽  
The Past ◽  
Carbon Carbon Bond ◽  
Transition Structures ◽  
The Subject ◽  
Experimental And Theoretical Studies

Vinyl carbocations have been the subject of extensive experimental and theoretical studies over the past five decades. Despite this long history in chemistry, the utility of vinyl cations in chemical synthesis has been limited, with most reactivity studies focusing on solvolysis reactions or intramolecular processes. Here we report synthetic and mechanistic studies of vinyl cations generated through silylium–weakly coordinating anion catalysis. We find that these reactive intermediates undergo mild intermolecular carbon-carbon bond–forming reactions, including carbon-hydrogen (C–H) insertion into unactivated sp3 C–H bonds and reductive Friedel-Crafts reactions with arenes. Moreover, we conducted computational studies of these alkane C–H functionalization reactions and discovered that they proceed through nonclassical, ambimodal transition structures. This reaction manifold provides a framework for the catalytic functionalization of hydrocarbons using simple ketone derivatives.

Inlet Fogging of Gas Turbine Engines: Experimental and Analytical Investigations on Impaction Pin Fog Nozzle Behavior

2006 ◽  
Vol 128 (4) ◽  
pp. 826-839 ◽  
Author(s):  
Mustapha A. Chaker ◽  
Cyrus B. Meher-Homji ◽  
Thomas Mee
Keyword(s):  
Gas Turbine ◽  
Evaporation Rate ◽  
Climatic Conditions ◽  
Turbine Engines ◽  
Theoretical Studies ◽  
Gas Turbine Engines ◽  
The Past ◽  
The Subject ◽  
Evaporation Dynamics ◽  
Experimental And Theoretical Studies

The inlet fogging of gas turbine engines for power augmentation has seen increasing application over the past decade. This paper provides the results of extensive experimental and theoretical studies conducted on impaction pin fog nozzles. It covers the important area of the fog plume pattern of impaction pin nozzles and examines fog-plume uniformity. The subject of sprinkle (large droplet formation) from the nozzles is also examined in detail and is shown to be nonsignificant. The effect, on evaporation rate, of ambient climatic conditions and the location of the fog nozzle with respect to the gas turbine inlet duct has been analytically and experimentally analyzed. An analytical model is used to study the evaporation dynamics of fog droplets injected in the inlet ducts. The model is validated experimentally in a wind tunnel.

Inlet Fogging of Gas Turbine Engines: Experimental and Analytical Investigations on Impaction Pin Fog Nozzle Behavior

2003 ◽  
Author(s):  
Mustapha A. Chaker ◽  
Cyrus B. Meher-Homji ◽  
Thomas Mee
Keyword(s):  
Gas Turbine ◽  
Evaporation Rate ◽  
Climatic Conditions ◽  
Turbine Engines ◽  
Theoretical Studies ◽  
Gas Turbine Engines ◽  
The Past ◽  
The Subject ◽  
Evaporation Dynamics ◽  
Experimental And Theoretical Studies

The inlet fogging of gas turbine engines for power augmentation has seen increasing application over the past decade. This paper provides the results of extensive experimental and theoretical studies conducted on impaction pin fog nozzles. It covers the important area of the fog plume pattern of impaction pin nozzles and examines fogplume uniformity. The subject of sprinkle (large droplet formation) from the nozzles is also examined in detail and is shown to be nonsignificant. The effect, on evaporation rate, of ambient climatic conditions and the location of the fog nozzle with respect to the gas turbine inlet duct has been analytically and experimentally analyzed. An Analytical model is used to study the evaporation dynamics of fog droplets injected in the inlet ducts the model is validated experimentally in a wind tunnel.

scholarly journals Experimental and theoretical studies on thymine photodimerization mediated by oxidatively generated DNA lesions and epigenetic intermediates

2020 ◽  
Vol 22 (44) ◽  
pp. 25661-25668
Author(s):  
Mauricio Lineros-Rosa ◽  
Antonio Francés-Monerris ◽  
Antonio Monari ◽  
Miguel Angel Miranda ◽  
Virginie Lhiaubet-Vallet
Keyword(s):  
Dna Lesions ◽  
Theoretical Studies ◽  
Computational Studies ◽  
Thymine Dimers ◽  
Different Types ◽  
Experimental And Theoretical Studies

Combined spectroscopic and computational studies reveal that, in spite of their structural similarities, 5-formyluracil and 5-formylcytosine photosensitize cyclobutane thymine dimers through two different types of mechanisms.

scholarly journals Mechanistic studies on the N-alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands

2018 ◽  
Vol 8 (9) ◽  
pp. 2381-2393 ◽  
Author(s):  
M. Victoria Jiménez ◽  
Javier Fernández-Tornos ◽  
Miguel González-Lainez ◽  
Beatriz Sánchez-Page ◽  
F. Javier Modrego ◽  
...  
Keyword(s):  
Bond Formation ◽  
Theoretical Studies ◽  
Mechanistic Studies ◽  
Carbene Ligands ◽  
Experimental And Theoretical Studies

Experimental and theoretical studies give support for an iridium-catalyzed C–N bond formation.

scholarly journals Cobalt-catalyzed deoxygenative triborylation of allylic ethers to access 1,1,3-triborylalkanes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Wei Jie Teo ◽  
Xiaoxu Yang ◽  
Yeng Yeng Poon ◽  
Shaozhong Ge
Keyword(s):  
Building Blocks ◽  
Mechanistic Studies ◽  
Deuterium Labeling ◽  
Bond Forming ◽  
Carbon Carbon Bond ◽  
Synthetic Utility ◽  
Reaction Proceeds ◽  
Site Selective ◽  
And Control ◽  
Allylic Ethers

Abstract Polyborylated organic compounds have been emerging as versatile building blocks in chemical synthesis. Here we report a selective cobalt-catalyzed deoxygenative 1,1,3-triborylation reaction of allylic ethers with pinacolborane to prepare 1,1,3-triborylalkane compounds. With naturally abundant and/or synthetic cinnamic methyl ethers as starting materials, we have achieved the synthesis of a variety of 1,1,3-triborylalkanes (25 examples). The synthetic utility of these 1,1,3-triborylalkanes is demonstrated through site-selective allylation, protodeborylation, and consecutive carbon-carbon bond-forming reactions. Mechanistic studies including deuterium-labeling and control experiments suggest that this 1,1,3-triborylation reaction proceeds through initial cobalt-catalyzed deoxygenative borylation of allylic ethers to form allylic boronates followed by cobalt-catalyzed 1,1-diborylation of the resulting allylic boronates.

scholarly journals Physical Models of Plasma Microfield

2010 ◽  
Vol 2010 ◽  
pp. 1-42 ◽  
Author(s):  
A. V. Demura
Keyword(s):  
Physical Models ◽  
Present Review ◽  
Current Status ◽  
Theoretical Studies ◽  
Gas Discharges ◽  
The Subject ◽  
Experimental And Theoretical Studies

The present review is devoted to the current status of microfield notion that was so successful and profitable for experimental and theoretical studies of plasma in gas discharges and thermonuclear modeling installations for many decades. The physical aspects and ideas of the main generally used microfield models are described and analyzed in detail. The review highlights the remaining vague and unclear questions in the subject.

The Swelling Behavior of Organoclays

2007 ◽  
Vol 353-358 ◽  
pp. 2239-2243
Author(s):  
Qing Hua Zeng ◽  
Donald R. Paul ◽  
Ai Bing Yu ◽  
Gao Qing Max Lu
Keyword(s):  
Research And Development ◽  
Linear Relationship ◽  
Clay Minerals ◽  
Polymer Nanocomposites ◽  
Polymer Materials ◽  
Theoretical Studies ◽  
Mass Ratio ◽  
Natural Clay ◽  
The Past ◽  
Experimental And Theoretical Studies

Natural clay minerals are ideal nanofillers for polymer materials and have been attracted tremendous research and development interests in the past decade. The manufacture of clay nanofillers relies largely on the exfoliation of clay particle into individual clay platelets. Thus, understanding the interlayer swelling of clay minerals upon the adsorption of surfactants is important to the fabrication and design of polymer nanocomposites. This paper reports our recent experimental and theoretical studies on a variety of organoclays that show a linear relationship between the increase of d-spacing and the mass ratio between organic and clay.

METHODS OF MODELING AND CALCULATION OF REINFORCED CONCRETE STRUCTURES OF OPERATED GTS, REINFORCED WITH PRESTRESSED BASALT COMPOSITE REINFORCEMENT

2021 ◽  
pp. 59-67
Author(s):  
E. N. BELLENDIR ◽  
◽  
O. D. RUBIN ◽  
S. E. LISICHKIN ◽  
I. V. BAKLYKOV
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Hydraulic Structures ◽  
Reinforced Concrete Structures ◽  
Theoretical Studies ◽  
Computational Studies ◽  
Ansys Software ◽  
Nite Element ◽  
Experimental And Theoretical Studies ◽  
Composite Reinforcement

The development of a methodology for numerical modeling and calculation of reinforced concrete structures of operated hydraulic structures, reinforced with prestressed basalt composite reinforcement, including on the basis of experimental research data carried out in the branch of JSC“Institute Hydroproject”-“NIIES” is presented. Computational studies were carried out on the basis of spatial fi nite element models in the framework of the ANSYS software package. Developing the models, the results of experimental and theoretical studies of hydrotechnical reinforced concrete structures were used in which prestressed basalt composite reinforcement is placed both in the tensioned and compressed zones of the structures.

Inlet Fogging of Gas Turbine Engines: Part A — Fog Droplet Thermodynamics, Heat Transfer and Practical Considerations

2002 ◽  
Author(s):  
Mustapha Chaker ◽  
Cyrus B. Meher-Homji ◽  
Thomas Mee
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Droplet Size ◽  
Gas Turbines ◽  
Turbine Engines ◽  
Theoretical Studies ◽  
Gas Turbine Engines ◽  
Size Measurement ◽  
The Past ◽  
Experimental And Theoretical Studies

The inlet fogging of gas turbine engines for power augmentation has seen increasing application over the past decade yet not a single technical paper treating the physics and engineering of the fogging process, droplet size measurement, droplet kinetics, or the duct behavior of droplets, from a gas turbine perspective, is available. This paper provides the results of extensive experimental and theoretical studies conducted over several years coupled with practical aspects learned in the implementation of nearly 500 inlet fogging systems on gas turbines ranging in power from 5 to 250 MW. Part A of the paper covers the underlying theory of droplet thermodynamics and heat transfer, and provides several practical pointers relating to the implementation and application of inlet fogging to gas turbine engines.

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