scholarly journals Measuring and Leveraging Electrostatic Effects in a Charged Phosphine

2020 ◽  
Author(s):  
Andrew J. McNeece ◽  
Margaret L. Kelty ◽  
Alexander S. Filatov ◽  
John Anderson
Keyword(s):  
Electric Fields ◽  
Phase Reaction ◽  
Reaction Conditions ◽  
Phosphine Selenide ◽  
Molecular Systems ◽  
Common Solution ◽  
Electrostatic Component ◽  
Theoretical Predictions ◽  
Charged Group ◽  
Space Effects

<div>Local electric fields have recently been investigated for optimizing reactivity in synthetic systems. However, disentangling the relative contributions of inductive (through-bond) and electrostatic (through-space) effects in molecular systems has been a long-standing challenge. To understand the interplay of these effects and leverage electrostatic influences for enhanced reactivity, we have synthesized a distally charged phosphine, Ph<sub>2</sub>PCH<sub>2</sub>BF<sub>3</sub><sup>−</sup>, and studied the effect of the charged trifluoroborate group on its donor properties and reactivity. This charged phosphine displays solvent-dependent changes in donor strength as measured by the <i>J</i><sub>P-Se</sub> of the corresponding phosphine selenide. The variation with solvent dielectric illustrates a significant electrostatic component to the donor strength. Computations further support the importance of electrostatic contributions and highlight the effect of charge position and orientation. Finally, this charged group also greatly accelerates C–F oxidative addition reactivity in Ni complexes, experimentally</div><div>verifying recent theoretical predictions. These results show that covalently bound charged functionalities can exert a significant electrostatic influence even under common solution phase reaction conditions.</div>

scholarly journals Measuring and Leveraging Electrostatic Effects in a Charged Phosphine

2020 ◽  
Author(s):  
Andrew J. McNeece ◽  
Margaret L. Kelty ◽  
Alexander S. Filatov ◽  
John Anderson
Keyword(s):  
Electric Fields ◽  
Phase Reaction ◽  
Reaction Conditions ◽  
Phosphine Selenide ◽  
Molecular Systems ◽  
Common Solution ◽  
Electrostatic Component ◽  
Theoretical Predictions ◽  
Charged Group ◽  
Space Effects

<div>Local electric fields have recently been investigated for optimizing reactivity in synthetic systems. However, disentangling the relative contributions of inductive (through-bond) and electrostatic (through-space) effects in molecular systems has been a long-standing challenge. To understand the interplay of these effects and leverage electrostatic influences for enhanced reactivity, we have synthesized a distally charged phosphine, Ph<sub>2</sub>PCH<sub>2</sub>BF<sub>3</sub><sup>−</sup>, and studied the effect of the charged trifluoroborate group on its donor properties and reactivity. This charged phosphine displays solvent-dependent changes in donor strength as measured by the <i>J</i><sub>P-Se</sub> of the corresponding phosphine selenide. The variation with solvent dielectric illustrates a significant electrostatic component to the donor strength. Computations further support the importance of electrostatic contributions and highlight the effect of charge position and orientation. Finally, this charged group also greatly accelerates C–F oxidative addition reactivity in Ni complexes, experimentally</div><div>verifying recent theoretical predictions. These results show that covalently bound charged functionalities can exert a significant electrostatic influence even under common solution phase reaction conditions.</div>

Interplay between Fracture and Domain Switching of Ferroelectrics

2006 ◽  
Vol 306-308 ◽  
pp. 501-510
Author(s):  
Y.Q. Cui ◽  
Wei Yang
Keyword(s):  
Experimental Data ◽  
Crack Initiation ◽  
Electric Fields ◽  
Large Scale ◽  
Inner Core ◽  
Domain Switching ◽  
Global Scale ◽  
Theoretical Predictions ◽  
T Stress ◽  
Cylindrical Inclusions

Applications of above-coercive electric fields lead to domain switching of a large or global scale. Large scale switching model is proposed to deal with load-induced domains witching in experiment. Both a discussion of crack initiation via the stress intensity factor and a discussion of crack path stability via T-stress are presented. The theoretical predictions and the experimental data roughly coincide for crack initiation, propagation and stability phenomena. Attention is also extended to consider the effect of non-uniform ferro-elastic domain switching in the vicinity of a crack. The domain switching zone is divided into a saturated inner core and an active surrounding annulus. Toughening for ferroelectrics with different poling states is estimated via Reuss type approximation. Solutions obtained according to spherical and cylindrical inclusions cover the range of experimental data.

Synthesis of Fructone and Acylal Using Hexagonally Ordered Mesoporous Aluminosilicate Catalyst

2008 ◽  
Vol 73 (8-9) ◽  
pp. 1112-1124 ◽  
Author(s):  
Ajayan Vinu ◽  
Josena Justus ◽  
Veerappan Vaithilingam Balasubramanian ◽  
Shivappa Basappa Halligudi ◽  
Katsuhiko Ariga ◽  
...  
Keyword(s):  
Carbonyl Compounds ◽  
Phase Reaction ◽  
Reaction Conditions ◽  
Structure Directing Agent ◽  
Pluronic P123 ◽  
Ordered Mesoporous ◽  
Temperature Programmed ◽  
Hexagonally Ordered ◽  
Adsorption Desorption ◽  
Ionic Copolymer

Hexagonally ordered mesoporous AlSBA-15 with different nSi/nAl ratios have been hydrothermally synthesized using the non-ionic copolymer Pluronic P123 surfactant as the structure directing agent and characterized by XRD, N2 adsorption-desorption, and ammonia-temperature programmed desorption (pyridine-TPD). Acetal and acylal formation reactions of organic carbonyl compounds were efficiently catalyzed by AlSBA-15 under liquid-phase reaction conditions and the results were compared with the MFI, BEA and AlMCM-41(23). Of the catalysts studied, AlSBA-15(45) showed the highest activity in both the acetalization and acylal reactions of the carbonyl compounds under the optimized reaction conditions, and could be recycled several times without loss in activity. AlSBA-15(45) catalyst is highly stable, efficient, chemoselective, and environmental friendly, which could open the possibility for environment benign approach for the synthesis of acetals, acylals and its derivatives under mild reaction conditions.

scholarly journals Breakdown in CO2 and CO2/C2F4 Mixtures at Elevated Temperatures in the Range 1000-4000 K

2019 ◽  
Vol 6 (1) ◽  
pp. 39-42 ◽  
Author(s):  
M. Seeger ◽  
T. Votteler ◽  
S. Pancheshnyi ◽  
J. Carstensen ◽  
A. Garyfallos ◽  
...  
Keyword(s):  
Electric Fields ◽  
Experimental Validation ◽  
Elevated Temperatures ◽  
Electric Breakdown ◽  
Circuit Breakers ◽  
Critical Fields ◽  
Present Contribution ◽  
Fundamental Parameters ◽  
Theoretical Predictions ◽  
Temperature And Pressure

CO<sub>2</sub> is a promising gas for replacement of SF<sub>6</sub> in high voltage circuit breakers. The electric breakdown in CO<sub>2</sub> and mixtures with C<sub>2</sub>F4 from PTFE nozzles is, however, still not fully understood. To understand the electric breakdown in CO<sub>2</sub> and mixtures with C<sub>2</sub>F<sub>4</sub> from PTFE nozzles fundamental parameters like the temperature and pressure dependence of critical electric fields are needed. Data on critical fields is usually available based on simulations only and experimental validation is lacking so far. Our present contribution aims to close this gap and presents experiments where the breakdown fields in uniform and weakly non-uniform electric fields are determined at various temperatures and pressures. The gas temperatures were estimated from measurements with pyrometers. The results are compared to theoretical predictions.

Acid-Catalyzed Transesterification of Canola Oil to Biodiesel under Single- and Two-Phase Reaction Conditions

2007 ◽  
Vol 21 (4) ◽  
pp. 2450-2459 ◽  
Author(s):  
Fadi Ataya ◽  
Marc A. Dubé ◽  
Marten Ternan
Keyword(s):  
Canola Oil ◽  
Phase Reaction ◽  
Reaction Conditions ◽  
Two Phase ◽  
Acid Catalyzed

The breakdown of superfluidity in liquid 4 He V. Measurement of the Landau critical velocity for roton creation

1985 ◽  
Vol 315 (1532) ◽  
pp. 259-300 ◽  
Keyword(s):  
Critical Velocity ◽  
Electric Fields ◽  
High Pressures ◽  
Negative Ions ◽  
Pure Liquid ◽  
Small Deviations ◽  
Theoretical Predictions ◽  
The Matrix ◽  
Excitation Model

We report a precise experimental determination of the Landau critical velocity v L for roton creation in Hen. The technique used was based on measurements of the drift velocity, v , of negative ions through isotopically pure liquid 4 He at ca . 80 m K , under the influence of weak electric fields, E , for pressures, P , within the range 13 < P < 25 bar. It relied on the use of the equation ( v — v L ) oc E 1/3 , which is believed to correspond to the creation of rotons occurring predominantly in pairs and which fitted the experimental data to very high precision for E > 500 V m -1 . At lower values of E , however, small deviations from this equation were observed. These are tentatively attributed, not to the predicted onset of single-roton emission, but to a novel form of ion-vortex scattering. The values of v L ( P ) deduced from the measurements of v ( E ) at various pressures for E > 500 V m -1 agree to within 1.5% with theoretical predictions based on Landau’s excitation model of HeII, incorporating accepted numerical values of the roton parameters. The observed pressure dependence of v L ( P ) is significantly stronger than that predicted ; however, a discrepancy that appears to point towards the decreasing accuracy with which the roton parameters are known at high pressures. The modulus of the matrix element | V k0,k0 | characterizing roton-pair emission has also been deduced and is found to decrease rapidly with falling pressure. A linear extrapolation of the data suggests that | V k0,k0 | falls to zero at P « 3 bar (1 bar = 10 5 Pa).

scholarly journals Heterogeneous catalytic synthesis of quinoline compounds from aniline and C1–C4 alcohols over zeolite-based catalysts

RSC Advances ◽  
2017 ◽  
Vol 7 (76) ◽  
pp. 48275-48285 ◽  
Author(s):  
Chen Huang ◽  
An Li ◽  
Zi-Sheng Chao
Keyword(s):  
Gas Phase ◽  
Catalytic Synthesis ◽  
Phase Reaction ◽  
Reaction Conditions ◽  
Gas Phase Reaction ◽  
Heterogeneous Catalytic

The synthesis of quinolines from aniline and a C1–C4 alcohol was conducted under gas-phase reaction conditions over a series of zeolite-based catalysts.

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