scholarly journals Further Studies on the Pyrolytic Domino Cyclization of Stabilized Phosphonium Ylides Bearing an Ortho-Aminophenyl Group

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2153 ◽  
Author(s):  
R. Aitken ◽  
Lorna Murray ◽  
Alexandra Slawin
Keyword(s):  
Gas Phase ◽  
Phenyl Group ◽  
Phase Flow ◽  
Flow Conditions ◽  
X Ray ◽  
Benzyl Radicals ◽  
C And N

Four new, stabilized phosphonium ylides containing a 2-(benzyl(methyl)amino)phenyl group have been prepared and characterized and are found, upon pyrolysis under gas-phase flow conditions, to lose Ph3PO and benzyl radicals to afford new heterocyclic products resulting from domino cyclization of both C- and N-centered radicals. Most products arise from processes of the former type and have quinoline, phenanthridine, or ring-fused phenanthridine structures, while in one case, a process of the latter type leads to a benzocarbazole product. The X-ray structure of a 2-(methyl(tosyl)amino)phenyl ylide is also reported.

Molecular structure and substituent electronic effects in 10-arylidenanthrones-9

2000 ◽  
Vol 215 (5) ◽  
Author(s):  
O.V. Shishkin ◽  
A.Yu. Kovalevsky ◽  
M. Yu. Antipin ◽  
Z.N. Tarakhno
Keyword(s):  
Gas Phase ◽  
Phenyl Group ◽  
Conformational Flexibility ◽  
Am1 Method ◽  
Equilibrium Geometry ◽  
Boat Conformation ◽  
Structural Studies ◽  
Electronic Effects ◽  
X Ray ◽  
Derivatives Of

X-ray structural studies of derivatives of 10-arylidenanthrone-9 containing π-electron donating and withdrawing substituents within arylidene fragment have been carried out. In the crystal the molecules are strongly disflattened with the central dihydrocycles adopting an asymmetric boat conformation. This geometry of the molecules is a result of unfavourable non-valence interactions between atoms at the C=C bond and the hydrogens at the peri-positions of the anthraquinone fragment. Calculations performed by the semiempirical quantum-chemical AM1 method demonstrate that in the gas phase equilibrium geometry of the molecules was similar to that in the crystal. It was shown as well that the central dihydrocycle possesses high conformational flexibility in spite of steric overcrowding in all of the compounds. Electronic effects of the substituents had significant influence only on the arylidene moiety, resulting in different rotation angles of the phenyl group around the C=C exocyclic bond and virtually no effect on the anthraquinone part of the molecules.

Inorganic Fullerenes of MX2 (M=W,Mo;X=S,Se)

1994 ◽  
Vol 359 ◽  
Author(s):  
R. Tenne ◽  
L. Margulis ◽  
Y. Feldman ◽  
M. Homyonfer
Keyword(s):  
Gas Phase ◽  
Elevated Temperatures ◽  
Local Area ◽  
Phase Reaction ◽  
Flow Conditions ◽  
X Ray ◽  
Reducing Atmosphere ◽  
Preparation Conditions ◽  
Oxide Substrates ◽  
Average Size

ABSTRACTThe gas-phase reaction between MoO3-x and H2S in a reducing atmosphere and at elevated temperatures (800° to 950°C) has been used to synthesize large quantities of an almost pure nested inorganic fullerenes (IFs) phase of MoS2. A uniform IF phase with a relatively narrow size distribution was obtained. The x-ray spectra of the different samples show that as the average size of the IF decreases the van der Waals gap along the c axis increases, largely because of the strain involved in folding of the lamella. Large amount of quite uniform nanotubes were obtained under modified preparation conditions.In the second part of this work MoS2 nested fullerenes were grown on Ti and Nb and Mo oxide substrates. In one set of conditions hollow nested fullerenes of MoS2 were collected on a titanium oxide matrix, and analyzed by local area energy dispersive analysis. Under different flow conditions of the reacting gasses nested fullerenes with endohedral metal oxides were obtained and analyzed by electron diffraction.

GAS PHASE X-RAY ABSORPTION SPECTROSCOPY WITH AN ELECTRON YIELD DETECTOR

1986 ◽  
Vol 47 (C8) ◽  
pp. C8-149-C8-151
Author(s):  
F. W. LYTLE ◽  
R. B. GREEGOR ◽  
G. H. VIA ◽  
J. M. BROWN ◽  
G. MEITZNER
Keyword(s):  
Gas Phase ◽  
Absorption Spectroscopy ◽  
X Ray ◽  
Electron Yield ◽  
X Ray Absorption

scholarly journals Integration of Dental Implants in Conjunction with EDTA-Conditioned Dentin Grafts: An Experimental Study

2021 ◽  
Vol 9 (6) ◽  
pp. 63
Author(s):  
Payam Farzad ◽  
Ted Lundgren ◽  
Adel Al-Asfour ◽  
Lars Andersson ◽  
Christer Dahlin
Keyword(s):  
Direct Contact ◽  
Mineral Content ◽  
X Rays ◽  
X Ray ◽  
Dentin Surface ◽  
Significant Difference ◽  
C And N ◽  
Micro Implants ◽  
Demineralized Dentin

This study was undertaken to investigate the integration of titanium micro-implants installed in conjunction with previously dentin-grafted areas and to study the morphological appearance, mineral content, and healing pattern of xenogenic EDTA-conditioned dentin blocks and granules grafted to cavities in the tibial bone of rabbits. Demineralized and non-demineralized dentin blocks and granules from human premolars were implanted into cavities prepared on the lateral aspects of the tibias of rabbits. After a healing period of six months, micro-implants were installed at each surgical site. Histological examinations were carried out after 24 weeks. Characterization of the EDTA-conditioned dentin blocks was performed by means of light microscopy, dental X-rays, scanning electron microscopy, and energy dispersive X-ray analysis (EDX). No implants were found to be integrated in direct contact with the dentin particles or blocks. On the EDTA-conditioned dentin surface, the organic marker elements C and N dominated, as revealed by EDX. The hydroxyapatite constituents Ca and P were almost absent on the dentin surface. No statistically significant difference was observed between the EDTA-conditioned and non-demineralized dentin, as revealed by BIC and BA. The bone-inductive capacity of the dentin material seemed limited, although demineralization by means of EDTA indicated higher BIC and BA values in conjunction with the installed implants in the area. A 12 h EDTA treatment did not fully decalcify the grafts, as revealed by X-ray analysis.

A review of molecular effects in gas-phase KL X-ray emission

2013 ◽  
Vol 188 ◽  
pp. 53-61 ◽  
Author(s):  
Renaud Guillemin ◽  
Stéphane Carniato ◽  
Loïc Journel ◽  
Wayne C. Stolte ◽  
Tatiana Marchenko ◽  
...  
Keyword(s):  
Gas Phase ◽  
X Ray ◽  
Molecular Effects

Numerical Analysis of Two-Phase Pipe Flow of Liquid Helium Using Multi-Fluid Model

2001 ◽  
Vol 123 (4) ◽  
pp. 811-818 ◽  
Author(s):  
Jun Ishimoto ◽  
Mamoru Oike ◽  
Kenjiro Kamijo
Keyword(s):  
Phase Transition ◽  
Gas Phase ◽  
Liquid Helium ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Numerical Results ◽  
Phase Flow ◽  
Two Dimensional ◽  
Two Phase ◽  
Normal Fluid

The two-dimensional characteristics of the vapor-liquid two-phase flow of liquid helium in a pipe are numerically investigated to realize the further development and high performance of new cryogenic engineering applications. First, the governing equations of the two-phase flow of liquid helium based on the unsteady thermal nonequilibrium multi-fluid model are presented and several flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the two-phase flow of liquid helium is shown in detail, and it is also found that the phase transition of the normal fluid to the superfluid and the generation of superfluid counterflow against normal fluid flow are conspicuous in the large gas phase volume fraction region where the liquid to gas phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase. According to these theoretical results, the fundamental characteristics of the cryogenic two-phase flow are predicted. The numerical results obtained should contribute to the realization of advanced cryogenic industrial applications.

Imaging and Resistivity Studies of Saturation Gradients in Two-Phase Flow in 3-D Porous Media

1996 ◽  
Vol 464 ◽  
Author(s):  
E. H. Kawamoto ◽  
Po-Zen Wong
Keyword(s):  
Computed Tomography ◽  
Porous Media ◽  
Two Phase Flow ◽  
Water Saturation ◽  
Glass Beads ◽  
Water Phase ◽  
Phase Flow ◽  
Two Phase ◽  
Vertical Column ◽  
X Ray

ABSTRACTWe have carried out x-ray radiography and computed tomography (CT) to study two-phase flow in 3-D porous media. Air-brine displacement was imaged for drainage and imbibition experiments in a vertical column of glass beads. By correlating water saturation Sw with resistance R, we find that there is a threshold saturation S* ≈ 0.2, above which R(SW) ∼ Sw−2, in agreement with the empirical Archie relation. This holds true for both drainage and imbibition with littlehysteresis, provided that Sw remains above S*. Should Sw drop below S* during drainage, R(Sw) rises above the Archie prediction, exhibiting strong hysteresis upon reimbibition. This behavior suggests a transition in the connectivity of the water phase near S*, possibly due to percolation effects.

CsOH and its Lighter Homologues – a Comparison

2014 ◽  
Vol 69 (11-12) ◽  
pp. 1229-1236
Author(s):  
Matthias Wörsching ◽  
Constantin Hoch
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Structure Type ◽  
Alkali Metal Hydroxide ◽  
X Ray ◽  
Raman Spectroscopic ◽  
Cesium Hydroxide ◽  
Free Ion ◽  
The One ◽  
First Time

Abstract Cesium hydroxide, CsOH, was for the first time characterised on the basis of single-crystal data. The structure is isotypic to the one of the room-temperature modification of NaOH and can be derived from the NaCl structure type thus allowing the comparison of all alkali metal hydroxide structures. Raman spectroscopic investigations show the hydroxide anion to behave almost as a free ion as in the gas phase. The X-ray investigations indicate possible H atom positions.

Sign in / Sign up

Export Citation Format

Share Document