Experimental study on the reaction pathway of α-haloacetophenones with nucleophiles: direct substitution or carbonyl addition?

2012 ◽  
Vol 25 (8) ◽  
pp. 680-685 ◽  
Author(s):  
Mika Katayama ◽  
Keita Sasagawa ◽  
Hiroshi Yamataka
Keyword(s):  
Experimental Study ◽  
Reaction Pathway ◽  
Direct Substitution ◽  
Carbonyl Addition

scholarly journals Ring-Opening Carbonyl-Olefin Metathesis of Norbornenes

2019 ◽  
Author(s):  
Janis Jermaks ◽  
Phong K. Quach ◽  
Zara M. Seibel ◽  
Julien Pomarole ◽  
Tristan Lambert
Keyword(s):  
Experimental Study ◽  
Theoretical Investigation ◽  
Olefin Metathesis ◽  
Ring Opening ◽  
Activation Barrier ◽  
Reaction Pathway ◽  
Next Generation ◽  
Methyl Group ◽  
Optimized Conditions ◽  
Hydrolysis Of

<div> <p>A computational and experimental study of the hydrazine-catalyzed ring-opening carbonyl-olefin metathesis of norbornenes is described. Detailed theoretical investigation of the energetic landscape for the full reaction pathway with six different hydrazines revealed several crucial aspects for the design of next-generation hydrazine catalysts. This study indicated that a [2.2.2]-bicyclic hydrazine should offer substantially increased reactivity versus the previously reported [2.2.1]-hydrazine due to a lowered activation barrier for the rate-determining cycloreversion step, a prediction which was verified experimentally. Optimized conditions for both cycloaddition and cycloreversion steps were identified, and a brief substrate scope study for each was conducted. A complication for catalysis was found to be the slow hydrolysis of the ring-opened hydrazonium intermediates, which were shown to suffer from a competitive and irreversible cycloaddition with a second equivalent of norbornene. This problem was overcome by the strategic incorporation of a bridgehead methyl group on the norbornene ring, leading to the first demonstrated catalytic carbonyl-olefin metathesis of norbornene rings.</p> </div>

scholarly journals Ring-Opening Carbonyl-Olefin Metathesis of Norbornenes

2019 ◽  
Author(s):  
Janis Jermaks ◽  
Phong K. Quach ◽  
Zara M. Seibel ◽  
Julien Pomarole ◽  
Tristan Lambert
Keyword(s):  
Experimental Study ◽  
Theoretical Investigation ◽  
Olefin Metathesis ◽  
Ring Opening ◽  
Activation Barrier ◽  
Reaction Pathway ◽  
Next Generation ◽  
Methyl Group ◽  
Optimized Conditions ◽  
Hydrolysis Of

<div> <p>A computational and experimental study of the hydrazine-catalyzed ring-opening carbonyl-olefin metathesis of norbornenes is described. Detailed theoretical investigation of the energetic landscape for the full reaction pathway with six different hydrazines revealed several crucial aspects for the design of next-generation hydrazine catalysts. This study indicated that a [2.2.2]-bicyclic hydrazine should offer substantially increased reactivity versus the previously reported [2.2.1]-hydrazine due to a lowered activation barrier for the rate-determining cycloreversion step, a prediction which was verified experimentally. Optimized conditions for both cycloaddition and cycloreversion steps were identified, and a brief substrate scope study for each was conducted. A complication for catalysis was found to be the slow hydrolysis of the ring-opened hydrazonium intermediates, which were shown to suffer from a competitive and irreversible cycloaddition with a second equivalent of norbornene. This problem was overcome by the strategic incorporation of a bridgehead methyl group on the norbornene ring, leading to the first demonstrated catalytic carbonyl-olefin metathesis of norbornene rings.</p> </div>

Experimental Study on the Reaction Pathway of α-Haloacetophenones with NaOMe: Examination of Bifurcation Mechanism

2014 ◽  
Vol 87 (1) ◽  
pp. 119-126 ◽  
Author(s):  
Kohei Tagawa ◽  
Keita Sasagawa ◽  
Ken Wakisaka ◽  
Shunsuke Monjiyama ◽  
Mika Katayama ◽  
...  
Keyword(s):  
Experimental Study ◽  
Reaction Pathway ◽  
Bifurcation Mechanism

Experimental study on the restoration from a tilt-azimuth series for improvement in resolution

1995 ◽  
Vol 53 ◽  
pp. 636-637
Author(s):  
Norio Baba ◽  
Norihiko Ichise ◽  
Syunya Watanabe
Keyword(s):  
Experimental Study ◽  
Spherical Aberration ◽  
Incident Beam ◽  
Optical Parameters ◽  
Beam Tilting ◽  
Illumination Method ◽  
Restoration Method ◽  
Illumination Mode

The tilted beam illumination method is used to improve the resolution comparing with the axial illumination mode. Using this advantage, a restoration method of several tilted beam images covering the full azimuthal range was proposed by Saxton, and experimentally examined. To make this technique more reliable it seems that some practical problems still remain. In this report the restoration was attempted and the problems were considered. In our study, four problems were pointed out for the experiment of the restoration. (1) Accurate beam tilt adjustment to fit the incident beam to the coma-free axis for the symmetrical beam tilting over the full azimuthal range. (2) Accurate measurements of the optical parameters which are necessary to design the restoration filter. Even if the spherical aberration coefficient Cs is known with accuracy and the axial astigmatism is sufficiently compensated, at least the defocus value must be measured. (3) Accurate alignment of the tilt-azimuth series images.

An Experimental Study of Some Properties of Stuttered Words

1962 ◽  
Vol 5 (4) ◽  
pp. 387-394 ◽  
Author(s):  
Bruce Quarrington ◽  
Jerome Conway ◽  
Nathan Siegel
Keyword(s):  
Experimental Study

Experimental study of total body washout employing extracorporeal circulation and hypothermia

1974 ◽  
Vol 126 (2) ◽  
pp. 243-248
Author(s):  
A WAKABAYASHI ◽  
T KUBO ◽  
K CHARNEY ◽  
Y NAKAMURA ◽  
J CONNOLLY
Keyword(s):  
Experimental Study ◽  
Extracorporeal Circulation ◽  
Total Body

Gastric Freezing: An Experimental Study

1963 ◽  
Vol 45 (3) ◽  
pp. 374-383 ◽  
Author(s):  
Donald C. McIlrath ◽  
George A. Hallenbeck ◽  
Hubert A. Allen ◽  
Charles V. Mann ◽  
Edward J. Baldes ◽  
...  
Keyword(s):  
Experimental Study

The Effect of Cortisone and Corticotropin on The Healing of Gastric Ulcer: An Experimental Study

1958 ◽  
Vol 34 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Henry D. Janowitz ◽  
Vernon A. Weinstein ◽  
Rhoda G. Shaer ◽  
James F. Cereghini ◽  
Franklin Hollander
Keyword(s):  
Experimental Study ◽  
Gastric Ulcer
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