Effect of fatty amine and perfluorocarbon as anti-fouling agent on the catalyst activity and titanium oxidation state in slurry polymerization of ethylene

2006 ◽  
Vol 102 (1) ◽  
pp. 257-260 ◽  
Author(s):  
Mojtaba Mousavi ◽  
Shokoofeh Hakim ◽  
Mehdi Nekoomanesh
Keyword(s):  
Oxidation State ◽  
Catalyst Activity ◽  
Fatty Amine ◽  
Titanium Oxidation

Titanium-magnesium catalysts for olefin polymerization - effect of titanium oxidation state on catalyst performance

Polimery ◽  
2008 ◽  
Vol 53 (05) ◽  
pp. 353-357 ◽  
Author(s):  
TATIANA B. MIKENAS ◽  
ANDREY A. TREGUBOV ◽  
VLADIMIR A. ZAKHAROV ◽  
LUDMILA G. ECHEVSKAYA ◽  
MIKHAIL A. MATSKO
Keyword(s):  
Oxidation State ◽  
Olefin Polymerization ◽  
Titanium Oxidation

Moving up and down the Titanium Oxidation State in Ziegler−Natta Catalysis

2011 ◽  
Vol 44 (4) ◽  
pp. 778-783 ◽  
Author(s):  
Naeimeh Bahri-Laleh ◽  
Andrea Correa ◽  
Shahram Mehdipour-Ataei ◽  
Hassan Arabi ◽  
Mehdi Nekoomanesh Haghighi ◽  
...  
Keyword(s):  
Oxidation State ◽  
Titanium Oxidation

Segregation and Color Change on (Cr,Ca) Codoped Nanocrystalline Tin Dioxide

2014 ◽  
Vol 87 ◽  
pp. 73-78
Author(s):  
Douglas Gouvêa ◽  
Danielle Ucha Rocha ◽  
Lorena Batista Caliman
Keyword(s):  
Oxidation State ◽  
Surface Segregation ◽  
Tin Dioxide ◽  
Color Change ◽  
Catalyst Activity ◽  
Oxide System ◽  
Environment Change ◽  
Chromium Ions ◽  
High Particle ◽  
Oxide Addition

The intense violet color and the high catalyst activity of Cr-doped SnO2 nanoparticles have motivated several authors to understand the solid solution formation and the oxidation state of chromium ions after synthesis. Recent work has demonstrated the ability of surface segregation in chromium-doped tin oxide system but the oxidation state is still misunderstood. Calcium oxide addition changes the color of (Cr,Ca) codoped nanocrystalline tin dioxide pigments from violet to yellow simultaneously to a high particle size stabilization demonstrating that co-segregation could be associated to color change due to chemical environment change of chromium ions and specific surface area increase. High solubility of Cr+6 and Ca+2 allow us to determine the surface excess of both cations by ionic chromatography and the color change after surface solubilization.

Oxidation of 1,2,3,4-tetrahydronaphthalene by dioxygen. Effect of the free radical initiators 1,2,3,4-tetrahydro-1-naphthylhydroperoxide and 2,2'-azobis(2-methylpropionitrile) on the reaction catalyzed by 2,4-pentanedionates of 3d transition metals

1990 ◽  
Vol 55 (4) ◽  
pp. 1015-1021 ◽  
Author(s):  
Stanislav Luňák ◽  
Marie Vašková ◽  
Pavel Lederer
Keyword(s):  
Free Radical ◽  
Transition Metal ◽  
Transition Metals ◽  
Oxidation State ◽  
Metal Ion ◽  
Catalyst Activity ◽  
Transition Metal Ion ◽  
Free Radical Initiator ◽  
Radical Initiators ◽  
Catalyzed Oxidation

The effect of the free radical initiators 1,2,3,4-tetrahydro-1-naphthylhydroperoxide and 2,2'-azobis(2-methylpropionitrile) on the oxidation of 1,2,3,4-tetrahydronaphthalene (tetraline) by dioxygen catalyzed by Cr(III), Mn(III), Fe(III), Co(II), Co(III) and Cu(II) 2,4-pentanedionates (acac) has been investigated. It has been found that the addition of a free radical initiator can increase the rate of catalyzed oxidation or decrease it. Which effect will operate depends on the kind of the catalyzing transition metal ion and its oxidation state. The results obtained indicate that the above free radical initiators act on the catalyzed oxidation of tetraline by affecting the catalyst activity.

Reduction of nitrogen oxide by ammonia. Oxidation state of V2O5/Al2O3 catalysts and reaction mechanism

1990 ◽  
Vol 55 (10) ◽  
pp. 2390-2394 ◽  
Author(s):  
Milan Čížek
Keyword(s):  
Phase Composition ◽  
Gas Phase ◽  
Oxidation State ◽  
Reaction Rate ◽  
Ammonia Oxidation ◽  
Catalyst Activity ◽  
Oxidation Mechanism ◽  
Initial Oxidation ◽  
Catalyst Reduction ◽  
Reduction And Oxidation

When the (NO + NH3 + O2) reaction is carried out over V2O5/Al2O3, the catalysts are partially reduced, and prereduced catalysts are oxidized by the reaction mixture at a slower rate than by an O2 + N2 mixture. The degree of catalyst reduction in the (NO + NH3 + O2) reaction depends on the gas phase composition and particularly on the vanadium loading of the catalyst. The initial oxidation state of catalyst has an effect on the catalyst activity for the reaction. Rate-determining reduction and oxidation steps of the so-called reduction-oxidation mechanism are proposed on the basis of a comparison of the reduction and oxidation of the catalyst by the reaction components.

Chromium oxidation state mapping in human cells

2003 ◽  
Vol 104 ◽  
pp. 289-292 ◽  
Author(s):  
R. Ortega ◽  
B. Fayard ◽  
M. Salomé ◽  
G. Devès ◽  
J. Susini
Keyword(s):  
Oxidation State ◽  
Human Cells ◽  
Chromium Oxidation

A Short Synthesis of (+)-Brefeldin C via Enantioselective Radical Hydroalkynylation

2019 ◽  
Author(s):  
Lars Gnägi ◽  
Severin Vital Martz ◽  
Daniel Meyer ◽  
Robin Marc Schärer ◽  
Philippe Renaud
Keyword(s):  
Total Synthesis ◽  
Natural Product ◽  
Oxidation State ◽  
Single Step ◽  
Radical Process ◽  
Target Molecule ◽  
Short Synthesis ◽  
The One

<div><div><div><div><p>A very concise total synthesis of (+)-brefeldin C starting from 2-furanylcyclopentene is described. This approach is based on an unprecedented enantioselective radical hydroalkynylation process to introduce the two cyclopentane stereocenters in a single step. The use of a furan substituent allows to achieve a high trans diastereoselectivity during the radical process and it contains the four carbon atoms C1–C4 of the natural product in an oxidation state closely related to the one of the target molecule. The eight-step synthesis require six product purifications and it provides (+)-brefeldin C in 18% overall yield.</p></div></div></div></div>

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