A Kinetic Study of Ethylene and 1-Hexene Homo- and Copolymerization Catalyzed by a Silica-Supported Cr(IV) Complex:  Evidence for Propagation by a Migratory Insertion Mechanism

2000 ◽  
Vol 122 (37) ◽  
pp. 8968-8976 ◽  
Author(s):  
Jamila Amor Nait Ajjou ◽  
Susannah L. Scott
Keyword(s):  
Kinetic Study ◽  
Migratory Insertion ◽  
Insertion Mechanism

scholarly journals Electrophilic Sulfur Reagent Design Enables Catalytic syn-Carbosulfenylation of Unactivated Alkenes

2021 ◽  
Author(s):  
Zi-Qi Li ◽  
Yilin Cao ◽  
Taeho Kang ◽  
Keary Engle
Keyword(s):  
Reaction Kinetics ◽  
Side Reactions ◽  
Computational Studies ◽  
Transfer Processes ◽  
Leaving Group ◽  
Migratory Insertion ◽  
Component Approach ◽  
Insertion Mechanism ◽  
Weakly Coordinating ◽  
And Control

A multi-component approach to structurally complex organosulfur products is described via the nickel-catalyzed 1,2-carbosulfenylation of unactivated alkenes with organoboron nucleophiles and tailored organosulfur electrophiles. Key to the development of this transformation is the identification of a modular N-alkyl-N-(arylsulfenyl)arenesulfonamide family of sulfur electrophiles. Tuning the electronic and steric properties of the leaving group in these reagents controls pathway selectivity, favoring three-component coupling and suppressing side reactions, as examined via computational studies. The unique syn-stereoselectivity differs from traditional electrophilic sulfenyl transfer processes involving a thiiranium ion intermediate and arises from the directed arylnickel(I) migratory insertion mechanism, as elucidated through reaction kinetics and control experiments. Reactivity and regioselectivity are facilitated by a collection of monodentate, weakly coordinating native directing groups, including sulfonamides, alcohols, amines, amides, and azaheterocycles.

A kinetic study of controlling nitrogen in process for boron steel by using30N2isotope gas

2008 ◽  
Vol 105 (12) ◽  
pp. 601-608
Author(s):  
Seung Min Han ◽  
Dong Joon Min ◽  
Joo Hyun Park ◽  
Jung Ho Park ◽  
Jong Min Park
Keyword(s):  
Kinetic Study ◽  
Boron Steel

Kinetic Study of the Effect of Heparin on the Amidase Activity of Trypsin, Plasmin and Urokinase

1983 ◽  
Vol 49 (03) ◽  
pp. 199-203 ◽  
Author(s):  
V M Yomtova ◽  
N A Stambolieva ◽  
B M Blagoev
Keyword(s):  
Kinetic Study ◽  
Active Center ◽  
Simultaneous Presence ◽  
Amidase Activity ◽  
Competitive Inhibitors ◽  
Uncompetitive Inhibitor

SummaryIt was found that the effect of heparin on the amidase activity of urokinase (E C 3.4.21.31), plasmin (E C 3.4.21.7) and trypsin (E C 3.4.21.4) depended on the substrate used. No effect of heparin on the amidase activity of urokinase and trypsin was observed when Pyro Glu-Gly-Arg-p-nitroanilide (S-2444) and α-N-acetyl-L-lysine-p-nitroanilide (ALNA) were used as substrates. Heparin acted as a uncompetitive inhibitor of trypsin (Ki = 1.2×10-6 M), plasmin (Ki = 4.9×10-6 M) and urokinase (Ki = l.0×10-7 M) when Bz-Phe-Val-Arg-p-nitroanilide (S-2160), H-D-Val-Leu-Lys-p-nitroanilide (S-2251) and plasminogen, respectively, were used as substrates. These results, as well as the data obtained by studying the effect of the simultaneous presence of heparin and competitive inhibitors suggest that although heparin is not bound at the active center of these enzymes, it may influence the effectivity of catalysis.

A kinetic study of the metathesis of propene on a rhenium-aluminium catalyst

1981 ◽  
Vol 31 (1) ◽  
pp. 388-394 ◽  
Author(s):  
Mahmoud El-Sawi ◽  
Antonio Iannibello ◽  
Fernando Morelli ◽  
Ganfranco Gatalano ◽  
Francesco Intrieri ◽  
...  
Keyword(s):  
Kinetic Study
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