Hydrogen effects in TiCl4/MgCl2/THF catalysts with second Lewis acid addition on ethylene polymerization behaviors

2017 ◽  
Vol 75 (7) ◽  
pp. 3211-3226
Author(s):  
Thanyathorn Niyomthai ◽  
Bunjerd Jongsomjit ◽  
Piyasan Praserthdam
Keyword(s):  
Lewis Acid ◽  
Ethylene Polymerization ◽  
Acid Addition

Ethylene polymerization on lewis acid sites of a reduced V2O5/Al2O3 catalyst

1992 ◽  
Vol 46 (1) ◽  
pp. 199-207 ◽  
Author(s):  
S. Ishida ◽  
S. Imamura ◽  
F. Ren ◽  
Y. Tatematsu ◽  
Y. Fujimura
Keyword(s):  
Lewis Acid ◽  
Ethylene Polymerization ◽  
Acid Sites ◽  
Lewis Acid Sites ◽  
Al2o3 Catalyst

Hafnium–phosphinimide complexes

2009 ◽  
Vol 87 (8) ◽  
pp. 1163-1172 ◽  
Author(s):  
Osamah Alhomaidan ◽  
Gregory C. Welch ◽  
Guangcai Bai ◽  
Douglas W. Stephan
Keyword(s):  
Lewis Acid ◽  
Related Species ◽  
Ethylene Polymerization ◽  
Preliminary Testing ◽  
Redistribution Reactions

A series of phosphinimide complexes of Hf are prepared and characterized. Reaction of the phosphinimine t-Bu3PNH with Hf(NEt2)4 gave (t-Bu3PN)Hf(NEt2)3 (1) but this species was not readily converted to the corresponding HfCl3-derivative. The reaction of 2 equiv. of t-Bu3PNH with Hf(NEt2)4, however, gave (t-Bu3PN)2Hf(NEt2)2 (2), which was readily converted to (t-Bu3PN)2HfCl2 (3) and (t-Bu3PN)2HfMe2 (4). Employing t-Bu3PNLi and HfCl4 afforded (t-Bu3PN)3HfCl (5) while reaction with CpHfCl3 gave rise to ligand redistribution reactions affording (t-Bu3PN)2HfCl2 and Cp2HfCl2. However, Cp(t-Bu3PN)2HfCl (7) was prepared by treating (t-Bu3PN)2HfCl2 with CpNa. The related species of Cp2(t-Bu3PN)HfCl (8) was synthesized by the reaction of Cp2HfCl2 and t-Bu3PNLi. Ligand redistribution was avoided in the reaction of Cp*HfCl3 as Cp*(t-Bu3PN)HfCl2 (9) and Cp*(i-Pr3PN)HfCl2 (10) were readily obtained and derivatized as Cp*(t-Bu3PN)Hf(NMe2)2 (11) and Cp*(t-Bu3PN)HfMe2 (12), respectively. Similarly, ((Me3Si)2C5H3)(t-Bu3PN)HfCl2 (13) was converted to ((Me3Si)2C5H3)(t-Bu3PN)HfMe2 (14). Reactions with Lewis acid activators were used to prepare Cp*(t-Bu3PN)HfMe(THF)MeB(C6F5)3 (15), (Cp*(t-Bu3PN)HfMe)(B(C6F5)4) (16), and (t-Bu3PN)2Hf(H2B(C6F5)2)2 (17). Preliminary testing of 3, 9, and 13 in ethylene polymerization is reported. Compounds 3, 4, 7, 9, and 17 are characterized crystallographically.

Supported ( n BuCp)2 ZrCl2 Catalysts: Effects of Selected Lewis Acid Organotin Silica Surface Modifiers on Ethylene Polymerization

2008 ◽  
Vol 2 (4) ◽  
pp. 339-349 ◽  
Author(s):  
Muhammad N. Akhtar ◽  
Muhammad Atiqullah ◽  
Akhlaq A. Moman ◽  
Atieh H. Abu-Raqabah ◽  
Neaz Ahmed
Keyword(s):  
Lewis Acid ◽  
Ethylene Polymerization ◽  
Silica Surface ◽  
Surface Modifiers

scholarly journals Synthesis and reactivity of an N-triphos Mo(0) dinitrogen complex

2018 ◽  
Vol 47 (33) ◽  
pp. 11386-11396 ◽  
Author(s):  
Samantha L. Apps ◽  
Andrew J. P. White ◽  
Philip W. Miller ◽  
Nicholas J. Long
Keyword(s):  
Alkali Metal ◽  
Lewis Acid ◽  
Acid Addition ◽  
Dinitrogen Complex

N-Triphos/Mo(0)-dinitrogen reactivity: hydrogenation; Lewis acid addition; and alkali metal mediated ligand rearrangement.

Ligand–metal secondary interactions in phosphine–sulfonate palladium and nickel catalyzed ethylene (co)polymerization

2020 ◽  
Vol 11 (2) ◽  
pp. 411-416 ◽  
Author(s):  
Chen Tan ◽  
Muhammad Qasim ◽  
Wenmin Pang ◽  
Changle Chen
Keyword(s):  
Lewis Acid ◽  
Ethylene Polymerization ◽  
Secondary Interactions

Ligand secondary interactions and Lewis acid modulation are simultaneously achieved in palladium and nickel catalyzed ethylene polymerization and copolymerization.

Cobalt/Lewis Acid Catalysis for Hydrocarbofunctionalization of Alkynes via Cooperative C–H Activation

2020 ◽  
Author(s):  
Chang-Sheng Wang ◽  
Sabrina Monaco ◽  
Anh Ngoc Thai ◽  
Md. Shafiqur Rahman ◽  
Chen Wang ◽  
...  
Keyword(s):  
Catalytic System ◽  
Lewis Acid ◽  
Hydrogen Transfer ◽  
Acid Catalysis ◽  
Rate Limiting Step ◽  
Site Selectivity ◽  
Set Up ◽  
Site Selective ◽  
First Time ◽  
Rate Limiting

A catalytic system comprised of a cobalt-diphosphine complex and a Lewis acid (LA) such as AlMe3 has been found to promote hydrocarbofunctionalization reactions of alkynes with Lewis basic and electron-deficient substrates such as formamides, pyridones, pyridines, and azole derivatives through site-selective C-H activation. Compared with known Ni/LA catalytic system for analogous transformations, the present catalytic system not only feature convenient set up using inexpensive and bench-stable precatalyst and ligand such as Co(acac)3 and 1,3-bis(diphenylphosphino)propane (dppp), but also display distinct site-selectivity toward C-H activation of pyridone and pyridine derivatives. In particular, a completely C4-selective alkenylation of pyridine has been achieved for the first time. Mechanistic stidies including DFT calculations on the Co/Al-catalyzed addition of formamide to alkyne have suggested that the reaction involves cleavage of the carbamoyl C-H bond as the rate-limiting step, which proceeds through a ligand-to-ligand hydrogen transfer (LLHT) mechanism leading to an alkyl(carbamoyl)cobalt intermediate.

Catalytic Carbonyl-Olefin Metathesis of Aliphatic Ketones: Iron(III) HomoDimers as Lewis Acidic Superelectrophiles

2018 ◽  
Author(s):  
Haley Albright ◽  
Paul S. Riehl ◽  
Christopher C. McAtee ◽  
Jolene P. Reid ◽  
Jacob R. Ludwig ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Olefin Metathesis ◽  
Acid Activation ◽  
Lewis Acid Catalysts ◽  
Distinct Mode ◽  
Aliphatic Ketones ◽  
Carbon Carbon Bond ◽  
Metathesis Reactions ◽  
Acid Catalyzed

<div>Catalytic carbonyl-olefin metathesis reactions have recently been developed as a powerful tool for carbon-carbon bond</div><div>formation. However, currently available synthetic protocols rely exclusively on aryl ketone substrates while the corresponding aliphatic analogs remain elusive. We herein report the development of Lewis acid-catalyzed carbonyl-olefin ring-closing metathesis reactions for aliphatic ketones. Mechanistic investigations are consistent with a distinct mode of activation relying on the in situ formation of a homobimetallic singly-bridged iron(III)-dimer as the active catalytic species. These “superelectrophiles” function as more powerful Lewis acid catalysts that form upon association of individual iron(III)-monomers. While this mode of Lewis acid activation has previously been postulated to exist, it has not yet been applied in a catalytic setting. The insights presented are expected to enable further advancement in Lewis acid catalysis by building upon the activation principle of “superelectrophiles” and broaden the current scope of catalytic carbonyl-olefin metathesis reactions.</div>

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