The Roles of Entropy and Enthalpy in Stabilizing Ion-Pairs at Transition States in Zeolite Acid Catalysis

2011 ◽  
Vol 45 (2) ◽  
pp. 229-238 ◽  
Author(s):  
Rajamani Gounder ◽  
Enrique Iglesia
Keyword(s):  
Acid Catalysis ◽  
Ion Pairs ◽  
Transition States

Role of Ion-Pairs in Brønsted Acid Catalysis

ACS Catalysis ◽  
2015 ◽  
Vol 5 (11) ◽  
pp. 6630-6633 ◽  
Author(s):  
Heejae Kim ◽  
Erli Sugiono ◽  
Yuki Nagata ◽  
Manfred Wagner ◽  
Mischa Bonn ◽  
...  
Keyword(s):  
Acid Catalysis ◽  
Ion Pairs ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Bronsted Acid Catalysis

Lewis Acid Catalysis Alters the Shapes and Products of Bis-Pericyclic Diels−Alder Transition States

2007 ◽  
Vol 129 (15) ◽  
pp. 4528-4529 ◽  
Author(s):  
Nihan Çelebi-Ölçüm ◽  
Daniel H. Ess ◽  
Viktorya Aviyente ◽  
K. N. Houk
Keyword(s):  
Lewis Acid ◽  
Acid Catalysis ◽  
Transition States ◽  
Diels Alder ◽  
Lewis Acid Catalysis

Reactivity descriptors in acid catalysis: acid strength, proton affinity and host–guest interactions

2020 ◽  
Vol 56 (54) ◽  
pp. 7371-7398
Author(s):  
Prashant Deshlahra ◽  
Enrique Iglesia
Keyword(s):  
Proton Affinity ◽  
Acid Catalysis ◽  
Transition States ◽  
Acid Strength ◽  
Reactivity Descriptors

Acid strength and proton affinity, the independent properties of catalysts and molecules, are incomplete descriptors of because cations and conjugate anions reorganize their charges as they interact as bound intermediates and transition states.

Chemistry of gaseous ion pairs produced by thermal collisions

1980 ◽  
Vol 77 ◽  
pp. 759-768 ◽  
Author(s):  
R. Stephen Berry
Keyword(s):  
Ion Pairs

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.

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