Role of Brønsted acid centres for alkene double bond migration over alumina at temperatures above 450 K

1978 ◽  
Vol 74 (0) ◽  
pp. 498 ◽  
Author(s):  
Christopher S. John ◽  
Akio Tada ◽  
Lois V. F. Kennedy
Keyword(s):  
Double Bond ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Double Bond Migration ◽  
Brönsted Acid

scholarly journals Nickel Hydride Catalyzed Cleavage of Allyl Ethers Induced by Isomerization

Synlett ◽  
2021 ◽  
Author(s):  
Andreas Berkefeld ◽  
Ivana Fleischer ◽  
Prasad M. Kathe
Keyword(s):  
Double Bond ◽  
Functional Groups ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Double Bond Migration ◽  
Allyl Ethers ◽  
Nickel Hydride ◽  
Brönsted Acid ◽  
Key Steps

AbstractThis report discloses the deallylation of O- and N-allyl functional groups by using a combination of a Ni-H precatalyst and excess Brønsted acid. Key steps are the isomerization of the O- or N-allyl group through Ni-catalyzed double-bond migration followed by Brønsted acid induced O/N–C bond hydrolysis. A variety of functional groups are tolerated in this protocol, highlighting its synthetic value.

scholarly journals On the Role of Protonic Acid Sites in Cu Loaded FAU31 Zeolite as a Catalyst for the Catalytic Transformation of Furfural to Furan

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2015
Author(s):  
Łukasz Kuterasiński ◽  
Małgorzata Smoliło-Utrata ◽  
Joanna Kaim ◽  
Wojciech Rojek ◽  
Jerzy Podobiński ◽  
...  
Keyword(s):  
Active Sites ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acid Sites ◽  
Protonic Acid ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

The aim of the present paper is to study the speciation and the role of different active site types (copper species and Brønsted acid sites) in the direct synthesis of furan from furfural catalyzed by copper-exchanged FAU31 zeolite. Four series of samples were prepared by using different conditions of post-synthesis treatment, which exhibit none, one or two types of active sites. The catalysts were characterized by XRD, low-temperature sorption of nitrogen, SEM, H2-TPR, NMR and by means of IR spectroscopy with ammonia and CO sorption as probe molecules to assess the types of active sites. All catalyst underwent catalytic tests. The performed experiments allowed to propose the relation between the kind of active centers (Cu or Brønsted acid sites) and the type of detected products (2-metylfuran and furan) obtained in the studied reaction. It was found that the production of 2-methylfuran (in trace amounts) is determined by the presence of the redox-type centers, while the protonic acid sites are mainly responsible for the furan production and catalytic activity in the whole temperature range. All studied catalysts revealed very high susceptibility to coking due to polymerization of furfural.

Critical role of Bronsted acid in Lewis-acid-catalyzed synthesis of Amadori and Heyns compounds of β-amino acids

2021 ◽  
pp. 1-11
Author(s):  
Debasree Chanda ◽  
Gangothri M. Venkataswamy ◽  
Lagamawwa V. Hipparagi ◽  
Nanishankar V. Harohally
Keyword(s):  
Amino Acids ◽  
Lewis Acid ◽  
Critical Role ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Acid Catalyzed

Domino construction of a bullataketal core via double bond cleavage in activated dihydrofurans

2018 ◽  
Vol 5 (10) ◽  
pp. 1655-1663 ◽  
Author(s):  
Konstantin L. Ivanov ◽  
Ivan M. Vatsouro ◽  
Stanislav I. Bezzubov ◽  
Mikhail Ya. Melnikov ◽  
Ekaterina M. Budynina
Keyword(s):  
Double Bond ◽  
Bond Cleavage ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Biologically Relevant ◽  
Brönsted Acid

A new rapid approach to structurally challenging and biologically relevant methanobenzodioxepines was developed via a Brønsted acid-triggered domino transformation of 3-carbonyl-4,5-dihydrofurans, substituted with MOM-protected o-hydroxyaryls at the C4 atom.

scholarly journals BTX abatement using Chilean natural zeolite: the role of Brønsted acid sites

2012 ◽  
Vol 66 (8) ◽  
pp. 1759-1765 ◽  
Author(s):  
S. Alejandro ◽  
H. Valdés ◽  
M.-H. Manero ◽  
C. A. Zaror
Keyword(s):  
Natural Zeolite ◽  
Acid Sites ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brønsted Acid Sites ◽  
Modified Zeolite ◽  
Brönsted Acid ◽  
Brönsted Acid Sites ◽  
Bronsted Acid Sites

In wastewater treatment facilities, air quality is not only affected by conventional unpleasant odour compounds; toxic volatile organic compounds (VOCs) are also found. In this study, the adsorptive capacity of Chilean natural zeolite toward VOC removal was evaluated. Moreover, the influence of zeolite chemical surface properties on VOC elimination was also investigated. Three modified zeolite samples were prepared from a natural Chilean zeolite (53% clinoptilolite, 40% mordenite and 7% quartz). Natural and modified zeolite samples were characterised by nitrogen adsorption at 77 K, elemental analyses and X-ray fluorescence (XRF). Chemical modifications of natural zeolite showed the important role of Brønsted acid sites on the abatement of VOCs. The presence of humidity has a negative effect on zeolite adsorption capacity. Natural zeolites could be an interesting option for benzene, toluene and xylene vapour emission abatement.

New role of carbon dioxide in Lewis assisted Brönsted acid accelerated diiodination of alkynes in water

2002 ◽  
Vol 4 (5) ◽  
pp. 505-506 ◽  
Author(s):  
Jin-Heng Li ◽  
Ye-Xiang Xie ◽  
Du-Lin Yin
Keyword(s):  
Carbon Dioxide ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid
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