scholarly journals Brønsted Acid Catalysis in the Oxidation of Purine Based Alkaloids by Mn(VII) in Aqueous Acetonitrile and Sodium Fluoride Medium: A Kinetic Approach

2021 ◽  
Vol 33 (5) ◽  
pp. 1051-1057
Author(s):  
A. Ramakrishna Reddy ◽  
Bhooshan Muddam ◽  
A. Sambashiva Rao ◽  
K.C. Rajanna ◽  
A. Panasa Reddy ◽  
...  
Keyword(s):  
Sodium Fluoride ◽  
Slow Step ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Aqueous Acetonitrile ◽  
H2so4 Concentration ◽  
Purine Alkaloids ◽  
Brönsted Acid ◽  
Acidity Functions ◽  
Fluoride Medium

Brønsted acid (HClO4, H2SO4) catalyzed Mn(VII) oxidation of purine alkaloids such as caffeine, theophylline and theobromine in aqueous acetonitrile and sodium fluoride medium revealed first order kinetics in both [(Mn(VII)] and [Alkaloid] at constant acidity and temperature. Sodium fluoride was added to the reaction mixture in order to avoid/suppress auto catalytic reaction due to the generation of Mn(III) and Mn(IV) species during the course of Mn(VII) oxidations in acidic solutions. An increase in the Brønsted acids (HClO4, H2SO4) concentration accelerated the rate of oxidation. Rate enhancements observed here in are analyzed by Zucker-Hammett, Bunnett and Bunnett-Olsen criteria of acidity functions. On the basis of observed Bunnett-Olsen criteria of acidity functions, the most plausible mechanism has been proposed with the involvement of water molecule in the slow step (as proton transferring agent).

Solvent-Free Acetalization of Glycerol with n-Octanal using Combined Brønsted Acid-Surfactant Catalyst

2017 ◽  
Vol 54 (1) ◽  
pp. 54-63 ◽  
Author(s):  
Xu Li ◽  
Lan Wu ◽  
Qiong Tang ◽  
Jinxiang Dong
Keyword(s):  
Solvent Free ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid

Synthetic Scope of Brønsted Acid-Catalyzed Reactions of Carbonyl Compounds and Ethyl Diazoacetate

2021 ◽  
Author(s):  
Mizzanoor Rahaman ◽  
M. Shahnawaz Ali ◽  
Khorshada Jahan ◽  
Damon Hinz ◽  
Jawad Bin Belayet ◽  
...  
Keyword(s):  
Carbonyl Compounds ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Ethyl Diazoacetate ◽  
Brönsted Acid ◽  
Acid Catalyzed ◽  
Catalyzed Reactions

scholarly journals Tailoring Lewis/Brønsted acid properties of MOF nodes via hydrothermal and solvothermal synthesis: simple approach with exceptional catalytic implications

2021 ◽  
Author(s):  
Sergio Rojas-Buzo ◽  
Benjamin Bohigues ◽  
Christian W. Lopes ◽  
Débora M. Meira ◽  
Mercedes Boronat ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Active Site ◽  
Solvothermal Synthesis ◽  
Simple Approach ◽  
Organic Reactions ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Acid Properties ◽  
Brönsted Acid

The Brønsted/Lewis acid properties of Hf-MOF-808 can be tuned by simply controlling the solvent employed in its synthesis, with direct catalytic implications on the activity and selectivity of organic reactions sensitive to the active site nature.

Brønsted Acid-Catalyzed Friedel-Crafts-type Alkylation of Arenes with αAryl Diazoacetates

2021 ◽  
pp. 152751
Author(s):  
Wenming Chen ◽  
Guifang Chen ◽  
Biao Wang ◽  
Wei Wang ◽  
Wei Huang ◽  
...  
Keyword(s):  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid ◽  
Acid Catalyzed

scholarly journals Bioinspired Brønsted Acid-Promoted Regioselective Tryptophan Isoprenylations

ACS Omega ◽  
2021 ◽  
Vol 6 (16) ◽  
pp. 10840-10858
Author(s):  
Tushar M. Khopade ◽  
Kalyani Ajayan ◽  
Swapnil S. Joshi ◽  
Amy L. Lane ◽  
Rajesh Viswanathan
Keyword(s):  
Bronsted Acid ◽  
Brønsted Acid ◽  
Brönsted Acid

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.

Effects of Brønsted acid site proximity in chabazite zeolites on OH infrared spectra and protolytic propane cracking kinetics

2021 ◽  
Vol 395 ◽  
pp. 210-226
Author(s):  
Philip M. Kester ◽  
Jerry T. Crum ◽  
Sichi Li ◽  
William F. Schneider ◽  
Rajamani Gounder
Keyword(s):  
Infrared Spectra ◽  
Acid Site ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Bronsted Acid Site ◽  
Brønsted Acid Site ◽  
Brönsted Acid ◽  
Propane Cracking
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