scholarly journals Arenium cation or radical cation? An insight into the cyclodehydrogenation reaction of 2-substituted binaphthyls mediated by Lewis acids

RSC Advances ◽  
2020 ◽  
Vol 10 (37) ◽  
pp. 21974-21985
Author(s):  
Patricia Camargo Solórzano ◽  
María T. Baumgartner ◽  
Marcelo Puiatti ◽  
Liliana B. Jimenez
Keyword(s):  
Radical Cation ◽  
Lewis Acid ◽  
Reaction Mechanisms ◽  
Lewis Acids ◽  
Acid Synthesis ◽  
Theoretical Studies ◽  
Insight Into

Cyclodehydrogenation reactions of 2-substituted binaphthyls induced by a Lewis acid. Synthesis and theoretical studies of the reaction mechanisms.

Effects of Ultrasounds on Neat nitrobenzene

2019 ◽  
Vol 70 (8) ◽  
pp. 3085-3088
Author(s):  
Carmen Eugenia Stavarache ◽  
Yasuaki Maeda ◽  
Mircea Vinatoru
Keyword(s):  
Nitro Group ◽  
Radical Cation ◽  
Reaction Mechanisms ◽  
Diphenyl Ether ◽  
Argon Atmosphere ◽  
Phenyl Radical ◽  
Dissolved Gas ◽  
Decomposition Products ◽  
Oxygenated Compounds ◽  
Phenyl Cation

Neat nitrobenzene was continuously irradiated at two ultrasonic frequencies: 40 and 200 kHz, under air and argon atmosphere, respectively. Samples taken at intervals of 1, 5, 10 and 24 h were analyzed by GC-MS and decomposition products were identified. Possible reaction mechanisms are discussed. Presence of air as dissolved gas leads to oxygenated compounds such as 1,4-benzoquinone, 2,4-dinitrophenol, m-dinitrobenzene while argon inhibits the decomposition of nitrobenzene, especially at sonication times under 5 h. Based on the nature of the compounds identified we advanced a mechanism, involving a divergent splitting of unstable radical cation of NB in air and argon respectively. Thus, under air, the phenyl cation formation is preferred leading to 1,4-benzoquinone nitro-biphenyls and dinitrobenzene, while under argon, the phenyl radical formation seems to be favored, leading to phenol and diphenyl ether. The oxygenated compounds detected under argon clearly are a consequence of the nitro group splitting.

scholarly journals Theoretical Insight into the Reversal of Chemoselectivity in Diels-Alder Reactions of α,β-Unsaturated Aldehydes and Ketones Catalyzed by Brønsted and Lewis Acids

Organics ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 38-49
Author(s):  
Lakhdar Benhamed ◽  
Sidi Mohamed Mekelleche ◽  
Wafaa Benchouk
Keyword(s):  
Lewis Acids ◽  
Major Product ◽  
Diels Alder ◽  
Unsaturated Ketone ◽  
Unsaturated Aldehydes ◽  
Aldehydes And Ketones ◽  
Theoretical Insight ◽  
Insight Into ◽  
Good Agreement

Experimentally, a reversal of chemoselectivity has been observed in catalyzed Diels–Alder reactions of α,β-unsaturated aldehydes (e.g., (2E)-but-2-enal) and ketones (e.g., 2-hexen-4-one) with cyclopentadiene. Indeed, using the triflimidic Brønsted acid Tf2NH as catalyst, the reaction gave a Diels–Alder adduct derived from α,β-unsaturated ketone as a major product. On the other hand, the use of tris(pentafluorophenyl)borane B(C6F5)3 bulky Lewis acid as catalyst gave mainly the cycloadduct of α,β-unsaturated aldehyde as a major product. Our aim in the present work is to put in evidence the role of the catalyst in the reversal of the chemoselectivity of the catalyzed Diels–Alder reactions of (2E)-but-2-enal and 2-Hexen-4-one with cyclopentadiene. The calculations were performed at the ωB97XD/6-311G(d,p) level of theory and the solvent effects of dichloromethane were taken into account using the PCM solvation model. The obtained results are in good agreement with experimental outcomes.

THEORETICAL STUDIES ON THE COUPLING INTERACTIONS AND SELF-EXCHANGE REACTION MECHANISMS IN THE COMPLEXES OF NO WITH ONH AND NOH

2008 ◽  
Vol 07 (03) ◽  
pp. 435-446 ◽  
Author(s):  
PING LI ◽  
XIAOYAN XIE ◽  
YUXIANG BU ◽  
WEIHUA WANG ◽  
NANA WANG ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Exchange Reaction ◽  
Reaction Mechanisms ◽  
Natural Bond Orbital ◽  
Theoretical Studies ◽  
Exchange Reactions ◽  
Electron Transfer Mechanism ◽  
Proton Coupled Electron Transfer ◽  
Planar Geometries ◽  
Transfer Mechanisms

The coupling interactions and self-exchange reaction mechanisms between NO and ONH (NOH) have been systematically investigated at the B3LYP/6-311++G** level of theory. All the equilibrium complexes are characterized by the intermolecular H-bonds and co-planar geometries. The cisoid NOH/ON species is the most stable one among all the complexes considered due to the formation of an N – N bond. Moreover, all the cisoid complexes are found to be more stable than the corresponding transoid ones. The origin of the blueshifts occurring in the selected complexes has been explored, employing the natural bond orbital (NBO) calculations. Additionally, the proton transfer mechanisms for the self-exchange reactions have been proposed, i.e. they can proceed via the three-center proton-coupled electron transfer or five-center cyclic proton-coupled electron transfer mechanism.

Lewis Acid-Promoted Suzuki Reaction using Palladium Chloride Anchored on a Polymer as a Catalyst

2008 ◽  
Vol 61 (8) ◽  
pp. 610 ◽  
Author(s):  
Guozhi Fan ◽  
Hanjun Zhang ◽  
Siqing Cheng ◽  
Zhandong Ren ◽  
Zhijun Hu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Heterogeneous Catalysts ◽  
Suzuki Reaction ◽  
Cross Coupling ◽  
Palladium Chloride ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Recoverable Catalyst

Palladium chloride anchored on polystyrene modified by 5-amino-1,10-phenanthroline was prepared and used as an efficient recoverable catalyst for Suzuki cross-coupling reactions. The heterogeneous catalysts can be easily separated from the reaction mixture and reused for five cycles without significant Pd leaching and loss of catalytic activity. Rate enhancement in the Suzuki reaction by Lewis acids was also studied.

Synthesis of pyrrolo[1,2-a]naphthyridines by Lewis acid mediated cycloisomerization

2017 ◽  
Vol 15 (15) ◽  
pp. 3216-3231 ◽  
Author(s):  
Anika Flader ◽  
Silvio Parpart ◽  
Peter Ehlers ◽  
Peter Langer
Keyword(s):  
Lewis Acid ◽  
Lewis Acids

Functionalized pyrrolo[1,2-a]naphthyridines were synthesized by application of PtCl2 and Bi(OTf)3 as simple Lewis acids in a cycloisomerization reaction.

Understanding propyl cyanide and its isomers formation: ab initio study of the spectroscopy and reaction mechanisms

2019 ◽  
Vol 21 (42) ◽  
pp. 23375-23384 ◽  
Author(s):  
Boutheïna Kerkeni ◽  
Victoria Gámez ◽  
Maria Luisa Senent ◽  
Nicole Feautrier
Keyword(s):  
Ab Initio ◽  
Reaction Mechanisms ◽  
Galactic Center ◽  
Theoretical Studies ◽  
Ab Initio Study ◽  
Star Forming ◽  
Branched Structures ◽  
Experimental And Theoretical Studies

Recent detection of propyl cyanide (C3H7CN) toward the Galactic Center star-forming source Sagittarius B2(N) with both linear and branched structures has stimulated many experimental and theoretical studies.

The emerging molecular structure of the nitrogen cycle: an introduction to the proceedings of the 10th annual N-cycle meeting

2005 ◽  
Vol 33 (1) ◽  
pp. 113-118 ◽  
Author(s):  
C.S. Butler ◽  
D.J. Richardson
Keyword(s):  
Structural Biology ◽  
Nitrogen Cycle ◽  
Reaction Mechanisms ◽  
Spectroscopic Analysis ◽  
Three Dimensional ◽  
Chemical Transformations ◽  
Redox Active ◽  
Active Metal ◽  
Insight Into ◽  
Redox Active Metal

Over the last 10 years, during the lifetime of the nitrogen cycle meetings, structural biology, coupled with spectroscopy, has had a major impact of our understanding enzymology of the nitrogen cycle. The three-dimensional structures for many of the key enzymes have now been resolved and have provided a wealth of information regarding the architecture of redox active metal sites, as well as revealing novel structural folds. Coupled with structure-based spectroscopic analysis, this has led to new insight into the reaction mechanisms of the diverse chemical transformations that together cycle nitrogen in the biosphere. An overview of the some of the key developments in field over the last decade is presented.

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