International Journal of Advances in Science, Engineering and Technology(IJASEAT)
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Volume-7,Issue-3  ( Jul, 2019 )
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  Journal Paper

Paper Title
Computational Study of the Effect of the Lewis and Bronsted Acids on the Mechanism of the Diels-Alder Reaction of Dimethylfuran. He Biomass Supports

Abstract
In the present work, a theoretical study of the catalytic effect according to Lewis and according to Bronsted on the Diels-Alder reaction of 2,5-dimethylfuran(DMF) and maleic anhydride (MA) was carried out. The mechanism of reaction in the presence and in absence of the catalyst using the M062X / 6-311 + G (d, p) method was investigated. The global reactivity of DMF and MA has been shown using the global indices of the conceptual DFT. The important effect of Bronsted catalysis on the electrophilicity of MA and on the polarity of the reaction, when the carbonyl function is protonated with an H+ was also shown. It is noted that Lewis acid has a negligible effect on the electrophilicity of MA. The mechanistic study of the mechanism of the uncatalyzed reaction gives a synchronous concerted mechanism. a negligible effect on the mechanism and on the synchronicity on the Lewis acid catalysis was shown. On the other hand, catalysis with Bronsted acid by the protonation of the carbonyl function of MA accelerates the reaction in a dramatic manner and changes the synchronous concerted mechanism in the case of the uncatalyzed reaction to the mechanism In two steps (stepwise) very asynchronous in the case of the Bronsted acid catalysis reaction. Moreover, this protonation makes the reaction exothermic. The obtained results are in good agreement with the experimental findings which show the important role played by Bronsted catalysis on the DA reaction of to produce aromatic systems (eg p-xylene) which are reagents of Industrial scale. Keyword - Diels-Alder reaction, Bronsted and Lewis acid catalysis, reaction Mechanism, DFT indices, M06-2X DFT method.


Author - Hafida Chemouri

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