Metal-free synthesis of quinolines catalyzed by carbon aerogels: Influence of the porous texture and surface chemistry
| Autor: | Marina Godino-Ojer, Elena Soriano, Francisco J. Maldonado-Hódar, Elena Pérez-Mayoral, Vanesa Calvino-Casilda |
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| Přispěvatelé: | Ministerio de Economía y Competitividad (España) |
| Rok vydání: | 2017 |
| Předmět: |
Reaction mechanism
General Chemical Engineering Inorganic chemistry chemistry.chemical_element 010402 general chemistry 01 natural sciences Industrial and Manufacturing Engineering Porous catalytic system Catalysis chemistry.chemical_compound Carbon aerogels Computational methods Environmental Chemistry Friedländer reaction Reactivity (chemistry) 010405 organic chemistry Quinoline General Chemistry Surface chemistry Nanomaterial-based catalyst 0104 chemical sciences chemistry Ethyl acetoacetate Reagent Carbon |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| ISSN: | 1385-8947 |
| Popis: | We report herein an experimental and theoretical study of the Friedländer reaction, from 2-amino-5-chlorobenzaldehyde and ethyl acetoacetate, catalyzed by free-metal nanocatalysts based on carbon aerogels, to afford quinoline 3a. The developed methodology implies the combined use of carbon aerogels with solvent-free technologies under MW irradiation yielding the corresponding quinoline with moderated yield (66%) in only 5 min of reaction time. Our results demonstrated that the reactivity of the samples upon MW irradiation is strongly dependent on the porosity and surface chemistry of the carbon aerogels, the most active catalytic species being the most acidic oxygenated functional groups, –COH groups originated by oxidant treatment, or even in situ by hydrolysis of –CO–O–CO–, over the carbon surface. The theoretical investigation of the reaction mechanism, by using computational methods, demonstrated that the synthesis of quinoline 3a in the absence or in the presence of carbon aerogels takes place by aldolization, subsequent heterocyclization and finally double dehydration. Relatively strong π-π stacking interactions between carbon support and reagents could be behind of the observed catalytic performance also extended for the oxygenated models. Furthermore, the concentration of –COH groups over the carbon surface is a key factor favoring each step of the reaction but acting as individual catalytic sites. This work has been supported by MICINN (CTM 2014-56668-R project). We are also grateful to the Centro de Supercomputación de Galicia (CESGA) for generous allocation of computing resources. MGO also thanks UNED for her PhD fellowship and VCC for her postdoctoral contract |
| Databáze: | OpenAIRE |
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