Persona:
López Peinado, Antonio José

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ORCID
0000-0002-6162-3151
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López Peinado
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Antonio José
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2023 - 20242
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  • Miniatura
    Publicación
    P-Doped carbon catalyst highly efficient for benzodiazepine synthesis. Tires valorisation
    (Elsevier, 2023-07-01) Godino Ojer, Marina; Ripoll Morales, Vanessa; López Peinado, Antonio José; Matos, Inés; Bernardo, María; Lapa, Nuno; Fonseca, Isabel M.; Pérez Mayoral, María Elena
    Carbon catalysts prepared from pyrolysis of spent tires are found to efficiently catalyse the synthesis of benzodiazepine 1, from o-phenylendiamine 2 and acetone 3, with high conversions and selectivity, under mild reaction conditions, according to Scheme 1. The most acidic catalyst, CPN_H3PO4, obtained by chemical activation with H3PO4, resulted on the most efficient catalyst affording conversion values higher than 90 %, after 4 h of reaction time, and selectively leading to benzodiazepine 1 (90 %). On the other hand, the CPN and CPN_CO2 catalysts reached high conversions of 2 although diminished selectivity to 1, confirming that the carbon matrix is involved in the first steps of the reaction mainly catalyzing the formation of intermediate 4 as the main reaction product. Note that all the investigated catalysts are macroporous materials with pore size distribution large enough to favor diffusion of reactants and products. Therefore, the catalytic performance is mainly governed by the chemical surface, in particular by the presence of acid functions as phosphate groups anchored to the carbon surface or as SiP2O7 supported phase. Finally, considering both experimental and theoretical results, it seems that the most probable catalytic centers comprise phosphate functions in SiP2O7 catalyzing the last cyclization step to 1. Although electrophilicity of carbon acceptor (Cdouble bondN moiety) in the presence of model simulating phosphate groups anchored to the carbon surface was slightly superior, transition structure in the presence of model simulating SiP2O7 showed the smallest free energy barrier.
  • Miniatura
    Publicación
    Amino-grafted basic mesoporous silicas: a type of highly performant catalysts for the green synthesis of 2-amino-4H-chromenes
    (Elsevier, 2024-03-15) González Rodal, Daniel; Godino Ojer, Marina; Palomino Cabello, Carlos; Turnes Palomino, Gemma; López Peinado, Antonio José; Pérez Mayoral, María Elena
    Novel series of amino-grafted mesoporous silica materials applied to the green and efficient synthesis of 2-amino-4H-chromenes, from salicylaldehydes and ethyl cyanoacetate, under mild and free-solvent conditions, is herein reported for the first time. These catalysts are easily prepared by using the post-synthetic method, by functionalizing the SBA-15 silica with the corresponding amino silanes. The observed catalytic performance is mainly controlled by the type and concentration of basic sites. The methodology herein reported could be considered as an environmentally friendly alternative for the selective chromene synthesis, which allows to achieve high yields in short reaction times using notably small amounts of the catalysts. The experimental results are also supported with theoretical calculations, which suggest that the amine groups at the silica surface are behind the observed catalytic performance with the assistance of the silica matrix.