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Projeto de investigação
Synthesis of high added-value Products Using Hybrid Catalysts and microwave irradiation
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Novel organotin-PTA complexes supported on mesoporous carbon materials as recyclable catalysts for solvent-free cyanosilylation of aldehydes
Publication . Mahmoud, Abdallah G.; Librando, Ivy L.; Paul, Anup; Carabineiro, Sónia A. C.; Ferraria, Ana Maria; Botelho do Rego, Ana Maria; Guedes da Silva, M. Fátima C.; Geraldes, Carlos F. G. C.; Pombeiro, Armando J. L.; LAQV@REQUIMTE; DQ - Departamento de Química; Elsevier
New organotin compounds with general formula [(PTA-CH2-C6H4-p-COO)SnR3]Br (where R is Me for 3 and Ph for 4; PTA = 1,3,5-triaza-7-phosphaadamantane), bearing the methylene benzoate PTA derivative, were synthesized through a mild two-step process. The compounds were characterized by Fourier transform infrared spectroscopy, electrospray ionization mass spectrometry, elemental analysis and nuclear magnetic resonance spectroscopy (NMR). They were heterogenized on commercially available activated carbon (AC) and multi-walled carbon nanotubes (CNT), as well as on their chemically modified analogues. The obtained materials were characterized by scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Complex 3 supported on activated carbon (3-AC) was found to be an active and recyclable catalyst for the cyanosilylation of several aromatic and aliphatic aldehydes. Using 3-AC with a low loading of 0.1 mol% several substrates were quantitatively converted, within just 5 min at 50 °C and under microwave irradiation in solvent-free conditions. Multinuclear NMR analysis suggested a mechanism that potentially involves a double activation process, where the nucleophilic phosphorus at the PTA derivative acts as a Lewis base and the Sn(IV) metal centre as a Lewis acid.
Triazaphosphaadamantane-functionalized terpyridine metal complexes
Publication . Librando, Ivy L.; Paul, Anup; Mahmoud, Abdallah G.; Gurbanov, Atash V.; Carabineiro, Sónia A. C.; Silva, M. Fátima C. Guedes da; Geraldes, Carlos F. G. C.; Pombeiro, Armando J. L.; LAQV@REQUIMTE; DQ - Departamento de Química; RSC - Royal Society of Chemistry
In accordance with UN's Sustainable Development Goal (UN's SDG) 12 which encompasses the sustainable use of chemical products and a sound circular economy, this work is focused on the synthesis of Co(II), Ni(II) and Mn(II) complexes bearing combined 1,3,5-triaza-7-phosphaadamantane and benzyl terpyridine core moieties (PTA–Bztpy) as ligand, followed by their evaluation as catalysts for the microwave-assisted cyclohexane oxidation using tert-butyl hydroperoxide (TBHP) as oxidant. The most active catalyst, with a manganese metal center, was heterogenized on six different carbon materials. The results disclosed the influence of several reaction parameters, such as catalyst loading, temperature, reaction time and solvent, on the catalytic activity and selectivity of the homogeneous and carbon-supported catalysts. Recyclability of the carbon-supported catalyst allowed facile separations, recovery and reuse for five consecutive cycles.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
OE
Número da atribuição
PD/BD/135555/2018