resumo
The hybrid metal oxide-triazole materials [MoO3(trz)(0.5)] (1) and [W2O6(trz)] (2) (trz = 1,2,4-triazole) have been hydrothermally synthesized and characterized by different techniques (TGA, SEM, H-1 and C-13 MAS NMR, FT-IR spectroscopy, and structure determination by Rietveld analysis of high resolution synchrotron powder XRD data). Materials 1 and 2 display distinct behaviors when applied as catalysts for oxidation reactions with alcohol, aldehyde, olefin and sulfide substrates, and are more effective with hydrogen peroxide as the oxidant than with tert-butylhydroperoxide. The Mo-VI hybrid 1 transforms into soluble active species during cis-cyclooctene epoxidation with H2O2. When consumption of H2O2 reaches completion, spontaneous reassembly of the 2-dimensional molybdenum oxide network of 1 takes place and the hybrid precipitates as a microcrystalline solid that can be easily separated and recycled. Reaction induced self-separation behavior occurs with 1, H2O2 and other substrates such as methyl oleate and methylphenylsulfide. The W-VI hybrid 2 behaves differently, preserving its structural features throughout the heterogeneous catalytic process. (C) 2016 Elsevier Inc. All rights reserved.
palavras-chave
CONTROLLED PHASE-TRANSFER; OLEFIN EPOXIDATION; SELECTIVE OXIDATION; HYDROGEN-PEROXIDE; BENZYL ALCOHOL; CYCLOOCTENE EPOXIDATION; OXIDE/BIPYRIDINE HYBRID; STRUCTURAL ELUCIDATION; HOMOGENEOUS CATALYSTS; CRYSTAL-STRUCTURE
categoria
Chemistry; Engineering
autores
Amarante, TR; Neves, P; Valente, AA; Paz, FAA; Pillinger, M; Goncalves, IS
nossos autores
Anabela Tavares Aguiar Valente
Investigador Principal
Filipe Alexandre Almeida Paz
Investigador Principal
Isabel Maria de Sousa Gonçalves
Professor associado
Martyn Pillinger
Investigador Principal
Patrícia dos Santos Neves
Investigador Auxiliar
Tatiana Ribau Amarante
Investigador JúniorProjectos
Use of molecular containers to modify metallocene-based catalysts (PTDC/QEQ-SUP/1906/2012)
agradecimentos
We acknowledge funding by FEDER (Fundo Europeu de Desenvolvimento Regional) through COMPETE (Programa Operacional Factores de Competitividade). National funding through the FCT (Fundacao para a Ciencia e a Tecnologia) within the projects FCOMP-01-0124-FEDER-029779 (FCT ref. PTDC/QEQ-SUP/1906/2012) and FCOMP-01-0124-FEDER-041282 (FCT ref. EXPL/CTM-NAN/0013/2013) is thanked. This work was developed in the scope of the project CICECO - Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and co-financed by FEDER under the PT2020 Partnership Agreement. The FCT and the European Union are acknowledged for postdoctoral grants to P.N. (SFRH/BPD/73540/2010) and T.R.A. (SFRH/BPD/97660/2013) cofunded by MCTES and the European Social Fund through the program POPH of QREN. The authors are grateful to the ESRF (Grenoble, France) for approving the experiment CH-4254 (ID22).