resumo
A new mesoporous hybrid material (denoted LP-TEPPPO-Mo) has been prepared by tethering [MoO(2)Cl(2)] onto mesoporous silica previously functionalised with phosphane oxide spacer ligands. The LP-TEPPPO-Mo material was tested in the liquid-phase epoxidation of olefins [cis-cyclooctene, (R)-(+)-limonene, trans-2-octene and 1-octene] with tBuOOH, at 55 degrees C, and without a co-solvent, giving at least 90% selectivity to the corresponding epoxide at 36-77% conversion: in the case of limonene, regioselectivity favours the epoxidation of the endocyclic double bond, giving mainly 1,2-epoxy-p-menth-8-ene. The catalytic system based on a liquid-liquid biphasic system containing the homogeneous complex [MoCl(2)(O)(2)[OP(CH(2)CH(3))(Ph)(2)}(2)] dissolved in the ionic liquid 1-butyl-4-methylpyridinium tetrafluoroborate leads to lower epoxide selectivity (91% at 64 % conversion) in the reaction of cyclooctene in comparison to that observed for LPTEPPPO-Mo (100 % at 87 % conversion). The reused solid-liquid and liquid-liquid biphasic catalytic systems show partial loss of catalytic activity.
palavras-chave
TERT-BUTYL HYDROPEROXIDE; OLEFIN EPOXIDATION; CRYSTAL-STRUCTURES; HETEROGENEOUS CATALYSTS; MCM-41 MATERIALS; LEWIS-BASE; COMPLEXES; MOLYBDENUM; CYCLOOCTENE; LIGANDS
categoria
Chemistry
autores
Castro, A; Alonso, JC; Neves, P; Valente, AA; Ferreira, P
nossos autores
Anabela Tavares Aguiar Valente
Investigador Principal
Patrícia dos Santos Neves
Investigador Auxiliar
Paula Celeste da Silva Ferreira
Investigador CoordenadorGrupos
G1 - Materiais Porosos e Nanossistemas
G2 - Materiais Fotónicos, Eletrónicos e Magnéticos
G4 - Materiais Renováveis e Economia Circular
agradecimentos
The authors are grateful to Programa Operacional Ciencia a Inovacao - 2010, Fundo Europeu de Desenvolvimento Regional and Fundaqao para a Ciencia e a Tecnologia for financial support (POCI/CTM/ 55648/2004 and PPCDT/CTM/55648/2004). The authors wish to express their gratitude to Doctors Ana S. Dias and Martyn Pillinger (Centre for research in ceramics and composite materials - CICECO) for supplying the LP silica.