resumo
The cyclopentadienyl molybdenum tricarbonyl complex CpMo(CO)(3)(CH2-pC(6)H(4)-CO2CH3) (1) (Cp = eta(5)-C5H5) and its 1:1 inclusion complexes with heptakis(2,6-di-O-methyl)-beta-cyclodextrin (1@DIMEB) and heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (1@TRIMEB) were prepared and characterized by elemental and thermogravimetric analyses, powder X-ray diffraction, NMR, FT-IR and Raman spectroscopy. All three compounds were investigated as catalyst precursors for olefin epoxidation using cis-cyclooctene (Cy) as a model substrate, a reaction temperature of 55 degrees C, and different types of oxidants (tert-butylhydroperoxide in decane;(TBHPdec) or in water (TBHPaq), and aqueous hydrogen peroxide). With the aim of facilitating recycling of the homogeneous catalytic systems, different solvent mixtures were tested: biphasic liquid-liquid solvent systems [(water, glycerol, ionic liquid)-(n-hexane, alpha,alpha,alpha-trifluorotoluene (TFT), iso-butyl methyl ketone)], and in some cases no cosolvent was added. Excellent epoxide selectivity (100%) was observed for all tested catalytic systems. An example of an interesting catalytic system is that of 1@TRIMEB/TBHPaq/TFT/H2O since the catalyst can be easily separated in the form of an aqueous solution, by decantation, from the organic phase containing the reaction products and recycled. (C) 2013 Elsevier B.V. All rights reserved.
palavras-chave
CYCLOPENTADIENYL-MOLYBDENUM COMPLEXES; TUNGSTEN COMPLEXES; ETA(5)-CYCLOPENTADIENYL MOLYBDENUM; MESOPOROUS MATERIALS; TRICARBONYL COMPLEX; CYCLOALKYL MOIETIES; CARBONYL-COMPLEXES; BETA-CYCLODEXTRIN; BRIDGING UNITS; ANSA COMPOUNDS
categoria
Chemistry
autores
Gomes, AC; Bruno, SM; Tome, C; Valente, AA; Pillinger, M; Abrantes, M; Goncalves, IS
nossos autores
Ana Catarina Costa Gomes Alves
Investigador Auxiliar
Anabela Tavares Aguiar Valente
Investigador Principal
Isabel Maria de Sousa Gonçalves
Professor associado
Martyn Pillinger
Investigador Principal
Sofia M. Bruno
Investigador AuxiliarProjectos
agradecimentos
We are grateful to the Fundacao para a Ciencia e a Tecnologia (FCT, Portugal), the Programa Operacional Ciencia e Inovacao (POCI) 2010, Orcamento do Estado (OE), European Union, Fundo Europeu de Desenvolvimento Regional (FEDER), QREN, COMPETE, the Associate Laboratory CICECO (Pest-C/CTM/LA0011/2011), and CQE (Pest-OE/QUI/UI0100/2011) for continued support and funding. The FCT and the European Social Fund (ESF) are acknowledged for a post-doctoral grant to S.M.B. (FCT and ESF, ref. SFRH/BPD/46473/2008) and a research grant (BI) to C.T. (FCT, project ref. PTDC/EQU-EQU/121677/2010). The authors also thank the Portuguese NMR Network (IST-UTL Center) for providing access to the NMR facilities.