Nanostructured Dioxomolybdenum(VI) Catalyst for the Liquid-Phase Epoxidation of Olefins
authors Castro, A; Alonso, JC; Valente, AA; Neves, P; Brandao, P; Felix, V; Ferreira, P
nationality International
journal EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
author keywords Molybdenum; Mesoporous materials; Heterogeneous catalysis; Epoxidation
keywords MESOPOROUS MCM-41 MATERIALS; INORGANIC HYBRID MATERIALS; TERT-BUTYL HYDROPEROXIDE; PHOSPHINE OXIDE LIGANDS; HETEROGENEOUS CATALYSTS; ALKENE EPOXIDATION; CRYSTAL-STRUCTURES; COMPLEXES BEARING; LEWIS-BASE; MOLYBDENUM(VI)
abstract A new organosilica hybrid mesoporous material (HM) containing phosphane oxide surface groups was prepared via the "dual" organosilane templated co-condensation of 4-bis-(triethoxysilyl)benzene and (diphenylphosphanyl)propyltriethoxysilane, followed by post-synthesis oxidation of the phosphane surface groups. The HM material was used to immobilise the [Mo(O)(2)Cl(2)] complex. The resultant material (HM-Mo) is an active and selective catalyst in the liquid-phase epoxidation of olefins [cis-cyclooctene, (R)-(+)-limonene, trans-2-octene, 1-octene] with tBuOOH at 55 degrees C and gives comparable epoxide yields to those observed for the free complex [MoCl(2)(O)(2){OP(CH(2)CH(3))(Ph)(2)}(2)] (1), under similar reaction conditions: the crystal structure of complex 1 remains the same after reaction with tBuOOH. The oxidant is essentially consumed in the HM-Mo or 1 catalysed epoxidation of the olefin. In the case of limonene (possesses endo- and exocyclic C=C bonds), the molar ratio of 1,2-epoxy-p-menth-8-ene/1,2-8,9-diepoxy-p-menthane at ca. 90% conversion (reached after 24 h reaction) is ca. 5 and 10 for 1 and HM-Mo, respectively, indicating a favourable regioselectivity towards the epoxidation of the endocyclic C1-C2 double bond, especially in the case of the heterogeneous catalyst.
publisher WILEY-V C H VERLAG GMBH
issn 1434-1948
year published 2010
issue 9
beginning page 1405
ending page 1412
digital object identifier (doi) 10.1002/ejic.200901093
web of science category Chemistry, Inorganic & Nuclear
subject category Chemistry
unique article identifier WOS:000276370300010
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journal impact factor 2.529
5 year journal impact factor 2.284
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