Catalytic olefin epoxidation with cationic molybdenum(VI) cis-dioxo complexes and ionic liquids
authors Gago, S; Balula, SS; Figueiredo, S; Lopes, AD; Valente, AA; Pillinger, M; Goncalves, IS
nationality International
journal APPLIED CATALYSIS A-GENERAL
author keywords Dioxomolybdenum(VI); Tripodal ligands; Benzimidazole; Olefin epoxidation; Ionic liquids
keywords ALPHA-PINENE OXIDE; DIOXOMOLYBDENUM(VI) COMPLEXES; CRYSTAL-STRUCTURES; ORGANOMOLYBDENUM(VI) OXIDES; LIGAND; CYCLOOCTENE; BEARING; REACTIVITY; ORGANORHENIUM(VII); REARRANGEMENT
abstract The complexes [MoO(2)Cl(HC(bim)(3))]Y (Y = Cl (1), BF(4) (2) and PF(6) (3)) have been prepared by reaction of MoO(2)Cl(2)(THF)(2) (for 1) or [MoO(2)Cl(THF)(3)]Y (for 2 and 3) with the tridentate ligand HC(bim)(3) = tris(benzimidazolyl)methane, and characterized by IR and Raman spectroscopy, and (1)H NMR. The turnover frequencies for the epoxidation of cis-cyclooctene at 55 degrees C with tert-butyl hydroperoxide (TBHP, in decane) as the oxidant and complexes 1-3 as catalysts are in the range of 70-200 mol mol(Mo)(-1) h(-1). 1,2-Epoxycyclooctane is always the only reaction product for reaction times up to 24 h. With the aim of facilitating the recyclability of the complexes, the ionic liquids (ILs) [BMIM]Y and [BMPy]Y(BMIM = 1-n-butyl-3-methylimidazolium,BMPy = 1-n-butyl-3-methylpyridinium:Y = BF(4) or PF(6)) were applied as ionic solvents. The catalytic performance for cyclooctene epoxidation depends strongly on the catalyst solubility in the IL. Of the 12 catalyst/IL mixtures examined, the systems 1/[BMIM]PF(6) and 1/[BMPy]PF(6) exhibit the most favorable reaction rates allied with good recyclability. The 1/[BMIM]PF(6) system was further applied using different oxidants (aqueous TBHP, aqueous H(2)O(2) and urea-hydrogen peroxide adduct) and olefins (norbornene, cyclohexene, styrene, alpha-pinene). (C) 2009 Elsevier B.V. All rights reserved.
publisher ELSEVIER SCIENCE BV
issn 0926-860X
year published 2010
volume 372
issue 1
beginning page 67
ending page 72
digital object identifier (doi) 10.1016/j.apcata.2009.10.016
web of science category Chemistry, Physical; Environmental Sciences
subject category Chemistry; Environmental Sciences & Ecology
unique article identifier WOS:000273933800009
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