Catalytic properties of the dioxomolybdenum siloxide MoO2(OSiPh3)2 and its 2,2'-bipyridine adduct MoO2(OSiPh3)2(bpy)
| Autor: | Martyn Pillinger, Bernardo Monteiro, Maria Salete Balula, Paulo J. A. Ribeiro-Claro, Anabela A. Valente, Sofia M. Bruno, Catarina Lourenço, Isabel S. Gonçalves |
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| Rok vydání: | 2006 |
| Předmět: |
Magnetic Resonance Spectroscopy
Spectrophotometry Infrared Inorganic chemistry Pharmaceutical Science Decane 010402 general chemistry Spectrum Analysis Raman 01 natural sciences Medicinal chemistry 2 2'-Bipyridine Catalysis Article Analytical Chemistry Adduct Dioxomolybdenum(VI) complexes Reaction rate lcsh:QD241-441 Bipyridine chemistry.chemical_compound 2 2'-Dipyridyl lcsh:Organic chemistry Drug Discovery Physical and Theoretical Chemistry Molybdenum Olefin fiber Lewis base adducts 010405 organic chemistry Organic Chemistry Siloxide 0104 chemical sciences 2'-bipyridine siloxide ligands chemistry olefin epoxidation Chemistry (miscellaneous) Molecular Medicine |
| Zdroj: | Molecules, Vol 11, Iss 4, Pp 298-308 (2006) Molecules Volume 11 Issue 4 Pages 298-308 |
| ISSN: | 1420-3049 |
| Popis: | The tetrahedral triphenylsiloxy complex MoO(2)(OSiPh(3))(2) (1) and its Lewis base adduct with 2,2'-bipyridine, MoO(2)(OSiPh(3))(2)(bpy) (2), were prepared and characterised by IR/Raman spectroscopy, and thermogravimetric analysis. Both compounds catalyse the epoxidation of cis-cyclooctene at 55 degrees C using tert-butylhydroperoxide (t-BuOOH) is decane as the oxidant, giving 1,2-epoxycyclooctane as the only product. The best results were obtained in the absence of a co-solvent (other than the decane) or in the presence of 1,2-dichloroethane, while much lower activities were obtained when hexane or acetonitrile were added. With no co-solvent, catalyst 1 (initial activity 272 mol x molMo(-1) x h(-1)for a catalyst:substrate: oxidant molar ratio of 1:100:150) is much more active than 2(initial activity 12 mol x molMo(-1) x h(-1)). The initial reaction rates showed first order dependence with respect to the initial concentration of olefin. With respect to the initial amount of oxidant, the rate order dependence for 1 (1.9) was higher than that for 2 (1.6).The dependence of the initial reaction rate on reaction temperature and initial amount of catalyst was also studied for both catalysts. The lower apparent activation energy of 1 (11 kcal x mol(-1)) as compared with 2 (20 kcal x mol(-1)) is in accordance with the higher activity of the former. |
| Databáze: | OpenAIRE |
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