V/MCM-41 as Catalyst for Asymmetric and Non-Asymmetric Oxidation of Methyl Phenyl Sulfide

V/MCM-41 was prepared by impregnation of MCM-41, calcined at two different temperatures (550 and 750 °C), with vanadium (V) oxytriisopropoxide (VO(O i Pr) 3 ). The calcination temperature of the support controls the surface silanol density, leading to different surface organometallic species, as sho...

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Bibliographic Details
Published in:Journal of chemical research 2013-12, Vol.37 (12), p.766-773
Main Authors: Zid, T Ben, Khedher, I, Fraile, J M
Format: Article
Language:English
Subjects:
Asymmetry
Density
Ligands
Oxidation
Phenyls
Sulfides
Surface chemistry
Vanadium
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Summary:V/MCM-41 was prepared by impregnation of MCM-41, calcined at two different temperatures (550 and 750 °C), with vanadium (V) oxytriisopropoxide (VO(O i Pr) 3 ). The calcination temperature of the support controls the surface silanol density, leading to different surface organometallic species, as shown by different characterisation techniques, such as 29 Si CP-MAS NMR, UV-Vis and FT-IR. Monopodal ≡SiO–VO(O i Pr) 2 and bipodal (≡SiO) 2 –VO(O i Pr) species are the major ones in V-MCM 750 , whereas bipodal and tripodal (≡SiO) 3 –VO are the major ones in V-MCM 550 . Monopodal and bipodal species are more active in the oxidation of methyl phenyl sulfide with alkyl hydroperoxides, with higher selectivity to sulfoxide than tripodal ones, but at the same time they are more easily deactivated. It is possible to perform the enantioselective oxidation using ( S,S)-(+)- N,N‘-bis(3,5-di- tert-butylsalicylidene)-1,2-cyclohexanediamine as chiral ligand, with the monopodal species being the most efficient.
ISSN:1747-5198
2047-6507
DOI:10.3184/174751913X13846900634620