title: Preparation of crystal-like periodic mesoporous phenylene-silica derivatized with ferrocene and its use as a catalyst for the oxidation of styrene.
abstract: The surface silanol groups in crystal-like mesoporous phenylene-silica have been derivatized with trimethylsilyl, benzyldimethylsilyl and dimethylsilyl(ferrocene) groups by performing a post-synthetic grafting reaction with the corresponding chlorosilane precursors. The success of the grafting procedure was demonstrated by transmission FT-IR spectroscopy and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and (13)C and (29)Si magic-angle spinning (MAS) NMR spectroscopy. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and N2 adsorption data for the modified materials indicated preservation of the mesostructure as well as the molecular-scale periodicity in the pore walls. Ferrocene and the ferrocenyl-modified periodic mesoporous organosilica (PMO) were employed in the catalytic oxidation of styrene at 55 °C using either hydrogen peroxide or tert-butylhydroperoxide as an oxidant. The main reaction product was always benzaldehyde (BzCHO), and other products included styrene oxide, benzoic acid and 2-hydroxyacetophenone. Using a styrene:H2O2 molar ratio of 1:5, the highest BzCHO yields at 24 h were 65% (85% selectivity) for ferrocene (semibatch conditions involving stepwise addition of H2O2, 1 mol% Fe) and 34% (83% selectivity) for the modified PMO (batch conditions, 0.06 mol% Fe). The modified PMO could be recovered and reused, albeit with a drop in catalytic activity due to partial metal leaching during the first catalytic run.
authors.affiliation: Department of Chemistry, CICECO, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal. igoncalves@ua.pt.
authors.forename: Ana C
authors.initials: AC
authors.lastname: Gomes
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Ferreira
authors.forename: Sofia M
authors.initials: SM
authors.lastname: Bruno
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bion
authors.forename: Paula
authors.initials: P
authors.lastname: Ferreira
authors.forename: Anabela A
authors.initials: AA
authors.lastname: Valente
authors.forename: Martyn
authors.initials: M
authors.lastname: Pillinger
authors.forename: João
authors.initials: J
authors.lastname: Rocha
authors.forename: Isabel S
authors.initials: IS
authors.lastname: Gonçalves