MCM-41-Supported Oxo-vanadium(IV) Complex: A Highly Selective Heterogeneous Catalyst for the Bromination of Hydroxy Aromatic Compounds in Water

Abstract

An ecofriendly solid catalyst has been synthesized by anchoring vanadium(IV) into organically modified MCM-41. First, the surface of Si-MCM-41 was modified with 3-aminopropyl-triethoxysilane (3-APTES), the amine group of which upon condensation with ortho-hydroxy-acetophenone affords a N(2)O(2)-type Schiff base moiety in the mesoporous matrix. The Schiff base moieties were used to anchor oxo-vanadium(IV) ions. The prepared catalyst has been characterized by UV-vis, IR spectroscopy, small-angle X-ray diffraction (SAX), nitrogen sorption, and transmission electron microscopy (TEM) studies. It is observed that the mesostructure has not been destroyed in the multistep synthesis procedure, as evidenced by SAX and TEM measurements. The catalyst has shown unprecedented high conversion as well as para selectivity toward the bromination of hydroxy aromatic compounds using aqueous 30% H(2)O(2)/KBr in water. The reaction proceeds according to the stoichiometric ratio, and the monobrominated product was obtained as the major product using a stoichiometric amount of the bromine source. The immobilized complex does not leach or decompose during the catalytic reactions, showing practical advantages over the free metal complex.

Immobilization of cerium (IV) and erbium (III) in mesoporous MCM‐41: Two novel and highly active heterogeneous catalysts for the synthesis of 5‐substituted tetrazoles, and chemo‐ and homoselective oxidation of sulfides

“…The X‐ray patterns of MCM‐41 exhibit three peaks, a strong reflection due to the d100, and two peaks with weaker reflections corresponding to d110 and d200, respectively. This is an indication of the organization of high‐ordered mesoporous material . The XRD patterns of MCM‐41@Serine/Ce and MCM‐41@Serine/Er exhibit that the three‐peak of MCM‐41 has been preserved after the introduction of cerium (IV) and erbium (III) complexes in MCM‐41.…”

Synthesis and characterization of MCM‐41‐Biurea‐Pd as a heterogeneous nanocatalyst and using its catalytic efficacy in C–C, C–N and C–O coupling reactions

“…Finally, in order to achieve various redox catalysts, it is also possible to introduce transition metals (e.g. Cr, VO, Mn, Cu, Ni and Pd) into the MCM‐41 structure.…”

Zeolite-encapsulated Co(II), Mn(II), Cu(II) and Cr(III) salen complexes as catalysts for efficient selective oxidation of benzyl alcohol

“…The dimmer species formation caused deactivation of the catalysts and as a consequence the re-used catalysts leads to lower substrate conversion [7][8][9]. Thus, heterogenization of metal salen-type catalysts, which can avoid the formation of dimerization species, has attracted many researcher attentions [10][11][12].…”