MCM-41-supported oxo-vanadium(IV) complex: a highly selective heterogeneous catalyst for the bromination of hydroxy aromatic compounds in water.
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.
Department of Chemistry, Jadavpur University, Kolkata 700 032, India.
Susmita
S
Bhunia
Debraj
D
Saha
Subratanath
S
Koner
D001965:Bromides / Q000737:chemistry; D001978:Bromphenol Blue / Q000138:chemical synthesis; D002384:Catalysis; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D056831:Coordination Complexes / Q000737:chemistry*; D055772:Green Chemistry Technology; D054879:Halogenation; D006861:Hydrogen Peroxide / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D010637:Phenolsulfonphthalein / Q000737:chemistry; D017680:Potassium Compounds / Q000737:chemistry; D011437:Propylamines; D053838:Scattering, Small Angle; D012545:Schiff Bases / Q000737:chemistry; D012821:Silanes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D017968:Vanadium Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
D001965:Bromides; D056831:Coordination Complexes; C509968:MCM-41; D017680:Potassium Compounds; D011437:Propylamines; D012545:Schiff Bases; D012821:Silanes; D017968:Vanadium Compounds; D014867:Water; D001978:Bromphenol Blue; D012822:Silicon Dioxide; D006861:Hydrogen Peroxide; D010637:Phenolsulfonphthalein; C477625:amino-propyl-triethoxysilane; C039004:potassium bromide