title: Xerogel-sequestered silanated organochalcogenide catalysts for bromination with hydrogen peroxide and sodium bromide.
abstract: While H2O2 is a powerful oxidant, decomposing into environmentally benign H2O and O2, a catalyst is often required for reactions with H2O2 to proceed at synthetically useful rates. Organotellurium and organoselenium compounds catalyze the oxidation of halide salts to hypohalous acids using H2O2. When sequestered into xerogel monoliths, the xerogel-chalcogenide combinations have demonstrated increased catalytic activity relative to the organochalcogen compound alone in solution for the oxidation of halide salts to hypohalous acids with H2O2. Diorganotellurides, diorganoselenides, and diorganodiselenides bearing triethoxysilane functionalities were sequestered into xerogel monoliths and their catalytic activity and longevity were investigated. The longevity of the catalyst-xerogel combinations was examined by isolating and recycling the catalyst-xerogel combination. It was found tellurium-containing catalyst 3 and selenium-containing catalyst 8 maintained their catalytic activity through three recycling trials and adding electron-donating substituents to catalyst 3 also increased the catalytic rate. The presence of organotellurium and organoselenium groups in the +4 oxidation state was determined by X-ray photoelectron spectroscopy.
authors.affiliation: Department of Chemistry, The State University of New York at Buffalo, Buffalo, NY 14260, USA. cgatley@buffalo.edu.
authors.forename: Caitlyn M
authors.initials: CM
authors.lastname: Gatley
authors.affiliation: Department of Chemistry, The State University of New York at Buffalo, Buffalo, NY 14260, USA. lmmuller@buffalo.edu.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Muller
authors.affiliation: Department of Chemistry, The State University of New York at Buffalo, Buffalo, NY 14260, USA. malang@buffalo.edu.
authors.forename: Meredith A
authors.initials: MA
authors.lastname: Lang
authors.affiliation: Department of Chemistry, The State University of New York at Buffalo, Buffalo, NY 14260, USA. albertoee@gmail.com.
authors.forename: Eduardo E
authors.initials: EE
authors.lastname: Alberto
authors.affiliation: Department of Chemistry, The State University of New York at Buffalo, Buffalo, NY 14260, USA. mdetty@buffalo.edu.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Detty
mesh_terms: D001965:Bromides / Q000737:chemistry*; D002384:Catalysis; D017743:Equipment Reuse; D005782:Gels; D054879:Halogenation; D006861:Hydrogen Peroxide / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D016566:Organoselenium Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D056951:Photoelectron Spectroscopy; D012821:Silanes / Q000737:chemistry*; D017670:Sodium Compounds / Q000737:chemistry*; D013691:Tellurium / Q000737:chemistry*
chemical_list: D001965:Bromides; D005782:Gels; D009942:Organometallic Compounds; D016566:Organoselenium Compounds; D012821:Silanes; D017670:Sodium Compounds; D006861:Hydrogen Peroxide; C027938:sodium bromide; D013691:Tellurium
keywords: catalytic bromination; diorgano diselenides; organoselenides; organotellurides; xerogel