Chemistry Commons^™

The Critical Role Of Water At The Gold-Titania Interface In Catalytic Co Oxidation, Johnny Saavedra, H. Doan, Christopher J. Pursell, L. C. Grabow, Bert D. Chandler

Chemistry Faculty Research

We provide direct evidence of a water-mediated reaction mechanism for room-temperature CO oxidation over Au/TiO2 catalysts. A hydrogen/deuterium kinetic isotope effect of nearly 2 implicates O-H(D) bond breaking in the rate-determining step. Kinetics and in situ infrared spectroscopy experiments showed that the coverage of weakly adsorbed water on TiO2 largely determines catalyst activity by changing the number of active sites. Density functional theory calculations indicated that proton transfer at the metal-support interface facilitates O2 binding and activation; the resulting Au-OOH species readily reacts with adsorbed Au-CO, yielding Au-COOH. Au-COOH decomposition involves proton transfer to water and was suggested to be …

Characterization Of Organic Carbon In Sediments From Old Rifle, Co, A Former Uranium Mill, Francis Michael Tee, Morris Jones, Sharon Bone, Michael Schaefer, Scott Fendorf, John Bargar

STAR Program Research Presentations

Characterization of sediments from Old Rifle, CO, a former uranium mill

More than 34 million gallons (~129 million liters) of groundwater are contaminated with uranium at Old Rifle, Colorado – a former uranium-processing site that operated until 1958. The original Department of Energy strategy for remediation, involving natural flushing of U from the groundwater through mixing with surface water, has not been as successful as predicted. The uranium plume is replenished when insoluble U(IV) is oxidized to the more mobile U(VI). Relatively thin pockets of silt-, clay-, and organic-rich sediments contain reduced uranium, iron and sulfur and are referred to …

Selective Oxidations By Iron(Iii) Porphyrins And Iron(Iii) Corroles, Aaron Dalnamath Carver

Masters Theses & Specialist Projects

The selective oxidation of organic compounds represents a leading technology for chemical industries. They are used in chemical synthesis in the pharmaceutical and petrochemicals industries, and possible the decontamination of harmful substances. However, oxidations reaction are among the most challenging processes to control. Many stoichiometric oxidants with heavy metals are expensive, or toxic maybe both, and therefore unfeasible to be utilized. The ideal processes for catalytic oxidation would use molecular oxygen or hydrogen peroxide as the primary oxygen source, with transition metal catalysts to mimic the predominant oxidation catalysts in Nature, the cytochrome P450 enzymes. This study focuses on the …

Selective Oxidations By Metalloporphyrins And Metallocorroles, Tse-Hong Chen

Masters Theses & Specialist Projects

Highly reactive transition metal-oxo intermediates are important active oxidant involved in numerous enzymes such as cytochrome P450 monooxygenases as well as in many useful metal-catalyzed oxidations. Many transition metal catalysts are designed for biomimetic studies of the predominant oxidation catalysts in Nature, the cytochrome P450 enzymes. In this work, a series of metalloporphyrin and metallocorrole complexes have been successfully synthesized and spectroscopically characterized by UV-vis, GCMS and ¹H-NMR. The utilization of these complexes as catalysts for selective oxidation of sulfides and photocatalytic aerobic oxidations of activated hydrocarbons were investigated. Ruthenium(II) porphyrin complexes (2) and iron(III) corrole complexes (4) with …

Electronic Effects In Oxidation Reactions Utilizing Dinuclear Copper Complexes With The Bis[3-(2-Hydroxybenzylideneamino)Phenyl] Sulfone Ligand, Armando M. Guidote Jr, Ronald L. Reyes, Riyo Kashihara, Yasuhiko Kurusu, Yoshihiro Masuyama

Chemistry Faculty Publications

Copper acetate and the ligands bis[3-(3-tert-butyl-2-hydroxy-5-methoxybenzylideneamino)phenyl] sulfone and bis[3-(3,5-di-tert-butyl-2-hydroxybenzylideneamino)phenyl] sulfone were reacted to form the complexes with 2:1 copper:ligand ratio, Cu2[B(t-Bu) (OMe)BAPS](µ-OCH3)2 (4) and with 2:2 copper:ligand ratio, Cu2[B(t-Bu)2BAPS]2 (5), respectively. Structures of 4 and 5 were determined based on IR, UV-Vis, and FAB-MS data in comparison with previously characterized related copper complexes. The two complexes 4 and 5 were utilized in the oxidation of the substrates 2,4- and 2,6-di-tertbutylphenol (dtbp) at -50C with H2O2 in CH2Cl2. The coupling products are preferred in both cases. For 2,4-dtbp, yields of 4,600% and 7,200% of 3,3’,5,5’-tetra-tert-butyl-2,2’- biphenol were achieved with the use …