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Catalytic Reduction using Oxorhenium (v) Oxazoline ComplexesLos Angeles, CASource: Abstract Clean and Efficient Catalytic Reduction of Perchlorate by Mahdi M. Abu-Omar,* Lee D. McPherson, Joachin Arias, and Virginie M. Béreau, Department of Chemistry and Biochemistry, University of California, 405 Hilgard Avenue, Los Angeles, CA 90095-1569, USA, January 2001 Project Summary: The following text was excerpted from abstract Clean and Efficient Catalytic Reduction of Perchlorate by Mahdi M. Abu-Omar,? Lee D. McPherson, Joachin Arias, and Virginie M. Béreau Department of Chemistry and Biochemistry, University of California, 405 Hilgard Avenue, Los Angeles, CA 90095-1569, USA, January 2001: Perchlorate (ClO4-) has been recognized recently as a water contaminant in the U.S., and has been added to EPA's (Environmental Protection Agency) "Contaminant Candidate List" (CCL) and "Unregulated Chemicals Monitoring Rule" (UCMR). Removal of perchlorate from water is difficult because of its high solubility and kinetic inertness. Oxorhenium(V) oxazoline complexes catalyze the reduction of perchlorate to chloride with organic sulfides (Scheme 1). Turnover numbers of 280 hr-1 are easily achieved without any sign of catalyst deactivation. The rate-controlling step under steady-state conditions is the oxidation of oxorhenium(V) to dioxorhenium(VII). However, product inhibition with respect to chloride is observed. In the absence of a reductant, oxorhenium(V) oxazoline complexes could be used for spectrophotometric detection of perchlorate since the green oxorhenium(V) reacts with ClO4- to give the red dioxorhenium(VII). The oxazoline ligand is being functionalized to allow for catalyst tethering and immobilization on solid support. The development of a highly active heterogeneous catalyst is necessary since catalyst recovery and recycling is a prerequisite to application. Another avenue that we are currently exploring is the utility of these oxorhenium(V) complexes as catalysts in the electrochemical reduction of perchlorate. Additional Info Source: Abu-Omar, M.M., L. D. McPherson, J. Arias, and V. M. Béreau, 2000. "Clean and Efficient Reduction of Perchlorate." Angew. Chem. Int. Ed. 2000, 39, 4310-4313. Abu-Omar, M.M. and J. H. Espenson, 1995. "Facile Abstraction of Successive Oxygen Atoms from Perchlorate Ions by Methylrhenium Dioxide." Inorg. Chem. 1995, 34, 6239-6240. Abu-Omar, M.M., E. H. Appleman, and J. H. Espenson, 1996. "Oxygen-Transfer Reactions of Methylrhenium Oxides." Inorg. Chem. 1996, 35, 7751-7757. Abu-Omar, Mahdi M., 2000. "Clean and Efficient Catalytic Remediation of Perchlorate" in Perchlorate Treatment Technology Workshop, 5th Annual Joint Services Pollution Prevention & Hazardous Waste Management Conference & Exhibition, August 21-24, 2000, Henry B. Gonzalez Convention Center, San Antonio, Texas. |
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