Molecular Oxidations in Homogeneous and Heterogeneous Media

点击翻译按钮获取中文摘要

With this renewal award the Organic and Macromolecular Chemistry Program supports the work of Dr. Edward L. Clennan in the Department of Chemistry at the University of Wyoming in Laramie, Wyoming. The work involves detailed studies of the reactions of singlet oxygen with organosulfur compounds in solution and with organosulfur compounds and olefins inside NaY zeolite containing methylene blue sensitizer. The solution studies include examinations of the Foote reaction surface, intramolecular electron transfer in the hydroperoxy sulfonium ylide, its Pummerer rearrangement, and singlet oxygen induced epimerization of 1,3-dithianes. The zeolite work will include experiments to explore the extent of positive charge buildup on the carbon framework of the substrate, and the mechanism of intrazeolite oxidation.Sensitizers, such as methylene blue, in the presence of light, are able to convert normal triplet O2 into the excited singlet state, which is much more reactive toward organosulfur compounds and olefins. Different products of these reactions are observed in zeolites - microporous aluminum silicate solids - because of steric constraints and the presence of positively charged ions inside the structure. These studies are expected to improve our mechanistic understanding of oxidation reactions, lead to potentially improved synthetic methods for making useful compounds, and provide state-of-the-art training for developing scientists.