This renewal award in the Organic Dynamics Program is in support of the research of Dr. Tad Koch at the University of Colorado at Boulder. The research will focus on captodative radicals which are stabilized through the combined effect of electron-donating and electron-withdrawing groups. This effect should be maximum with amino and carboxy substituents. The research will explore further the 2-oxomorpholinyl free radical whose substituents are in a rigid ring which maximizes the electronic interaction. These free radicals exist in equilibrium with their dimers in solution and function as mild one-electron reducing agents in a wide variety of solvents including water. Depending upon the placement of alkyl groups, the radicals reduce stoichiometrically molecular oxygen to hydrogen peroxide or form isolable peroxides. The long range goal of the research is the design, preparation and use of captodative radicals. The specific objectives are the design, synthesis and characterization of new 2-oxomorpholinyl radicals and diradicals which will either bind oxygen reversibly, form useful peroxides or serve as crosslinking agents for macromolecular structures. The thermal and photochemical reactivity of the resulting peroxides will be established. The redox activity and captodative stabilization of 2-oxomorpholinyl radicals as a function of structure and medium will be determined. New structures with enhanced redox activity will be designed and synthesized.
