Studies in Organic Free Radical and Excited State Chemistry

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This award in the Organic Dynamics Program provides support for the continuing research of Dr. Paul Engel of Rice University. The main thrust of the research is a study of the chemistry of azoalkanes and the transient intermediates formed in their thermal and photochemical decomposition. This chemistry will be approached on a broad front. Several different approaches to understanding the behavior of transient intermediates will be undertaken. The mechanism of bond-breaking in azoalkanes will be investigated by nanosecond transient absorption experiments. The effect of azoalkane structure on the cation-radicals formed by one-electron oxidation will be studied by flash photolysis of azoalkanes with electron-deficient sensitizers. Thermolysis kinetics and mass spectroscopic measurements will be used to determine the stabilization energies of a series of carbon-centered free radicals containing alpha-nitrogen functionality. Biradical lifetimes will be "clocked" by generation and rearrangement of cyclopropylcarbinyl radical centers. It is expected that these varied studies will lead to new experimental approaches to observing excited states in chemical reactions.