RUI: Kinetic and Mechanistic Studies of Reactive Intermediates in Solution and Confined Environments.

Csu Fullerton Auxiliary Services Corporation, Fullerton CA

Investigators

Abstract

With support of the Organic Dynamics Program in the Chemistry Division, Professor Peter de Lijser's proposed research will provide kinetic and mechanistic information on structure and reactivity of high-energy intermediates formed in the photooxidation of oximes and related compounds. These reactive intermediates, oxime radical cations, and other reactive oxygen or nitrogen species derived from these, such as iminoxyl and iminoyl radicals, will be studied in solution as well as in a confined environment (zeolites) in order to provide extra stabilization for the reactive intermediates. The proposal's primary research goals are: 1)To investigate the structure-reactivity relationships of oxime radical cations. This will require the PI and his research group to find conditions to observe these reactive intermediates directly. Both aldoxime and ketoximes will be studied and the formation of nitriles from aldoximes is of specific interest. 2)To probe the structure-reactivity relationships of oxime ethers, specifically the hypothesis that these species undergo nucleophilic addition or substitution at nitrogen. The PI's efforts will be focused on intramolecular reactions. 3)To selectively generate and study iminoxyl and iminoyl radicals, which are the proposed intermediates in the photooxidation of ketoximes and aldoximes, respectively. Oximes and related compounds have found use as pesticides and drugs. Release of these chemicals into the environment (including cells and tissue of plants and higher animals) may result in photochemical (sensitized or direct) or enzymatic oxidations leading to the formation of reactive intermediates such as radical ions and radicals. The chemistry and potential dangers of these types of species are virtually unknown, and there exists a need for accurate kinetic and other reactivity data so that a general structure-reactivity pattern can be developed. The knowledge gained from these fundamental mechanistic and kinetic studies will establish a foundation for understanding experimental observations. The research will also provide much-needed tools to successfully utilize radical ions and other high-energy species for new chemical processes in synthesis and possibly in materials applications. The proposed research will also provide an outstanding educational experience for students. Students will learn basic chemical laboratory principles such as how to synthesize, purify, and characterize compounds by means of spectroscopic techniques. Additionally, they will receive a solid education in learning mechanistic methodologies and advanced problem skills. Students will also receive training in less traditional techniques and areas such as electrochemistry, computational chemistry and nanosecond transient absorption spectroscopy; the last will be achieved by means of the newly purchased laser flash photolysis instrumentation with funds from this award. Professor de Lijser continues to build on his track record for increasing involvement of undergraduate students in scientific activities. The Department of Chemistry and Biochemistry at California State University, Fullerton (CSUF) has long been recognized as offering a rigorous and contemporary curriculum that is responsive to future developments, reflects the interdisciplinary nature and diversity of the chemical science and enables students to become successful professionals, scholars, and scientifically literate citizens. Because the CSU provides a substantial percentage of the technical workforce, teachers and graduate student applicants in California, exposing students to modern research methods and environments will sustain regional, state-wide and national capabilities for education and training of undergraduates and Masters' students in the chemical sciences.