Project Summary (2009-2011)

Dr. Strongin’s research focuses on the characterization of emissions of brominated and mixed chlorinated/brominated hydrocarbons from combustion/thermal processing of Superfund wastes. These poorly characterized pollutants are readily formed by reactions of chlorinated hydrocarbons and brominated flame retardants present during many waste remediation processes. These compounds are potential sources of oxidative stress, cardiovascular disease, and cancer induced by combustion-generated ultra-fine particles.

The study of the chemistry of bromo- and bromo-/chlorobenzenes and phenols on surrogates of combustion-generated ultrafine particles is a primary focus of this project. Additionally, in spite of the growing recognition of their presence in combustion effluents, mixed chlorinated/brominated dibenzo-p-dioxins and dibenzofurans (PXDD/Fs) have eluded extensive study due to a lack of available standards. Dr. Strongin’s research group plans on using a combinatorial solid phase synthesis approach to furnish these materials efficiently. The proposed syntheses will minimize contact with the toxins and allow for a significant degree of regiocontrol over halogen substitution patterns. Carbon-13 labeled PXDD/Fs and their appropriate precursors will be synthesized and subjected to gas-phase and CuO surface-mediated pyrolysis and oxidations. Their mechanism of formation and reactivity will be elucidated.

This project also addresses combustion-generated pollutants with chiral centers that have not been examined as possible environmental pollutants. The concern is that optically active pollutants may also be biologically active such that the environment is adversely impacted. Thermodynamics suggests that optically active pollutants formed via gas-phase pathways may be present as racemates if formed at high temperatures. However, chemisorption to the surface of particulate matter can result in them becoming chiral. The initial characterization and separation of the novel stereoisomeric materials derived from Superfund waste processing will be undertaken. A team of investigators with expertise in synthetic and physical organic as well as in spectroscopy, chiral separations and combustion has been assembled to ensure the success of this research.