Title

Formation and Stabilization of Persistent Free Radicals

Document Type

Article

Journal or Conference Title

Proceedings of the Combustion Institute

ISSN

1540-7489

Volume

31

Issue

1

First Page

521

Last Page

528

Publication Date

9-1-2006

Department

Natural Sciences and Mathematics

Abstract

We demonstrate that stable and relatively unreactive “environmentally persistent free radicals (PFRs)” can be readily formed in the post-flame and cool-zone regions of combustion systems and other thermal processes. These resonance-stabilized radicals, including semiquinones, phenoxyls, and cyclopentadienyls, can be formed by the thermal decomposition of molecular precursors including catechols, hydroquinones and phenols. Association with the surfaces of fine particles imparts additional stabilization to these radicals such that they can persist almost indefinitely in the environment. A mechanism of chemisorption and electron transfer from the molecular adsorbate to a redox-active transition metal or other receptor is shown through experiment, and supported by molecular orbital calculations, to result in PFR formation. Both oxygen-centered and carbon-centered PFRs are possible that can significantly affect their environmental and biological reactivity.

Rights

Copyright © 2006 Elsevier. All rights reserved.

Publisher Statement

Originally published as Dellinger, B., Lomnicki, S., Khachatryan, L., Maskos, Z., Hall, R. W., Adounkpe, J., ... & Truong, H. (2007). Formation and stabilization of persistent free radicals. Proceedings of the Combustion Institute, 31(1), 521-528.