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Effect of Bromine Substitution on the Lifetimes and Ozone Depletion Potentials of Organic Compounds.


pdf icon Effect of Bromine Substitution on the Lifetimes and Ozone Depletion Potentials of Organic Compounds. (1559 K)
Huie, R. E.; Orkin, V. L.; Louis, F. L.; Kozlov, S. N.; Kurylo, M. J.

NIST SP 984; June 2002.

Halon Options Technical Working Conference, 12th. Proceedings. HOTWC 2002. April 30-May 2, 2002, Albuquerque, NM, Gann, R. G.; Reneke, P. A., Editor(s)(s), 1-9 pp, 2002.

Available from:

Both the presentations and the papers are available on the HOTWC web site: http://www.bfrl.nist.gov/866/HOTWC/HOTWC2002/index.htm

Keywords:

halons; halon alternatives; bromine; ozone

Abstract:

Although the bromofluorocarbon compounds known as halons are excellent fire suppressants, their production is being phased out due to the considerable danger they pose to the Earth's ozone layer. A number of non-brominated substances have been proposed and tested, but the effort to find replacements continues to return to bromine due to the chemical characteristics of this element as a chemically active flame suppressant. Thus, a number of classes of brominecontaining molecules have been proposed for investigation as to their fire-suppression characteristics. Before candidate replacements can be placed into service, it is important to establish their environmental effects, particularly the projected ozone depletion potential. Generally, these replacement compounds are designed to be reactive toward atmospheric hydroxyl radicals. This reaction leads to chemical transformations that ultimately lead to the removal of the bromine from the atmosphere. Additionally, photolysis of these compounds in the atmosphere will release Br and may further shorten their lifetimes. In order to quantitatively evaluate the impact of these compounds in the atmosphere, we have investigated the reactivity of several classes of reactants toward OH, both experimentally and computationally. Rate constants were determined over the temperature range of at least 250 K to 370 K. In addition, we have measured the absorption spectra of most of these compounds down to 160 nm. We have then utilized this information to derive predicted ozone depletion potentials.