Free Radical Chemistry in Smoke From Household and Cellulosic Materials, Automobile Fuel, and Perfluoropolymers.

Abstract

Free radicals have been detected in smoke resulting from the combustion of household and cellulosic materials, automobile fuel, and perfluoropolymers. Materials were pyrolyzed by a variety of methods, but the most reproducible results were obtained by heating the materials in a heated quartz tube. The smoke was reacted with $\alpha$-phenyl-N-t-butylnitrone (PBN), and the resulting nitroxide spin adducts were detected by electron spin resonance. Oxygen-centered radical spin adducts predominate, lesser amounts of carbon-centered radical spin adducts and an oxidation product of PBN were also observed when smoke from several cellulosic materials, dried exterior paint, polyethylene, rubber, and automobile exhaust was allowed to react with the spin trap. When cellulose smoke is dissolved in solution, radicals are produced for at least 20 min, suggesting that metastable species in the gas-phase smoke decompose to form radicals in solution. No radicals were spin trapped polyvinyl chloride or nylon smoke. Fluorine- and chlorine-atoms were spin trapped, and the spin trap was oxidized when smoke from perfluoropolymers (PFP) was allowed to react with PBN in aromatic solvents. In addition, a radical was trapped, whose structure has been tentatively assigned as a perfluoroalkoxyl radical. The spin adducts in PFP smoke result from the thermal initiated polymerization of tetrafluoroethylene in the spin trapping solution. Several low molecular weight perfluorocompounds have been ruled out as the source of the spin adducts in PFP smoke. These results imply that free radicals may contribute to PFP smoke toxicity.