ACD Seminar - presenter Roger Atkinson

“Products of OH + Furan Reactions and Some Implications for Aromatic Hydrocarbon Atmospheric Degradation”


Unsaturated 1,4-dicarbonyls are important products of the atmospheric degradations of aromatic hydrocarbons such as benzene, toluene, xylenes and trimethylbenzenes, which comprise ~20% of the non-methane volatile organic compounds present in urban air masses in the USA.  However, in many cases the measured formation yields of the unsaturated 1,4-dicarbonyls are significantly lower than those of these presumed co-product 1,2-dicarbonyls.  These discrepancies could be due to analytical problems and/or rapid photolysis of unsaturated 1,4-keto-aldehydes and unsaturated 1,4-dialdehydes, or to incorrect reaction mechanisms for the OH radical-initiated reactions of aromatic hydrocarbons.  Since unsaturated 1,4-dicarbonyls are major products of OH + furans, with apparently simpler product distributions and mechanisms, we have investigated the reactions of OH radicals with furan, 2- and 3-methylfuran, and 2,3- and 2,5-dimethylfuran, in the presence of NO.  Using direct air sampling atmospheric pressure ionization tandem mass spectrometry and gas chromatography, the unsaturated 1,4-dicarbonyls were observed and quantified.  The measured unsaturated 1,4-dicarbonyl formation yields ranged from 8 ± 2% from OH + 2,3-dimethylfuran to 75 ± 5% from OH + furan.  Other products were also formed.  These data will be presented and discussed and, time permitting, a brief discussion of in situ nitro-aromatic and nitro-PAH formation from the atmospheric degradations of aromatic hydrocarbons and PAHs will also be presented.


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Tuesday, November 19, 2013 - 3:30pm