Products of the Gas-Phase Reactions of 1,3-Butadiene with OH and NO₃ Radicals

1,3-Butadiene is emitted into the atmosphere from a number of sources including combustion sources and is listed in the United States as a hazardous air pollutant. In the atmosphere, 1,3-butadiene reacts with OH radicals, NO 3 radicals, and O 3 with the dominant tropospheric removal processes being daytime reaction with the OH radical and nighttime reaction with the NO 3 radical. We have used gas chromatography, in situ Fourier transform infrared (FT-IR) absorption spectroscopy, and in situ atmospheric pressure ionization tandem mass spectrometry (API-MS) to identify and quantify the products formed from the reactions of 1,3-butadiene with OH radicals (in the presence of NO) and NO 3 radicals. Acrolein, formaldehyde, and furan were identified and quantified from the OH radical-initiated reaction, with formation yields of 0.58 ± 0.04, 0.62 ± 0.05, and 0.03−0.04, respectively. Organic nitrates were observed by FT-IR spectroscopy with an estimated yield of 0.07 ± 0.03, and the API-MS analyses indicated that these organic nitrates are mainly the hydroxynitrate HOCH 2 CH CHCH 2 ONO 2 and/or its isomers. API-MS analyses showed the formation of a hydroxycarbonyl with the formula C 4 H 6 O 2, attributed to HOCH 2 CH CHCHO and/or its isomers. The major products of the NO 3 radical-initiated reaction were organic nitrates; the API-MS analyses indicated the formation of acrolein, 1,2-epoxy-3-butene, and unsaturated C 4 -hydroxycarbonyls, hydroxynitrates, carbonyl nitrates, and nitrooxyhydroperoxides. Acrolein, HCHO, and furan were again quantified by gas chromatographic and FT-IR analyses. Our data are compared with previous literature studies, and detailed reaction mechanisms are presented and discussed.