Products of the gas-phase reaction of the OH radical with 3-methyl-1-butene in the presence of NO

Abstract

The products of the gas-phase reaction of the OH radical with 3-methyl-1-butene in the presence of NO have been investigated at room temperature and 740 torr total pressure of air by gas chromatography with flame ionization detection, in situ Fourier transform infrared absorption spectroscopy, and direct air sampling atmospheric pressure ionization tandem mass spectrometry. The products identified and quantified by GC-FID and in situ FT-IR absorption spectroscopy were HCHO, 2-methylpropanal, acetone, glycolaldehyde, and methacrolein, with formation yields of 0.70±0.06, 0.58±0.08, 0.17±0.02, 0.18±0.03, and 0.033±0.007, respectively. In addition, IR absorption bands due to organic nitrates were observed, consistent with API-MS observations of product ion peaks attributed to the β-hydroxynitrates (CH3)2CHCH(ONO2)CH2OH and/or (CH3)2CHCH(OH)CH2ONO2 formed from the reactions of the corresponding β-hydroxyalkyl peroxy radicals with NO. A formation yield of ca. 0.15 for these nitrates was estimated using IR absorption band intensities for known organic nitrates. These products account for essentially all of the reacted 3-methyl-1-butene. Analysis of the potential reaction pathways involved shows that H-atom abstraction from the allylic C(SINGLEBOND)H bond in 3-methyl-1-butene is a minor pathway which accounts for 5–10% of the overall OH radical reaction. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet: 30: 577–587, 1998