PRODUCTS OF THE GAS-PHASE REACTIONS OF A SERIES OF 1-ALKENES AND 1-METHYLCYCLOHEXENE WITH THE OH RADICAL IN THE PRESENCE OF NO

The products of the gas-phase reactions of the OH radical with 1-pentene, 1-hexene, 1-heptene, 1-octene, 2,3-dimethyl-1-butene, and 1-methylcyclohexene have been investigated in the presence of NO at room temperature and 740 Torr total pressure of air. Products were identified and quantified by gas chromatography and in situ Fourier transform infrared absorption spectroscopy. The carbonyl products identified acid their yields were as follows: from 1-pentene, butanal (0.73 +/- 0.09) and HCHO (0.88 +/- 0.11); from 1-hexene, pentanal (0.46 +/- 0.07) and HCHO (0.57 +/- 0.08); from 1-heptene, hexanal (0.30 +/- 0.04) and HCHO (0.49 +/- 0.06); from 1-octene, heptanal (0.21 +/- 0.03) and HCHO (0.39 +/- 0.06); from 2,3-dimethyl-1-butene, acetone (0.27 +/- 0.04), 3-methyl-2-butanone, (0.45 +/- 0.06), and HCHO (0.50 +/- 0.04); and from 1-methylcyclohexene, 5-acetylpentanal (0.31 +/- 0.08). These product yield data suggest that the intermediate beta-hydroxyalkoxy radicals undergo isomerization and/or reaction with O-2 in competition with decomposition, and the decrease in the carbonyl and HCHO yields with increasing carbon number in the 1-alkenes 1-pentene through 1-octene suggests that isomerization of the intermediate beta-hydroxyalkoxy radical is occurring.