Alkoxy Radical Isomerization in the OH Radical-Initiated Reactions of C₄−C₈ n-Alkanes

Isomerizations of the alkoxy radicals formed from the OH radical reactions with n -butane through n -octane and n -pentane- d 12 through n -octane- d 18 have been studied in the presence of NO at 296 ± 2 K and 740 Torr total pressure of air. In addition to carbonyls of the same carbon number as the alkane precursors, the previously predicted δ-hydroxycarbonyls were detected by direct air sampling atmospheric pressure ionization triple quadrupole mass spectrometry. The formation yields of carbonyl compounds containing the same number of carbons as the parent n -alkane decreased with increasing carbon number in the n -alkane, while the hydroxycarbonyl/carbonyl formation yield ratios increased markedly from n -butane through n -octane, in agreement with previous theoretical predictions.