Gas‐phase reaction of hydroxyl radicals with m‐, o‐ and p‐cresol

The gas-phase reaction of oxygenated aromatic compounds m-cresol, o-cresol, and p-cresol with hydroxyl radicals has been studied by GC-MS. Experiments have been performed in a large-volume photoreactor (8000 L) at 294 ± 2 K and atmospheric pressure. The relative kinetic method was used to determine the rate constants for these reactions, with 1,3,5-trimethylbenzene as a reference compound. The rate constants obtained are kOH(m-cresol) = (5.88 ± 0.92) × 10−11 cm3 molecule−1 s−1, kOH(o-cresol) = (4.32 ± 0.52) × 10−11 cm3 molecule−1 s−1, and kOH(p-cresol) = (4.96 ± 0.75) × 10−11 cm3 molecule−1 s−1. The degradation products observed and their respective molar yields were methyl-1,4-benzoquinone 12.4 ± 1.2%, 5-methyl-2-nitrophenol 1.5 ± 0.3%, and 3-methyl-2-nitrophenol 1.4 ± 0.3% from m-cresol, methyl-1,4-benzoquinone 5.6 ± 0.9%, and 6-methyl-2-nitrophenol 4.7 ± 0.8% from o-cresol, and 4-methyl-2-nitrophenol 17.2 ± 2.5% from p-cresol. This kinetic and product data are compared with the literature, and the reaction mechanisms are discussed. Our results are in accordance with the previous studies (Atkinson, J Phys Chem Ref Data 1989, Monograph (1), 1–246; Atkinson and Aschmann, Int J Chem Kinet 1990, 22, 59–67; Atkinson et al., Environ Sci Technol 1992, 26, 1397–1403; Atkinson et al., J Phys Chem 1978, 82, 2759–2805; Olariu et al., Atmos Environ 2002, 36, 3685–3697; Semadeni et al., Int J Chem Kinet 1995, 27, 287–304) and confirm the methyl-1,4-benzoquinone yields determined by a different experimental technique (long-path Fourier transform infrared FT-IR (Olariu et al., 2002)). © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 553–562, 2006