ChemInform Abstract: Kinetics of the Reactions of Acenaphthene and Acenaphthylene and Structurally-Related Aromatic Compounds with OH and NO3 Radicals, N2O5 and O3 at 296 .+-.2 K

Abstract

The kinetics of the atmospherically important gas-phase reactions of acenaphthene and acenaphthylene with OH and NO3 radicals, O3 and N2O5 have been investigated at 296 ± 2 K. In addition, rate constants have been determined for the reactions of OH and NO3 radicals with tetralin and styrene, and for the reactions of NO3 radicals and/or N2O5 with naphthalene, 1- and 2-methylnaphthalene, 2,3-dimethylnaphthalene, toluene, toluene-α,α,α-d3 and toluene-d8. The rate constants obtained (in cm3 molecule−1 s−1 units) at 296 ± 2 K were: for the reactions of O3; acenaphthene, <5 × 10−19 and acenaphthylene, ca. 5.5 × 10−16; for the OH radical reactions (determined using a relative rate method); acenaphthene, (1.03 ± 0.13) × 10−10; acenaphthylene, (1.10 ± 0.11) × 10−10; tetralin, (3.43 ± 0.06) × 10−11 and styrene, (5.87 ± 0.15) × 10−11; for the reactions of NO3 (also determined using a relative rate method); acenaphthene, (4.6 ± 2.6) × 10−13; acenaphthylene, (5.4 ± 0.8) × 10−12; tetralin, (8.6 ± 1.3) × 10−15; styrene, (1.51 ± 0.20) × 10−13; toluene, (7.8 ± 1.5) × 10−17; toluene-α,α,α-d3, (3.8 ± 0.9) × 10−17 and toluene-d8, (3.4 ± 1.9) × 10−17. The aromatic compounds which were observed to react with N2O5 and the rate constants derived were (in cm3 molecule−1 s−1 units): acenaphthene, 5.5 × 10−17; naphthalene, 1.1 × 10−17; 1-methylnaphthalene, 2.3 × 10−17; 2-methylnaphthalene, 3.6 × 10−17 and 2,3-dimethylnaphthalene, 5.3 × 10−17. These data for naphthylene and the alkylnaphthalenes are in good agreement with our previous absolute and relative N2O5 reaction rate constants, and show that the NO3 radical reactions with aromatic compounds proceed by overall H-atom abstraction from substituent-XH bonds (where X = C or O), or by NO3 radical addition to unsaturated substituent groups while the N2O5 reactions only occur for aromatic compounds containing two or more fused six-membered aromatic rings.