Kinetics and nitro‐products of the gas‐phase OH and NO3 radical‐initiated reactions of naphthalene‐d8, Fluoranthene‐d10, and pyrene

Abstract

The kinetics and nitroarene product yields of the gas‐phase reactions of naphthalene‐d8, fluoranthene‐d10, and pyrene with OH radicals in the presence of NOx and in N 2 O 5NO 3NO 2air mixtures have been investigated at 296 ± 2 K and atmospheric pressure of air. Using a relative rate method, naphthalene‐d8 was shown to react in N 2 O 5NO 3NO 2air mixtures a factor of 1.22 ± 0.10 times faster than did naphthalene, with the 1‐ and 2‐nitronaphthalene‐d7 product yields being similar to those of 1‐ and 2‐nitronaphthalene from naphthalene. From the measured PAH concentrations and the nitroarene product yields, formation yields of 2‐, 7‐, and 8‐nitrofluoranthene‐d9 and 2‐ and 4‐nitropyrene of 0.03, 0.01, 0.003, 0.005, and 0.0006, respectively, were determined from the OH radical‐initiated reactions. Effective rate constants for the reactions of fluoranthene‐d10 and pyrene with N 2 O 5 in N 2 O 5;NO 3NO 2air mixtures of ca. 1.8 × 10−17 cm 3 molecule−1 s−1 and ca. 5.6 × 10−17 cm 3 molecule−1 s−1, respectively, were derived. Formation yields of 2‐nitrofluoranthene‐d9 and 4‐nitropyrene of ca. 0.24 and ca. 0.0006, respectively, were estimated for these reaction systems. 2‐Nitropyrene was also observed to be formed in these N 2 O 5NO 3NO 2 reactions, but was found to be a function of the NO 2 concentration and, therefore, would be a negligible product under ambient NO 2 concentrations. These product and kinetic data are consistent with ambient air measurements of the nitroarene concentrations.