Rate Constants for the Reactions of OH Radicals with Aromatics: Benzene, Phenol, Aniline, and 1,2,4‐Trichlorobenzene

Abstract

Reactions of OH radicals with aromatics were investigated in the presence of He at pressures ranging from 5 to 800 mbar using pulsed vacuum uv photolysis of H2O for the production of OH and time resolved resonance fluorescence for the detection of OH. At room temperature (296 K) in the presence of 133 mbar He the rate constants, k, were observed to be in the high pressure limit. The rate constants, (k ± Δk)/10−12 cm3 s−1, were determined to be: (1.0 ± 0.2) for benzene; (120 ± 24) for aniline; (28 ± 6) for phenol, (0.50 ± 0.10) for 1,2,4‐trichlorobenzene. — For the temperature dependence of the rate constant for 1,2,4‐trichlorobenzene the Arrhenius expression (k ± 3σ) = (2.3 ± 1) · 10−12 exp [ — (430 ± 125) K/T] cm3 s−1 is obtained from measurements at 273 to 368 K. — The rate constants at room temperature can be correlated with the ionization potential, I, of the aromatics, yielding the equation: logk/cm3s−1 = 0.74–1.36 · I/eV. This equation is seen to represent the rate data on 18 aromatics to within a precision of a factor of two; with some precautions it might be used to predict rate constants for further substituted benzene aromatics. Outliers in such a diagram are benzaldehyde and the cresols (being more reactive than predicted), and diphenyl and chlorinated aromatics (being less reactive).

Benchmarking of DFT functionals for the kinetics and mechanisms of atmospheric addition reactions of OH radicals with phenyl and substituted phenyl‐based organic pollutants

“… k OH ×10 −12 (Experimental values): (1.20 ± 0.15) by Perry et al (297.6 K); (1.24 ± 0.12) by Hansen et al (298 K); (1.59 ± 0.12) by Davis et al (298 K); (1.24 ± 0.09) by Tully et al (298 K); (1.2 ± 0.2) by Bjergbakke et al (298 K); (1.15± 0.25) by Lorenz and Zellner (298 K); (1.06 ± 0.09) by Knispel et al (298 K); (1.02 ± 0.2) by Rinke and Zetzsch (296 K); (1.05 ± 0.05) by Witte et al (299 K); (1.29 ± 0.14) by Wallington et al (296 K); (1.17 ± 0.06) by Semadeni et al (299 K); (1.22 ± 0.45) by Edney et al (300 K) …”

Consecutive reactions of aromatic-OH adducts with NO, NO<sub>2</sub> and O<sub>2</sub>: benzene, naphthalene, toluene, m- and p-xylene, hexamethylbenzene, phenol, m-cresol and aniline

“…Reaction (1/-1) and (2), have been observed over a wide range of temperature and pressure. They have been studied in our laboratory as well (Wahner and Zetzsch, 1983;Rinke and Zetzsch, 1984;Witte et al, 1986) and are fairly well understood.…”

Prediction of the abiotic degradability of organic compounds in the troposphere

“…It is interesting to note that the data points for the reference chemicals from Table I are located quite well along the two least square lines in Figure 3. The two linear Equations (2) and (3) of the OH radical reactivity with aromatics and aliphatics obviously reflect alternative reaction paths of the OH radical at 300 K. This view is supported by the kinetic data of Rinke and Zetzsch (1984) and Lorenz and Zellner (1983). The temperature dependency of the OH rate constants with aromatics indicates that at room temperature addition of OH to the aromatics is the dominant path of the reaction.…”

“…It was recently demonstrated by Rinke and Zetzsch (1984) that the OH rate constants of substituted benzene derivatives (with the exception of benzaldehyde and cresols) are linearly correlated with their ionisation potentials. In Figure 2 Fig.…”