| Abstract
| - The homogeneous, gas-phase pyrolytic thermal degradationof 2-chlorophenol was studied in a 1 cm i.d. fusedsilica flow reactor at a concentration of 90 ppm, with areaction time of 2.0 s, and over a temperature range of 300−1000 °C. Observed products included dibenzo-p-dioxin(DD), 1-monochlorodibenzo-p-dioxin (1-MCDD), dibenzofuran(DF), naphthalene, chloronaphthalene, phenol, chlorobenzene, and benzene. These results differed significantly fromother reported lower temperature studies with reactiontimes of 10−100 s. At temperatures lower than 700°C, formation of the 2-chlorophenoxyl radical, whichdecomposes through CO elimination to form a chlorocyclopentadienyl radical, forms naphthalene and 2-chloronaphthalene through radical recombination/rearrangementreactions. The formation of DD and 1-MCDD are attributedto radical−radical reactions involving the 2-chlorophenoxylradical with the carbon−chlorine-centered radicalmesomer and the carbon−hydrogen-centered radicalmesomer of 2-chlorophenoxyl radical, respectively. Unlikepreviously reported studies with 2-chlorophenol, 4,6-dichlorodibenzofuran, which is purported to be due to radical−radical recombination pathways, was not detected. Thisis attributed to pyrolytic conditions of our experiments andthe resulting shorter reaction times and higher temperaturesthat favor reaction intermediates that form DD and1-MCDD.
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