Priority Research Centre for Energy, Faculty of Engineering & Built Environment, The University of Newcastle , Callaghan NSW 2308, Australia.
Environ Sci Technol. 2013 Oct 1;47(19):11040-7. doi: 10.1021/es4009823. Epub 2013 Sep 10.
This contribution investigates the thermochemical and kinetic parameters pertinent to the homogeneous gas-phase formation of two groups of pollutants, polychlorinated dibenzothiophenes (PCDT) and polychlorinated thianthrenes (PCTA) from their 2-chlorothiophenol (2-CTP) precursor. We compare the enthalpic profiles of the formation mechanism of PCDT/TA with the corresponding reactions involved in the gas-phase synthesis of PCDD/F (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, also known as dioxins). Overall, the presence of sulfur atoms greatly reduces the activation enthalpies of the rate determining steps in reference to the oxygenated system of PCDD/F. The rate constants of all elementary reactions are calculated using the transition state theory (TST) over a wide temperature range of 300-1200 K. We performed kinetic calculations for the formation of chlorinated dibenzothiophenes and chlorinated thianthrenes that could be applied to predict yields of these pollutants from 2-CTP up to ∼1200 K, that is, prior to the emergence of dechlorination and oxidation reactions. The results presented herein provide a greatly improved understanding of the gas-phase formation of the sulfur analogs of the notorious dioxins compounds.
本研究旨在探讨两组污染物（多氯二苯并噻吩（PCDT）和多氯噻蒽（PCTA））从其 2-氯噻酚（2-CTP）前体在均相气相中形成的热化学和动力学参数。我们将 PCDT/TA 形成机制的焓变曲线与气相中多氯二苯并-p-二恶英和多氯二苯并呋喃（也称为二恶英，PCDD/F）合成反应的相应反应进行了比较。总的来说，与含氧的 PCDD/F 体系相比，硫原子的存在大大降低了速率决定步骤的活化焓。所有基元反应的速率常数都是在 300-1200 K 的宽温度范围内通过过渡态理论（TST）计算得到的。我们对氯化二苯并噻吩和氯化噻蒽的形成进行了动力学计算，这些计算可以用来预测 2-CTP 到约 1200 K 之间这些污染物的产率，即在脱氯和氧化反应出现之前。本文的研究结果提供了对臭名昭著的二恶英化合物的硫类似物在气相中形成的更深入的理解。
