**1. Introduction**

Most chlorinated and especially polychlorinated arenes (such as polychloro-dibenzo-*p*-dioxins **1**, polychloro-dibenzofurans **2**, or polychlorobiphenyls **3**) are persistent organic pollutants (POPs) that are harmful to both man and the environment [1–5].-

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As a result, numerous techniques and procedures were implemented for their destruction/- degradation [6–11]. Initially, these procedures focused on the separation/extraction of polychlorinated compounds and subsequent treatment. Nowadays, researchers value the in situ procedures the most, with the advantage of time and the economic aspects [7, 12–14]. Indeed, such compounds are stable molecules, which are resistant to hydrolysis, oxidation, and temperature changes, thus being difficult to degrade and showing long half-life times in the environment [15]. For example, dioxins could have atmospheric half-lives of 10–20years, while, in soils, they can reach staggering values of up to 150years.-

This means that it might be an impossible task to deliver a dioxin-free Earth for future generations, but it lies on the present generation of scientists and engineers to try to do so. In that spirit, early attempts appealed to mankind's most powerful discovery of destructive technology—fire [16]. In the early 1990s, most of the processes were thermal. But as it was soon discovered, these procedures were in fact a source for a de novo polychlorinated compound synthesis, the process by which dioxins are re-formed being investigated in the recent years [17–19]. Therefore, greater attention was focused on more chemical-based processes [6, 10, 20-23], along with microbial ones [24].-

In particular, attention was focused on those procedures that were based on the combination of a metal and a hydrogen donor, processes that allowed the hydrodechlorination of the polychlorinated aromatic substrate to less toxic hydrocarbons [6–9, 14, 21–23]. Since these are among the most studied procedures in the past few years, we turned our attention to the particular reaction mechanism of the hydrodechlorination reaction. Indeed, understanding the reaction mechanism of a particular process is important in view of understanding the role played by each reagent but also in view of the predictive modeling of similar processes or the same process applied to various other substrates [25].-
