A Reactive Molecular Dynamics Study of Chlorinated Organic Compounds. Part II: A ChemTraYzer Study of Chlorinated Dibenzofuran Formation and Decomposition Processes

Abstract

In our two-paper series, we first present the development of ReaxFF CHOCl parameters using the recently published ParAMS parametrization tool. In this second part, we update the reactive Molecular Dynamics -Quantum Mechanics coupling scheme ChemTraYzer and combine it with our new ReaxFF parameters from Part I to study formation and decomposition processes of chlorinated dibenzofurans. We introduce a self-learning method for recovering failed transition-state searches that improves the overall ChemTraYzer transition-state search success rate by 10 percentage points to a total of 48 %. With ChemTraYzer, we automatically find and quantify more than 500 reactions using transition state theory and DFT. Among the discovered chlorinated dibenzofuran reactions are numerous reactions that are new to the literature. In three case studies, we discuss the set of reactions that are most relevant to the dibenzofuran literature: (i) bimolecular reactions of the chlorinated-dibenzofuran precursors phenoxy radical and 1,3,5-trichlorobenzene, (ii) dibenzofuran chlorination and pyrolysis, and (iii) oxidation of chlorinated dibenzofurans.

A Reactive Molecular Dynamics Study of Chlorinated Organic Compounds. Part I: Force Field Development

“…This set includes the study outcomes of (chlorinated) dibenzofuran formation and decomposition reactions from Part II [69] . Figures 4 and 5 show the absolute deviations of our force field's reaction energies and barriers, from the B3LYP/TZVP reference, respectively.…”

“…Figures 4 and 5 show the absolute deviations of our force field's reaction energies and barriers, from the B3LYP/TZVP reference, respectively. The reactions were discovered and quantified automatically with CTY, and are discussed in detail in the second part of our paper series [69] . The reaction list with B3LYP and ReaxFF energies can be found in Table S1 of the SI.…”

“…The validation set includes reactions with DFT barriers and DFT reaction energies up to 800 kJ mol −1 . As rMD simulations are often performed at elevated temperatures to accelerate reactions, [33,49,69] high‐energy regions in chemical space are accessible during the simulation. Therefore, validation sets probing the force field's capability of describing relevant regions of chemical space should include high‐barrier reactions.…”

“… Absolute deviations of our force field reaction barriers from B3LYP/TZVP reaction barriers. The reactions are taken from the case studies described in the second part of our paper series [69] . The classes have a width of 30 kJ mol −1 .…”

“…Results from the following reaction systems are included: CDF precursors phenoxy radical plus 1,3,5‐trichlorobenzene, dibenzofuran plus Cl 2 , and 1‐peroxy‐dibenzofuranyl radical reactions. An in‐depth methodology and discussion of these results is presented in Part II of our paper series [69] . The CTY validation set is computed at the B3LYP/TZVP level of theory using the quantum chemical software tool Gaussian16 [70] .…”