The development of a reaction model is often a time-consuming process, especially if unknown reactions have to be found and quantified. To alleviate the reaction modeling process, automated procedures for reaction space exploration are highly desired. We present ChemTraYzer-TAD, a new reactive molecular dynamics acceleration technique aimed at efficient reaction space exploration. The new method is based on the basin confinement strategy known from the temperature-accelerated dynamics (TAD) acceleration method. Our method features integrated ChemTraYzer bond-order processing steps for the automatic and on-the-fly determination of the positions of virtual walls in configuration space that confine the system in a potential energy basin. We use the example of 1,3-dioxolane-4-hydroperoxide-2-yl radical oxidation to show that ChemTraYzer-TAD finds more than 100 different parallel reactions for the given set of reactants in less than 2 ns of simulation time. Among the many observed reactions, ChemTraYzer-TAD finds the expected typical low-temperature reactions despite the use of extremely high simulation temperatures up to 5000 K. Our method also finds a new concerted β-scission plus O2 addition with a lower reaction barrier than the literature-known and so-far dominant β-scission.

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Biohybrid fuels are a promising solution for making the transportation sector more environmentally friendly. One such interesting fuel candidate is 1,3-dioxolane, which can be produced from inedible biomass. However, very little kinetics data are available for the low-temperature oxidation of this fuel molecule.To remedy this, we present the reaction kinetics of O 2 addition to 1,3-dioxolanyl radicals in this work. All energies have been calculated at the DLPNO-CCSD(T)/CBS//B2PLYPD3BJ/6-311+g(d,p) level of theory. Temperature-and pressure-dependent reaction rate constants have been calculated with the RRKM/ master equation method. The effects of heterocyclic oxygen atoms and ring strain on the low-temperature oxidation of 1,3-dioxolane are also compared to that of similar fuel molecules containing five heavy atoms: cyclopentane, tetrahydrofuran, and diethyl ether (DEE). The ring-opening β-scission reactions of the dioxolane hydroperoxy species are found to be the most dominant pathways following the oxidation of 1,3-dioxolanyl radicals. The heterocyclic oxygen atoms in 1,3-dioxolane weaken its C−O bonds, which leads to low barrier heights of the ring-opening reactions. Ring strain in 1,3-dioxolane increases the barriers for isomerization reactions of peroxy radicals compared to the similar reactions of DEE, which has a chain structure.