Theoretical Investigation of Key Properties of the Pyrolysis of Methyl, Ethyl, and Dimethyl Dioxolane Isomers.

Cyclic acetals are considered as carbon-neutral fuels that can be produced from biomass and renewable electricity. Recent investigations on 1,3-dioxolane, a five-membered cyclic acetal, revealed that unimolecular decomposition through H-atom migration within the ring governs thermal decomposition. For methyl- and ethyl-substituted dioxolane compounds, very limited information on thermodynamic, transport, bond dissociation, and thermal decomposition properties is available. The present study remedies this lack of information by providing these properties for methyl-, ethyl-, and dimethyl-substituted dioxolanes in a systematic manner. While adding substituents to the dioxolane ring has only a minor effect on the bond dissociation energies, the barrier heights for H-atom migration are clearly affected by the position of the substituents. Notably, the corresponding transition states are preferably in the boat ring configuration. However, two of the substituted dioxolanes do not allow for this configuration because of their respective bonding structures, resulting in larger barrier heights. The properties provided here will aid the detailed chemical kinetic modeling of substituted dioxolane combustion chemistry.