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

Abstract

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.

Combustion in a Sustainable World: From Molecules to Processes

“…Accordingly, their pyrolysis and oxidation have only recently been studied. Döntgen et al investigated the unimolecular decomposition of 1,3-dioxolane and found major influences of H atom ring migration; their theoretical study also includes combustion-related properties of methyl- and ethyl-substituted dioxolane compounds for which such information was largely lacking . Hellmuth et al performed an experimental and numerical study of the combustion of 1,3-dioxolane and 1,3-dioxane, five- and six-membered cyclic compounds of similar structure, comparing two representative biohybrid fuels .…”

“…Dontgen et al investigated the unimolecular decomposition of 1,3-dioxolane and found major influences of H atom ring migration; their theoretical study also includes combustion-related properties of methyland ethyl-substituted dioxolane compounds for which such information was largely lacking. 24 Hellmuth et al performed an experimental and numerical study of the combustion of 1,3dioxolane and 1,3-dioxane, five-and six-membered cyclic compounds of similar structure, comparing two representative biohybrid fuels. 25 They combined ignition delay times, laminar flame speeds, and species measurements in different experimental configurations with kinetic model development and analysis to explain differences in reactivity and aromatic species formation.…”

Stable cyclic ether as an electrolyte additive for high-performance lithium metal batteries

“…22 The inclusion of a methyl group adjacent to the oxygen atom in 4-Me DOL molecules introduces steric hindrance, impeding the accessibility of PF 5 to the oxygen atom. 23 Therefore, 4-Me DOL is a stable cyclic ether. To validate the above conclusions, two different solvent systems were prepared: 1 M LiPF 6 in DOL and 1 M LiPF 6 in 4-Me DOL.…”