H-Atom Abstraction Reactions by Ground-State Ozone from Saturated Oxygenates

Area of Science:

• Atmospheric Chemistry
• Theoretical Chemistry
• Chemical Kinetics

Background:

• H-abstraction reactions are crucial in atmospheric chemistry.
• Limited theoretical data exists for ozone reactions with saturated organic compounds.

Purpose of the Study:

• Investigate theoretical insights into H-abstraction by ozone from saturated species.
• Determine preferred reaction sites and products for ozone-ether interactions.

Main Methods:

• Computational chemistry methods were employed to calculate rate constants.
• Various levels of theory, including CCSD(T)/CBS and CCSDT(Q), were utilized.
• Reactions involving tetrahydrofuran derivatives, acyclic ethers, hydroperoxides, and alcohols were studied.

Main Results:

• H-abstraction predominantly occurs at carbons adjacent to the heterocyclic oxygen in tetrahydrofuran derivatives.
• Methyl groups are the least reactive sites for H-abstraction.
• Reaction products include hydrotrioxides (ROOOH) or alcohols and singlet oxygen (O2(1Δg)).
• Discrepancies in absolute rate constant values were observed across different theoretical methods.

Conclusions:

• Theoretical calculations provide insights into ozone H-abstraction mechanisms with saturated ethers.
• The regioselectivity of abstraction is influenced by the molecular structure.
• Further high-level theoretical treatments are necessary for precise barrier height determination.