Investigation of the reaction OH+CH2ClOOH of atmospheric interest

Alkyl hydroperoxides are essential intermediates in the atmospheric oxidation of hydrocarbons and in low-temperature combustion processes [1]. Chlorinated alkyl hydroperoxides play a similar role in the atmospheric oxidation of chlorinated hydrocarbons. It is important to study the thermodynamic parameters for these species to understand and predict the reaction pathways, rate constants, and equilibrium constants. There are relatively few experimental studies on the thermodynamic properties of alkyl hydroperoxides due to their rapid interconversion and instability, which makes the studies of these species complex.

The main objective of this work is to provide reliable kinetic and thermodynamic data for the gas phase reaction of hydroxyl radicals with chloromethyl hydroperoxyl (CH₂ClOOH). Several possible reaction pathways could be feasible: H-abstraction, Cl-abstraction, and OH-abstraction. The reaction mechanism involves many stationary points on the potential energy surface and reveals some unusual features for the H-abstraction. Theoretical calculations were performed with the augmented correlation consistent basis sets aug-cc-pVTZ for H and O atoms and the aug-cc-pV(T+d)Z for Cl atom including tight d polarization functions. The potential energies have been calculated at the DK-CCSD(T)/ANO-RCC (VTZP and VQZP) level of theory on the geometries optimized previously.

Implications for atmospheric chemistry are presented and discussed.

References

[1] H. Sun, C. Chen, and J. Bozzelli, “Structures, Intramolecular Rotation Barriers, and Thermodynamic Properties (Enthalpies, Entropies and Heat Capacities) of Chlorinated Methyl Hydroperoxides (CH₂ClOOH, CHCl₂OOH, and CCl₃OOH)”, The Journal of Physical Chemistry A, 2000; 104 (35): 8270-8282, https://doi.org/10.1021/jp0013917