Theoretical Investigation on Water-Free, Water- and Self-Assisted H-Abstraction Reactions from Dimethylamine by Hydroxy Radicals.
J Phys Chem A
; 128(30): 6264-6273, 2024 Aug 01.
Article
em En
| MEDLINE
| ID: mdl-39034617
ABSTRACT
Accurate branching ratios of the H-abstraction reactions from dimethylamine (DMA) by OH radicals are important in understanding the atmospheric fate of DMA. In this work, the reaction kinetics of the water-free, water-assisted, and self-assisted H-abstraction reactions between DMA and OH radicals are accurately determined using the multipath canonical variational theory with the small-curvature tunneling correction, to explore the catalytic effects of the reactant (DMA) and product (water). To choose a suitable method that well describes the current reaction systems, various combinations with seven DFT methods and six basis sets are first evaluated, and the M08-HX/ma-TZVP method is identified as the most appropriate, with a mean unsigned deviation of 0.9 kcal mol-1 against the gold-standard CCSD(T)/CBS(T-Q) method. Based on the determined potential energy surfaces with the considerations of ground-state structures and specific-reaction parameters of zero-point energies, rate constants and branching ratios are calculated in a wide temperature range. The calculations show that the participation of water and DMA can lead to three-body complexes with a lower energy and influence the energy barriers, but neither of them shows the catalytic effect on the H-abstraction reactions in terms of kinetics. Additionally, the branching ratio analysis demonstrates that the product distribution is significantly altered in the presence of DMA and water.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Phys Chem A
/
J. phys. chem. A
/
The journal of physical chemistry. A
Assunto da revista:
QUIMICA
Ano de publicação:
2024
Tipo de documento:
Article
País de publicação:
Estados Unidos