Theoretical study on HO₂‐initiated atmospheric oxidation of halogenated carbonyls

Abstract

ABSTRACT:The initial reactions of HO 2 with oxalyl dichloride, oxalyl dibromide, acetyl chloride, and acetyl bromide are studied for the first time using the density functional theory with CAM-B3LYP and wB97XD, CBS-QB3, and G3 theoretical methods and the transition state theory. The reactions occur via the similar mechanism that the prereactive complex is formed before the transition state and product. The calculated results demonstrate that the HO 2 radical with ClC(O)C(O)Cl and BrC(O)C(O)Br reactions is feasible and could play a significant role in the atmosphere because the barriers are 0.13 kcal/mol, À0.05 kcal/mol with respect to the free reactants, respectively at the CBS-QB3 level of theory. In addition, the rate constants of the HO 2 þ ClC(O)C(O)Cl and HO 2 þ BrC(O)C(O)Br reactions are computed to be 1.37 Â 10 À15 cm 3 mol À1 s À1 , 1.70 Â 10 À15 cm 3 mol À1 s À1 at 298 K. However, the HO 2 reactions with acetyl chloride and acetyl bromide are of no importance because of higher activated barrier and slower rate constant.

The atmospheric oxidation of hydroxyacetone: Chemistry of activated and stabilized CH3C(O)CH(OH)OO• radicals between 252 and 298 K

“…Numerous experimental and theoretical studies of reversible addition of HO 2 to various carbonyl‐containing compounds have been conducted . Perusal of the available data shows that our derived values for K 3 , k 3 , and k −3 are reasonable (ie, of similar magnitude to those previously reported).…”

“…The mechanism described here, involving an alcohol (RCH 2 OH), the corresponding carbonyl compound (RCH=O), and the interactions of these species with OH and/or HO 2 , is not unique to the HYAC/MGLY pair, but in fact is generally applicable: Numerous experimental and theoretical studies of reversible addition of HO 2 to various carbonyl-containing compounds have been conducted. 28,33,40,47,52,53 Perusal of the available data shows that our derived values for K 3 , k 3 , and k −3 are reasonable (ie, of similar magnitude to those previously reported). Our derived equilibrium constants for the HO 2 /MGLY system fall intermediate between those previously reported for HCHO and CH 3 CHO, 28,37-39 and thus represent one of the stronger HO 2 /carbonyl interactions identified to date.…”

Initial decomposition pathways of 1,1-diamino-2,2-dinitroethylene (α-FOX-7) in the condensed phase

“…Moreover, these methods provide a reasonable balance between the computational cost and chemical accuracy, which is crucial in studying large molecular clusters like the ones reported in this manuscript. 33,[53][54][55][56][57][58][59][60][61] All calculations were performed using the Gaussian16 software package. 62 As noted in the introduction, the crystal of FOX-7 possesses a wave-shaped structure (Fig.…”

Theoretical Study of the Reaction Mechanism and Kinetics of HO2 with XCHO (X = F, Cl)

“…HO 2 radical is not only one of the highest concentration oxidants that help in controlling the concentrations of many trace species in the atmosphere but is also of great interest and importance for radical–radical and radical–molecule reactions in the atmosphere . Of great interest is the possible importance of the reactions of HO 2 with FCHO and ClCHO.…”