Theoretical Perspectives on the Gas-Phase Oxidation Mechanism and Kinetics of Carbazole Initiated by OH Radical in the Atmosphere

Carbazole is one of the typical heterocyclic aromatic compounds (NSO-HETs) observed in polluted urban atmosphere, which has become a serious environmental concern. The most important atmospheric loss process carbazole reaction with OH radical. present work investigated mechanism OH-initiated oxidation degradation by using density functional theory (DFT) calculations at M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p) level. rate constants were determined Rice–Ramsperger–Kassel–Marcus (RRKM) theory. lifetime was compared other NSO-HETs. theoretical results show that initiated radical includes four types reactions: additions to “bend” C atoms, “benzene ring” H abstractions from C-H bonds and abstraction N-H bond. addition C1 atom bond are energetically favorable. main products hydroxycarbazole, dialdehyde, carbazolequinone, carbazole-ol, hydroxy-carbazole-one hydroperoxyl-carbazole-one. calculated overall constant 6.52 × 10−12 cm3 molecule−1 s−1 37.70 h under condition 298 K 1 atm. similar dibenzothiophene but lower than those pyrrole, indole, dibenzofuran fluorene. This provides investigation oxygenated NSO-HETs atmosphere should help clarify their potential health risk for determining pathways influence carbazole.