Atmospheric oxidation of 4‐(2‐methoxyethyl) phenol initiated by OH radical in the presence of O₂ and NO_x: A mechanistic and kinetic study

Abstract

4-(2-Methoxyethyl) phenol (MEP) plays an important role in the formation of secondary organic aerosols (SOA). The gas-phase mechanism and kinetics of MEP with OH reaction are studied by the density functional theory (DFT). The initial reactions of MEP with OH radical produce two different channels: OH addition and H abstraction. Subsequent reaction schemes of the main intermediates are investigated by using M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p) level. Ketene, diketones and nitrophenol compounds are demonstrated to be the dominant oxidation products in the presence of high O 2 and NO x . The total and individual rate constants are calculated by using the traditional transition state theory (TST) at 298K and 1atm.The calculated value of 5.62×10 −11 cm 3 molecule −1 s −1 is close to experimental data of similar systems. The lifetime of MEP is estimated to be 4.94 hours. These results provide a comprehensive explanation for atmospheric oxidation pathways of MEP.

A Theoretical Study on the Degradation Mechanism, Kinetics, and Ecotoxicity of Metronidazole (MNZ) in •OH- and SO4•−-Assisted Advanced Oxidation Processes

“…However, the reaction rate constants involving water vapor could be calculated by TST. Previous studies have shown that the kinetic calculations for gas-phase reactions could provide better results [ 40 , 49 , 54 ]. And gas-phase rate constants could be changed to aqueous-phase ones.…”

“…The tunneling correction factor κ ( T ) was calculated using the Wigner model: where lm( V ≠ ) is the transition state’s imaginary frequency. Some studies have used the KiSThelP program to calculate rate constants, with good results [ 48 , 49 , 50 ].…”

“…where lm(V = ) is the transition state's imaginary frequency. Some studies have used the KiSThelP program to calculate rate constants, with good results [48][49][50].…”

Theoretical Calculation on the Reaction Mechanisms, Kinetics and Toxicity of Acetaminophen Degradation Initiated by Hydroxyl and Sulfate Radicals in the Aqueous Phase

“…The conventional Transition State Theory (TST) was used to calculate the rate constants implemented by KiSThelP program [34] that has obtained accurate results for contaminants with free radicals reactions [35][36][37][38][39]. The calculation formula is employed in KiSThelP:…”

Hydroxyl‐initiated oxidation processes of phenylenediamines treated by the atmospheric plasma: A theoretical study in gas phase

“…Fan et al reported negative activation energies during the OH initiated oxidation processes of phenol [13]. Yao et al used M062X theory to study the oxidation processes of 4‐(2‐methoxyethyl) phenol initiated by OH radical [14]. However, the underlying reaction mechanisms of organic micropollutants oxidized by OH radical are still not totally understood.…”