Atmospheric oxidation of 4-(2-Methoxyethyl) phenol initiated by OH
radical in the presence of O2 and NOx: A mechanistic and kinetic study
Abstract
4-(2-Methoxyethyl) phenol (MEP) is an significant methoxypheolic
compound, which has been shown to play an important role in the
formation of secondary organic aerosols(SOA). The present work focuses
on the gas-phase oxidation mechanism and kinetics of MEP and OH radical
by the density functional theory (DFT). Energetically favourable
reaction channels and feasible products were identified. The initial
reactions of MEP with OH radical have two different channels: OH
addition and H abstraction. Subsequent reaction schemes of main
intermediates in the presence of O2 and NOx are investigated using
quantum chemical methods at M06-2X/6-311++G(3df,2p)//M06-2X/6-311+G(d,p)
level. Ketene, Phenyldiketones and nitrophenol compounds are
demonstrated to be possible oxidation products. The total rate
constant(1.69×10-11 cm3 molecule-1 s-1) and individual rate constant are
calculated using the traditional transition state (TST) theory at 298K
and 1atm. The lifetime of MEP is estimated to be 16.4 hours, which
provides a comprehensive explanation for atmospheric oxidation pathway
of MEP and shows MEP would be removed by OH radical in the atmosphere.