2011 Volume 53 Issue 165 Pages 165-171
Quantum chemical calculations were performed to investigate the mechanism for the low-temperature oxidation of ethylbenzenes and propylbenzenes. The equilibrium constant for the reaction between R + O2 ⇔ RO2 in the alkylbenzene system was found to be dependent on the position of O2 in RO2 relative to the aromatic ring. The activation energies and the pre-exponential factors for the isomerization reactions of RO2 were also calculated using the transition state theories based on the calculated structures predicted by the density functional theory. It was confirmed that (1, 3) H-atom migration in the alkyl side chain or O2-adduct formation played the key roles on the isomerization reactions of RO2 at relatively lower temperature range. At higher temperature HO2 formation is dominant for all reaction systems. The subsequent reactions of O2-adduct complex in the ethylbenzene system were also searched and the possible roles on the pathway of the benzene-ring cleavage reaction from the O2-adduct complex were suggested.
