Reaction of Ethylene with Methoxyl Radicals: A Quantum-Chemical Study

Abstract

The addition of methoxyl radical СН₃О^• to ethylene with the formation of various isomers and oxygen-coordinated forms of the СН₃ОСН₂СН₂^• radical was analyzed in detail. The scheme of possible reactions involving these species was analyzed. This radical and products of its further transformations can play a certain role in the mechanism of the gas-phase oxidation of hydrocarbons. The potential energy surface of the СН₃О^• + С₂Н₄ system was analyzed within the framework of B3LYP and M06-2X hybrid methods of the density functional theory (DFT) and of CBS-QB3 ab initio composite method of quantum-chemical calculations. The minimal energy pathways of the reactions CH₂O + C₂H₅^•, CH₃OH + C₂H₃^• and of the CH₃OCH₂CH₂^• adduct formation were calculated. In particular, the reactions of intermolecular hydrogen atom transfer with the formation of CH₂O + C₂H₅^• and CH₃OH + C₂H₃^• are less favorable energetically than the consecutive addition of СН₃О^• to ethylene, isomerization, and decomposition of the adduct with the generation of ethyl radical participating in the chain propagation.