Pathways of the Para-Pyridyl Reaction with Molecular Oxygen: Theoretical Study

The formation of nitrogen oxides during combustion of coal or biofuel containing fuel-bound nitrogen is an important environmental problem. As the simplest model system used to describe coal combustion, one can use a pyridine molecule, which, on one hand, has an aromatic structure and, on the other hand, contains a nitrogen atom in its structure. This paper describes a theoretical study of the reaction of para-pyridyl interaction with molecular oxygen. A potential energy surface of the para-pyridyl reaction with molecular oxygen is constructed. The para-pyridyl radical barrierlessly attaches an oxygen molecule with formation of the PyOO radical, and then the reaction can follow one of three paths, leading to four possible products: 3H-pyrrole-3-one, HCO + HCN, 1λ²-pyrrole, and 1λ³, 4-oxazine.