Reaction mechanism of pyridine radicals with molecular oxygen: A theoretical study

[Display omitted] •The detailed mechanism of interaction of ortho- and meta-pyridyls with O2 was studied.•Reactions of ortho- and meta-pyridyls with O2 proceeds leads to four main products.•Reactions pyridine radicals with O2 proceed following similar mechanisms.•The energies of the main intermediates of all three reactions have similar values. Pyridine is a suitable surrogate of the fuel-nitrogen in flame studies. The goal of the present work was to extend the analysis of reactions of pyridyl radicals with O2. All reactions proceed following similar mechanisms, through the barrier-free addition of an O2 molecule and further development along two main paths: through barrier-free abstraction of an oxygen atom and through the formation of a seven-membered ring. The energies of the main intermediates of all three reactions, calculated relative to the pyridyl + O2 system, have similar values. All three reactions are characterized by the formation of 1λ2-pyrrole, as well as HCO, HCN, C2H2 and CO.