Formation of Pyridyl Radicals by Hydrogen Atom Abstraction: Theoretical Study

Specific features of the pyridine structure make it a convenient model system to describe coal combustion; however, the main attention of researchers has been paid to the formation of the ortho-pyridyl, whereas the formation of meta- and para-pyridyls has been yet poorly studied. The rate constants of the formation of three pyridyl radicals originating from pyridine by hydrogen atom abstraction by another hydrogen atom are compared. The geometry of the reactants is optimized within the framework of the density functional theory with subsequent refinement of single-point energies by the ab initioG3(MP2,CC) hybrid method. The calculations show that the formation of ortho-pyridyl is more favorable, though the formation and further transformations of all three radicals should be taken into account for a detailed description of the coal combustion process.

Automated summary

Researchers have mainly focused on the formation of ortho-pyridyl in the pyridine structure, while the formation of meta- and para-pyridyls has received less attention. The rate constants of three pyridyl radicals formed from pyridine by hydrogen atom abstraction have been compared. The geometry of the reactants was optimized using density functional theory, followed by refinement of single-point energies using the ab initio G3(MP2,CC) hybrid method. The calculations indicate that the formation of ortho-pyridyl is more favorable, but all three radicals should be considered for a detailed description of coal combustion.