Molecular orbital approach for investigating the kinetics of cracking hydroperoxides

The autocatalytic oxidative cracking reactions, which originate from intermediate hydroperoxide compounds, are interesting from the industrial point of view, since they can be applied to the improvement of conventional recovering processes of plastic residues and organic residues. Quantum chemistry calculations were performed in order to estimate the activation energies as well as provide structural and surface data from oxidative cracking processes. Three transition mechanisms of oxidative cracking were investigated, i.e. carboxylic acid-paraffin, alcohol-aldehyde and alcohol-ketone, indicating smaller activation energies for the latter, which is provided by the tertiary carbon present in the chain. The activation energies of oxidative cracking of the model molecule C16 (methyl-pentadecane, relative to the alcohol-ketone mechanism) were smaller (about 2.5 kcal/mol) than polypropylene oxidative decomposition (15.5-17.9 kcal/mol), which would make possible the application of the first mechanism for the reutilization of heavy organic materials.