The Stability of alpha-Hydroperoxyalkyl Radicals

摘要

High-level ab initio and Born-Oppenheimer molecular dynamic calculations have been carried out on a series of hydroperoxyalkyl (alpha-QOOH) radicals with the aim of investigating the stability and unimolecular decomposition mechanism into QO + OH of these species. Dissociation was shown to take place through rotation of the C-O(OH) bond rather than through elongation of the CO-OH bond. Through the C-O(OH) rotation, the unpaired electron of the radical overlaps with the electron density on the O-OH bond, and from this overlap the C=O pi bond forms and the O-OH bond breaks spontaneously. The CH2OOH, CH(CH3)OOH, CH(OH)OOH, and alpha-hydroperoxycycloheptadienyl radical were found to decompose spontaneously, but the CH(CHO)OOH has a decomposition energy barrier of 5.95 kcal mol(-1) owing to its steric and electronic features. The systems studied in this work provide the first insights into how structural and electronic effects govern the stabilizing influence on elusive alpha-QOOH radicals.