Oxygen Atom Transfer to Positive Ions: A Novel Reaction of Ozone in the Gas Phase

This is the authors' abstract. We don't add key points for this paper.

In the gas phase, neutral ozone (O 3 ) transfers an oxygen atom to several positive ions, i.e. the radical cations of pyridines (R−Py +•; R = H, CH 3, C 2 H 5, and Cl), pyrimidine (Pi + • ), and alkyl halides (CH 3 X + •; X = Cl and I), and the halogen cations (X +; X = Cl, Br, and I). Reactivity changes drastically within the halogen series (Cl + ≪ Br + ≤ I + ), whereas no O-transfer occurs to F + . The oxide derivatives R−Py + −O •, Pi + −O •, CH 3 X + −O •, and XO + are formed, as demonstrated by pentaquadrupole (QqQqQ) double- and triple-stage mass spectrometry. No oxygen atom transfer occurs, however, in “inverse” reactions, i.e., those of ionized ozone (O 3 + • ) with the corresponding neutrals; and charge transfer dominates. Ab initio calculations suggest that O-transfer from ozone to ionized pyridine yields ionized pyridine N -oxide via simple nucleophilic addition of ozone as opposed to 1,3-dipolar cycloaddition. Similar nucleophilic addition followed by O 2 loss is also the most likely mechanism for O-transfer from ozone to the ionized alkyl halides and halogen cations. This novel O-transfer reaction to positive ions, which expands our knowledge of the rich chemistry of ozone, introduces a new pathway for the gas-phase oxidation of halogen atoms, pyridines, pyrimidines, alkyl halides, and analogues, and consequently for the gas-phase generation of their chemically interesting but difficult to access ionized oxides.