Hydrogen abstraction/nucleophilic addition: A novel reaction pathway between aromatic olefin radical cation and TEMPO

On the basis of ESI-MS and MS/MS techniques and DFT calculations, the experimental and theoretical investigation into the reaction mechanism of the aromatic olefin radical cation and TEMPO has been carried out. Besides the acknowledged radical coupling pathway, a novel reaction pathway, namely hydrogen abstraction/nucleophilic addition, has been proposed. The great difference between these two pathways is that the adduct ion formed by the novel proposed pathway can lose water, which has been supported by the MS/MS experiments. At the same time, DFT calculations indicate that the rate-determining step in the proposed pathway, namely hydrogen abstraction, can be supported enough by the energy released from the formation of the complex between the radical cation and TEMPO.

► Using ESI-MS and MS/MS and DFT to study the reaction mechanism of the radical cation and TEMPO.
► A novel reaction pathway, namely hydrogen abstraction/nucleophilic addition, has been assumed.
► The adduct formed by the novel pathway can lose water, while that from radical combination not.