Widespread Occurrence of the RDA Reaction

Any molecule that can at least formally be synthesized by a Diels-Alder reaction is a potential candidate for the mass spectral RDA reaction. In addition, the RDA reaction is not restricted to positive radical ions, but it may also occur from even-electron ions as well as from negative radical ions, NT. These findings remind us of the fact that ionic reactions are determined by the intrinsic properties and the internal energy of the ions, and thus only indirectly by the ionization technique used for their creation. 

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