EVIDENCE FOR ARYL PARTICIPATION IN MASS SPECTROMETRIC FRAGMENTATION PROCESSES

While heterolysis of oxonium ions generated upon electron‐impact in the mass spectrometer is a well documented phenomenon in the fragmentation of aliphatic ethers, little analogy exists for structurally comparable immonium ions. Exceptions are ions of the latter class in which dissociation is facilitated by the presence of proper substituents in position allowing satabilization of daughter ions. Two main types of subtitution were explored providing(1) resonance stabilization of the product ions by aryl substituents in benzylic,heterolysis,and (2) aryl neighboring group participation in homobenzylic heterolysis, possibly yielding phenonium ions (or isometric ions via further rearrangement) as stable products in the gas phase. In the discussion emphasis will be placed on Case 2. Copyright © 1969 John Wiley & Sons, Ltd.