The mechanisms of decomposition of the 1‐ and 2‐phenyltetralin radical cations

Mechanisms for decomposition of 1‐ and 2‐phenyltetralins were investigated using low resolution mass spectrometry and metastable ion techniques. Four primary decompositions were observed for 1‐phenyltetralin radical cations: (1) the loss of C₆H₆ via a 1,4‐elimination; (2) the elimination of ethene via competing losses from carbons 3 + 4 and carbons 2 + 3; (3) the loss of C₈H₈, probably through a stepwise Diels‐Alder cycloreversion to expel styrene; and (4) the loss of methyl radical involving carbon 2 and possibly carbon 4. Three major decompositions were observed for 2‐phenyltetralin radical cations: (1) the loss of C₈H₈, possibly through a Diels‐Alder cycloreversion to expel styrene; (2) the loss of C₆H₆ via a 1,3 elimination; and (3) the loss of methyl radical from carbon 1. Various exchange reactions occur prior to these losses, but they proved to be incomplete even for metastable ions.