Mass Spectra of Alkenes and Arenes. Resonance Stabilized Cations

Mass Spectra of Alkenes and Arenes. Resonance Stabilized Cations 

In general, fragmentation in a mass spectrometer gives rise to the most stable ions. For unsaturated compounds resonance stablized ions may be possible. 

Repeat your analysis for n-propylbenzene. (Compare geometries of 1-propylbenzene radical cation and 1-propylbenzene.) Where would you expect a strong peak in the mass spectrum Identify the ion responsible. 

Spin density surface for 1-propylbenzene radical cation shows location of unpaired electron. 

Electrostatic potential map for fraH.9-2-hexene radical cation shows most positively-charged regions (in blue) and less positively-charged regions (in red). 

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