Chemical properties of a para-benzyne.

5,8-Didehydroisoquinolinium ion, a para benzyne analogue, was generated in a Fourier transform ion cyclotron resonance mass spectrometer, and its reactivity toward various neutral reagents was examined. A direct comparison of the reaction kinetics of the para benzyne, a meta isomer, and analogous monoradicals, indicates that the para benzyne is a poorer electrophile but a more reactive radical than its meta isomer.