An e.s.r. investigation of radical cations formed in Friedel–Crafts reactions

The present study deals with the detection and identification of radical cations produced in a Friedel–Crafts alkylating system, with benzene, toluene, or ethylbenzene, and an alkyl chloride. Our results indicate that the observed e.s.r. spectra are due to polycyclic aromatic radical cations formed from the parent hydrocarbons.It is suggested that benzyl halides produced in the Friedel–Crafts alkylating reaction undergo Scholl self-condensation to give polycyclic aromatic hydrocarbons, which are converted into the corresponding polycyclic aromatic radical cations in the presence of aluminium chloride.