Intramolecular reactions of aromatic radical anion with halides. Electron-transfer and S N2 processes

Abstract

One-electron reduction of 1-(4-biphenylyl)-ω-chloroalkane (BP Cl- n) by electrons and the intramolecular reactions of the radical anion thus formed have been investigated by pulse radiolysis at room temperature and 77 K matrix γ-irradiation of the 2-methyltetrahydrofuran solutions. An intramolecular electron transfer from a biphenyl radical anion to a C-Cl bond was observed for BP Cl-0 and BP Cl-2 while an intramolecular nucleophilic displacement of the biphenyl radical anion on the chlorine center, S N2 reaction, has been presumed for BP Cl-3 and BP Cl-4. On the other hand, in 77 K matrix γ-irradiation an intramolecular electron transfer was observed for all these BP Cl- n, and S N2 reaction could not be detected in BP Cl-3 and BP Cl-4. The characteristic feature of the intramolecular reactivity of the BP Cl- n radical anion in both systems has been discussed.