Asymmetric annellation effects—II

Abstract

The comparison of the U.V. absorption spectra of acenes, 1:2–3:4-dibenzacenes and tetrabenzacenes shows a strong asymmetric annellation effect. This is explained on the basic assumption that an aromatic sextet or benzenoid ring can transfer only two electrons to another ring. Three benzenoid rings can thus produce an induced aromatic sextet in an included ring of the type of the central ring in triphenylene. The synthesis of tetrabenzotetracene is described.