abstract |
Hexaarylbisimidazoles I <IMAGE> I where Ar1, Ar2 and Ar3 are each aryl, of which Ar2 and Ar3 can be linked to form an anellated ring system, are prepared by oxidizing the corresponding triarylimidazoles II <IMAGE> II in an aqueous/organic two-phase system in the presence of active amounts of an onium salt III. |