Eine Porphinsynthese durch anodische Oxydation von Pyrrol in Anwesenheit von Aldehyden

Abstract

Pyrrole has been oxidized in an irreversible wave on a rotating Pt-disc electrode in acetonitrile. When oxidation was carried out in the presence of benzaldehyde it was possible to isolate tetraphenylporphine. The porphine synthesis is initiated by protons formed on the oxidation of pyrrole. Addition and condensation of protonated pyrrole molecules with benzaldehyde formed tetraphenyl· porphinogen, which was oxidized to tetraphenylporphine anodically or by redox reaction in solution. This redox reaction with pyrrole forms dihydropyrrole which proceeds finally to chlorins and explain also the current yield greater than a hundred per cent. This synthesis of porphine can be achieved in a few minutes at -70 °C by addition of acid to a solution of pyrrole and benzaldehyde.