Reaktivität von Koordinationsverbindungen XII [1] . Einfluss verschiedener Liganden auf den Mechanismus der Cu 2+ ‐Katalyersierten Autoxydation von o‐Phenylendiamin

The Cu 2+ ‐catalyzed oxidation of o ‐phenylenediaminc (H 2 B) by O 2 is strongly influenced by different organic and inorgarnic ligands. While chelating agents, e. g . ethylenediamine and ethylenediamine tetraacetic acid, inhibit the catalysis by Cu 2+ , the reaction is accelerated under the influence of some monodentate ligands, e.g . C1 − , Br − , NH 3 , pyridine and imidazolc (PYR). We have found that these latter ligands enable the cupric ion to react directly with H 2 B (I). The cuprous complexformed in equilibrium is then reoxidized by O 2 (II). The rate determining oxidation step (I) is much faster than any direct reaction between o‐phenylenediamine and O 2 catalyzed by cupric ion.