Autocatalytic Chemiluminescence Sheds New Light on the Classic Permanganate–Oxalate Reaction

The emission of light from the permanganate–oxalate reaction enables monitoring of intermediates not accessible through traditional spectrophotometric interrogation. Despite the inherent complexity of the underlying chemical reactions and equilibria, the emission intensity–time profile was characterized by a simple model combining previously independent minimalistic descriptions of chemiluminescence and autocatalysis. The generation of the electronically excited [MnII]* emitter and the acceleration of the reaction even in the presence of high initial concentrations of MnII (under conditions that preclude accumulation of colloidal MnIV) provide new evidence for the reduction of manganese species by a reactive radical intermediate as a supplementary positive feedback loop to the formation of MnII.