Comparison of μ-nitrido diiron phthalocyanine – H2O2 and Fenton systems in transformation of poly- and perfluorinated aromatics does not support the involvement of hydroxyl radicals

Abstract

μ-Nitrido diiron tetrabutylphthalocyanine, (FePctBu4)2N, in combination with H2O2 can perform an efficient defluorination of heavily fluorinated aromatics via an oxidative pathway. To check whether hydroxyl radicals might be involved in this reaction we have compared catalytic activities of (FePctBu4)2N – H2O2 and FeSO4 – H2O2 systems in the transformation of five differently fluorinated benzenes, perfluoronaphthalene, pentafluoropyridine, and eight functionalized perfluorinated benzenes. In sharp contrast with (FePctBu4)2N – H2O2 system, all fluorinated benzene derivatives were completely stable in the presence of FeSO4 and H2O2 at 60 °C during 15 h. Perfluorinated aromatic compounds functionalized with electron-donating or electron-withdrawing groups as well as pentafluoropyridine exhibited very low conversions. These results unambiguously show that Fenton chemistry is not responsible for the oxidative defluorination of highly fluorinated aromatic compounds performed by the (FePctBu4)2N – H2O2 system.