Catalytic and inhibitory effects of metal chelates in autoxidation reaction

Abstract

Certain aspects of catalyst-inhibitor conversion with bis(N-butylsalicylaldimino)cobalt(II) were further examined: they include variations in oxygen partial pressure, hydrocarbon substrate and solvent environment. The decrease of autoxidation rates with increasing polarity of environment, which is in contrast to AIBN-initiated autoxidation, was particularly noteworthy. Catalytic and inhibitory effects of α-dithiodiketone chelates were studied in detail: they included NiS₄C₄Ph₄, PdS₄C₄Ph₄, PtS₄C₄Ph₄, CoS₄C₄Ph₄. PBu₃ and similar cobalt chelates. They were shown to have catalytic activity as hydroperoxide decomposers of unprecedented magnitude. One mole of metal chelate decomposed catalytically at least 1000 moles of hydroperoxide and there was no evidence of free radical intermediates. These compounds were also free radical acceptors and were generally autoxidation inhibitors rather than catalysts at any concentration.