Roles of cobaltic salts as catalysts of oxidation

Abstract

Cobalt salts are usually held to catalyze autoxidation by decomposing hydroperoxides by reactions (i) and (ii): the latter may be questioned and (iii) is an alternative. Evidence showing that cobaltic salts of carboxylic acids decompose to alkyl radicals is summarized. The reaction (iv) is equivalent to (iii) as a catalytic process. Cobaltic ions attack unsaturated acids mainly at the double bond: this too may be important in relation to autoxidation. Co^II+ RO₂H → Co^III+ RO·+(OH)^–(i), Co^III+ RO₂H → Co^II+ RO₂·+ H⁺(ii), Co^III+ RH → Co^II+ R·+ H⁺(iii), R—CO—O—Co^III→ R·+ CO₂+ Co^II(iv)