The Role of Certain Organic Sulfur Compounds as Preventive Antioxidants. II. Activity as Peroxide Decomposers and Effect of Bases

Abstract

Abstract The results of this study of the activity of certain organic sulfur compounds as peroxide decomposers provides considerable insight to the mechanisms by which they function as preventive antioxidants. First, it is clearly evident that sulfides, disulfides, and their initial oxidation products are not the actual preventive antioxidants but rather the source from which the active materials are obtained. Thus, the sulfoxides and thiolsulfinates, formed in the initial reactions of sulfides and disulfides with hydroperoxides, serve as sources of sulfenic acid and thiosulfoxylic acid, which, together with their reaction products, are the real peroxide decomposers. It has also been demonstrated that sulfenic acid is the most effective peroxide decomposer, and that the acidic product of the initial reaction with hydroperoxide is also an effective peroxide decomposer. This product and the thiosulfoxylic acid from thiolsulfinate react with hydroperoxide by a catalytic mechanism which destroys many moles of hydroperoxide per mole of sulfur compound. The polar acidic character of these reactions was demonstrated by the effect of base. The catalytic decompositions were both effectively stopped by addition of CaCO3, and the thiosulfoxylic-acid-induced peroxide decomposition was stopped by complexing the acid with a sulfoxide.