Antioxidative properties of phenyl‐substituted phenols. III. Model studies of synergistic actions between primary and secondary antioxidants

Products originating from the action of primary and secondary antioxidants can account, after interaction, for the synergistic effects observed in some polymers, e.g., polypropylene. Marked synergistic actions were observed between 4-alkoxy-2,6-diphenylphenols and β,β′-disubstituted diethyl sulfides. Using the corresponding phenoxyl radicals and sulfoxides as the model compounds, several products arise and disappear. In the case of 4-methoxy-2,6-diphenylphenoxyl and β,β′-diphenyldiethyl sulfoxide, 4-methoxy-2,6-diphenylphenol (the primary antioxidant) and the formation of a variety of sulfur compounds, capable of acting as peroxide decomposers, were detected, isolated, and identified using high-pressure liquid chromatography (HPLC) as a separation technique followed by semipreparative isolation.