Phenolic antioxidants mechanism underlying action

The mode of action of these compounds, which are under investigation, is via an antioxidative mechanism. Since COX enzyme catalysis involves radical intermediates, a radical scavenging moiety such as a di-fenf-butylphenol interferes with the cyclooxygenase reaction. Linkage of phenolic substructure with a thiazolone, oxazolone, thiadiazole or oxadiazole derivative produces non-... 

This review analyzes the data on most important antioxidants for polyolefins, i. e. the data on phenols. To learn consistently the whole mechanism of polyolefin stabilization, it is not possible to consider only the facts about the kinetics of the process and relationships between the chemical structure of stabilizers and their observed efficiency. It is necessary to understand the mechanism of stabilizer action on the basis of knowledge of transformations which occur in the inhibited oxidation and of properties of resulting products. The product analyses were obtained above all from the study of models and from independent syntheses. The confirmation of results under real conditions cannot be always carried out consistently because of low concentrations, difficult isolation, and reactivity of transformation products. It is also difficult to analyze such reaction mixtures directly in a polymer6 ... 

It was shown with two types of phenolic sulphides that both reaction centres take part in transformation processes which proceed under the conditions of inhibited oxidation of polymers. The phenolic part of the molecule participates in the inhibition mechanism by processes which follow from its chain-breaking function. Not only the starting phenolic sulphides react in this way, but also the phenolic compounds which were formed by reactions at the second centre, i. e., at sulphidie sulphur, and the products of their consecutive transformations. Transformations of the sulphidie part of the molecule are connected with preventive mechanism of antioxidation action, which is characterized by the decomposition of hydroperoxides. 

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