Antioxidants and stabilizers. XXXV. On the character of discolouring compounds formed from 2,2′-methylene-bis-(4-methyl-6-tert.-butylphenol) during oxidative degradation of polymers

A model reaction of 2,2′-methylene-bis-(4-methyl-6-tert.-butylphenol) (I) with tert.-butylhydroperoxide in the presence of cobalt-II-acetylacetonate yielded coloured products which cause the discolouration of substrates stabilized with antioxidant I. Dimer V, trimer VI and tetramer VIII were identified, and their relation to the colourless oligomeric products II and III was proved. The structure of dimer V was confirmed by an independent synthesis. The formation of analogous compounds was proved by an investigation of the oxidation of tetralin; it is discussed in connection with the oxidation of isotactic polypropylene. Both materials were stabilized with antioxidant I.