Antioxidants and stabilizers—LXXII. Products of reaction between oxidized polypropylene and 2,6-ditert-butyl-4-methylphenol

Oxidation of atactic polypropylene (PPH) has been used in the preparation and characterization of hydroperoxide PPOOH, from which radicals PPOO- were generated. Their interaction with 2,6-ditert-butyl-4-methylphenol (BHT) demonstrated transformations of the antioxidant, leading, on the one hand, to peroxycyclohexadienone, PPOO-CHD, in which the residue of reacted BHT is bound on PPOO and, on the other, to compounds resulting from the oxidative coupling of BHT; of these, 4,4′-ethylenebis (2,6-ditert-butylphenol) and 3,3′,5,5′-tetratert-butylstilbenequinone were identified. Further products of coupling are light- to deep- brown; some of them contain phenolic and quinomethinoidic functions. PPOO-CHD may take an active part in the atmospheric ageing of PPH arising from decomposition caused by heat, radiation or catalytic impurities.