AbstractThe reaction of N‐phenyl‐1,4‐benzoquinoneimine(I)Decoding of abbreviations see p. 103/104.and 4‐hydroxydiphenylamine(II)with the carbon centred 1‐cyano‐1‐methylethyl radical (R·) was studied in connection with an investigation of the action mechanism of industrial antidegradants, such as N‐phenyl‐N′‐sec‐alkyl‐1,4‐phenylenediamines. The mixture ofIandIIreacts very readily with R·, giving rise toIII,VI, andVIII.Ialone reacts much slowlier, and the reaction mixture contains more products.IVandVIIwere identified along withIII. Under the conditions used,IIalone does not react at all.IVexists in two isomeric forms, syn and anti.VIIIis very labile;XIwas isolated from its transformation products. Reduction ofIVgivesV, whic