AbstractTransformations of N,N′‐disubstituted 1,4‐benzoquinonediimines have been investigated as a means for the elucidation of processes occurring in hydrocarbon polymers stabilized with amine antidegradants and of transformations accompanying the analyses of extracts of aged rubbers. N‐Phenyl‐N′‐isopropyl‐1,4‐benzoquinonediimine (1b) is quickly hydrolyzed on a silicagel surface, giving rise to N‐phenyl‐1,4‐benzoquinoneimine (3). The hydrolysis of N,N′‐diphenyl‐1,4‐benzoquinonediimine (1a) proceeds more slowly under the same conditions, but the released aniline quickly reacts with the initial (1a), giving rise to N,N′‐diphenyl‐1,4‐phenylenediamine(2a), 2‐(phenylamino)‐N,N′‐diphenyl‐1,4‐benzoquinonediimine (4) and azophenine (5). The Reaction is catalyzed by the weakly acid surface of silicagel. Compound (4) is readily disproportionated thermally to 1,2,4‐tris(phenylamino)‐benzene (8) and 2, 10‐dihydro‐10‐phenyl‐2‐(phenylimino)phenazine (9), even in the absence of a catalyst. A mechanism of the formation of compounds arising in the reaction has been suggested. Diimine (1a) possesses a higher oxidation potential than all the products derived from it, so that it is quickly reduced by these products to (2a). The gradual formation of (2a) may explain the retardati