Oxidation of tocopherols ("vitamin E") produces complex mixtures of compounds, with the ortho-quinone methide being a key intermediate. The conversion of the hitherto hypothetical aromatic zwitterion to the olefinic ortho-quinone methide would simply be controlled by bond rotation. In the present work, special tocopherol derivatives were synthesized that allowed detailed spectroscopic studies (NMR) on the zwitterionic intermediate, and thus a direct proof of its existence for the first time. Conventional, decade-old teaching on formation and chemistry of ortho-quinone methides will now have to be revised. Most recently the almost completely neglected class of tocopheramines tocopherols that bear an amino group instead of the phenolic hydroxyl group have undergone a surge of interest due to their potential in chemotherapy. A comprehensive knowledge about their chemistry, reactivity and products is a prerequisite to any application. Making use of EPR spectroscopy and chemical trapping, for the first time the one-electron and two-electron oxidation chemistry of tocopheramines was established. The bromination of different tocopherols can proceed, in principle, according to two different mechanisms, either by a classical electrophilic substitution at the aromatic core or by an oxidation-addition sequence leading to a bromomethyl derivative. The bromination behaviour of all four tocopherols was thoroughly studied. Based on the product ratios and computational studies, activation energies were calculated and the preferred pathways were identified. All bromination products were synthesized and fully analytically characterized, clarifying contradictory data in the pertinent literature and providing a reliable set of standard compounds for future studies. Over the past several years, some traditional teaching on the oxidation chemistry of tocopherols has proved to be erroneous. Oxidation products that so far have been explained based on tocopheroxyl radical chemistry are actually formed involving the ortho-quinone methide as key intermediate. The general mechanism of ortho-chinone methide formation was revised as well. To update the current knowledge of ortho-quinone methide chemistry related to tocopherols, also considering the new results of the present thesis, this topic was comprehensively reviewed.