Bond stabilisation in tocopherols. Part III. Structure of nitroso-tocopherols and conversion into quinones

Abstract

Spectroscopy indicates oxime structures for 5- and 7-nitroso-tocopherols. The existence of a Mills–Nixon effect in 6-chromanols suggests that the 5,6-chromanquinonoid structure is more stable than the 6,7-chromanquinonoid structure. In accordance with this expectation, 5-nitroso-γ-tocopherol was converted into γ-tocopherol-5,6-quinone whereas 7-nitroso-β-tocopherol gave 7-hydroxy-β-tocopherol-p-quinone.