The Semiquinone Radical of Tocopherol

Abstract

Tocopherol dissolved in a mixture of ether, alcohol, and pentene rapidly develops an orange-red color when the soln. is frozen at the temp. of liquid air and irradiated with u.-v. light. The color persists after the irradiation as long as the soln. is frozen, and is due to the formation of a semiquinone, similar to that formed by hydroquinone, in far higher concn. than is thermodynamically possible in liquid solvent. This places tocopherol in the category of reversible oxidation-reduction vitamin-enzyme systems.