Synonyms: 2,5-Cyclohexadiene-1,4-dione,2-(3-hydroxy-3,7,11,15-tetramethylhexadecyl)-3,5,6-trimethyl-, radical ion(1-),[3R-(3R*,7R*,11R*)]-; p-Benzoquinone,2-(3-hydroxy-3,7,11,15-tetramethylhexadecyl)-3,5,6-trimethyl-, radical ion(1-)(8CI); Vitamin E semiquinone