Antioxidant activity of 5-alkoxymethyl-6-chromanols

The 5-alkoxymethyl-2,2,7,8-tetramethyl-6-chromanols (II) are excellent antioxidants against autoxidising safflower oil (ASO), although not as good as 2,2,5,7,8-pentamethyl-6-chromanol (I), the model compound of alpha-tocopherol. The aim of this work was to determine whether the rate of reaction of (II) with the radicals diphenylpicrylhydrazyl (DPP*) and galvinoxyl (ArO*) was directly proportional to their antioxidant activity against ASO. Compounds (II) reacted faster with DPP* than with ArO* but, in each case, slower than compound (I). The rates of reaction of I and II with both radicals followed the order I > II (R = H) > II (R = CH3) > II (R = other alkyls) and were directly proportional to their antioxidant activity against ASO.