Nitroxides are an important class of radical trapping antioxidants whose promising biological activities connected to their ability scavenge peroxyl (ROO•) radicals. We have measured the rate constants reaction with ROO• (kinh) for a series 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) derivatives as 5.1 × 106, 1.1 5.4 105, 3.7 1.9 and 5.6 104 M–1 s–1 −H, −OH, −NH2, −COOH, −NHCOCH3, −CONH(CH2)3C...