Potentiometric studies of oxidation–reduction reactions with redox copolymers

Polymeric oxidants in the bead form that were macroporous styrene/divinylbenzene copolymers containing N ‐chlorosulfonamide functional groups (in sodium or hydrogen form) or N ‐bromosulfonamide groups (in sodium form) were synthesized and investigated to determine their oxidizing powers. The redox potentials of the N ‐chlorosulfonamide/sulfonamide and N ‐bromosulfonamide/sulfonamide systems were determined by potentiometric studies at different pH values with aqueous solutions of Na 2 SO 3 , KCN, and KSCN as reducers. The formal redox potentials of the N ‐chlorosulfonamide copolymers were 0.79, 0.44, and −0.12 V at pH's of 1.8, 8.45, and 13.6, respectively. The formal redox potential of the N ‐bromosulfonamide copolymer was about 100 mV higher in comparable conditions and in solutions over pH = 5 (e.g., 0.56 V at pH = 8.56). The comparatively higher oxidizing power of the N ‐bromosulfonamide copolymer was particularly evident in a strong alkaline medium (in which the N ‐chlorosulfonamide copolymer was not reactive). In contrast, the N ‐chlorosulfonamide copolymer showed strong oxidative properties in acidic media (in which the N ‐bromosulfonamide copolymer decomposed itself). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008