Preparation of macroreticular redox resins with hydroquinone and catechol units as pendant groups and their properties

Macroreticular redox resins with hydroquinone and catechol units as pendant groups were prepared by the Friedel‐Crafts reaction of macroreticular styrene/divinylbenzene copolymer with 2,5‐ and 3,4‐dimethoxybenzyl chlorides, followed by removal of the methyl groups with hydrobromic acid. The redox capacity of the macroreticular resins was determined by oxidation of hydrazobenzene with resins in oxidized form. Resins with 1,4‐benzoquinone units were capable of oxidizing hydrazobenzene, whereas those with 1,2‐benzoquinone (catechol quinone) units exhibited no apparent oxidative ability; this seems to be due to a complex formation between azobenzene and the catechol units in the reduced resins. Adsorption of metallic ions onto catechol‐containing resins showed a high selectivity for Hg2+ ion. The effects of pH, reaction time, and ion concentration on the adsorption were also studied.