anionic resin An ion exchange material that can exchange anions, such as Cl⁻ and OH⁻, for anions in the surrounding medium. Such resins are used for a wide range of analytical and purification purposes.
They are often produced by addition of a quaternary ammonium group (–N(CH₃)₃⁺) or a phenolic group (–OH⁻) to a stable polyphenylethene resin. A typical exchange reaction is:
resin–N(CH₃)₃⁺Cl⁻ + KOH ⇆ resin–N(CH₃)₃⁺OH⁻ + KCl
Anionic resins can be used to separate mixtures of halide ions. Such mixtures can be attached to the resin and recovered separately by elution.