The oxidation of hydroquinone catalysed by Cu(II) ions immobilized on acrylic resins. The influence of ionic liquid

Series of acrylic resins with aminoguanidyl groups were prepared by aminolysis of nitrile groups in acrylonitrile, vinyl acetate and divinylbenzene terpolymer using aminoguanidine bicarbonate and hydrazine and subsequent substitution with thiourea/ethyl iodide (TEI) mixture. Complexation of the carriers with copper(II) acetate leads to the heterogenized catalysts with immobilized copper. Their catalytic activity was measured in the model oxidation reaction of hydroquinone (H2Q) to p-benzoquinone (Q) using hydrogen peroxide. The catalysts were tested in the same reaction in the presence of ionic liquid [bmim]BF4 (1-butyl-3-methylimidazolium tetrafluoroborate). Under optimal conditions the main product, i.e. p-benzoquinone was obtained after 60 min with 66% yield. The catalytic activity of the catalysts depends on Cu(II) loading and concentration of ion-exchange groups after sorption. Selectivity increases slightly in the presence of ionic liquid.