The role of resin-amine transition metal complexes in hydrogen peroxide decomposition

Abstract

Dowex-50W resin in the form of ethylamine- and dimethylamine-transition metal ion (Co II, Ni II, Mn II) complexes have been used as potentially active catalysts for H 2O 2 decomposition in an aqueous medium. The rate constant (per g of dry resin) was evaluated with a resin containing 8% divinylbenzene crosslinkage over the temperature range 25 – 40 °C. With both ligands the reaction rate was directly proportional to [H 2O 2] for complexes with Co II and Ni II and to [H 2O 2] 2 for Mn II complexes. Probable mechanisms for the reactions have been proposed. The activation energy with both ligands was found to increase in the following sequence: Ni II < Co II < Mn II. The activation energies of the complexes with the Me 2NH ligand were smaller than those with the EtNH 2 ligand. The change in the entropy of activation, the rate constant (per g of dry resin) and the probability of activated complex formation with the secondary amine (Me 2NH)-transition metal complexes were smaller than those with the primary amine (EtNH 2)-transition metal complexes. This is due to the steric effect of the methyl groups in the Me 2NH ligand.