Peroxidation of benzaldehyde by polymer-immobilized cobalt–EDTA complex

Abstract

A polymer-immobilized cobalt–ethylenediamine-tetraacetic acid (EDTA) complex was prepared via copolymerization of methacrylic acid (MAA) and acrylonitrile (AN) with EDTA-2Na (ethylenediamine-tetraacetic acid disodium salt) and ceric ions (Ce 2+) as the redox initiator. Polyacrylonitrile is nearly insoluble in organic solvent and was suitable for use as a heterogeneous catalyst. The EDTA–cobalt complex was immobilized successfully on the copolymer as shown by the infrared spectrum, elementary analysis and the inductively coupled plasma (ICP) result. From 8.98 to 16.8 wt.% EDTA was contained in these copolymers. BET was used to measure the 25 m 2/g surface area, which presented sufficient reaction sites for the reactants and active groups. With no induction period, benzaldehyde was converted to perbenzoic acid at a rate of about 1.81×10 −2 M/m 2 min at 20 °C. The yield and the selectivity of benzoic acid were ∼82% and 83%, respectively, after 3 h. The high reaction conversion rates were attributed to the increased reaction potential of Co(II) with the EDTA chelating group. The high yield of perbenzoic acid may be related to the poor affinity of the catalyst to perbenzoic acid, and the polymer-immobilized cobalt–EDTA complex finds it hard to oxidize perbenzoic acid into benzoic acid. Moreover, water led to a co-active effect on oxidation. In conclusion, the polymer-immobilized cobalt–EDTA complex oxidizes efficiently during benzaldehyde peroxidation.