Copper complexes of polymer-bound 4-aminopyridine as redox catalysts for the oxidative coupling of 2,6-dimethylphenol

Abstract

To improve the process of oxidative coupling of 2,6-dimethylphenol (DMP) to polyphenyleneoxide (PPO) with homogeneous soluble copper catalysts, a new type of ligand for the copper complexation was tested, viz. 4-disubstituted aminopyridine ( I). Under comparable mild reaction conditions the new catalysts were able to transfer DMP within a short reaction period and with very good specificity to high molecular weight PPO. These ligands were bound to linear, partially chloromethylated, polystyrene in order to increase the re-oxidation rate of the catalyst in the nonpolar environment created by the polystyrene matrix. The intrinsic activities of the macromolecular catalysts, expressed as the rate-determining rate constant, k 2, was increased up to 0.14 s −, which is a thirty-five-fold increase compared to the low-molar mass catalysts based on pyridine.