Redox coupling phenolate ligands

The activated phenols are C-0 coupled each other. The dimer thus formed is activated by a similar mechanism, and polymerization occurs. The effects of the amine ligand (L) are to improve the solubility and stability of the Cu ion, to affect the stability of the substrate-coordinated complex, and to control the redox potential of the Cu ion. The Cu-complex catalyst not only enhances the rate of polymerization, but it also has an important effect on the coupling reaction. 

Dimethylphenol is oxidatively polymerized to poly(2,6-dimethyl-1,4-phenyl-ene ether) with a copper-amine complex by a laccaselike reaction. The activated phenols are coupled to form a dimer. The dimer is activated by a mechanism similar to that by which the polymerization proceeds. The effects of the amine ligands are to improve the solubility and the stability of the copper complex as well as the phenol-coordinated complex and to control the redox potential of the copper complex. 

---