Many 2,6-disubstituted phenols are readily oxidized with oxygen, a tertiary amine and a copper (I) salt being used as catalyst. The products are diphenoquinones (I) or 1,4-polyphenylene ethers (II) : [GRAPHICS] The effect of variation of the substituents on the phenol and the infrared spectra of the polymers is discussed. Amine complexes of copper salts are the only effective catalysts found for the polymer-forming reaction. The effect on the catalyst of varying the copper salt and the ligand is discussed.