In the present paper it has been shown that the 4‐halo‐2,6‐dimethylphenols can be polymerized to high molecular weight poly‐2,6‐dimethylphenylene ethers by the action of cupric ions, providing pyridine is also present. This reaction requires a stoichiometric amount of cupric ions and probably proceeds through complexed phenoxy radicals. Although the polymerization cannot be initiated by catalytic quantities of cupric ions, the same cupric salts which are active in the stoichiometric reaction will initiate the polymerization of the 4‐halo‐2,6‐dimethylphenols in basic solution. Here too, the products are high molecular weight polyarylethers and this reaction probably involves the displacement of halide ions by phenoxy radicals. The presumed di‐2,4,6‐trihalophenolate–bispyridine–copper(II) complexes were prepared and characterized. These complexes were decomposed under a variety of conditions, yielding polyhalophenylene ethers, which are highly branched as evidenced by their low intrinsic viscosities. Moreover, they are also terminated, probably through dioxin formation, since they show little or no residual hydroxyl in the infrared. Similarly, the polyhalophenylene ethers prepared by decomposition of the silver salts are also branched and terminated. In this connection, however, silver 4‐chloro‐ and silver 4‐bromo‐2,6‐dimethylphenolates were prepared and decomposed to a poly‐2,6‐dimethylphenylene ether of molecular weight 1800–2200 possessing one halogen and one hydroxyl per polymer chain. The infrared spectrum of this polymer, with the exception of the hydroxyl region, agrees in detail with the infrared spectrum of high molecular weight poly‐2,6‐dimethylphenylene ether prepared by oxidation of 2,6‐dimethylphenol and thus provides a proof for the gross structure of the polymer. Finally, it was found that the blue to blue‐green solutions produced from the decomposition of certain of the copper complexes and the silver salts, respectively, are diamagnetic. This finding mitigates against the participation of phenoxy radicals as the active species in these polymerizations.
