Removal of the catalyst from polyphenylene ethers

A process for the preparation of a high molecular weight polyphenylene ether from a monohydric phenol, which is alkyl-substituted at the two ortho-positions but not at the para-position and may or may not be alkyl-substituted at the meta-position, by an oxidative coupling reaction with oxygen at from 10.degree. to 50.degree. C. in the presence of a catalyst complex obtained from a copper salt and an organic amine, in the presence of from 1 to 20 parts by weight of a solvent per part by weight of the monomeric phenol, and in the presence or absence of an activator, wherein the metal component of the catalyst is removed after the polymerization by adding one or more organic ammonium salts of the formula ##STR6## where A.sup..crclbar. is an anion or polyanion of, a polycarboxylic acid, polyalkylenepolycarboxylic acid, aminocarboxylic acid, aminopolycarboxylic acid, polyaminocarboxylic acid, polyphosphonic acid or polyaminophosphonic acid, R.sup.1 is hydrogen, R.sup.2 and R.sup.3 are each hydrogen, alkyl of 1 to 18 carbon atoms or aryl and R.sup.4 is alkyl of 1 to 18 carbon atoms or aryl, and wherein the ammonium salt or salts are formed from monoalkylamines, dialkylamines, trialkylamines, arylamines or alkylarylamines.