Process for the preparation of bifunctional polyphenylene oxide

Process for the preparation of polyphenylene ether or polyphenylene oxide having two hydroxyl end groups, corresponding to formula (I):

• ##STR6## wherein R is identical or different and represents hydrogen, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or an aryl group having 6 carbon atoms,
• X represents a group ##STR7## wherein R.sup.1 represents hydrogen or an alkyl group having 1 to 4 carbon atoms, O, ##STR8## or SO.sub.2, and m and n represent integers from 1 to 200, wherein a mixture of phenols of formula (II) and (III) ##STR9## wherein X and R have the meaning indicated in formula (I) and Y represents Cl, Br or I,
• are reacted together in the presence of 1.times.10.sup.-5 to 1 mol per mol of phenol (II) of K.sub.3 Fe(CN).sub.6, copper halide copper sulphate, copper carboxylate or copper oxide.