PROCESS FOR PRODUCING POLYPHENYLENE ETHER

PROBLEM TO BE SOLVED: To provide a process for producing a polyphenylene ether wherein the polymerization of a polyphenylene ether is stopped and a metal catalyst is recovered. SOLUTION: In the process for producing a polyphenylene ether by polymerizing a polyphenylene ether in a nonaqueous polymerization solvent in the presence of a catalyst to give a polyphenylene ether solution, bringing the obtained solution into contact with an aqueous solution of a chelating agent to form a chelate compound of a metal catalyst to stop the polymerization, separating the aqueous solution containing the chelate compound of the metal catalyst from the polyphenylene ether solution, and adding an alkali metal sulfide to the aqueous solution to deposit the metal catalyst as its sulfide in the form of a solid material from the aqueous solution, the addition of the alkali metal sulfide is controlled by measuring the oxidation-reduction potential of the aqueous solution containing the chelate compound of the metal catalyst when the alkali metal sulfide is added to the aqueous solution.