Polyphenylene oxide

one of the five major universal engineering plastics in the world

was widely used in all walks of life. It has been more than half a century since polyphenylene ether was first synthesized. However

the synthesis mechanism of polyphenylene oxide was still not fully elucidated. In the paper

three possible mechanisms of the oxidative coupling in synthesizing polyphenylene oxide were introduced

including coupling mechanism of phenoxy radicals coordinated to catalyst complex

coupling mechanism of free phenoxy radicals and coupling mechanism of one-step two electron transfer. Of the three mechanism

coupling mechanism of one-step two electron transfer was generally accepted in the academic circles. Also

the chain extension mechanism including redistribution and rearrangement of quinine ketal intermediate was further elaborated.