Removal of catalyst from polyphenylene oxide reaction mixtures with nitrogenous salts of nitrilotriacetic acid

Claim 1

In a process for forming a polyphenylene oxide by an oxidative coupling reaction in the presence of a complex copper-amine catalyst comprising passing an oxygen-containing gas through an organic reaction solution of a phenol and said catalyst, the improvement which comprises separating the polyphenylene oxide from said organic reaction solution by contacting said reaction solution with a solution of from 1:1 to 20:1 moles per mole of copper of a nitrogenous salt of nitrilotriacetic acid that is formed from nitrilotriacetic acid and an amine of the formula: ##STR4## wherein R 2 , R 3 and R 4 are independently selected from the group consisting of hydrogen, alkyl of 1-20 carbon atoms, cycloalkyl of 3-6 carbon atoms and alkenyl of 1-20 carbon atoms with the proviso that no more than any two of R 2 , R 3 and R 4 may be hydrogen; or a compound of the formula: ##STR5## wherein R 5 and R 6 are independently selected from the group consisting of alkyl of 1-20 carbon atoms, aryl, alkaryl wherein the alkyl moiety has from 1-10 carbon atoms and aralkyl wherein the alkyl moiety has from 1-10 carbon atoms; to form a mixed organic reaction solution which contains a small aqueous phase from the water formed in the polymerization reaction, and thereafter, adding to said mixed organic reaction solution an antisolvent for the polyphenylene oxide that causes said polyphenylene oxide to precipitate.