HETEROCYCLE-ACTIVATED AROMATIC NUCLEOPHILIC-SUBSTITUTION - POLY(ARYL ETHER PHENYLQUINOXALINES) .2.

A synthetic approach for the preparation of poly(aryl ether phenylquin oxalines) has been developed wherein the generation of an aryl ether l inkage is the polymer-forming reaction. Fluorines located on the para position of the benzene rings of various 2,3-diphenylquinoxaline heter ocycles were found to be activated toward nucleophilic aromatic substi tution. Model reactions demonstrated that these fluorine atoms on the phenyl groups of the diphenylquinoxaline were displaced by phenoxides in high yield, and the process was deemed suitable as a polymer-formin g reaction. Thus, the pyrazine component of the phenylquinoxaline hete rocycle has an activating effect on both the annulated benzo ring and the pendant phenyl groups, albeit to a lesser extent in the latter cas e. The extent of activation of the diphenylquinoxaline aryl fluorides was evaluated by both H-1 NMR and F-19 NMR spectroscopy. Appropriately substituted bis(fluorophenyl)-quinoxaline monomers were prepared and polymerized with bisphenols in high-boiling aprotic dipolar solvents c ontaining potassium carbonate. High molecular weight polymers were obt ained with glass transition temperatures ranging from 190 to 240-degre es-C. Enhanced polymer solubility was achieved.