4,4'-Dicyanodiphenyl ether 4,4'-Oxydibenzonitrile 6508-04-9 Benzonitrile, 4,4'-oxybis- Benzonitrile, 4,4'-oxydi- Cyclohex-4-ene-1,2-dicarboxylic anhydride EINECS 229-399-1 NSC 87869