Reinvestigation of bromination of 8-substituted quinolines and synthesis of novel phthalonitriles

Bromination of a series of 8-substituted quinolines was reinvestigated and specified for optimum yields and isolation conditions. Mono bromination of 8-hydroxyquinoline (2a) and 8-aminoquinoline (2c) gave mixture of mono and dibromo derivatives 5,7-dibromo-8-hydroxyquinoline (3a), 5,7-dibromo-8aminoquinoline (3c), 7-bromo-8-hydroxyquinoline (3d), 5-bromo-8-aminoquinoline (3e) while 8methoxyquinoline (2b) furnished 5-bromo-8-methoxyquinoline (3f) as sole product. Novel phthalonitriles, 4(quinolin-8-yloxy) phthalonitrile (6) and 4-chloro-5-(quinolin-8-yloxy) phthalonitrile (8) of 8-hydroxyquinoline (2a) were synthesized and converted into their respective bromo derivatives 4-(5-bromoquinolin-8yloxy) phthalonitrile (7) and 4-((5-bromoquinolin-8-yl) oxy)-5-chlorophthalonitrile (9).