Two novel benzo 15 crown 5 derivatives containing thiocycle(3) and selenacycle(4) have been synthesized in the presence of Na 2S·9H 2O or Na 2Se 2 and characterized by elemental analysis and mass, IR, UV and 1H NMR spectroscopy. The cation binding abilities and selectivities of parent benzo 15 crown 5(1) and its derivatives 3 and 4 with alkali and heavy metal ions have been evaluated by solvent extraction of aqueous metal picrates. The results obtained indicated that novel selera...