Abstract
Azothiopyrine and methyl-azothiopyrine were synthesized as new chelating agents which form stable chelates with some metal ions at the mercapto and azo groups. Azothiopyrines are unusually stable in solution because of a strong intramolecular hydrogen bond between the mercapto and azo groups. The chelates of azothiopyrines with nickel (II), cobalt (II), copper (II), zinc (II), cadmium (II), mercury (II), Palladium (II) and silver (I) were prepared in a neutral or slightly acidic medium, and characterized by elementary analysis, and visible and ultraviolet absorption spectroscopy. The metal chelates are stable, insoluble in water, and extractable into some organic solvents, and the excess azothiopyrines can be removed by extraction with sodium hydroxide solution without decomposition of the metal chelates. Azothiopyrines may be applicable to extraction spectrophotometric determination of such metal ions as palladium (II), mercury (II), copper (II), nickel (II) and cobalt (II), in view of the high molar extinction coefficients of the chelates.
