Synthesis of 7-(4-Antipyrinylazo)-8-hydroxyquinoline and Study on Its Colour Reaction with In (III)

7-(4-Antipyrinylazo)-8-hydroxyquinoline was synthesized. The effect of order of dropping, temperature, time and solvent on the reaction was investigated. The structure of the product was identified by IR spectroscopy and ()~1H NMR spectroscopy. The spectrophotometric reaction of the reagent with indium was investigated. The results showed that in NaAc-HAc buffer solution with pH value of 4.5 7-(4-antipyrinylazo)-8-hydroxyquinoline reacts with indium to form a yellow 3∶1 complex. The maximum absorption wavelength of the complex is at 482 nm and its apparent molar absorptivity is 1.9×10~4 L/(mol·cm). Beer's law is obeyed in the range of 0 to 20 μg of indium per 25 mL.