Synthesis of A New Chromogenic Reagent p-Acetylantipyrylazo and its Application to Determination of Rare Earths

A new chromogenic reagent of asymmetric antipyrinylazoic compound: 2-(4-antipyrinylazo)7-(4-acetylphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid has been synthesized and conditions of its chromogenic reaction with rare earth ions have been studied.In hydrochloric acid media of pH=2.5,rare earth ions with reagent reacts to form a 1∶4 stable blue complex,the complex has maximum absorption at about 640 nm and the apparent molar absorptivity can reach 1×10~5 L·mol~(-1)·cm~(-1).Results of experiments show: the chromogenic agent which are studied can also be used in spectrophotometric analysis of complex sample which contain mixd rare earth.