Synthesis of 4-(4-Chlorobenzenediazo) amino-4′-chlorineazobenzene and Its Colour Reaction with Mercury(II)

A new reagent 4-(4-chlorobenzenediazo)amino-4′-chlorineazobenzene(CDACAB) was synthesized,and its colour reaction with mercury(Ⅱ) was studied.In the presence of OP,the reagent can react with mercury(Ⅱ) to form a stable orange-red complex in a medium of Na2B4O7-NaOH buffer of pH 10.5.The apparent molar absorptivity is 1.15×105 L·mol-1·cm-1at the maximum absorption of 498 nm.Beer's law was obeyed over the range of 0-7.0 μg mercury(Ⅱ) in 10 mL solution.The method has been directly applied for the determination of Hg(Ⅱ) in waste water with relative standard deviation of 1.6%-3.1% and recovery of 96.5%-103.8%.