新显色剂2-〔2,3,5-三氮唑〕-5-〔(N,N-二羧基甲基)氨基〕苯甲酸的合成及其与钯的显色反应

Synthesis of 2-〔2,3,5-Triazolyazo〕-5-〔(N,N-Dicarboxymethyl)Amino〕 Benzoic Acid and Its Color Reaction with Palladium

合成了新显色剂 2 -〔2 ,3,5-三氮唑〕 - 5-〔(N ,N -二羧基甲基 )氨基〕苯甲酸 (简称TZACAB) ,并研究了性质及其与Pd显色反应的条件。结果表明 :试剂的分子式C1 3H1 2 N6O6,分子量 349 2 7;在pH 3 1 8HAc -NaAc缓冲溶液中 ,试剂与Pd形成 1∶1蓝色络合物 ,λmax为 661 4nm ,Pd量在 0～ 1 2 μg·ml- 1 范围内遵守比耳定律 ,表观摩尔吸光系数为ε =1 72× 1 0 4 L·mol- 1 ·cm- 1 ,大量的其它金属离子共存时 ,不经预分离也无需掩蔽剂可直接测定Pd -Pt催化剂中的微量Pd ,操作简便 。

A new chromogenic reagent 2-〔2,3,5-Triazolyazo〕-5-〔(N,N-Dicarboxymethyl)amino〕benzoic acid was synthesized and its colour reaction with palladium was studied spectrophotometrically.The structure of the reagent was determined by elemental analysis,UV spectra,IR spectra.The reagent react with Pd(Ⅱ)to form a stable red complex(1∶1)in the presence of HAc-NaAc at pH 3 18.The apparent molar absorptivity is 1 72×10 4 L·mol -1 ·cm -1 at λ max =611 4 nm.Beer's law obeyed in the range of 0～1 2 μg·ml -1 .The method has been applied to the direct determination of Pd-Pt catalysts with satisfactory results.