新不对称偶氮羧衍生物的合成及其与钙离子的β型显色反应

我们合成了五种新的不对称偶氮羧衍生物,并研究了它们与钙离子之间的一种特殊反应-β型反应,考察了试剂分子结构与反应性能的关系。着重探讨了对羧基偶氮羧与钙离子的β型反应行为,在柠檬酸介质中,钙离子与该试剂形成组成比为1:2的灵敏的稳定配合物,最大吸收波长为718nm(Δλ=157nm),表观摩尔吸光系数ε=1.51×10^5L.mol^-^1.cm^-^1,测定条件下,1-13μgCa/25mL符合Beer定律,采用小体积显色,反应可在15分钟内进行完全,配合物可稳定4小时不变。动力学研究结果表明,对羧基偶氮羧与钙离子只发生β型反应,反应级数为2。

The synthesis of new unsymmetric derivatives of carboxylazo and their β-type colour reactions with calcium ion

Five new unsymmetric derivatives of carboxylazo, p- carboxycarboxylazo, p-chlorocarboxylazo, p-methylcarboxylazo, p- sulfocarboxylazo and m-nitrocarboxy-lazo were synthesized. A new type, β-type reactions of calcium ion with these reagents were studied. The relationship between the molecular structure of reagents and reaction conditions was detected. The β-type reaction behavior between calcium ion and p-carboxycarboxylazo was investigated in detail. calcium ion reacts with it to form a 1:2 sensitive and stable β-type complex in citric acid medium, having an absorption maximum at 718nm (Δλ=157nm). Beer's law is obeyed for 1-13μg of calcium in 25mL of solution with an apparent molar absorptivity oof 1.51× 10^5L.mol^-^1.cm^-^1 at 718nm. The complex formation is complete within 15 min in a small volume and the resulting complex is stable for 4h after dilution. Kinetic study on this system has shown that calcium ion reacts with p-carboxycarboxylazo to form only a β-type complex and the order of reaction is 2.