在邻羟基偶氮化合物的吡啶环上引入卤素原子,可以提高试剂的灵敏度和颜色对比度,但一般认为以引入一个卤素原子为好。另外,在芳环偶氮基的对位上引入较强的推电子官能团也有助于提高试剂的灵敏度。目前用的3,5-二溴-PEDAP就是根据上述原则合成的一种双卤素取代邻羟基偶氮试剂。我们用甲基代替乙基,合成了2-(3,5-二溴-2-吡啶偶氮)-5-二甲氨基酚[3,5-Br_2-DMPAP],并考察了它的基本性质和用作分析试剂的可能性。实验表明:在适当条件下,它可同很多阳离子发生颜色反 The introduction of a halogen atom to the pyridine ring of an ortho-hydroxyazo compound can improve the sensitivity and color contrast of the reagents, but it is generally considered to be a good idea to introduce a halogen atom. In addition, the introduction of a strong push electron functional group at the para position of the azo-aromatics also helps to increase the sensitivity of the reagents. The currently used 3,5-dibromo-PEDAP is based on the principle of synthesis of a double halogen substituted ortho-hydroxy azo reagent. We have substituted 2- (3,5-dibromo-2-pyridylazo) -5-dimethylaminophenol [3,5-Br_2-DMPAP] with methyl group and investigated its basic properties And for the possibility of analyzing reagents. Experiments show that: Under appropriate conditions, it can occur with a lot of cations color