苯偶氮罗丹宁类显色剂的合成及其与铜的显色反应

Synthesis of Rhodanine Color Reagents and the Color Reaction with Cu(Ⅱ)

报道５－（４＇－氯－２＇－羧基苯偶氮）罗丹宁（２），５－（４＇－溴－２＇－羧基苯偶氮）罗丹宁（３）和５－（４＇－碘－２＇羧基苯偶氮）罗丹宁（４）的合成及在水溶液中的离奶常数Ｋ和Ｋ研究它们与铜的显色反应，在弱酸性时，３种显色剂与铜均形成配位比为２：１的配合物，２与铜的显色反应，当铜浓度在０～２．５μｇ／ｍＬ范围内符合比耳定律。用分光光度法测定了合金中铜的含量。

Three rhodanine color reagents 5-(4'-chloro-2'-carboxylphenylazo)-rhodanine,5-(4'-bromo-2'-carboxylphenylazo )-rhodanine and 5-(4'-iodo-2'-carboxylphenylazo)-rho-danine have been synthesized. The dissociation constants of the color reagents K_(a1) and K_(a2) aregiven. The color reactions of them with Cu(Ⅱ)are studied.The molar ratio of Cu(Ⅱ) tothe color reagents are found to be 1 : 2. The Beer's law is obeyed in the range of 0～2.5μg/mL for Cu( Ⅱ ). The chloro reagent has been used for copper determination in alloy sam-ples with satisfactory results.