不对称的偶氮氯膦类试剂与稀土有灵敏的显色反应,近几年来我国分析工作者对其做了不少工作,筛选出一些具有实用价值的显色剂。纵观前面的工作,都是在较强的酸性条件下(pH1左右)进行的研究。为了进一步了解这类试剂的作用,本文选用弱酸介质(pH～4.5)对10种不对称的偶氮氯膦类试剂与稀土的反应做了研究。发现,对氯偶氮氯膦与钇有一特殊的β型反应,形成络合物的最大吸收波长为746 nm,摩尔吸光率为1.56×10~5升· Asymmetric chlorophosphonazo reagents with rare earth sensitive color reaction, in recent years, our analysts have done a lot of work to filter out some of the practical value of the developer. Throughout the previous work, are under strong acidic conditions (pH 1 or so) for the study. In order to further understand the role of these reagents, this article selected a weak acid medium (pH ~ 4.5) on the 10 kinds of asymmetric chlorophosphonazo reagents and rare earth reaction was studied. It was found that there was a special β-type reaction between chloro-chlorophosphonazo and yttrium, the maximum absorption wavelength of the complex formed was 746 nm and the molar absorptivity was 1.56 × 10-5 liters ·