4-(2′-噻唑偶氮)-邻苯二酚与Cr(Ⅲ)反应的分光光度研究

Spectrophotometric Study of the Reaction of Chromium (Ⅲ) with 4-(2-Thiazolylazo)-pyrocatechol

Cr（Ⅲ）直接显色反应研究报导较少,这与Cr（Ⅲ）的水合物具有惰性、显色反应难于进行有关。近年来报导某些杂环偶氮化合物与Cr（Ⅲ）的显色反应,但反应缓慢,需在沸水浴中长时间加热方能反应完全,噻唑偶氮邻苯二酚与Cr（Ⅲ）的反应尚未见报导。本文研究了我们合成的试剂与Cr（Ⅲ）的形成条件并用于含铬废水中微量铬的光度测定。试剂与仪器 1.铬标准溶液:准确称取金属铬0.5000g溶于1:1 HNO3中,移转至500ml容量瓶中,用水稀至刻度摇匀.1.0mgCr（Ⅲ）/ml.取适量上述溶液分别配成1.O×10-8M,10μg/ml.

Properties of 4-(2-thiazolylazo)-pyrocatechol and its complex formation with Cr(Ⅲ) were studied, and a new selective method for spectrophotometric determination of Cr(Ⅲ)was developed. The reaction of the complex formation in aqueous solution is very slow at room temerature, but speeds up under boiling water-bath. The molar absorption coefficient is 2.04×10~4 L·mol^(-1)cm^(-1). The stability constant of the complex is 3.71×10^(23). The method has been applied to the determination of chromium content in industrial waste waters.