某些不对称的双偶氮变色酸衍生物和稀土元素的络合反应(Ⅱ)——助色团、溶剂和α型β型反应的关系

THE COORDINATION REACTION OF SOME BISAZO DERIVATIVES OF CHROMOTROPIC ACID WITH RARE EARTH ELEMENTS(Ⅱ)——THE DISCUSSION ON THE RELATION BETWEEN THE AUXOCHROMES SOLVENTS ANDα-TYPEβ-TYPE REACTION

文章讨论了助色团、溶剂和α型β型反应的关系。指出只有含吸电子能力较强的助色团如—Cl,—NO2,—COCH3,—COOH等的变色酸衍生物能和稀土元素发生β型反应,而含助色团—SO_(3)H,—PO_(3)H_(2)—AsO_(3)H_(2)等的变色酸衍生物和稀土元素仅发生α型反应.含有助色团—COCH3,—NO2,—Cl的偶氮羧类、偶氮胂类、偶氮膦类的不对称变色酸试剂与稀土元素形成β型络合物,在一定实验条件下,在水溶液中的络合物能被异戍醇所萃取,而含助色团—SO_(3)H等的变色酸衍生物试剂的稀土络合物,则不能被萃取。同时指出乙醇丙酮等溶剂不仅能抑制β型络合物的形成,而且对于α型络合物来说,乙醇、丙酮等溶剂能大大提高反应的灵敏度。

The relation between the auxochromes,solvents and a-type,β-type reaction was investigated in this paper.It shows that only the bisazo derivaties of chromotropic acid containing stronger electrophilic auxochromes such as-Cl,-NO2,-COCH3,-COOH can formβ-type chelates with rare earth elements,and the auxochromes of-SO_(3)H,-PO3H,-AsO_(3)H_(2)only form in a-type.This paper points out that under proper conditions the bisazo derivatives which formβ-type chelates can be extracted by isoamyl alcohol,but not the a-type.The formation ofβ-type chelates can be inhibited by some solvents such as ethyl alcohol and acetone.But these solvents can greatly raise the sensitivity of the a-type reaction.