离子选择电极电位法测定有色冠醚与钠钾离子配合物的稳定常数

DETERMINATION OF THE STABILITY CONSTANT FOR COLOURED CROWN COORDINATES WITH SODIUM AND POTASSIUM ION BY ION SELECTIVE ELECTRODE POTENTIOMETRY

Frensdoff1] 曾用离子选择电极电位法测定冠醚与金属离子配合物的稳定常数.该文虽提到采用非线性最小二乘法处理实验结果,但未给出具体计算步骤和计算程序.本文用电位法测定了新合成的四种苯并-15-冠-5含偶氮基的衍生物与钠、钾离子配合物在甲醇中的稳定常数,并用自编的计算程序处理实验结果.

The stability constants for the coordinates of benzo-15-crown-5 and its coloured derivatives containing azo group with sodium and potassium ion in methanol have been determined by potentiometry with ion-selective electrodes.A non-linear regression analysis for treatment of data is described.The results is satisfactory.Benzo-15-crown-5 and its derivatives form 1:1 type coordinates with sodium ion,they form 2:1 type coordinates with potassium ion.The effects of substituents on the stability constants for 1:1 type are small,and the effects on 2:1 type are greater.Because the 2:1 type coordinates have a symmetrical“sandwich”structure,the stability constants for a second crown molecule to the 1:1 type ooordinates are larger than the first stability constant.