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本文报道以大环中性配体作为大块液膜载体时,冠醚结构对金属离子的传质选择性,以及迁移速度与配合物稳定常数之间的关系。实验结果表明,在一定的配合物稳定常数范围,其稳定常数越高,迁移速度也越快。对于4-取代苯并-15-冠-5类型的冠醚与Na~+的配合物,其配合物的稳定常数顺序与取代基的给电子或吸电子效应的强弱一致,而迁移速度与稳定常数的大小顺序一致。在影响着冠醚醚氧碱度的取代基效应的Hammett常数(δm+δ_P)同配合物稳定常数logk及离子迁移通量logJ之间存在着线性关系。对于其空腔直径与N_a~+相匹配的苯并-15-冠-5及空腔直径与K~+相匹配的苯并-18冠-6,当冠醚中的一个或两个1,2-亚乙基被1,3-亚丙基所代替而变成苯并-17-冠-5及苯并-19-冠-6时,其配合物的稳定常数减小,迁移速度也相应减小。
In this paper, we report the mass transfer selectivity of crown ether to metal ions and the relationship between the migration rate and the stability constant of the complex when the macrocyclic neutral ligand is used as bulk liquid membrane carrier. The experimental results show that the higher the stability constant, the faster the migration rate, in a certain stability range of the complex. For the complexes of 4-substituted benzo-15-crown-5 type crown ethers with Na ~ +, the order of the stability constants of the complexes is consistent with the electron-donating or electron-attracting effects of the substituents, The order of the stability constants is the same. There is a linear relationship between the Hammett constant (δm + δ_P) and the logarithm of the complex stability constant, log k, and the ion mobility, log J, for the substituent effects that affect the basicity of ethers. For benzo-15-crown-5, whose cavity diameter matches N_a ~ + and benzo-18 crown-6 whose cavity diameter matches K ~ +, when one or two of crown ether 1, 2-ethylidene is replaced by trimethylene to become benzo-17-crown-5 and benzo-19-crown-6, the stability constant of the complex decreases and the migration rate also corresponds to Decrease