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用电导法研究了甲醇溶液中Na~+,K~+,Rb~+,Cs~+与新合成的冠醚2,3-苯并-8,15-二甲基-18C6,2,3-苯并-8,11,15-三甲基-18C6以及苯并-15C5,18C6的配位作用,计算了1∶1配合物的稳定常数.18C6对碱金属离子具有显著的选择性,而其二甲基及三甲基取代物的选择性则较差.冠醚环上引入苯环及甲基使配合物的稳定常数降低,在甲醇中碱金属离子与18C6配合物稳定性次序为K~+>Rb~+>Cs~+>Na~+,2,3-苯并-8,15-二甲基-18C6配合物稳定性次序为K~+>Rb~+>Na~+>Cs~+,2,3-苯并-18,11,15-三甲基-18C6配合物稳定性次序为K~+>>Na~+>Rb~+>Cs~+.引入甲基对Na~+配合物稳定性的影响小于K~+,Rb~+,Cs~+,即阳离子半径对配合物稳定性有较大的影响.在所研究的浓度范围内,碱金属离子-冠醚体系当量电导的降低程度与按配合物结构的预测一致.本文结果为设计具有特定选择性的冠醚结构提供了线索.
The effects of Na ~ +, K ~ +, Rb ~ +, Cs ~ + and the newly synthesized crown ether 2,3-benzo-8,15-dimethyl-18C6,2,3- Benzo-8,11,15-trimethyl-18C6 and benzo-15C5,18C6, the stability constants of 1: 1 complexes were calculated .18C6 has obvious selectivity to alkali metal ions, and its The selectivity of dimethyl and trimethyl substitution was worse.The introduction of benzene ring and methyl group on the crown ether ring decreased the stability constant of the complex.The order of the stability of alkali metal ion and 18C6 complex in methanol was K ~ The order of stability of 2,3-benzo-8,15-dimethyl-18C6 complex is K ~ +> Rb ~ +> Na ~ +> Cs ~ The order of stability of 2,3-benzo-18,11,15-trimethyl-18C6 complex was K ~ + >> Na ~ +> Rb ~ +> Cs ~ +. The stability of the complex is less than that of K ~ +, and Rb ~ +, Cs ~ +, that is, the cation radius has a great influence on the stability of the complex.In the studied concentration range, the equivalent conductivity Is consistent with the prediction of the complex structure.The results of this paper provide clues for the design of crown ether structures with specific selectivity.