化学学报 ›› 1983, Vol. 41 ›› Issue (10): 877-883. 上一篇    下一篇

研究论文

冠醚配合物的热力学性质的研究 III. 碱金属离子与18C6甲基衍生物配位反应的电导研究

罗勤慧;沈孟长;诸葛卸梅;戴安邦;陆国元;胡宏纹   

  1. 南京大学化学系
  • 发布日期:1983-10-15

Studies on thermodynamic properties of the crown coordination compounds III: Conductometric study on the coordination compounds of benzo-15- crown-5, 18-crown-6 and methylated 18C6 with alkali metal ions in methanol

LUO QINHUI;SHEN MENGCHANG;ZHUGE XIEMEI;DAI ANBANG;LU GUOYUAN;HU HONGWEN   

  • Published:1983-10-15

关键词: 热力学性质, 冠式化合物, 电导法, 十八碳化合物, 碱金属络合物, 螯合反应

The coordination reaction of Na+, K+, Rb+ and Cs+ with benzo- 15-crown-5, 18-crown-6 and the newly synthesized cyclic polyethers 2, 3-benzo-8, 15-dimethyl-18-crown-6, 2, 3-benzo-8, 11, 15-trimethyl-18-crown-6 in methanol at 25`C has been studied by conductometric titration. The stability constants for the 1:1 coordination compounds were calculated. The marked selectivity of 18-crown-6 toward alkali metal ions was not found in its methyl derivatives. The induction effect of the benzene ring and methyl group on polyether ring reduced the stability of the coordination compounds. In methanol, the stability sequence of te compounds of alkali metal ions with 18-crown-6 was K+>Rb+>Cs+>Na+, that of its dimethyl derivative was K+>Rb+>Na+>Cs+ and that of its trimethyl derivative was K+>Na+>Rb+>Cs+, that is, the methyl substituent had a weaker influence on the stability of Na+ compound than on that of Rb+ or Cs+ compound. In the range of concentration studied, decrease in equivalent conductance is in agreement with the prediction on the basis of the structure of the complexes. The above results may give a clue for modifying the structure of a crown ether for specified selectivity.

Key words: THERMODYNAMIC PROPERTIES, CROWN ETHER COMPOUNDS, CONDUCTOMETRY, C18 COMPOUNDS, ALKALI METAL COMPLEX, CHELATION REACTION

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