Chem. J. Chinese Universities ›› 1990, Vol. 11 ›› Issue (7): 672.

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Studies on Bis-Crown Ether ( V )——Extractive Behaviour of Alkali Metal Picrates with Schiff Base and Secondary Amine Type Bis-Crown Ethers Containing Benzo-18-Crown-6 Moiety

Wang Dengjin, Wang Defen, Sun Xiaoqiang, Hu Hongwen   

  1. Department of Chemistry, Nanjing University, Nanjing
  • Received:1988-10-05 Online:1990-07-24 Published:1990-07-24

Abstract: Extraction of alkali metal picrates with two different kinds of schiff base and secondary amine type bis-crown ethers containing benzo-18-crown-6 moiety was carried out in chloroform at 25 ±0. 2℃. The distribution ratio of alkali metal picrates, the stoichiometry and extraction equilibrium constants Ke of bis-crown ether-cation complexes were determined. The results show that the bis-crown ethers form 1 : 1(crown unit : cation) cpmlexes with Na+,K+,Rb+ and probably form 2 : 1 intramolecular or intermolecuiar complexes -with Cs+, but mono Schiff base type bis-crown ethers preferably form 1 :1 complexes with Cs+. Moreover the Ke, values of the secondary amine type bis-crown ethers are much larger than those of the Schiff base type bis-crown ethers. N1 exhibits the greatest extractibility and selectivity for Cs+ ions. It is noteworthy that the bis-crown ethers N5 containing unsymmetrical crown rings has a larger extractibility for Rb+ ions.

Key words: Schiff base type bis-crown ether, Secondary amine type bis-crown ether, Distribution ratio, Extraction equilibrium constant

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