Conductance study of the complexation of substituted and lariat 16-crown-5 derivatives with alkali metal ions in nonaqueous solvents
Conductance study of the complexation of substituted and lariat 16-crown-5 derivatives with alkali metal ions in nonaqueous solvents
复制标题
取代和套索16-冠-5衍生物与碱金属离子在非水溶剂中络合的电导研究
DOI：
10.1007/bf01053636
复制
发表时间：
1992
期刊：
影响因子：
--
通讯作者：
T. Hakushi
中科院分区：
文献类型：
--
作者：
Y. Takeda;Itsumi Fujimaki;Shin;K. Aoki;Y. Kudo;H. Matsuda;Y. Inoue;T. Hakushi
用电导法测定了15-(2，5-二氧己基)-15-甲基-16-冠-5(L16C5)和15，15-二甲基-16-冠-5(DM16C5)与碱金属离子在25℃乙腈(AN)和碳酸丙烯酯(PC)中的1：1络合物的生成常数(KML)，除Li+和K+-16C5在PC中的选择性顺序外，L16C5和DM16C5的选择性顺序与母冠醚16-冠-5(16C5)的选择性顺序一致。Rb+和Gt；Cs+)，表现出大小适配关系。L16C5和DM16C5对碱金属离子的选择性不是由侧臂决定的，而是由腔的大小决定的。冠醚络合物的稳定性不取决于介电常数，而很大程度上取决于溶剂的给体数目。在M1=Na，M2=K和M1=Na，M2=Li的情况下，L16C5或16C5的KML(M1+)/KML(M2+)值随溶剂变化很大，而DM16C5的KML(M1+)/KML(M2+)值与溶剂无关。
Formation constants (KML) of 1:1 complexes of 15-(2,5-dioxahexyl)-15-methyl-16-crown-5 (L16C5) and 15,15-dimethyl-16-crown-5 (DM16C5) with alkali metal ions were determined in acetonitrile (AN) and propylene carbonate (PC) by conductometry at 25°C. Except for the case of Li+-and K+-16C5 complexes in PC, the selectivity sequences of L16C5 and DM16C5 are identical with those of the parent crown ether 16-crown-5 (16C5) regardless of the solvent (AN, PC, methanol) (Na1> Li+> K+> Rb+> Cs+), which show the size-fit correlation. The selectivities of L16C5 and DM16C5 for the alkali metal ions are governed not by the sidearms but by the cavity size. The stability of the crown ether complex is dependent not on the dielectric constant but largely on the donor number of the solvent. TheKML(M1+)/KML(M2+) ratio of L16C5 or 16C5 varies very much with the solvent in the cases of M1=Na, M2=K and M1=Na, M2=Li, but that of DM16C5 is almost constant regardless of the solvent.