溶液中のアルカリ金属イオンの化学結合力と溶液内平衡及び反応速度に及ぼす影響

Abstract

In poor solvating media, unexpected large chemical bonding forces of alkali metal ions, especially Li+, have been revealed. The chemical bonding forces of alkali metal ions and its effects on chemical equilibria and reaction rates in solution are reviewed. The complex formation constants of alkali metal ions with carboxylate ions as well as macrocyclic polyetheramines (L) in acetonitrile were obtained by the analysis of the shift in E1/2 of the mercury-dissolution wave of L. The higher ion aggregation, i.e., the formation of triple ions and quadrupoles, from 1:1 salts in higher permittivity solvents (er>10) was demonstrated by conductometry and spectrophotometry. The salt effects on the indicator acidity in acetonitrile have been attributed to the chemical interaction with the alkali metal ions (M+), alkaline earth metal ions (M2+), or anions. Stable carbocations were produced from (4-methoxy-substituted) trityl halides in acetonitrile, making use of the direct interaction between M+ of M2+ and the halide ions. A mixed-anion salt, BaCl(ClO4), was isolated from acetonitrile solution. The concentrated salt effects on the solvolysis reaction rates of organic halides (RX) in water-mixed solvents have been explained in terms of the direct interaction between M+ or M2+ and X-, and not just of medium effects. Alteration of the bulk water to isolated water molecules in the presence of concentrated salts is proposed.