Stability of the barium–benzo-15-crown-5 complex in nitrobenzene saturated with water

From extraction experiments and g-activity measurements, the exchange extraction constant corresponding to the equilibrium Ba2+(aq) + SrL22+(nb) D BaL22+(nb) + Sr2+(aq) occurring in the two-phase water–nitrobenzene system (L =benzo-15-crown-5; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex (Ba2+, SrL22+) = 0.3 ± 0.1. Furthermore, the stability constant of the benzo-15-crown-5–barium complex in nitrobenzene saturated with water was calculated for the temperature of 25 °C: log bnb (BaL22+)=13.3±0.1.