Stability of 18-crown-6-ammonium complex in nitrobenzene saturated with water

From extraction experiments with Na-22 as a tracer, the extraction constant corresponding to the equilibrium NH4+(aq)+NaL+(nb) = NH4L+(nb) + Na+(aq) t aking place in the two-phase water-nitrobenzene system (L=18-crown-6; aq = aqueous phase, nb = nitrobenzene phase) was determined as logK(ex)(NH4+,NaL +) = 1.9 +/- 0.1. Further. the stability constant of the complex NH4L+ in n itrobenzene saturated with water was calculated for a temperature of 25 deg reesC: log beta (nb)(NH4L+) = 8.6 +/- 0.1. Finally, the individual extracti on constant of the species NH4L+ in the water-nitrobenzene system correspon ding to the equilibrium NH4L+(aq) = NH4L+(nb) was evaluated: logK(NH4L+)(i) = 1.8 +/- 0.1.