Stability Constants of Ca2+, Cu2+, Zn2+, UO2+ 2 , Mn2+, Co2+ and Ni2+ Complexes of Tetraethyl p-tert-Butylcalix[4]arene Tetraacetate in Nitrobenzene Saturated with Water

From extraction experiments and y-activity measurements, the exchange extraction constants corresponding to the general equilibrium M2+ (aq) + SrL2+ (nb) ⇔__ML2+ (nb) + Sr2+ (aq) taking place in the two–phase water–nitrobenzene system (M2+ = Ca2+, Cu2+, Zn2+, UO2+ 2 , Mn2+, Co2+, Ni2+; L = tetraethyl p-tert-butylcalix[4]arene tetraacetate; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Further, the stability constants of the ML2+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order Mn2+ < Co2+ < Cu2+ < Zn2+ < UO2+ 2 , Ni2+ < Ca2+.