Aluminum(III)-Isocitrate Solution Chemistry. A Potentiometric Study

Abstract

The equilibrium reactions of isocitrate with protons and Al³⁺ have been studied by potentiometric titration in aqueous 0.10 M KCl at 25°C. The protonation constants, corrected for K⁺-isocitrate complexing , were logβ_0,1,1 = 5.838, logβ_0,2,1 = 10.126 and logβ_0,3,1 = 13.219. The stabilities and stoichiometries of the complexes, Al_pH_qL_r, were defined by the constants logβ_1,1,1 = 9.55(05), logβ_1,0,1 = 6.90(02), logβ_1,-1,1 = 3.06(04) and logβ_2,-3,2 = 4.08(04) or logβ_3,-4,3 = 10.36(06). Compared with the Al³⁺-citrate system, complexes are of lower thermodynamic stability, but equilibrate more rapidly.