Stability constants and rate coefficients for decarboxylation of oxalacetic acid and some metal oxalacetates

Abstract

Data collected at constant ionic strengths, from e.m.f. measurements of a glass electrode–calomel electrode cell, u.v. spectrophotometry, and a pressure-sensitive transducer, DVM, micro-computer system, have been used to calculate the stability constants of oxalacetic acid and some metal oxalacetates ML (L = oxalacetate, M = Cu^II, Ni^II, Zn^II, Co^II, or Mn^II) and the rate coefficients for decarboxylation of the species H₂L, HL, L, and ML. The stability constants of the ML species fit the Irving–Williams order (Zn < Cu > Ni > Co > Mn) but the order of the rate coefficients is Zn < Cu > Ni ≈ Co > Mn, and while the stability constant order is Ni > Zn the rate coefficient order is Ni ≈ Zn.