Determination of Redox Potential and Stability Constant of Iron(III)-3-Hydroxy-2-Methyl-4-Pyrone Complexes

Maltol (3-hydroxy-2-methyl-4-pyrone) is a monobasic bidentate ligand for a number of metal ions. it forms a stable 5-membered chelate ring with the metal ions. having a very low toxicity index it has found extensive use as a flavouring agent. depending on the oxidation state of the metal ion and the metal to ligand stoichiometry, the complex ion can be uncharged or it may have a +1 or +2 charge. this study describes the results of a potentiometric study for the determination of stability constants and a spectrophotometric determination of ph dependent redox potential at ph 3.0, 4.0, 5.0 and 7.0 using ascorbate as a reducing agent. at 25o c, the results were: log b1 = 11.20, log b2 = 21.90 & log b3 = 28.20 and eo complex (vs nhe) at ph 3.0 = 0.229; ph 4.0 = 0.144; ph 5.0 = 0.107; ph 7.00 = 0.0442. these results are interpreted in terms of efficacy of maltol for its proposed usage for different medical applications.