Studies on Iron Complexes. I

Analytical Studies on Ferric-Gluconic Acid Chelates

Abstract

Gluconic acid undergoes coördination bonding with Fe³⁺ and its aqueous solution colors markedly, absorption maximum of this coördination compound being present at around 345mμ. The position of this absorption maximum shifts towards a shorter wave-length as pH of the solution increases. It has been assumed that this shift is due to coördination of OH- to Fe³⁺ and to the ol-bridge of polynuclear iron ion. Absorption of the maximum and concentration of ferric ion at various pH's are in linear relationship. Effect of 13 kinds of coexisting ions was examined and it was found that their interference became less as the acidity increased. The gluconic acid-iron complex has the composition of 1-3 of iron to 1 of gluconic acid and the complex was found to undergo decomposition by light.