Induction of instantaneous chain reactions in the peroxodiphosphate–iron(II) system by selected substrates during a titrimetric procedure

Abstract

The reaction between peroxodiphosphate and iron(II) ions (in 1N-H₂SO₄) is instantaneous and is used to estimate the former quantitatively. But in the presence of some selected substrates such as methanol, ethanol, propan-2-ol, formaldehyde, glucose, and hypophosphite which do not react directly with peroxodiphosphate, an instaneous chain reaction is observed. This is explained by the competitive reaction between the substrate and iron(II) for the phosphate radical produced as the intermediate, and the ability of the substrate radical to reduce the oxidant, peroxodiphosphate.