Enolization and oxidation: IV. Iron ion catalyzed autoxidation of acetoin

Abstract

The catalytic effect of iron(III) and iron(II) perchlorate on the autoxidation of acetoin (3‐hydroxy‐2‐butanone) has been studied in perchloric acid solution ranging from 0.125 to 2 mol/1. The experiments have been carried out in water and in aqueous ethanol 1: 1 v/v. A mechanism is presented in which the formation of an intermediate iron(III) enolate is the slow step. In subsequent steps the enolate is oxidized either by iron(III) or by oxygen. In the latter case simultaneous oxidation of iron(II) probably occurs. Starting from iron(III) as well as from iron(II) a steady state is reached in which the ratio Fe(III)/Fe(II) is in the order of 100.