Role of copper dimers and the participation of copper(III) in the copper-catalysed autoxidation of ascorbic acid. Part III. Kinetics and mechanism in 0.100 mol dm-3 potassium chloride

Reginald F. Jameson, Ninian J. Blackburn

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

The kinetics of the copper(II)-catalysed oxidation of ascorbic acid by molecular oxygen have been investigated in the range pH 1.80-5.00 using 0.100 mol dm-3 KCl as background electrolyte. The reaction was followed both by continuous measurement of oxygen consumption (using a Clark-type oxygen-sensitive electrode) and by direct spectrophotometric measurement (on samples) of the unchanged ascorbic acid. At constant [H+] the rate law conforms to (i) where [L]T is the total concentration of ascorbic acid and [Cu]T is the total concentration -d[L]T/dt = -d[O2]/dt = k[Cu]T[L]T1/2[O2]1/2 (i) of CuII. On the basis of this, and on thermodynamic evidence, a chain mechanism is proposed in which a copper-copper binuclear species (containing both ascorbate and chloride ligands) is the reactive species. The dependence on [H+] is too complex, however, to be fully explained. Both one- and two-electron transfer mechanisms are discussed and preference is shown for that involving an initial two-electron transfer to the dioxygen and consequently to the participation of what is formally CuIII.

Original languageEnglish (US)
Pages (from-to)1596-1602
Number of pages7
JournalJournal of the Chemical Society, Dalton Transactions
Issue number16
DOIs
StatePublished - 1976

ASJC Scopus subject areas

  • Chemistry(all)

Fingerprint Dive into the research topics of 'Role of copper dimers and the participation of copper(III) in the copper-catalysed autoxidation of ascorbic acid. Part III. Kinetics and mechanism in 0.100 mol dm<sup>-3</sup> potassium chloride'. Together they form a unique fingerprint.

  • Cite this