title: The benzaldehyde oxidation paradox explained by the interception of peroxy radical by benzyl alcohol.
abstract: Benzaldehyde readily undergoes autoxidation to form benzoic acid on exposure to air at room temperature. Yet it can be formed in high yield from, for example, benzyl alcohol by oxidation using a variety of procedures and catalysts. Here we report the evidence to resolve this apparent paradox. It is confirmed that benzyl alcohol (and a number of other alcohols), even at low concentrations in benzaldehyde, inhibits the autoxidation. Furthermore we report on the structural features required for inhibition. Electron paramagnetic resonance spin trapping experiments demonstrate that benzyl alcohol intercepts, by hydrogen atom transfer, the benzoylperoxy radicals that play a key role in benzaldehyde autoxidation. A similar inhibition effect has also been observed for the aliphatic octanal/1-octanol system.
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK.
authors.forename: Meenakshisundaram
authors.initials: M
authors.lastname: Sankar
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK.
authors.forename: Ewa
authors.initials: E
authors.lastname: Nowicka
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Carter
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK.
authors.forename: Damien M
authors.initials: DM
authors.lastname: Murphy
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK.
authors.forename: David W
authors.initials: DW
authors.lastname: Knight
authors.affiliation: Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD, UK.
authors.forename: Donald
authors.initials: D
authors.lastname: Bethell
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff CF10 3AT, UK.
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Hutchings