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Issue 7, 2009
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Radical intermediates in chloroform reactions over triphenylphosphine-protected Au nanoparticles

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Abstract

Reactions of chloroform over triphenylphosphine-protected Au nanoparticles have been studied using electron paramagnetic resonance (EPR) spectroscopy and a spin trapping technique. Two competing reactions, abstraction of hydrogen and halogen atoms, were identified. The hydrogen abstraction reaction showed an inverse kinetic isotope effect. Treatment of nanoparticles with oxidizing or reducing reagents made it possible to tune the selectivity of radical formation from halogen to hydrogen (deuterium) abstraction. Treatment with PbO2 promoted the deuterium abstraction reaction followed by the loss of nanoparticle activity, whereas treatment with NaBH4 regenerated the nanoparticle activity towards Cl atom abstraction. X-ray photoelectron spectroscopy showed an increased Au:P ratio upon treatment with oxidizing reagents. This is likely due to the oxidation of some phosphine ligands to phosphine oxides which then desorb from the nanoparticle surface.

Graphical abstract: Radical intermediates in chloroform reactions over triphenylphosphine-protected Au nanoparticles

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Supplementary files

Article information


Submitted
04 Nov 2008
Accepted
19 Dec 2008
First published
03 Feb 2009

Org. Biomol. Chem., 2009,7, 1361-1367
Article type
Paper

Radical intermediates in chloroform reactions over triphenylphosphine-protected Au nanoparticles

M. Conte, K. Wilson and V. Chechik, Org. Biomol. Chem., 2009, 7, 1361
DOI: 10.1039/B819627C

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