1 Tunable Gold Catalysts for Selective Hydrocarbon Oxidation under Mild Conditions Mathew D. Hughes, Yi-Jun Xu, Patrick Jenkins, Paul McMorn, Philip Landon1, Dan I. Enache, Albert F. Carley, Gary A. Attard1, Graham J. Hutchings, Frank King, E. Hugh Stitt, Peter Johnston, Ken Griffin & Christopher J. Kiely Nature. 2005, 437,

2 Catalytic oxidations of organic molecules Gallezot, P. et. al. Catal. Today. 1997, 37, Enzymatic oxidation Free radical auto-oxidations initiated by transition metal cations Metal ion oxidation of coordinated substrates such as Pd II -catalyzed oxidations of olefins Oxygen transfer to the organic substrate mediated by metaloxo or peroxo complexes Oxidative dehydrogenation on metal surfaces

3 Epoxides

4 Selective oxidation of glycerol to glyceric acid using a gold catalyst Table 1 Oxidation of glycerol using Au/carbon catalystsa Hutchings, G. J. et. al. Chem. Commun. 2002, 37,

5 Direct formation of hydrogen peroxide from H 2 /O 2 using a gold catalyst Table 2 Formation of H 2 O 2 using Au catalysts Hutchings, G. J. et. al. Phys. Chem. Chem. Phys. 2003, 5, Scheme 2

6 Synthesis of Gold Catalyst Bi-doped catalyst

7 Effect of solvent on selective oxidation of cyclohexene using Au/C catalyst

8

9 Styrene oxidation with molecular oxygen using Au/C catalysts AlkeneSolventInitiatorGoldConversi on Product Selectivity  Cn Cn (mol%)(wt%)(%)SelYield TolueneTBHP (5) ,4- Dimethylbenze ne TBHP (5) ,2,4,5- TMB/1,4- Dimethylbenze ne TBHP (5) ,4- Difluorobenzen e TBHP (5)

10 cis-Stilbene oxidation with molecular oxygen using a 1% Au/C catalyst SolventConversionSelectivity (%)cis:trans ratio  sel C 6 a  yield C 6 b (%)cis-Stilbene oxide trans-Stilbene oxide Toluene ,4-Dimethylbenzene Durene/p-Xylene i-Propylbenzene t-Butylbenzene ,3,5-tri-i- Propylbenzene

11 Cyclohexene oxidation with molecular oxygen using unmodified and Bi- modified Au/C catalysts

12 XPS (X-ray photoelectron spectroscopic) (a)graphite support (b) as prepared Bi-doped 1 wt % Au-graphite catalyst, (c) catalyst after reaction, (d) catalyst in (c) after further reaction with a fresh reactant mixture

13 Cyclic voltammograms of 0.5 wt% Au/carbon catalyst a, Changes in voltammetric response as a function of irreversibly adsorbed Bi. The feature at 0.4–0.5V is associated with Bi in the first monolayer. Multi-layers of Bi are associated with a stripping peak at 0.2V. Bi loading (mmol): solid line, 0; dot-dashed, 0.3; dashed, 1.48; dotted, b, Loss of multi-layer Bi after reaction as demonstrated by the attenuation of the Bi stripping peak. The presence of the Bi monolayer feature suggests that some Bi remains on the catalyst. Solid line, before reaction; dotted line, after reaction.

14 cis-Cyclooctene oxidation with molecular oxygen in the absence of a solvent

15 Conclusions The results show the gold catalyst to have significant potential for selective epoxide formation rather than the competing allylic oxidation. Author anticipate that our finding will initiate attempts to understand more fully the mechanism of oxygen activation at gold surfaces, which might lead to commercial exploitation of the high redox activity of gold nanocrystals.