Gold Catalysis: In Situ EXAFS Study of Homogeneous Oxidative Esterification

Abstract

Gold complexes were prepared and investigated as catalysts for the oxidative esterification of aldehydes. Stabilisation by pyridine ligands gave good conversions and the in situ extended X-ray absorption fine structure (EXAFS) study of the reactions indicated that the reaction mixtures contained only mononuclear gold species. Thus, this is the first proof for a homogeneous gold-catalysed oxidation reaction; the presence of nanoparticles could be excluded experimentally.

Biomass Derived Chemicals: Furfural Oxidative Esterification to Methyl-2-furoate over Gold Catalysts

“…The use of these substances has a strong negative impact on the environment. There have already been efforts to modify furfural-based derivatives by homogeneous catalysis [26].…”

Deconvolution of the Mechanism of Homogeneous Gold-Catalyzed Reactions

“…More recently, Hashmi and Bertagnolli used EXAFS to successfully exclude the presence of nanoparticles and to monitor the oxidation state of their catalyst during a catalytic oxidation of aldehydes to esters. 11 In this communication we report our studies of two different gold-catalyzed reactions using solution EXAFS at the L3-edge (11.919 keV) in combination with more traditional analytical tools, i.e. NMR and mass spectrometry.…”

Gold nanoparticles supported on TiO2catalyse the cycloisomerisation/oxidative dimerisation of aryl propargyl ethers

“…In recent years there are several examples in the literature describing oxidative dimerisation reactions under Au(III) 14 conditions, yet in catalytic versions, an external added oxidant 20 PhI(OAc) 2 , Selectfluor) is always necessary to reoxidise Au(I) to Au(III). While 2H-chromenes can be formed by either cationic Au(I) or Au(III) species present in Au/TiO 2 , the dimers apparently are formed by oxidative Au(III)-catalysis.…”