Recent Progress in Wacker Oxidations:  Moving toward Molecular Oxygen as the Sole Oxidant

Abstract

Wacker oxidations, the conversion of terminal olefins to methyl ketones with Pd(II) catalysts, have seen widespread use in synthetic applications. Standard synthetic Wacker conditions use catalytic PdCl2 with stoichiometric CuCl under an aerobic atmosphere in a mixed-solvent system of N,N-dimethylformamide and H2O. Though much attention has been directed toward elucidating the rate-determining step and the mechanism of nucleopalladation, the assumption that Cu does not participate in this portion of the catalytic cycle has recently been called into question based on an isolated Pd/Cu bimetallic species and the influence of Cu on product selectivity. Fortunately, recent advancements have been made toward the elimination of Cu additives, thereby alleviating these issues. Success in this area has come from the application of information gained in studying other direct-O2-coupled Pd(II) oxidation systems, including ligand modulation, something which could not be achieved in the presence of Cu. The developments in peroxide-mediated and direct-O2-coupled Wacker oxidations are highlighted herein.

Utilization of Volatile Organic Compounds as an Alternative for Destructive Abatement

“…Another important industrial application is the production of aldehydes from alkenes. For example the Wacker-type of reaction is important in synthetic chemistry and pharmaceutical industry [233,234]. More recently, several researchers have reported the development of new types of catalysts for aldehyde production with better selectivities and without the C=C bond cleavage.…”

Vanadium dispersion and catalytic activity of Pd/VOx/SBA-15 catalysts in the Wacker oxidation of ethylene

“…In absence of copper O 2 must directly re-oxidize Pd 0 . The olefin oxidation in Pd-containing copper-free medium is usually referred to as direct O 2 -coupled Wacker type oxidation [5,6].…”

Palladium-Catalysed Oxidation of Bicycle Monoterpenes by Hydrogen Peroxide in Acetonitrile Solutions: A Metal Reoxidant-Free and Environmentally Benign Oxidative Process

“…For these reasons, to develop alternative syntheses processes based in non-toxic oxidant is one of the main challenges to overcome by chemical industry. As an option, the employment of the dioxygen as final oxidant has been extensively explored, especially in palladiumcatalyzed reactions [4,5]. However, the palladium black formation along the process difficult those reactions [6].…”