Timothy T. Wenzel

Cationic palladium nitro complexes as catalysts for the oxygen-based oxidation of alkenes to ketones, and for the oxydehydrogenation of ketones and aldehydes to the α, β-unsaturated analogues

Cationic palladium nitro complexes permit more rapid and more selective oxidation of alkenes to ketones than existing metal nitro catalysts; they also oxidatively dehydrogenate ketones and aldehydes to the corresponding α, β-unsaturated analogues under extremely mild conditions.

Oxidation of Olefins to Aldehydes Using a Palladium-Copper Catalyst

The oxidation of terminal olefins with palladium salts usually affords methyl ketones.1–3 However, in 1986 it was reported that aldehydes could be obtained using a catalyst comprising (CH3CN)2Pd(NO2)Cl and CuCl2 in t-butanol solvent, which was proposed to be bimetallic with the NO2 group intact.4 Our studies suggest that this catalyst is best described as a Wacker-like oxidation catalyst modified by an alkyl nitrite, and we report an improved version of this catalyst. Moreover, the application of our system to the oxidation of terminal olefins with allylic substituents has led to some insight as to the potential role of the copper co-catalyst in Wacker-like reactions.

Attempted Catalytic Epoxidation of Alkenes Using a Metal Hydroperoxide: Dioxygen Insertion into a Pt-H Bond

Abstract A potential cycle for olefin epoxidation using air as the oxidant was investigated. The proposed cycle comprised three steps: (1) epoxidation of an olefin using an organoplatinum hydroperoxide [Pt]OOH; (2) conversion of the resulting metal hydroxide [Pt]OH to the hydride [Pt]H using hydrogen or an alcohol; and (3) reaction of the hydride [Pt]H with oxygen to generate the hydroperoxide. All three steps were found to be feasible, although not necessarily simultaneously. Step (3) was studied in the most detail. This reaction was greatly accelerated by adding freeradical initiators, which strongly suggests that it proceeds by a radical chain mechanism.