Wacker Oxidation of Terminal Alkenes Over ZrO₂‐Supported Pd Nanoparticles Under Acid‐ and Cocatalyst‐Free Conditions

Abstract

Highly efficient Wacker oxidation of aromatic or aliphatic terminal alkenes into methyl ketones and benzofurans is developed by using reusable Pd nanoparticles (NPs) supported on ZrO under acid- and cocatalyst-free conditions. Molecular oxygen or air can be utilized as the terminal oxidant, which results in the formation of H O as the only theoretical byproduct. The activation of the Pd NPs by O plays an important role in promoting this reaction. Interestingly, PdO supported on ZrO showed no activity. Additionally, the Pd particle size significantly affects the catalytic activity, with an apparent optimal diameter of 4-12 nm. In addition to the heterogeneous catalyst forms, the Pd NPs can be generated from a Pd complex during the reaction, and these particles are even recyclable.

Aerobic Homocoupling of Arylboronic Acids Catalyzed by Regenerable Pd(II)@MIL‐88B‐NH2(Cr)

“…Heterogeneous Pd‐catalyzed protocols based on the use of molecular oxygen now represent a highly promising and versatile approach to achieving this goal. Examples of dehydrogenation reactions or Wacker processes, of C−H functionalization and of C−C bond formation through heterogeneous Pd‐catalyzed aerobic oxidation have recently been reported. Representative examples of the latter type of reaction include the oxidative coupling of carbon nucleophiles such as arylboronic acids to obtain biaryls, or the Glaser‐Hay reaction to synthesize diynes …”

Oxide-Supported Palladium and Gold Nanoparticles for Catalytic C-H Transformations

“…26 27 First, styrene (16a) was chosen as a model substrate for Wacker oxidation, and the reaction conditions were optimized using Pd/ZrO 2 ( Table 8). Screening of solvents (entries 1 6) revealed that MeOH was suitable (entry 4).…”

“…Relation between Pd particle size and catalytic activity for Wacker oxidation of stryrene (16a). 27 The interaction and stabilization of positively charged Pd species on these metal oxides may contribute to activation of the Pd surface for allylic C H acetoxylation and Wacker oxidation.…”

Particle size effect of ZrO2 supports on catalytic liquid-phase oxidation of phenol over Pt/CeO2-ZrO2-Bi2O3/ZrO2 catalysts

“…Some ZrO 2 -supported catalysts show higher activities compared to other supported catalysts for the oxidation of carbon monoxide, methane, etc [10][11][12][13][14][15]. In addition to gas-phase oxidation, ZrO 2 has also been applied to liquid-phase oxidation, and ZrO 2 -supported catalysts have demonstrated promising results in processes such as selective oxidation [16][17][18] and wastewater pollutant treatment, e.g. Kraft plant wastewater [19], carboxylic acid [20,21], N, N-dimethylformamide [22].…”