Room Temperature Chemoselective Deoxygenation of Aromatic Ketones and Aldehydes Promoted by a Tandem Pd/TiO₂ + FeCl₃ Catalyst

Abstract

A rapid and practical protocol for the chemoselective deoxygenation of various aromatic ketones and aldehydes was described, which used a tandem catalyst composed of heterogeneous Pd/TiO + homogeneous FeCl with the green hydrogen source, polymethylhydrosiloxane (PMHS). The developed catalytic system was robust and scalable, as exemplified by the deoxygenation of acetophenone, which was performed on a gram scale in an atmospheric environment utilizing only 0.4 mol % Pd/TiO + 10 mol % FeCl catalyst to give the corresponding ethylbenzene in 96% yield within 10 min at room temperature. Furthermore, the Pd/TiO catalyst was shown to be recyclable up to three times without an observable decrease in efficiency and it exhibited low metal leaching under the reaction conditions. Insights toward the reaction mechanism of Pd-catalyzed reductive deoxygenation for aromatic ketones and aldehydes were investigated through operando IR, NMR, and GC-MS techniques.

Synergy Effects between Oxygen Groups and Defects in Hydrodeoxygenation of Biomass over a Carbon Nanosphere Supported Pd Catalyst

“…During reactions, the hydrophobic surface of catalyst and the release of HCl from chlorobenzene contribute to significant catalytic performance. In these studies, the acidic sites provided by the additive chlorobenzene or hydrochloric acid were important, which enhanced the deoxidation ability in the reaction systems. ,− However, the recovery and recyclability of these additives are difficult, so it is highly desired to design novel catalysts to avoid the use of additives.…”

Nanoparticle-Catalyzed Green Chemistry Synthesis of Polybenzoxazole

“…Another criterion to ensure an effective condensation reaction (Scheme c) is the complete consumption of all formic acid from previous reactions (Scheme a,b) before the Scheme c reaction is started. Otherwise, the extra formic acid could reduce −CHO to −CH 3 under the current catalytic condition (Figure S7), which is also common in the Pd-catalyzed deoxygenation of aldehyde to a methyl group, lowering the PBO formation yield. − Overreduction was avoided by performing the first two steps (Scheme a,b) at 353 K and carrying out the subsequent condensation polymerization at 403 K with the addition of aldehyde and toluene to the reaction mixture under a gentle flow of Ar (Figure S8). This furnished the Schiff-base product in greater than 90% yield.…”

Highly effective and chemoselective hydrodeoxygenation of aromatic alcohols

“…To date, researchers have developed many methods for chemoselective HDO of oxygen-containing molecules, such as alcohols, aldehydes, ketones, amides and nitrogencontaining compounds. [21][22][23] Among them, alcohols are widely used as versatile precursors for the production of other organic molecules in the chemical industry. The selective HDO of alcohols is one of the most fundamental transformations in organic chemistry and plays a crucial role in the total synthesis of complex natural products bearing multifunctional groups.…”