Formic Acid as a Hydrogen Source for the Additive-Free Reduction of Aromatic Carbonyl and Nitrile Compounds at Reusable Supported Pd Catalysts

Tomar, Pooja; Nozoe, Yuou; Ozawa, Naoto; Nishimura, Shun; Ebitani, Kohki

doi:10.3390/catal10080875

Cited by 6 publications

(4 citation statements)

References 39 publications

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“…Kohki Ebitani et al conducted a study involving a supported palladium catalyst for the reduction of aromatic carbonyl compounds, utilizing formic acid as a hydrogen source under mild reaction conditions (Scheme 16). The most efficient support materials were found to be carbon and alumina, providing optimal results for the reduction of benzaldehyde and benzonitrile, respectively [98].…”

Section: Formic Acid and Its Saltsmentioning

confidence: 99%

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Exploring Hydrogen Sources in Catalytic Transfer Hydrogenation: A Review of Unsaturated Compound Reduction

Taleb,

Jahjah,

Cornu

et al. 2023

Molecules

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Catalytic transfer hydrogenation has emerged as a pivotal chemical process with transformative potential in various industries. This review highlights the significance of catalytic transfer hydrogenation, a reaction that facilitates the transfer of hydrogen from one molecule to another, using a distinct molecule as the hydrogen source in the presence of a catalyst. Unlike conventional direct hydrogenation, catalytic transfer hydrogenation offers numerous advantages, such as enhanced safety, cost-effective hydrogen donors, byproduct recyclability, catalyst accessibility, and the potential for catalytic asymmetric transfer hydrogenation, particularly with chiral ligands. Moreover, the diverse range of hydrogen donor molecules utilized in this reaction have been explored, shedding light on their unique properties and their impact on catalytic systems and the mechanism elucidation of some reactions. Alcohols such as methanol and isopropanol are prominent hydrogen donors, demonstrating remarkable efficacy in various reductions. Formic acid offers irreversible hydrogenation, preventing the occurrence of reverse reactions, and is extensively utilized in chiral compound synthesis. Unconventional donors such as 1,4-cyclohexadiene and glycerol have shown a good efficiency in reducing unsaturated compounds, with glycerol additionally serving as a green solvent in some transformations. The compatibility of these donors with various catalysts, substrates, and reaction conditions were all discussed. Furthermore, this paper outlines future trends which include the utilization of biomass-derived hydrogen donors, the exploration of hydrogen storage materials such as metal-organic frameworks (MOFs), catalyst development for enhanced activity and recyclability, and the utilization of eco-friendly solvents such as glycerol and ionic liquids. Innovative heating methods, diverse base materials, and continued research into catalyst-hydrogen donor interactions are aimed to shape the future of catalytic transfer hydrogenation, enhancing its selectivity and efficiency across various industries and applications.

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Section: Formic Acid and Its Saltsmentioning

confidence: 99%

“…Scheme 16. Catalytic transfer hydrogenation of benzonitrile using a palladium-supported catalyst in the presence of formic acid as a hydrogen donor (Tomar et al, 2020) [98].…”

Section: Formic Acid and Its Saltsmentioning

confidence: 99%

Exploring Hydrogen Sources in Catalytic Transfer Hydrogenation: A Review of Unsaturated Compound Reduction

Taleb,

Jahjah,

Cornu

et al. 2023

Molecules

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“…Formic acid, when used in the presence of transition metal-based catalysts, has been shown to act as an effective TH reagent in the reduction of nitroarenes, 14 furfural, 15 5-hydroxymethylfurfural, 16 and aromatic nitriles. 17 The use of formic acid in such TH reactions has been reviewed recently. 18 Secondary alcohols have also been shown to act as TH reagents in the context of facilitating the reduction of aldehydes/ketones when used in the presence of aluminum alkoxides (i.e., the so-called Meerwein−Ponndorf−Verley reduction).…”

Section: ■ Introductionmentioning

confidence: 99%

“…Several organic molecules have also been shown to act as TH reagents, but such reactions generally require the use of a catalyst. Formic acid, when used in the presence of transition metal-based catalysts, has been shown to act as an effective TH reagent in the reduction of nitroarenes, furfural, 5-hydroxymethylfurfural, and aromatic nitriles . The use of formic acid in such TH reactions has been reviewed recently .…”

Section: Introductionmentioning

confidence: 99%

Intramolecular Proton-Coupled Hydride Transfers with Relatively Low Activation Barriers

2023

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We report that bifunctional molecules containing hydroxyl and carbonyl functional groups can undergo an effective transfer hydrogenation via an intramolecular proton-coupled hydride transfer (PCHT) mechanism. In this reaction mechanism, a hydride transfer between two carbon atoms is coupled with a proton transfer between two oxygen atoms via a cyclic bond rearrangement transition structure. The coupled transfer of the two hydrogens as Hδ+ and Hδ− is supported by atomic polar tensor charges. The activation energy for the PCHT reaction is strongly dependent on the length of the alkyl chain between the hydroxyl and carbonyl functional groups but relatively weakly dependent on the functional groups attached to the hydroxyl and carbonyl carbons. We investigate the PCHT reaction mechanism using the Gaussian-4 thermochemical protocol and obtain high activation energy barriers (ΔH ‡ 298) of 210.5–228.3 kJ mol–1 for chain lengths of one carbon atom and 160.2–163.9 kJ mol–1 for chain lengths of two carbon atoms. However, for longer chain lengths containing 3–4 carbon atoms, we obtain ΔH ‡ 298 values as low as 101.9 kJ mol–1. Importantly, the hydride transfer between two carbon atoms proceeds without the need for a catalyst or hydride transfer activating agent. These results indicate that the intramolecular PCHT reaction provides an effective avenue for uncatalyzed, metal-free hydride transfers at ambient temperatures.

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Catalytic Transfer Hydrogenation of Lignocellulosic Biomass Model Compounds Furfural and Vanillin with Ethanol by an Air‐stable Iron(II) Complex

et al. 2022

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The chemical transformation of lignocellulosic biomass into various fine chemicals is the necessity for sustainable developments. A significant research interest has been devoted to develop catalysts for the reduction of cellulose and lignin model compounds furfural and vanillin, respectively. An iron(II) complex ( 1) was readily synthesized by facile coordination of NNO pincer ligand with FeCl 2 .4H 2 O. The air-stable complex 1 was efficiently utilized for the catalytic transfer hydrogenation of furfural and vanillin using ecologically benign but challenging primary alcohol ethanol. Secondary alcohol isopropanol was also utilized. Various other biomass model compounds and structurally related aldehydes were also effectively reduced. Kinetic studies suggested first order kinetics in catalyst and zeroth order in substrate. Based on the experimental evidences and published reports, a catalytic cycle is proposed which proceed via iron(II)-dialkoxides and alkoxide-hydride intermediates. Finally, CHEM21 green metrics toolkit was utilized to evaluate the sustainable and green credentials of the catalytic protocols.

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Formic Acid as a Hydrogen Source for the Additive-Free Reduction of Aromatic Carbonyl and Nitrile Compounds at Reusable Supported Pd Catalysts

Abstract: Formic acid can be used as a hydrogen source for the hydrogenations of various aromatic carbonyl and nitrile compounds into their corresponding alcohols and amines using reusable heterogeneous Pd/carbon and Pd/Al2O3 catalysts, respectively, under additive-free and mild reaction conditions.

Cited by 6 publications

References 39 publications

Exploring Hydrogen Sources in Catalytic Transfer Hydrogenation: A Review of Unsaturated Compound Reduction

Exploring Hydrogen Sources in Catalytic Transfer Hydrogenation: A Review of Unsaturated Compound Reduction

Intramolecular Proton-Coupled Hydride Transfers with Relatively Low Activation Barriers

Catalytic Transfer Hydrogenation of Lignocellulosic Biomass Model Compounds Furfural and Vanillin with Ethanol by an Air‐stable Iron(II) Complex

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