Catalytic Transfer Hydrogenation Research Articles

Impact of hafnium dioxide morphology on catalytic transfer hydrogenation of methyl levulinate to γ-valerolactone: A comparative study

BackgroundThe catalytic transfer hydrogenation (CTH) of methyl levulinate (ML) to γ-valerolactone (GVL) is a promising method for producing renewable fuels and chemicals. The efficiency of this process depends heavily on the choice of catalysts, with morphology playing a critical role in their performance. MethodsThis study synthesized and characterized rice-like (r-HfO₂) and ball-like (b-HfO₂) hafnium oxide nanostructures. r-HfO₂ was prepared using a microwave system, while b-HfO₂ was synthesized via a solvothermal method. The catalysts were characterized using SEM, TEM, XRD, TPD-NH₃ analysis, and nitrogen sorption isotherms to determine their morphological, structural, and acidic properties. The catalytic performance of these nanostructures was tested under optimal conditions of 160 °C and 2 h in a batch-type solvothermal reactor. Significant FindingsThe results showed that b-HfO₂ exhibited a conversion efficiency of 90 % and a GVL yield of 90 %, outperforming r-HfO₂, which achieved 94.8 % conversion and 75.2 % yield. Recyclability tests confirmed the durability of both catalysts, with b-HfO₂ maintaining better activity. Detailed analyses revealed that b-HfO₂ exhibits superior catalytic activity and energy efficiency, achieving higher GVL yield and better energy efficiency. The conversion rates reached up to 100 % for both catalysts at 200 °C, with b-HfO₂ achieving a higher GVL yield and better energy efficiency. These findings demonstrate the potential of HfO₂-based catalysts, especially b-HfO₂, in efficiently converting biomass-derived feedstocks to valuable chemicals.

Regioselective intermolecular carboamination of allylamines via nucleopalladation: empowering three-component synthesis of vicinal diamines.

An intermolecular carboamination reaction of allyl amines under Pd(ii)-catalysis is reported, expediting the synthesis of valuable vicinal diamines embedded in a functionally enriched linear carbon framework with high yields and exclusive Markovnikov selectivity. Central to our approach is the strategic use of a removable picolinamide auxiliary, which directs the regioselectivity during aminopalladation and stabilizes the crucial 5,5-palladacycle intermediate. This stabilization facilitates oxidative addition to carbon electrophiles, enabling the simultaneous incorporation of diverse aryl/styryl groups as well as important amine motifs, such as sulfoximines and anilines, across carbon-carbon double bonds. The protocol features broad substrate compatibility, tolerance to various functional groups, and scalability. The utility of this method is further demonstrated by the site-selective diversification of pharmaceutical agents. Additionally, these products serve as versatile intermediates for synthesizing heterocycles and function as effective ligands in catalytic transfer hydrogenation reactions. Notably, this work represents a rare instance of nucleopalladation-guided intermolecular carboamination of allylamines.

Catalytic Asymmetric Transfer Hydrogenation of β,γ-Unsaturated α-Diketones.

Asymmetric transfer hydrogenation (ATH) has been recognized as a highly valuable strategy that allows access to enantioenriched substances and has been widely applied in the industrial production of drug molecules. However, despite the great success in ATH of ketones, highly efficient, regio- and stereoselective ATH on enones remains underdeveloped. Moreover, optically pure acyloins and 1,2-diols are both extremely useful building blocks in organic synthesis, medicinal chemistry, and materials science, but concise asymmetric approaches allowing access to different types of acyloins and 1,2-diols have scarcely been discovered. We report in this paper the first highly efficient ATH of readily accessible β,γ-unsaturated α-diketones. The protocol affords four types of enantioenriched acyloins and four types of optically pure 1,2-diols in highly regio- and stereoselective fashion. The synthetic value of this work has been showcased by the divergent synthesis of four related natural products. Moreover, systematic mechanistic studies and density functional theory (DFT) calculations have illustrated the origin of the reactivity divergence, revealed the different roles of aromatic and aliphatic substituents in the substrates, and provided a range of unique mechanistic rationales that have not been disclosed in ATH-related studies.

Boosting Catalytic Hydrogen Transfer Cascade Reactions via Tandem Catalyst Design by Coupling Co Single Atoms with Adjacent Co Clusters

Boosting Catalytic Hydrogen Transfer Cascade Reactions via Tandem Catalyst Design by Coupling Co Single Atoms with Adjacent Co Clusters

N, N-Mn(I)-catalyzed transfer hydrogenation of ketones

Compared with other inexpensive metals-based catalysts for transfer hydrogenation, the use of manganese is rather more limited. Herein, a series of N, N-Mn(I)-Catalysts based on previous work were synthesized for transfer hydrogenation of ketones. Differential aromatic, heterocyclic ketones, as well as aliphatic ketones could be employed in this catalytic system, delivering the desired alcohol products in moderate to excellent yields. This N, N-Mn(I)-based catalytic system provides an alternative protocol for transfer hydrogenation of ketones to produce alcoholic products.

Role of Copper Species in Copper Phyllosilicate Catalysts for the Catalytic TransferHydrogenation of Furfural to γ‐Valerolactone

Role of Copper Species in Copper Phyllosilicate Catalysts for the Catalytic TransferHydrogenation of Furfural to γ‐Valerolactone

Highly efficient Zr-based coordination polymer for catalytic transfer hydrogenation of 5-hydroxymethylfurfural: Tuning acid strength and enhancing stability

In this study, Zr-based coordination polymers were synthesized via solvothermal method for the Meerwein-Ponndorf-Verley reduction of biomass-derived aldehydes and ketones. The morphology and strength of Lewis acid sites could be tuned by using different solvent during catalyst preparation. A 98.5 % yield of 2,5-bis(hydroxymethyl)furan (BHMF) was achieved at 100 °C using Zr-PDC/DMF-DCB, which was synthesized with pyridine-2,6-dicarboxylic acid (PDC) as ligand in a mixed solvent of N, N-dimethylformamide (DMF) and 1,2-dichlorobenzeneisopropanol (DCB) and exhibited moderate Lewis acid sites. Conversely,while Zr-PDC synthesized in alcohols (Zr-PDC/MeOH and Zr-PDC/EtOH) were used as catalysts, etherification products formed instead of BHMF. Further investigation into the role of solvents during catalyst preparation revealed that coordination between Zr sites and DMF increased the electron cloud density of Zr sites, thus weakening Lewis acidity. In addition, the inclusion of hydrophobic DCB resulted in the formation of spherical morphology, which improved resistance to carbon deposition and enhanced anti-agglomeration properties. This work presents a strategy for controlling acid strength and improving catalytic stability of coordination polymers.

Optimizing Cu 3d Bands with Nanotubular SnO2 to Boost Their Catalytic Transfer Hydrogenation Activity.

Catalytic transfer hydrogenation (CTH) using Cu nanocatalysts offers significant advantages over direct high-pressure hydrogenation. However, the active hydrogen (H*) in this process exhibits poor adsorption and tends to release H2 readily due to the fully occupied 3d states of Cu. To address this issue, a tubular SnO2 support with electron-accepting ability was selected to host Cu nanoparticles, aiming to optimize the Cu 3d bands. The Cu/SnO2 nanohybrids were prepared through an electrospinning technique, followed by hydrothermal synthesis. As evidenced by X-ray photoelectron spectroscopy (XPS) binding energy shifts and density functional theory (DFT) simulations, some electrons from Cu transferred to SnO2 in the Cu/SnO2 nanohybrids due to their different work functions. Such electron transfer enables the Cu 3d orbitals to lose electrons and alters its valence configuration from 3d10 to 3d10-x, which enhances the adsorption of active H* atoms and thereby inhibits undesirable H2 release. The 15 wt % Cu/SnO2 exhibits improved catalytic hydrogenation of 4-nitrophenol with NaBH4, with an optimal normalized rate constant of 56.98 mg-1 min-1 and a turnover frequency of 4.82 min-1, surpassing most reported catalysts. The enhanced activity is attributed to the optimized electronic states, improved hydrogen adsorption, and the tubular structure of the support. This work might shed light on developing more non-noble metal nanocatalysts for CTH by tuning their d bands with appropriate oxide supports.

The effect of modulator in the synthesis of UiO-66(Zr) and UiO-67(Zr) and their performances in catalytic transfer hydrogenation reaction of α-angelica lactone to γ-valerolactone

The effect of modulator in the synthesis of UiO-66(Zr) and UiO-67(Zr) and their performances in catalytic transfer hydrogenation reaction of α-angelica lactone to γ-valerolactone

Synthesis and Characterization of Ru(II)−NSHC Catalysts Bearing Thiamine Analogs in Water‐Solvent Transfer Hydrogenation Catalysis

AbstractThiamine analogues with 3‐methyl and 4‐(2‐hydroxyethyl) substituents on the backbone of thiazole ring, were used to synthesize monodentate Ru(II)‐thiazolylidene complexes in a single step via transmetalation under mild conditions. These novel complexes catalyze the conversion of ketones and aldehydes to alcohols by transfer hydrogenation in a 5 : 2 HCO2H/NEt3 buffer in water. However, their efficiency was found to be much lower than the thiamine‐derived bidentate Ru(II) complexes, which strongly indicates that the ‘N−H’ plays a crucial role in the reaction.

Micellar Transfer Hydrogenation Catalysis in Water with Monocarbonyl Ruthenium(II)-poly(vinylphosphonate)-Containing Polymers: Achieving Reduction of Biomass-Derived Aldehydes

Micellar Transfer Hydrogenation Catalysis in Water with Monocarbonyl Ruthenium(II)-poly(vinylphosphonate)-Containing Polymers: Achieving Reduction of Biomass-Derived Aldehydes

A Novel Mesoporous SBA‐15 Supported Bifunctional Heterogeneous Catalyst for Base‐Free Transfer Hydrogenation Reaction of Ketones

ABSTRACTAmong the problems encountered in the catalytic transfer hydrogenation reactions of ketones, the base sensitivity of ketones and the corrosive effects of the bases used in the reaction have an important place especially in industrial terms. Although there are various approaches to overcome this problem, solutions based on the intrinsic properties of the catalyst used seem more suitable. Within the scope of this study, a novel heterogeneous catalyst was prepared for the transfer hydrogenation reaction of ketones, which can operate in base‐free environment. To prepare the heterogeneous catalyst, 1,2‐diphenylethane‐1,2‐diamine was first tosylated and then the silyl derivative was synthesized and grafted onto mesoporous silica SBA‐15. Characterizations of the obtained heterogeneous catalyst and SBA‐15 were carried out by X‐ray diffractometer (XRD), N2 sorption, thermogravimetric analysis (TGA), scanning electron microscope (SEM), energy dispersive X‐ray analysis, and Fourier transform infrared (FT‐IR) analysis. The results obtained showed that the functionalized 1,2‐diphenylethane‐1,2‐diamine compound was successfully immobilized into the SBA‐15 structure. Determination of the catalytic activity of the heterogeneous catalyst was carried out in transfer hydrogenation reactions of various aromatic ketones. After determining the optimum reaction conditions with acetophenone, a conversion rate of (70%) was observed in the acetophenone to 1‐phenylethanol reaction that took place without a base. Under same conditions a higher conversion rate of (73%) was observed in the 4′‐chloroacetophenone to 1‐(4‐chlorophenyl)ethanol reaction. In the reactions performed to determine recyclability, after a 70% conversion rate, 61% and 65% conversion rates, respectively, were observed in the reaction from acetophenone to 1‐phenylethanol under the same conditions.

The Role of Frustrated Lewis Pair in Catalytic Transfer Hydrogenation of Furfural using Nickel Single-Atom Catalysts: A Theoretical Study.

The burgeoning field of frustrated Lewis pair (FLP) heterogeneous catalysts has garnered significant interest in recent years, primarily due to their inherent ability to activate H-source molecules, thereby facilitating hydrogenation reactions. In this study, non-precious transition metal atoms were anchored onto several models of pyridinic nitrogen incorporated graphene sheet. Theoretical calculations substantiated energy barriers as low as 0.10 eV for isopropanol activation, thereby positioning these catalysts as highly promising candidates for catalytic transfer hydrogenation of furfural. Electronic structure analyses revealed that the H-O bond breakage in isopropanol molecules was significantly facilitated by the presence of FLP sites within the catalysts. Notably, both Ni-C2N and Ni-N6-C demonstrated exceptional potential as selective catalysts for the hydrogenation of furfural into furfuryl alcohol, exhibiting remarkably low barriers of only 0.65-0.72 eV for the rate-determining steps. The findings in this study are helpful to design FLP containing single atom catalysts for hydrogenation reactions.

Boosting catalytic transfer hydrogenation of alkyl levulinate to γ-valerolactone using ionic liquid modified UiO-66

Boosting catalytic transfer hydrogenation of alkyl levulinate to γ-valerolactone using ionic liquid modified UiO-66

Single nickel atoms anchored on porous N-doped nanocarbon with dual reaction sites for highly-efficient transfer hydrogenation of furfural to furfuryl alcohol

The non-precious metal single-atom catalysts (SACs) supported on carbon materials for the catalytic transfer hydrogenation (CTH) of α,β-unsaturated aldehydes (UAL) still suffer from the problems of harsh reaction conditions and low activity. In this work, nickel SACs anchored on porous N-doped nanocarbon (Ni1/NC900) with dual reaction sites were synthesized using the high internal-phase emulsion (HIPE) template method combined with impregnation. The Ni1/NC900 catalyst exhibited remarkable catalytic activity for the CTH of furfural (FF) to furfuryl alcohol (FFA), achieving > 99.0 % conversion and selectivity at 100 °C for 60 min, with a turnover frequency (TOF) of 2908.1 h−1, surpassing other reported nickel-based catalysts by 1–3 orders of magnitude. The excellent catalytic performance of Ni1/NC900 was attributed to the high mass transfer efficiency (HMTE) of the support and the dual reaction sites of Ni–N4 and pyridinic N, where Ni–N4 as Lewis acidic site for adsorption of FF and isopropanol (i-PrOH), while the adjacent pyridinic N as Lewis basic site for the deprotonation of i-PrOH. The isotope labeling experiments revealed that the hydrogenation of FF was accomplished by proton transfer with i-PrOH, in agreement with the intermolecular hydride transfer mechanism. Furthermore, Ni1/NC900 demonstrated excellent stability and well general applicability, demonstrating its potential for industrial applications. This work provides a reference for the application of carbon-based non-precious metal SACs in the CTH reaction of UAL.

Unraveling the Metal–Ligand Cooperativity in a Phosphine-Free Mn(II)-Catalyzed Transfer Hydrogenation of Nitriles to Primary Amines and Dehydrogenation of Dimethylamine Borane

Unraveling the Metal–Ligand Cooperativity in a Phosphine-Free Mn(II)-Catalyzed Transfer Hydrogenation of Nitriles to Primary Amines and Dehydrogenation of Dimethylamine Borane

Structure sensitivity in the formic acid-driven catalytic transfer hydrogenation of maleic acid to succinic acid over Pd/C catalysts

A series of carbon-supported palladium catalysts (Pd/C) with average particle size in the range from 3 to 7 nm was prepared by varying the Pd loading. These materials and the influence of their physicochemical properties in the catalytic transfer hydrogenation (CTH) of maleic acid (MAc) to succinic acid (SAc) using formic acid (FAc) as H2 donor were evaluated. The chemical, textural, and surface properties were studied by a number of characterization techniques (ICP-OES, XRD, TEM, and XPS). It was found that the intrinsic rate of SAc formation per surface Pd atom (turn-over frequency, TOF Pdsur) is structure-sensitive. The TOF Pdsur rate increases with the particle size following a volcano-type curve, reaching a maximum for an average particle size of ca. 6 nm. Assuming a cuboctahedral shape with a cubic close-packed structure, an approximation frequently adopted for Pd particles, it was found that, for the series of catalysts, neither the calculated TOF of Pd surface atoms at low coordination sites nor at high coordination are constant. This suggests that no geometric effect is responsible for the structure-sensitivity. Among the different Pd species present in the catalysts (i.e., metallic Pd (Pd0), palladium carbide (PdCx), and oxidized Pd), it was observed that the relative number of surface Pd0 sites also follows a volcano-type curve, which indicates that Pd0 sites are necessarily involved in the most active centers. For particles with an average size larger than 4 nm, the TOF rate of surface Pd0 sites was constant and in the range of 0.12 s−1. For smaller sizes, a more accurate determination of their Pd0 surface concentration is required to obtain reliable surface Pd0 TOF rates.

Indium-captured zirconium-porphyrin frameworks displaying rare multi-selectivity for catalytic transfer hydrogenation of aldehydes and ketones

Indium-captured zirconium-porphyrin frameworks displaying rare multi-selectivity for catalytic transfer hydrogenation of aldehydes and ketones

Advances in Sustainable γ-Valerolactone (GVL) Production via Catalytic Transfer Hydrogenation of Levulinic Acid and Its Esters.

γ-Valerolactone (GVL) is a versatile chemical derived from biomass, known for its uses such as a sustainable and environmentally friendly solvent, a fuel additive, and a building block for renewable polymers and fuels. Researchers are keenly interested in the catalytic transfer hydrogenation of levulinic acid and its esters as a method to produce GVL. This approach eliminates the need for H2 pressure and costly metal catalysts, improving the safety, cost effectiveness and environmental sustainability of the process. Our Perspective highlights recent advancements in this field, particularly with respect to catalyst development, categorizing them according to catalyst types, including zirconia-based, zeolites, precious metals, and nonprecious metal catalysts. We discuss factors such as reaction conditions, catalyst characteristics, and hydrogen donors and outline challenges and future research directions in this popular area of research.

Air-Stable Triazole-Based Ru(II) Complexes Catalyzed Transfer Hydrogenation of Ketones and Aldehydes Using Ethanol as a Solvent and a Hydrogen Donor

Abstract. The synthesis and characterization of two air-stable ruthenium (II) complexes from readily available triazole-based ligands are described. Both ruthenium complexes, one bearing a bidentate ligand (C-1) and the other a tridentate ligand (C-2), were tested as catalysts in the transfer hydrogenation of ketones and aldehydes using ethanol as a sustainable hydrogen source under aerobic conditions. Notably, the C-2 complex displayed exceptional efficiency under relatively mild conditions, demonstrating a wide substrate tolerance encompassing both alkyl and aryl ketones, as well as aryl aldehydes. Furthermore, our findings highlight the potential of Ru(II) complexes as effective catalysts for the hydrogenation of carbonyl bonds using ethanol, representing a green and sustainable approach without the necessity for an inert gas. Resumen. En este trabajo se describe la síntesis y caracterización de dos complejos de rutenio(II) estables al aire con ligantes basados en triazoles. En general, los triazoles pueden obtenerse fácilmente a través de reacciones simples utilizando reactivos comercialmente disponibles. Ambos complejos de rutenio, uno con un ligante bidentado (C-1) y el otro con un ligando tridentado (C-2), se probaron como catalizadores en reacciones de hidrogenación por transferencia de cetonas y aldehídos, utilizando etanol como fuente sostenible de hidrógeno en condiciones aeróbicas. En particular, el complejo C-2 mostró una eficiencia excepcional en condiciones relativamente suaves, demostrando una amplia tolerancia tanto con cetonas alquílicas como aromáticas, además de hidrogenar eficientemente aldehídos aromáticos. Estos resultados ponen de manifiesto el potencial de los complejos de Ru(II) como catalizadores eficaces para la hidrogenación de enlaces carbonilo utilizando etanol, lo que representa un enfoque ecológico y sostenible sin necesidad de un gas inerte.