Reductive Amination Of Levulinic Acid Research Articles

Spectroelectrochemical Exploration of Biogenic Substrates for Electrosynthesis

AbstractSpectroelectrochemistry, especially ATR‐SEIRAS, is an emerging method to identify key descriptors for optimizing reaction systems in organic electrosynthesis. Here, the upgrading of biogenic acids via Kolbe electrolysis and reductive transformations was studied. The findings affirm acid group adsorption on electrodes, consistent with existing literature. The effectiveness of Kolbe reaction in suppressing the parasitic ethanol oxidation reaction was observed, whereas it faces stiff competition from the methanol oxidation reaction. Parallel reduction and reductive amination of levulinic acid were uncovered, both relying on adsorbed organic species rather than molecular H2. Intriguingly, the electrode's polarization influences the bond strength, enabling discrimination between acid and ketone species within levulinic acid.

Sustainable synthesis and extraction of 5-methyl-N-phenyl-2-pyrrolidone produced via reductive amination of levulinic acid

5-methyl-N-substituted-2-pyrrolidones (5MPs) have been proposed as alternatives to N-methyl-2-pyrrolidone, a solvent with industrial and commercial applications which is considered hazardous and undesired by regulators. 5MPs are produced via reductive amination of levulinic acid with a catalyst and a reducing agent like H2. However, the separation of 5MPs from the reaction media is scarcely studied to understand industrial and commercial viability. This work is centered on producing 5-methyl-N-phenyl-2-pyrrolidone from levulinic acid via reductive amination followed by its liquid–liquid extraction using specifically selected extracting solvents. The extraction step considers not only the separation performance but also the environmental, health, and safety (EHS) criteria of the selected solvents. Thus, COSMO-RS, along with EHS guides, were used to screen solvents to extract 5-methyl-N-phenyl-2-pyrrolidone from methanol or water, which are used as reaction solvents. Some promising extracting solvents were studied in ternary liquid–liquid equilibrium experiments based on the partition of 5-methyl-N-phenyl-2-pyrrolidone and the reactants in the extracting solvent + (water or methanol) biphasic system. Subsequently, the solvents were tested for the extraction of the 5-methyl-N-phenyl-2-pyrrolidone from a real reaction mixture, produced by a Pt/TiO2 catalyzed reductive amination at 25 °C and 1.013 bar. Predictions and further validations of the distribution coefficients and selectivities for the solute show that anisole and limonene are favorable solvents for extracting 5-methyl-N-phenyl-2-pyrrolidone from water and methanol media, respectively. Both solvents are attractive alternatives due to their biobased nature, with the former ranked as recommended by EHS guides and the latter having some concerns with environmental criteria. However, both solvents show advantages for a scale-up of the reaction + separation process.

Reductive Amination of Levulinic Acid to Pyrrolidones: Key Step in Biomass Valorization towards Nitrogen-Containing Chemicals.

Nowadays, the field of biomass conversion is gradually moving towards an encouraging stage. The preparation of nitrogen-containing chemicals using various biomass resources instead of fossil resources do not only reduce carbon emissions, but also diversify the products of biomass conversion, thus increasing the economic competitiveness of biomass refining systems. Levulinic acid (LA) can be used as a promising intermediate in biomass conversion for further synthesis of pyrrolidone via reductive amination. However, there are still many critical issues to be solved. Particularly, the specific effects of catalysts on the performance of LA reductive amination have not been sufficiently revealed, and the potential impacts of key conditional factors have not been clearly elucidated. In view of this, this review attempts to provide theoretical insights through an in-depth interpretation of the above key issues. The contribution of catalysts to the reductive amination of LA as well as the catalyst structural preferences for improving catalytic performance are discussed. In addition, the role of key conditional factors is discussed. The insights presented in this review will contribute to the design of catalyst nanostructures and the rational configuration of green reaction conditions, which may provide inspiration to facilitate the nitrogen-related transformation of more biomass platform molecules.

A CoPd nanoalloy embedded N-doped porous carbon catalyst for the selective reduction and reductive amination of levulinic acid using formic acid in water

Formic acid-mediated levulinic acid valorization was conducted using a CoPd nanoalloy embedded N-doped carbon catalyst for the production of γ-valerolactone and pyrrolidones.

Highly Efficient and Recyclable Nitrogen-Doped Mesoporous Carbon-Supported Ru Catalyst for the Reductive Amination of Levulinic Acid/Esters to Pyrrolidones

A highly effective transformation from renewable biomass and its derivatives into high-value-added chemicals and biofuels is important and challenging. Herein, a N-doped mesoporous carbon (NMC)-supported Ru catalyst developed by an incipient wetness impregnation method was reported for the reductive amination of levulinic acid (LA)/esters with amines to N-substituted 5-methyl-2-pyrrolidinones. A complete conversion of LA with a 99.8% yield of N-hexyl-5-methyl-2-pyrrolidinone (HMP) was achieved over 0.05 mol % Ru/NMC under mild conditions of 120 °C and 1.5 MPa H2 for 4 h, giving a high turnover frequency (3667 h–1). Furthermore, Ru/NMC exhibited superior stability and recyclability (reusable 21 cycles without loss of activity). The excellent performance of the Ru/NMC catalyst was mainly attributed to the introduction of N species to the mesoporous carbon, which not only improved the anchoring and the dispersion of Ru nanoparticles on the catalyst surface but also provided moderate basic sites and transferred electrons from NMC to Ru nanoparticles, as revealed by detailed characterizations. Additionally, the developed Ru/NMC catalytic system was applicable to LA/esters and various amines to afford the corresponding N-substituted 5-methyl-2-pyrrolidinones with excellent yields (80–99%).

Sustainable Efficient Synthesis of Pyrrolidones from Levulinic Acid over Pd/C Catalyst

AbstractThe synthesis of 5‐methyl‐2‐pyrrolidone through reductive amination of levulinic acid (LA) with ammonium formate (AF) as a source of both hydrogen and nitrogen over Pd/C catalyst was investigated. The effects of various reaction parameters, such as solvent, catalyst dosage, ammonium formate amount and temperature on the conversion of LA into 5‐methyl‐2‐pyrrolidone (MPD) were systematically investigated. The results showed that a MPD yield as high as 98 % was obtained in water at 180 °C for 4 h under a low metal content (0.28 mol% Pd relative to LA), which is higher than many previous reports. The Pd/C catalyst could be reused for at least 9 times with only a slight loss in activity. Meanwhile, Pd/C catalyst was efficient for the conversion of LA/ester into various N‐substituted‐5‐methyl‐2‐pyrrolidones (80–93 % yield) by using a mixture of formic acid and the corresponding primary amines.

A Catalyst and Solvent Free Route for the Synthesis of N-Substituted Pyrrolidones from Levulinic Acid.

An efficient, metal-free, catalyst-free and solvent-free methodology for the reductive amination of levulinic acid with different anilines has been developed using HBpin as the reducing reagent. This protocol offers an excellent method to avoid solvents and added catalysts on the synthesis of different kinds of N-substituted pyrrolidones under metal free conditions. It is also the first report for the synthesis of different pyrrolidones by solvent-free as well as catalyst-free methods. The proposed mechanism for the formation of pyrrolidone has been supported by DFT calculations and control experiments.

Cobalt single-atom catalysts for domino reductive amination and amidation of levulinic acid and related molecules to N-heterocycles

The development of single-atom-based catalysts (SACs), which bridge the traditional areas of homogeneous and heterogeneous catalysis, continues to be important for achieving organic synthesis in a more efficient and practical manner. Here, we report reusable cobalt-based SACs for the selective and general reductive amination of levulinic acid and related keto acids, which is of interest in the context of valorization of biomass. The optimal Co-SAC-based catalyst is prepared by pyrolysis (800°C) of cobalt-phenanthroline complexe on carbon and subsequent acid treatment. The resulting Co-SACs showed amazing activity compared with the corresponding Co-nanoparticles and displayed an excellent substrate scope for various reductive domino transformations including reactions of levulinic acid with nitro compounds and nitriles to produce various N-substituted pyrrolidones in good to excellent yields. Further, the synthesis of diverse isoindolinones from aromatic ketoacids and amines/nitro compounds was performed with the optimal catalyst system. • Preparation of stable and reusable Co-SACs catalysts • Reductive amination and amidation of levulinic acid and related molecules • Synthesis of >90 functionalized and structurally diverse N-heterocycles • Applicable for the preparation of bioactive molecules The effective catalytic conversion of biomass-based feedstocks to produce bulk and fine chemicals is a major goal of current chemical research. In this respect, specifically reductive aminations and amidations are interesting, too. To improve the sustainability of such processes, inexpensive, earth-abundant base metals should be employed as catalysts to replace precious metals that currently dominate in this field. Here, we show that cobalt catalysts with isolated metal sites (SACs) enable efficient domino reductive amination and amidation of levulinic acid and related molecules to give a wide array of N-heterocycles. We anticipate that these Co-catalytic systems will create more opportunities for the conversion of biomass-based feedstocks to many value-added compounds. The effective conversion of renewable resources, especially biomass-based feedstocks, to produce chemicals, fuels, and energy is of central importance. To valorize these feedstocks, the development of suitable catalysts, especially single-atom catalysts (SACs), which bridge traditional homogeneous and heterogeneous catalysis, is highly desired. In this respect, we developed Co-based SACs, which allow for the domino reductive amination and amidation of levulinic acid and related molecules to produce functionalized and structurally diverse N-heterocycles including bioactive molecules.

Co single-atom catalysts enable efficient reductive amination of biomass-derived levulinic acid

In this issue of Chem Catalysis, Gao et al. describe the first example of synthesis of cobalt single-atom catalysts (SACs) for reductive amination of levulinic acid and various ketoacids with amines, nitros, or nitriles. The cobalt SACs showed remarkable catalytic activity and excellent substrate applicability.

Selectively reductive amination of levulinic acid with aryl amines to N-substituted aryl pyrroles

Synthesizing nitrogen (N)-containing molecules from biomass derivatives is a new strategy for production of this kind of chemicals. Herein, for the first time we present the synthesis of N-substituted aryl pyrroles via reductive amination/cyclization of levulinic acid (LA) with primary aromatic amines and hydrosilanes (e.g., PMHS) over CsF, and a series of N-substituted aryl pyrroles could be obtained in good to excellent yields at 120 °C. The mechanism investigation indicates that the reaction proceeds in two steps: the cyclization between amine and LA occurs first to form intermediate 5-methyl-N-alkyl-1,3-dihydro-2H-pyrrolones and their isomeride (B), and then the chemo- and region-selective reduction of intermediates take place to produce the final products. This approach for synthesis of N-substituted aryl pyrroles can be performed under mild and green conditions, which may have promising applications.

Influence of Brønsted acid sites on chemoselective synthesis of pyrrolidones over H-ZSM-5 supported copper catalyst

Cu(0)/H-ZSM-5 was identified as a chemoselective catalyst in the reductive amination of levulinic acid for the synthesis of pyrrolidones at ambient pressure and in aqueous media. The chemoselective nature of Cu was explained by carbonyl interaction with surface Brønsted acid sites deduced by pyridine and acetone adsorbed in situ infrared (IR) spectroscopic studies in conjunction with N2O titration. A strong polarization of band at 1685 cm−1 and an increase in its intensity with a decrease in Si/Al ratio of the H-ZSM-5 was found to be a key factor in the reductive amination activity. Structure activity relationship was established using the physicochemical characteristics of the catalysts analyzed by XRD, BET-SA, H2-TPR, NH3-TPD and XPS analyses.

Mild reduction with silanes and reductive amination of levulinic acid using a simple manganese catalyst

A manganese-based catalytic system using the commercially available complex [Mn(CO)5Br] was studied for the selective reduction of levulinic acid (LA) to 2-methyl-tetrahydrofuran (MTHF). We further studied the production of pyrrolidines via its reductive amination using silanes (phenylsilane and tetramethyldisiloxane). The results showed high efficiency and selectivity for this reaction leading to high yields using mild reaction conditions.

Investigation towards the reductive amination of levulinic acid by B(C6F5)3/hydrosilane system

The selective transformation of the renewable biomass resources into the highly value-added platform chemicals is essentially important for sustainable chemistry. Here we report a simple and highly efficient strategy for the synthesis of N-heterocyclic compounds from the reductive amination of the bio-derived levulinic acid and a wide range of anilines by metal-free B(C6F5)3/hydrosilane catalyst system. Through adjusting the amounts of hydrosilane, we can synthesize a series of pyrrolidones or pyrrolidines, respectively. Isotope-labeled NMR experiments were conducted to investigate the possible reaction pathway.

Reductive amination of levulinic acid to N-substituted pyrrolidones over RuCl3 metal ion anchored in ionic liquid immobilized on graphene oxide

Reductive amination of biomass derived Levulinic acid (LA) for the synthesis of N-substituted pyrrolidones is one of the highly attractive routes for biomass valorization. The supported homogeneous metal precursor into the solid surface is an important context in the field of catalysis because these types of catalysts provide the heterogeneous nature and meet the needs of recyclability. Herein, we have reported a synthesis of catalyst with ruthenium ion supported on ionic liquid immobilized into graphene oxide (Ru@GOIL) and its application for reductive amination reaction. Synthesized catalyst is characterized using different analytical techniques such as FT-IR, XRD, XPS, TGA, FEG-SEM, TEM and EXAFS analysis. The prepared Ru@GOIL found to be highly effective for reductive amination of LA and under these optimized conditions various N-substituted pyrrolidones derivatives were synthesized in excellent yield (78–93%). Ru@GOIL catalyst demonstrated great catalytic performance for reductive amination reaction of LA giving good turnover frequency (TOF = 62 h−1) value in comparison with other catalysts. The Ru@GOIL catalyst was recycled for six reaction runs with slight drop-in activity after 4th cycle. Practical applicability of the developed catalyst was successfully demonstrated by direct transformation of biomass waste (rice husk and wheat straw) derived LA to N-substituted pyrrolidones.

A Multiphase Protocol for Selective Hydrogenation and Reductive Amination of Levulinic Acid with Integrated Catalyst Recovery.

At 60-150 °C and 15-35 bar H2 , two model reactions of levulinic acid (LA), hydrogenation and reductive amination with cyclohexylamine, were explored in a multiphase system composed of an aqueous solution of reactants, a hydrocarbon, and commercial 5 % Ru/C as a heterogeneous catalyst. By tuning the relative volume of the immiscible water/hydrocarbon phases and the concentration of the aqueous solution, a quantitative conversion of LA was achieved with formation of γ-valerolactone or N-(cyclohexylmethyl)pyrrolidone in >95 and 88 % selectivity, respectively. Additionally, the catalyst could be segregated in the hydrocarbon phase and recycled in an effective semi-continuous protocol. Under such conditions, formic acid additive affected the reactivity of LA through a competitive adsorption on the catalyst surface. This effect was crucial to improve selectivity for the reductive amination process. The comparison of 5 % Ru/C with a series of carbon supports demonstrated that the segregation phenomenon in the hydrocarbon phase, never previously reported, was pH-dependent and effective for samples displaying a moderate surface acidity.

Formic acid as a hydrogen source for the iridium-catalyzed reductive amination of levulinic acid and 2-formylbenzoic acid

A robust iridium catalyst performs the reductive amination of the renewable levulinic acid and of 2-formylbenzoic acid in water under mild conditions. This catalyst tolerates very bulky reagents.

Conversion of levulinic acid to N-substituted pyrrolidinones over a nonnoble bimetallic catalyst Cu15Pr3/Al2O3

A nonnoble bimetallic metal catalyst Cu15Pr3/Al2O3 readily prepared through incipient-wetness impregnation method was developed for the reductive amination of levulinic acid (LA) with amines to N-substituted-5-methyl-2-pyrrolidinones. A wide variety of N-substituted-5-methyl-2-pyrrolidinones were obtained in high yield over this catalyst. The characterization results from XRD, H2-TPR, XPS, TEM, NH3-TPD and N2 adsorption-desorption revealed that Cu0 species are the active species for the hydrogenation in the reductive amination reaction. Besides, the doping of praseodymium into γ-Al2O3 supported copper catalyst greatly enhanced the catalytic performance of Cu/γ-Al2O3 due to better dispersion of Cu0.

Catalyst-free reductive amination of levulinic acid to N-substituted pyrrolidinones with formic acid in continuous-flow microreactor

The reductive amination of levulinic acid to N-substituted pyrrolidinones was performed in a continuous-flow microreactor (CFMR) in high yield, using formic acid as hydrogen source and acetonitrile as the reaction solvent. The developed protocol allows the avoidance of high boiling solvents such as DMSO and the additive triethylamine, more commonly associated with this synthetic transformation. As a result, the reaction products are more readily separated from the low boiling solvent.

Heterogeneous Nickel Catalysts for Reductive Amination of Levulinic Acid

Key words atomic layer deposition - nickel catalysis - carbon nanotubes - reductive amination - levulinic acid

Selective and Efficient Iridium Catalyst for the Reductive Amination of Levulinic Acid into Pyrrolidones.

The catalytic reductive amination of levulinic acid (LA) into pyrrolidones with an iridium catalyst using H2 as hydrogen source is reported. The chemoselective iridium catalyst displayed high efficiency for the synthesis of a variety of N-substituted 5-methyl-2-pyrrolidones and N-arylisoindolinones. N-Substituted 5-methyl-2-pyrrolidone was also evaluated as a biosourced substitute solvent to NMP (N-methylpyrrolidone) in the catalytic arylation of 2-phenylpyridine.