Levulinic Acid Research Articles

Influence of pH on the synthesis of carbon spheres and the application of carbon sphere-based solid catalysts in esterification

Abstract Size uniformity is a key challenge in the preparation of hydrothermal carbon spheres and a prerequisite for size effect research and many applications of carbon spheres. To solve the scientific problem of low uniformity due to the slow carbonization in traditional preparation of glucose carbon spheres, we propose to add acid/base catalysts to accelerate nucleation, shorten the nucleation time, and improve the size uniformity of carbon spheres. The carbon spheres prepared under base conditions versus acid conditions have higher uniformity and smaller particle size (particle size = 503 nm). This result is due to the faster accumulation of aromatic clusters, shorter nucleation time, and larger number of carbon spheres in alkaline systems. The NaOH-HCSs-based solid acid catalyst as-prepared exhibits excellent catalytic activity, and the esterification rates of levulinic acid and n-butanol maximize to 96.36%.

Catalytic Conversion of Levulinic Acid over Sn-BTC and Sn-H3-5-SIP Heterogeneous Acid Catalysts

This work presents the synthesis and characterization of materials that contain Sn metal clusters formed by ligands of trimesic acid (Sn-BTC) or 5-sulfobenzene-1,3-dicarboxylic acid (Sn-H3-5-SIP). These catalysts were used to convert levulinic acid with ethanol to produce ethyl levulinate under mild reaction conditions. The characterization results confirmed that Sn is mainly present in the cassiterite crystalline phase with a tetragonal rutile structure in octahedral and tetrahedral coordination in the materials. The assembly of trimesic acid (a hard base) with metal species (Sn) results in the formation of acid and thermally stable metal–organic frameworks. The use of 5-sulfobenzene-1,3-dicarboxylic acid instead of trimesic acid in the synthesis incorporates sulfonic groups in the material, enhancing the total acidity of the Sn-H3-5-SIP catalyst compared to the Sn-BTC material. The Sn-H3-5-SIP catalyst exhibited the highest catalytic activity when converting levulinic acid with ethanol, resulting in a turnover frequency (TOF) of 0.0495 s−1, which is a 50% increase compared to the TOF of the Sn-BTC catalyst (0.0329 s−1). This result can be attributed to its higher concentration of acid sites (2.23 ± 0.05 mmol H+/gcat) and specific area (139 m2/g). Thus, materials containing tin metal clusters and sulfonic groups are promising materials that could be used as catalysts for synthesizing ethyl levulinate under mild reaction conditions.

Harnessing Biomass for a Sustainable Future: The Role of Starch and Lignin

The global climate crisis, driven by unchecked industrialization and ecological negligence, compels humanity to seek alternative ways to either avert or mitigate the disastrous environmental phenomena encountered, particularly in recent years. The significant quantities of biomass generated by human activities may serve as important resources for technological applications, and biomass valorization offers dual benefits. This review emphasizes the potential of starch and lignin as adaptable materials for the advancement of sustainable and eco-friendly technologies. By investigating catalytic alterations, we may advance a more sustainable future and tackle the escalating issues of environmental pollution and sustainability. Catalytic alterations of lignin and starch have become essential techniques for their valorization. Biopolymers can be changed into useful chemicals and materials, like levulinic acid, lactic acid, 5-HMF and modified starch, which are used in the paper, textile, and coatings industries. Besides transforming into chemicals, lignin and starch can produce reactive carbon compounds that find application in both classical chemistry and photocatalysis. Additionally, we can use their highly functionalized polymeric matrices as catalysts. We can change the polymeric matrices’ chemical backbone to make them better at speeding up reactions like cross-coupling and multicomponent reactions.

Borane‐Catalyzed Selective Transformation of Levulinic Acid and Hydrazines into Hexahydropyridazines and Tetrahydropyridazin‐3(2H)‐ones Using Hydrosilane

Abstract. Borane‐catalyzed one‐pot tandem cyclization/hydrosilylation of levulinic acid and other γ‐ketoacids with hydrazines for selective access to hexahydropyridazines and tetrahydropyridazin‐3(2H)‐ones has been developed. The combination of B(C6F5)3 and Et3SiH allows for synthesis of various hexahydropyridazines and tetrahydropyridazin‐3(2H)‐ones in 67‐97% yields with tolerance towards various functional groups and easy scale‐up. This reaction can be rendered enantioselective by using a chiral borane catalyst generated in situ from HB(C6F5)2 and a binaphthyl‐based chiral diene and PhMe2SiH, affording the target products in 70‐92% yields with up to >99% ee. The judicious choice of borane catalyst and hydrosilane reductant proves to be critical for catalysis. Mechanistic investigations elucidate the catalytic pathway.

Enhanced Yield of Methyl Ethyl Ketone through Levulinic Acid Decarboxylation in the AgNO3/K2S2O8 System: Mechanistic Insights and Characterization of Metallic Species.

Methyl ethyl ketone (MEK) is among the most extensively utilized solvents in various industrial applications. In this study, we present a highly efficient synthesis route for MEK via the decarboxylation of biomass-derived levulinic acid, using potassium persulfate (K2S2O8) and silver nitrate (AgNO3) as key reagents. The specific roles of AgNO3 and K2S2O8 were thoroughly investigated. Additional silver species, such as Ag2O and AgO, were also detected during the reaction. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses provided evidence of the evolution of solid phases throughout the reaction. Based on these findings, we propose a radical decarboxylation mechanism initiated by the generation of sulfate radicals (SO4•⁻) through the catalytic breakdown of K2S2O8 by AgNO3. This mechanistic understanding, combined with a parametric study, enabled us to achieve an unprecedented level of levulinic acid conversion (97.9%) and MEK yield (86.6%) with this system, surpassing all previously reported results in the literature.

Effect of water on the excess properties of eutectic solvents

Three eutectic solvents were created utilizing a heating and stirring process. The solvents consist of tetrabutylammonium bromide and levulinic acid, as well as tetrabutylammonium chloride with either levulinic acid or lactic acid. The characterization of the samples was conducted using 1H NMR and IR techniques. The density and viscosity of three different low eutectic solvent and water binary mixture systems were determined within the temperature range of 293.15 to 333.15 K. The volume properties (excess molar volume, coefficient of expansion, coefficient of excess expansion) of the binary mixtures with different amounts of water were thoroughly investigated across the complete range of mole fraction. The study also investigated the impact of viscosity parameters, such as viscosity deviation and Excess activation Gibbs free energy of viscous flow. Furthermore, an analysis was conducted on the interaction between the eutectic solvent and the solvent molecules in the binary mixture. This analysis revealed the presence of hydrogen bonds between the eutectic solvent and water molecules. Moreover, it was confirmed that the excess properties could be fitted with the Redlich-Kister equation with r2 ≥ 0.99,demonstrating high suitability for binary mixes consisting of low eutectic solvents and water.

Chemical Profiling and Evaluation of Antioxidant Activity of Artichoke (Cynara cardunculus var. scolymus) Leaf By-Products’ Extracts Obtained with Green Extraction Techniques

This study aimed to determine the effectiveness of different green extraction techniques (GETs) on targeted bioactive compounds from artichoke leaf by-products using deep eutectic solvent extraction (DESE), supercritical CO2 extraction (SCO2E), subcritical water extraction (SWE), and ultrasound-assisted extraction (UAE). Moreover, (HR) LC-ESI-QTOF MS/MS and HPLC-PDA analyses were used to perform qualitative–quantitative analysis on the extracts, enabling the detection of several bioactive compounds, including luteolin, luteolin 7-O-glucoside, luteolin 7-O-rutinoside, apigenin rutinoside, chlorogenic acid, and cynaropicrin as the most representative ones. SWE showed better results than the other GETs (TPC: 23.39 ± 1.87 mg/g of dry plant, dp) and appeared to be the best choice. Regarding UAE, the highest total phenols content (TPC) was obtained with 50:50% v/v ethanol: water (7.22 ± 0.58 mg/g dp). The DES obtained with choline chloride:levulinic acid showed the highest TPC (9.69 ± 0.87 mg/g dp). Meanwhile, SCO2E was a selective technique for the recovery of cynaropicrin (48.33 ± 2.42 mg/g dp). Furthermore, the study examined the antioxidant activity (1.10–8.82 mmol Fe2+/g dp and 3.37–31.12 mmol TEAC/g dp for DPPH• and FRAP, respectively) and total phenols content via Folin–Ciocalteu’s assay (198.32–1433.32 mg GAE/g dp), of which the highest values were detected in the SWE extracts. The relationship among the GETs, antioxidant assays, and compounds detected was evaluated using Principal Component Analysis (PCA). PCA confirmed the strong antioxidant activity of SWE and showed comparable extraction yields for the antioxidant compounds between UAE and DESE. Consequently, GETs selection and extraction parameters optimization can be employed to enrich artichoke leaf by-products’ extracts with targeted bioactive compounds.

Liquid-Liquid equilibrium Behavior and intermolecular interactions of Levulinic acid and water with isopropyl ether and methyl Tert-Butyl ether

Levulinic acid (LA) is a crucial bio-based chemical with extensive industrial applications. Due to its significant share in the cost of production, the development of efficient techniques for the separation of LA is essential. Traditional separation using sulphuric acid raises environmental and cost concerns, making liquid–liquid extraction a more sustainable and cost-effective alternative. liquid–liquid equilibrium (LLE) investigation was carried out for two ternary mixtures of water + LA + isopropyl ether / methyl tert-butyl ether (MTBE) at two temperatures and 101.3 kPa. The results indicated that the solvent MTBE, as an extractant, showed a higher partition coefficient and selectivity for LA than isopropyl ether, demonstrating its superior effectiveness in recovering LA. The interaction insights between LA and the extractants were explored using quantum chemistry calculations, which aligned well with the collected results. The ascertained LLE data was modeled using the NRTL equation, achieving the RMSD values below 0.01, demonstrating a good concordance between the collected data and computed values. The fitted NRTL model parameters are conducive to the designing and optimizing the LA separation process.

KINETIC STUDY OF ESTERIFICATION CATALYZED WITH ALUMINUM SULFATE AIMED AT CONVERTING LEVULINIC ACID INTO METHYL LEVULINATE

Recycling lignocellulosic biomass is a sustainable alternative to the petrochemical industry since it allows the production of valuable, sustainable, and environmentally friendly chemical products, such as levulinic acid (LVA) and levulinate esters. Methyl levulinate (MLV), for example, has been assessed as a fuel additive with low toxicity, high lubricity, and flash point stability. In this respect, the present investigation details a kinetic study of methyl esterification catalyzed with aluminum sulfate aimed at converting levulinic acid into methyl levulinate. The reactions were carried out in a Parr Instruments stainless steel reactor to assess the effect of temperature (120, 140 and 160 °C) and reaction time (30, 60, 120 and 180 min) on LVA conversion into MLV, maintaining a constant LVA:methanol ratio of 1:8 and aluminum sulfate catalyst concentration of 0.04 mol.L-1. The maximum LVA-MLV conversion of 93.04 % was obtained at a temperature of 160 °C and reaction time of 60 minutes. The pseudo first-order kinetic model exhibited the best fit to the experimental data, with correlation coefficients (R²) greater than 0.96, and it was used to calculate activation energy, obtaining a value of 10.19 kcal.mol-1.

Heteropoly Acid‐Based Ionic Liquid Catalyzes Cellulose into Levulinic Acid in a Bi‐Phase Solvent System

AbstractLevulinic acid is an important chemical intermediate, which has many applications in organic synthesis, industry, agriculture, and medicine. In this word, three kinds of heteropoly acid based ionic liquids ([IMPS]H2PW12O40、[PyPS] H2PW12O40 [TEAPS] H2PW12O40) were used to catalyze the one‐pot conversion of cellulose to levulinic acid. [IMPS]H2PW12O40 has the highest catalytic activity due to its strong Hammett acidity (H0). In addition, the effect of biphasic solvent systems on the conversion of cellulose to levulinic acid was also studied. The results showed that the GVL/H2O system could effectively promote the conversion of cellulose and increase the yield of levulinic acid. The yield of levulinic acid could reach 52.6% and the conversion rate of cellulose was 91.2% at 180 °C for 180 min under the GVL/H2O volume ratio of 1:1 with [IMPS]H2PW12O40 as a catalyst at 1 Mpa N2 and cellulose as raw material. And [IMPS]H2PW12O40 can be recycled up to five times without significant performance loss. This study provides a promising method for efficiently converting cellulose and other biomass resources to levulinic acid extraction.

Facile construction of a stable biomass-derived carbon-supported AlZr composite with crystalline solid solution and Brønsted-Lewis dual acidity for efficient catalytic conversion of cellulose.

Exploiting cellulose-derived levulinic acid (LA) in biorefinery has potential application prospects, and the development of efficient and stable catalysts is crucial yet challenging. In this study, a bimetallic synergy strategy was proposed to construct an efficient and durable solid acid catalyst with crystalline solid solution by a totally solid-phase method. Mechanical activation (MA)-treated precursor (metal salts, starch, and urea) was calcined to obtain a stable biomass-derived carbon (BC)-supported AlZr (MA-AZ/BC) composite, which was applied for catalytic conversion of cellulose to LA in aqueous-phase system. The results indicate that the synergistic effect of bimetallic crystalline solid solution and the existence of Brønsted-Lewis dual-acid sites in the MA-AZ/BC catalyst contributed to a cellulose conversion efficiency of 97.5% and a LA yield of 67.1%. Benefiting from the strong bimetal-support interaction, the MA-AZ/BC catalyst exhibited favorable stability and recoverability. On the basis of comprehensive analysis, a reaction mechanism of Brønsted-Lewis dual-acid sites for synergistic catalytic conversion of cellulose was proposed. This study provides a new idea for the rational design and environmentally friendly fabrication of functional BC-based catalysts for efficiently producing platform compounds derived from biomass.

Deep eutectic solvent combined with permeation enhancer strategy to convert tandospirone from oral to transdermal formulations improving drug bioavailability

Tandospirone(Tan) is a commonly used drug for anxiety treatment. However, it has a significant first-pass effect and needs to be taken three times a day. To increase the bioavailability of the drug and reduce the number of administrations, this work amid to prepare a Tan patch that can be administered once a day by using the strategy of therapeutic deep eutectic solvent(THEDES) in cooperation with chemical permeation enhancer(CPE). In this study, four organic acids and five permeation enhancers were selected, and the optimized formulation was obtained by single-factor investigation and Box-Behnken design. The optimized formulation could significantly enhance drug loading by 2.5-fold and skin permeation up to 586.6 ± 17 μg/cm2 in rats. Based on pharmacokinetic results, compared to oral administration, the drug exhibited a substantially elevated bioavailability, registering a 17-fold increase(from 3.01 % to 52.17 %), alongside a 10-fold rise in the mean residence time(MRT). Meanwhile, the patch was not irritating. The results of the mechanistic study showed that levulinic acid(LeA) acted as a bridge to increase the interaction between the Tan and the matrix and inhibited the crystallization of the drug in the patch, and THEDES together with CPE improved the matrix fluidity and skin permeability. This study provides a reference for the joint application of THEDES and CPEs in patch development.

Effect of the carbon surface chemistry on the metal speciation in Ru/C catalysts. Impact on the transformation of levulinic acid to γ-valerolactone

A set of Ru/C catalysts prepared using a commercial active carbon and a series of carbon materials derived from it (treatment in N2 flow, at 300, 600 or 900 °C that selectively removes surface oxygen complexes), of similar textural properties and different surface chemistry, were used, without reduction treatment, in the aqueous phase transformation of levulinic acid (LA) to γ-valerolactone (GVL) at 70 °C. The prepared Ru/C catalysts were active, being activity and selectivity strongly dependent on the support surface chemistry. It was confirmed that the supported Ru species became reduced under reaction conditions, and this process was more efficient in catalysts prepared with the heat treated supports, due to the different interactions created between Ru species and the support surface. In a cleaner carbon surface, the anchorage of the Ru species on carbon oxygen groups was limited, and they were more prone to be reduced and to move, forming more defined metallic structures. The carbon surface chemistry determined the Ru speciation (reduced and oxidized species), and the proportion of reduced Ru drived the H spill over process, which was related to the creation of protonic acid sites, proposed to be key point to explain the trend in selectivity to GVL.

Highly efficient hydrogenation of levulinic acid into γ-valerolactone over modified bifunctional yolk-shell catalyst

Highly efficient hydrogenation of levulinic acid into γ-valerolactone over modified bifunctional yolk-shell catalyst

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

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

Microbial production of levulinic acid from glucose by engineered Pseudomonas putida KT2440

Levulinic acid(LA) is produced through acid-catalyzed hydrolysis and dehydration of lignocellulosic biomass. It is a key platform chemical used as an intermediate in various industries including biofuels, cosmetics, pharmaceuticals, and polymers. Traditional LA production uses chemical conversion, which requires high temperatures and pressures, strong acids, and produces undesirable side reactions, repolymerization products, and waste problems Therefore, we designed an integrated process to produce LA from glucose through metabolic engineering of Pseudomonas putida KT2440. As a metabolic engineering strategy, codon optimized phospho-2-dehydro-3-deoxyheptonate aldolase (AroG), 3-dehydroshikimate dehydratase (AsbF), and acetoacetate decarboxylase (Adc) were introduced to express genes of the shikimate and β-ketoadipic acid pathways, and the 3-oxoadipate CoA-transferase (pcaIJ) gene was deleted to prevent loss of biosynthetic intermediates. To increase the accumulation of the produced LA, the lva operon encoding levulinyl-CoA synthetase (LvaE) was deleted resulting in the high LA-producing strain P. putida HP203. Culture conditions such as medium, temperature, glucose concentration, and nitrogen source were optimized, and under optimal conditions, P. putida HP203 strain biosynthesized 36.3 mM (4.2 g/L) LA from glucose in a fed-batch fermentation system. When lignocellulosic biomass hydrolysate was used as the substrate, this strain produced 7.31 mM of LA. This is the first report of microbial production of LA from glucose by P. putida. This study suggests the possibility of manipulating biosynthetic pathway to produce biological products from glucose for various applications.

Utilizing environment-friendly eugenol as a diluent with trioctylamine for the reactive extraction of aqueous levulinic acid

This paper focuses on the reactive extraction of levulinic acid (LA) from aqueous solution by reactive extraction. This goal is achieved using eugenol, a green alternative in the industry, as a solvent in the liquid-liquid equilibrium (LLE) measurements for the ternary system of LA + Eugenol + H2O and quaternary systems of LA + Eugenol/ Methanol (MeOH) + H2O + Tri-n-octylamine (TOA) at T = 293.15 K. Additionally, the distribution coefficients (KD) were calculated for LA using the two diluents. Also, the ability of different diluents with TOA, in the extraction of LA were compared. The distribution coefficient of eugenol with TOA (KD = 9.44) is compared with other organic diluents which indicated that eugenol is a suitable option. MeOH, being the shortest chain alcohol, also turned out to be a diluent that could be utilized for extraction of LA with TOA. Furthermore, the Non-Random Two-Liquid (NRTL) excess Gibbs energy model was applied to correlate the measured phase equilibria. The obtained parameters were further validated using a decanter model.

Valorization of levulinic acid by esterification with 1-octanol using a novel biocatalyst derived from Araujia sericifera

Levulinic acid, which can be obtained from biomass, has sparked great interest as a biologically-based chemical building block with wide versatility and potential. Its esterification with alcohols of different chain lengths is a promising valorization process for obtaining esters with various applications in the areas of biofuels/biolubricants, food and cosmetics, among others. In this work, the enzymatic esterification of levulinic acid and 1-octanol using a biocatalyst derived from Araujia sericifera latex was studied in systems with and without solvent. The influence of the molar ratio between alcohol and acid (ranging from 2:1–1:9), the biocatalyst loading (between 7.5 % and 17.5 % relative to the acid), the volume of n-heptane used as reaction solvent (from 0 to 4 ml), and the reaction time (6 hours) were investigated. The activity and stability of the biocatalyst in successive uses were also analyzed. A conversion of 49 % was achieved when the reaction was carried out in a solvent-free system, using an alcohol/acid molar ratio of 1:7 and after 5 h of reaction. On the other hand, the conversion was 65.1 % when the reaction was conducted in a system containing 1 ml of n-heptane as solvent, an alcohol/acid molar ratio of 1:8, and 5 h of reaction. In both cases, a temperature as low as 30 °C and an agitation speed of 300 RPM were used.

Enhanced hydrothermal stability by a semi-embedded structure: An efficient Ru catalyst for levulinic acid conversion in the aqueous phase

Catalyst stability is believed to be one of the greatest challenges faced for the supported metal catalysts in the catalytic conversion of biomass and its derivatives because many biomass transformations are conducted in the aqueous phase. In this work, we report a simple yet efficient coating-impregnation-pyrolysis (CIP) strategy to fabricate Al2O3 supported Ru catalyst (Ru-Al2O3@CN) with Ru NPs (nanoparticles) semi-embedded into N-doped carbon (CN) layer for the efficient hydrogenation of levulinic acid (LA) to γ-valerolactone in the aqueous phase. Benefit from the special structure of Ru-Al2O3@CN catalyst, it possesses both high catalytic activity and stability, giving a TOF of 28,099 h-1 for LA hydrogenation at 120 °C and 2 MPa H2, which is superior to the most of reported Ru-based catalysts. More importantly, compared with conventional impregnated Ru/Al2O3 catalyst, the Ru-Al2O3@CN catalyst exhibits a remarkably improved hydrothermal stability. Based on series of catalyst characterizations and control experiments, it was found that the presence of CN can weak the interaction between Ru and Al2O3, as well as protect the Al2O3 and Ru NPs from hydrolysis and aggregation, respectively. We anticipate that such a novel strategy may provide some valuable insights into the synthesis of oxides-supported metal catalyst with high hydrothermal stability.

Determination of mometasone furoate solubility, using deep eutectic systems, and topical formulation- experimental and computational studies

The low solubility of some drugs in aqueous medium, is currently a challenge for the pharmaceutical industry, affecting drug bioavailability and treatment efficacy, so there is the need to find new solutions for this challenge. In this work, the solubility of a glucocorticoid drug, mometasone furoate (MF), in different deep eutectic systems (DES) is studied. DES present the advantage of being sustainable solvents, which can be used directly in the final formulation, and establish a synergistic effect with the drug. The solubility of MF in different DES is increased, when compared to the solubility of this drug in an aqueous medium, particularly in DES composed by levulinic acid and terpenes such as menthol and thymol, where the solubility of MF was of 24.1 and 103.3 mgMF/gDES, respectively. Solubility was also assessed using the computational determination of the Hansen solubility parameters of MF in these DES, in particular the total solubility parameter (δT) and Relative Energy Difference (RED). The obtained results correlate well with the MF measured experimentally, showing that this computational tool can be further used to predict MF solubility in DES. Furthermore, oil-in-water emulsions containing DES with MF were developed, allowing more versatility compared to the drug in powdered form, and were prepared containing 1 and 5 % of DES with MF. This work highlights that DES can have an important role in drug solubilization and in the development of new formulation strategies for the pharmaceutical industries.