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The current energy crisis has prompted the development and utilization of renewable energy and energy storage material. In this study, levulinic acid (LA) and 1,4-butanediol (BDO) were used to synthesize a novel levulinic acid 1,4-butanediol ester (LBE) by both enzymatic and chemical methods. The enzymatic method exhibited excellent performance during the synthesis process, and resulted in 87.33% of LBE yield, while the chemical method caused more by-products and higher energy consumption. What's more, the thermal properties of the obtained LBE as a phase change material (PCM) were evaluated. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that the melting temperature, latent heat of melting, and pyrolysis temperature were 50.51 °C, 156.1 J/g, and 150–160 °C, respectively. Compared with the traditional paraffin, the prepared PCM has a superior phase transition temperature, a higher latent heat of melting, and better thermal stability. The thermal conductivity could be increased to 0.34 W/m/k after adding expanded graphite (EG). In summary, LBE has great potential in the application of energy storage as a low-temperature phase change energy storage material. [ABSTRACT FROM AUTHOR]

Levulinic acid (LA) is an important platform chemical and used for the production of various biofuels and bio-based chemicals. Formic acid (FA) is a major product of biomass conversion and sustainable biomass-derived energy source for hydrogen production. Due to the growing demand for the use of renewable sources, cellulose-containing plant wastes/lignocelluloses can act as substrates for LA and FA production. Among various cellulose conversion strategies, solid acid appears to be a promising alternative for mineral acids recently. Hitherto only harsh conditions and strong mineral acids have been used for carbon solid acid synthesis. Therefore, recyclable non-corrosive catalysts with suitable thermal and chemical stability for cellulose hydrolysis are in great demand. Methane sulfonic acid (MSA) is a green acid since it is non-oxidizing, readily biodegradable, and less toxic than mineral acids. In this work, we have explored the use of this milder acid-based carbon solid acid catalyst synthesized from inedible mahua (Madhuca longifolia) oil cake through one-step hydrothermal synthesis and examined its efficiency for LA and FA production from cellulose. The catalyst was characterized using Raman spectroscopy, FTIR, BET, XPS, TGA, and XRD analysis. A drastic change in catalyst surface area from < 1 to 319 m2/g and acid site density (0–5.77 mmol/g) was achieved by increasing synthesis temperature above 240 °C which reflected in increased cellulose conversion to LA and FA. This indicated a need for significant change in synthesis temperature while using milder acids than the conventionally used temperature of 180 °C for strong acids. The increase in synthesis time to 24 h resulted in a catalyst with a good surface area of 367 m2/g. The use of high acid concentration for catalyst synthesis (1:4, oil cake: acid ratio) destroyed porous structures leading to reduced surface area (277 m2/g) and pore volume but increased the amount of catalyst acid sites. Interestingly, the lowering of LA and FA yield for this catalyst signified the importance of surface area and acid site concentration in determining the catalyst efficiency. The catalyst achieved efficient conversion of cellulose with an LA and FA yield of 38 and 65%, respectively. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HAp) supported nickel catalysts were synthesised via simple urea precipitation method with various nickel loadings ranging from 5 to 20 wt% and tested in vapour phase hydrogenation of levulinic acid (LA) under ambient pressure. The as-prepared catalysts were systematically characterized by using X-ray diffraction, UV-DRS, HR-TEM, SEM, BET surface area, TPR and TPD-CO2 techniques. The active nickel surface area and the Ni dispersion over the HAp support were measured by using H2 chemisorption method. The XRD results confirmed that the nickel oxide particles were well dispersed over HAp support at lower loadings and NiO crystallites were formed at higher loadings. The HR-TEM images revealed that ultra small (2.49 ± 0.4 nm) and homogenously distributed nickel nanoparticles are formed over 5 wt% NiHAp catalyst. Moreover, UV-DRS analysis is also confirmed the similar phenomena. The H2-TPR analysis revealed that the presence of strong interaction between nickel particles and hydroxyapatite support was observed. Among several HAp supported Ni catalysts tested in this study, we found that 5 wt% NiHAp catalyst is the most active and selective due to the presence of high number of active surface Ni particles over HAp support and this was confirmed by the H2 chemisorption analysis and HR-TEM. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel Cr/MCM-22 was synthesized and tested as catalyst to synthesize levulinic acid. • Catalytic efficiency was high for many renewable biomass-derived starting materials. • High reusability was achieved, and comprehensive catalytic mechanism was presented. The novel Cr-loaded MCM-22 zeolite (Cr/MCM-22) was successfully synthesized, fully characterized, and applied as a heterogeneous catalyst for the transformation of biomass-derived materials (glucose, sucrose, cellulose, starch, agricultural residues, and other municipal wastes) into levulinic acid via hydrothermolysis. The novel Cr/MCM-22 gives higher yields of levulinic acid compared to other reported catalysts. Specifically, Cr/MCM-22 produced 73.2% levulinic acid yield from glucose at relatively high concentrations (solvent:biomass 20:1). For starting materials with higher structural complexity, pretreatment was required to maintain a high yield of levulinic acid. The novel catalyst was studied and compared to other related catalysts. The high efficiency is attributed to the synergistic effect induced by confinement control of the microporous material as well as Lewis and Brønsted acid sites of Cr/MCM-22. A reaction mechanism including all reaction steps has been proposed. The Cr/MCM-22 was successfully recycled three times. [ABSTRACT FROM AUTHOR]

In this study, a microwave-assisted process was developed for the production of 5-hydroxymethylfurfural (HMF), furfural, and hydrochar from bamboo (Phyllostachys nigra "Boryana") in a biphasic reaction system. The system consisted of an acidified aqueous phase and methyl isobutyl ketone (MIBK) as the organic phase and enabled the instantaneous extraction of HMF and furfural in the organic phase. In this way, unwanted side and rehydration reactions are avoided. The aim of the study was to maximize HMF and furfural yields from bamboo in short reaction times. Building on previous studies, an HCl concentration of 0.13 M was used to ensure the simultaneous conversion of cellulose and xylan to HMF and furfural, respectively. To shorten the reaction time considerably, higher reaction temperatures were applied in this study (200–240°C). The use of microwave irradiation allowed very short reaction rates for maximum HMF and furfural production. Yields of 21 wt% HMF, 13 wt% furfural, and 39.5 wt% hydrochar were achieved using bamboo culm particles and by applying 0.13 M HCl (10 wt% NaCl) and 220°C with a reaction time of 2 min. The results show that the required reaction time to reach a maximum HMF and furfural yield was not significantly influenced by the particle size (< 200μm–2 mm). The effect of NaCl in the production of HMF and furfural was assessed. It was clear that the addition of NaCl increased the maximum HMF yield but also enhanced the unwanted rehydration reaction to levulinic acid. Results indicated that NaCl could be absorbed on the surface of the hydrochar. [ABSTRACT FROM AUTHOR]

Pyrrolidones has gained much attention because of extensive use in agrochemical, pharmaceutical, industrial materials and chemical production. In that context, we demonstrated a novel and highly competent protocol for the reductive amination of biomass-based levulinic acid into N-alkyl pyrrolidone. The protic ionic liquid (PIL) [HmPip][OTf] used in this study plays a dual role as a catalyst for reductive amination as well as for dehydrogenation of dimethylamine borane complex (DMAB). Metal-free construction of N-alkyl pyrrolidone and its derivatives in remarkable yields are obtained with operational comfort because of the milder reaction conditions. The PIL could be recycled up to five times without significant loss in its catalytic activity. The developed process is promising drop-in technology because of the reductive heterocyclisation of direct biomass derived LA to pyrrolidones. [ABSTRACT FROM AUTHOR]

Catalytic hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) was investigated over four different types of mesoporous silica (SBA-15, MCM-48, MCM-41, and KIT-6) supported copper (5 wt.%) catalysts. The Cu was incorporated into mesoporous silica supports by a sequential impregnation method. A detailed investigation of the support structure–activity correlation and the performance of the catalysts in LA conversion was studied. Detailed characterisation techniques were used to evaluate the physical and catalytic properties of the studied catalysts. The structure type and physicochemical properties of the silica support had a significant effect on the overall performance of the catalysts. Among them, over Cu/SBA-15 catalyst, a complete levulinic acid (LA) conversion with ~ 98% gamma valerolactone (GVL) selectivity was achieved at 265 °C under ambient H2 pressure. The superior performance of Cu/SBA-15 catalyst was attributed to the high surface acidity, reducibility of Cu oxides species, and highly dispersed Cu particles over SBA-15 structure. The results confirmed that the activity of the catalysts is significantly influenced by the textural properties, surface acidity and copper dispersion. Durability of all the catalysts were also tested for 50 h time on stream and over SBA-15 catalyst, only a small drop in the activity was observed. [ABSTRACT FROM AUTHOR]

Glucose is one of the primary derivative products from lignocellulosic biomass, which is abundantly available. Glucose has excellent potential to be converted into valuable compounds such as ethanol, sorbitol, gluconic acid, and levulinic acid (LA). Levulinic acid is an exceptionally promising green platform chemical. It comprises two functional groups, ketone and carboxylate, acting as highly reactive electrophiles for a nucleophilic attack. Therefore, it has extensive applications, including fuel additives, raw materials for the pharmaceutical industry, and cosmetics. This study reports the reaction kinetics of LA synthesis from glucose catalyzed by hydrochloric acid (HCl), a Bronsted acid, that was carried out under a wide range of operating conditions; i.e. the temperature of 140-180 °C, catalyst concentration of 0.5-1.5 M, and initial glucose concentration of 0.1-0.5 M. The highest LA yield of 48.34 % was able to be obtained from an initial glucose concentration of 0.1 M and by using 1 M HCl at 180 °C. The experimental results show that the Bronsted acid-catalyzed reaction pathway consists of glucose decomposition to levoglucosan (LG), conversion of LG to 5-hydroxymethylfurfural (HMF), and rehydration of HMF to LA. The experimental data yields a good fitting by assuming a first-order reaction model. [ABSTRACT FROM AUTHOR]

The conversion of waste cardboard using microwave assisted hydrothermal method to obtain reducing sugars and versatile chemical blocks is reported in this work. The findings revealed that microwave assisted dilute acid hydrothermal conversion of cardboard is effective and efficient, as it removed considerable amount of CaCO 3 in cardboard to keep the microwave conversion pressure at a stable status and can selectively produce value-added chemicals by changing the conversion temperature. The optimum conversion conditions for maximum aqueous bio-oil yield (29.76 wt%) was using 0.1 g of cardboard and 10 g of 2.5 wt% of phosphoric acid at MW hydrothermal condition of 175 °C for 30 min. Products compositions were changed and refined by changing the dilute acid MW hydrothermal conditions. At 150 °C, sugars were the main products; at 175 °C, levoglucosan was the main product whereas at 200 °C the major product was levulinic acid. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Ni precursor affected the metallic dispersion and Ni/CNT catalyst activity. • Highest activity for catalysts prepared from nickel nitrate and hydroxide salts. • All catalysts were selective to GVL (> 90 %). • The catalyst with nickel loaded outside CNTs showed highest activity. Carbon nanotubes (CNT) supported (10 wt.%) nickel catalysts were evaluated for the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) using a trickle-bed reactor at 180 °C and 30 bar. The effect of nature of the nickel precursors salts (Ni NIT - Ni(NO 3) 2.6H 2 O, Ni ACET - Ni(CH 3 COO) 2.4H 2 O) and Ni HYD - Ni(OH) 2) and the preparation method on the distribution of Ni particles inside (CNT IN) and outside (CNT OUT) of the carbon nanotubes were investigated. The nickel catalysts were synthesized by incipient wetness impregnation method without opening or functionalization of CNTs. The difference between the preparation of Ni/CNT IN and Ni/CNT OUT catalysts was the pre-filling of the pores of the CNT with p-xylene before the impregnation of the nickel salts for the Ni/CNT OUT samples. These methodologies led to the complete deposition of Ni particles outside of pores for Ni/CNT OUT samples, but partial deposition of Ni particles inside of CNTs for Ni/CNT IN samples, regardless of the nickel precursor salt. It was estimated by TEM only 30 % of Ni particles inside CNTs for Ni NIT /CNT IN. The Ni/CNT OUT catalysts prepared from nickel nitrate and nickel hydroxide salts showed the highest activity for LA hydrogenation, compared to those prepared from nickel acetate salts, which is likely due to the higher metal dispersion. [ABSTRACT FROM AUTHOR]

This study investigated the effect of various hydrophobic fillers on polyethersulfone (PES) membrane support properties. Graphene, kaolin, ZIF-8, and fluoroalkylsilane were loaded from 0.1 wt% to 5 wt% in membrane casting solution. The structure and properties of the membrane changed accordingly based on the type of filler used. The finger-like pores in the PES membrane were extended, providing additional space for the liquid membrane impregnation. The contact angle value in the mixed matrix membranes was increased compared to the pristine PES membrane. The highest contact angle was shown by the additional of 0.5 ZIF-8 wt% in PES membrane with top and bottom contact angle value of 92.5° and 103.9°, respectively. PES membrane with 0.1 wt% graphenes showed the highest porosity of 87.1%. PES membrane loaded with 0.1 wt% ZIF-8 showed the most elevated tensile stress among the membrane support fabricated with a value of 1,036kPa. The best extraction of levulinic acid (LA) from 10 g/L LA feed solution was achieved using 0.1 wt% graphene-PES membrane support with 89.2% extraction percentage. [ABSTRACT FROM AUTHOR]

Bamboo shoots are a popular food in Asia and throughout the world. As only the tip of the bamboo shoot is edible, significant quantities of processing byproducts are generated, with potential for valorization of these wastes. Deep eutectic solvents (DESs) are emerging as eco-friendly solvents for the extraction of bioactive compounds from natural products. This work investigated the extraction of protein from the tip of the bamboo shoot (TBS), as well as its processing byproducts (basal bamboo shoot (BBS) and sheath) using a DES comprised of compounds accepted as food additives: choline chloride (ChCl) as hydrogen bond acceptor (HBA) and levulinic acid as hydrogen bond donor (HBD). Central composite design (CCD) and Response Surface Methodology (RSM) were used to predict optimum extraction parameters for all bamboo shoot parts with HBA-to-HBD molar ratio of 6, temperature of 80 °C, time of 50 min, water content of 40% (v/v), and solid-to-liquid ratio of 30 mg/mL for TBS, 70 mg/mL for BBS and sheath. Under the optimal conditions, the protein extraction yields were 39.16 ± 1.22 mg/g dry weight (DW) for TBS, 15.46 ± 0.30 mg/g DW for BBS, and 9.54 ± 0.17 mg/g DW for sheath. Compared with conventional extraction using sodium hydroxide (NaOH) solution, significantly higher protein yield was recovered with DES for TBS, and comparable yields obtained for BBS and sheath. Results show the potential of this DES as a carrier for extracted bamboo proteins in functional food applications, as a biorefinery approach for bamboo shoot processing. [ABSTRACT FROM AUTHOR]

The massive use of petroleum and its possible exhaustion are driving the current research trend to study alternative raw materials from biomass for organic reactions. In this context, the present article presents a study of the catalytic esterification of levulinic acid, a platform molecule, with ethanol. Metal-organic framework (MOF) type compounds UiO-66-NH2 have been synthesized. Zirconium was incorporated, using zirconium chloride as a metal precursor, together with 2-aminoterephthalic acid as an organic binding agent. An alternative route of synthesis was proposed using more favorable conditions from an economic and environmental point of view, replacing dimethylformamide by 50 and 75% acetone as substitute solvent. The physicochemical properties of the materials were evaluated by X-ray diffraction (XRD), Infrared Spectrometry with Fourier Transform (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), microwave plasma atomic emission spectroscopy (MP-AES) and N2 adsorption to understand their morphology, crystalline, chemical and pore structure. The progress of the reaction was followed by gas chromatography and mass spectroscopy. The catalytic activity result of MOF25% in autoclave reactor, showed 100% of selectivity to ethyl levulinate and a turnover number (TON) of 66.18 moles of product/moles of Zr. This good catalytic performance obtained by partial solvent replacement in the synthetic material provides a more economical and eco-friendly process for ethyl levulinate generation. [ABSTRACT FROM AUTHOR]

This study aims to validate and investigate the power of green coconut biomass (mesocarp) for the production of levulinic acid (LA). Several methods have been applied to characterize this biomass physically and chemically, in order to provide an assertive direction in the use of this residue. The LA conversion was performed with different catalysts, hydrochloric acid (HCl) and sulfuric acid (H2SO4). The conversion reactions were performed by varying time (t) and temperature (T) according to the optimum conditions described in the literature for each catalyst. In order to increase the yield of LA, the biomass was pretreated with sulfuric acid (H2SO4), sodium hydroxide (NaOH), and water (H2O in soxhlet) solutions. There were significant increases in the release of sugars, xylose, and arabinose (p < 0.05), after the pretreatments with NaOH solution (assay 9). The maximum yield of LA was 43.8% under the following reaction conditions: 3 h, 180 °C, and 0.045 M of hydrochloric acid (HCl). In addition to the levulinic acid, the 5-hydroxymethylfurfural (HMF) and furfural (FF) furanics were also quantified with yields of 13.4% and 4.4% respectively. The results have shown the power of green coconut shells within biorefineries to produce value-added chemicals. [ABSTRACT FROM AUTHOR]

The selective reductive amination of levulinic acid (LA) into pyrrolidone derivatives is regarded as one of the most promising reactions in the fields of biomass conversion into high value-added chemicals. Herein, we report a one-pot synthesis of N-substituted-5-methyl-2-pyrrolidones by reductive amination of LA/ester with nitriles over several commercial catalysts. Among the catalysts texted, Pd/C was found to be the most efficient for the reductive amination of LA/ester with various nitriles to give high yields of pyrrolidones (up to 92%) under mild reaction conditions (80 °C, 1.6 MPa H2, tetrahydrofuran solvent). And the catalyst showed good reusability. [ABSTRACT FROM AUTHOR]

In this study, sulfonic acid-functionalized lignin-montmorillonite complex (LMT-SO3H) was prepared and employed as an efficient heterogeneous catalyst for the esterification of levulinic acid (LA) into n-butyl levulinate (BL). An intermediate pseudo-butyl levulinate (p-BL) was determined by distilled water treatment and nuclear magnetic resonance (NMR) analysis, and a possible mechanism for the esterification of LA is proposed. The effects of various process parameters were studied and the results showed that the LMT-SO3H catalyst had the excellent catalytic performance for esterification of the LA. Under optimum reaction conditions, the yield of BL was 99.3% and the conversion of LA was 99.8%. The LMT-SO3H catalyst exhibited strong acidic sites and high stability even after seven cycles of usage. Furthermore, esterification of the LA with various alcohols over the LMT-SO3H was further investigated

Sorghum stems, an agricultural biomass waste, can be used as a raw-material carbon source for platform chemicals, such as levulinic acid. Levulinic acid can be produced with high percentage yields using delignified sorghum stems as starting materials. The purpose of this study was to evaluate manganese-based catalysts (Mn2+ and Mn3O4) as Fenton-like reagents for the production of levulinic acid from sorghum stems. A mixture of finely powdered delignified sorghum stems (containing 76.66% cellulose) dispersed in a mixture of phosphoric acid (40%), H2O2 (30%), and either 2% Mn2+ or 2% Mn3O4 as a catalyst in a one-pot mini reactor was observed at 130°C for 10 h. The yield of the conversion products was quantitatively analyzed for levulinic acid using high-performance liquid chromatography. The reaction using the Mn3O4 catalyst yielded a higher percentage of levulinic acid (26.57%) than the Mn2+ catalyst (25.59 %) reaction after 8 hours. This study points to the opportunity of the one-pot synthesis of levulinic acid using renewable biomass waste resources.

In this review key processes for the synthesis of greener or more sustainable solvents derived from renewable sources (saccharides, lignocellulose and triglycerides) are discussed. It is shown that a series of platform chemicals such as glycerol, levulinic acid and furans can be converted into a variety of solvents through catalytic transformations that include hydrolysis, esterification, reduction and etherification reactions. It was also considered several aspects of each class of solvent regarding performance within the context of the reactions or extractions for which it is employed.

In this study, a novel enzymatic approach to transform levulinic acid (LA), which can be obtained from biomass, into value-added (R)-4-aminopentanoic acid using an engineered glutamate dehydrogenase from Escherichia coli (EcGDH) was developed. Through crystal structure comparison, two residues (K116 and N348), especially residue 116, were identified to affect the substrate specificity of EcGDH. After targeted saturation mutagenesis, the mutant EcGDHK116C, which was active toward LA, was identified. Screening of the two-site combinatorial saturation mutagenesis library with EcGDHK116C as positive control, the kcat/Km of the obtained EcGDHK116Q/N348M for LA and NADPH were 42.0- and 7.9-fold higher, respectively, than that of EcGDHK116C. A molecular docking investigation was conducted to explain the catalytic activity of the mutants and stereoconfiguration of the product. Coupled with formate dehydrogenase, EcGDHK116Q/N348M was found to be able to convert 0.4 M LA by more than 97% in 11 h, generating (R)-4-aminopentanoic acid with >99% enantiomeric excess (ee). This dual-enzyme system used sustainable raw materials to synthesize (R)-4-aminopentanoic acid with high atom utilization as it utilizes cheap ammonia as the amino donor, and the inorganic carbonate is the sole by-product.

This article presents the conditions for the conversion of hemicellulose with different contents of C6 and C5 carbohydrates and uronic acids based on the OrganoCat process, and the abbreviations M1, M2, and M3 are used. Homogenous catalysis with sulfuric acid (VI) in the concentration range of 0.1–1 M was used in the study to determine its activity on the ability to transform a hemicellulose mixture. The process was carried out using the one-pot technique in the temperature range of 100–250 °C for 1–5 h. Based on the use of the chromatographic technique (HPLC-RID) together with a comparison with standard substances, the resulting chemical compounds were determined and identified from the post-reaction mixtures. The degree of covalence of the raw material, the selectivity of the obtained chemical compounds, and the yield of lactic acid were also determined. Based on the obtained results, lactic acid with the highest yield (64.57%) was obtained after 1 h of the process from the M1 mixture at the temperature of 100 °C with 0.1 M sulfuric acid (VI) as a catalyst. The formation of oxalic acid was also observed, which is present in all post-reaction mixtures, regardless of the composition of the raw material, temperature, and time. Its efficiency was determined at an average level of 90%.

Currently, there is a great interest in the development of sustainable and green technologies for production of biofuels and chemicals. In this sense, much attention is being paid to lignocellulosic biomass as feedstock, as alternative to fossil-based resources, inasmuch as its fractions can be transformed into value-added chemicals. Two important platform molecules derived from lignocellulosic sugars are furfural and levulinic acid, which can be transformed into a large spectrum of chemicals, by hydrogenation, oxidation, or condensation, with applications as solvents, agrochemicals, fragrances, pharmaceuticals, among others. However, in many cases, noble metal-based catalysts, scarce and expensive, are used. Therefore, an important effort is performed to search the most abundant, readily available, and cheap transition-metal-based catalysts. Among these, copper-based catalysts have been proposed, and the present review deals with the hydrogenation of furfural and levulinic acid, with Cu-based catalysts, into several relevant chemicals: furfuryl alcohol, 2-methylfuran, and cyclopentanone from FUR, and γ-valerolactone and 2-methyltetrahydrofuran from LA. Special emphasis has been placed on catalytic processes used (gas- and liquid-phase, catalytic transfer hydrogenation), under heterogeneous catalysis. Moreover, the effect of addition of other metal to Cu-based catalysts has been considered, as well as the issue related to catalyst stability in reusing studies.

Agroforestry wastes are industrial byproducts available locally such as eucalyptus sawdust (EUC) and sugarcane bagasse (SCB). These byproducts can be used as lignocellulosic raw materials to produce high-value products. This study is a techno–economic analysis of four potential scenarios to produce polyhydroxybutyrate (PHB) and levulinic acid (LA) from hemicellulosic sugars by a fermentative pathway in a biomass waste biorefinery. Mass and energy balances were developed, and technical and economic assessments were carried out to obtain gas, char, and tar from residual solids from autohydrolysis treatment. It was determined that microbial culture could be an attractive option for added-value product production. More than 1500 t/year of PHB and 2600 t/year of LA could be obtained by the proposed pathways. Microbial and enzymatic conversion of LA from sugars could significantly improve energy consumption on the conversion strategy. The products from solid residual valorization (char and tar) are the most important for economic performance. Finally, a variation in specific variables could mean substantial improvements in the final indicators of the processes, reaching a higher NPV than USD 17 million.

Methylorubrum extorquens AM1 is an efficient platform strain possessing biotechnological potential in formate- and methanol-based single carbon (C1) bioeconomy. Constitutive expression or costly chemical-inducible expression systems are not always desirable. Here, several glucose-, xylose-, and levulinic acid (LA)-inducible promoter systems were assessed for the induction of green fluorescent protein (GFP) as a reporter protein. Among them, the LA-inducible gene expression system (HpdR/PhpdH) showed a strong expression of GFP (51-fold) compared to the control. The system was induced even at a low concentration of LA (0.1 mM). The fluorescence intensity increased with increasing concentrations of LA up to 20 mM. The system was tunable and tightly controlled with meager basal expression. The maximum GFP yield obtained using the system was 42 mg/g biomass, representing 10% of the total protein content. The efficiency of the proposed system was nearly equivalent (90%–100%) to that of the widely used strong promoters such as PmxaF and PL/O4. The HpdR/PhpdH system worked equally efficiently in five different strains of M. extorquens. LA is a low-cost, renewable, and sustainable platform chemical that can be used to generate a wide range of products. Hence, the reported system in potent strains of M. extorquens is highly beneficial in the C1-biorefinery industry to produce value-added products and bulk chemicals.

Conversion of hemicellulose streams and the constituent monosaccharides, xylose, arabinose, glucose, mannose, and galactose, was conducted to produce value-added chemicals, including furfural, hydroxymethylfurfural (HMF), levulinic acid and anhydrosugars. The study aimed at developing a kinetic model relevant for direct post-Organosolv hemicellulose conversion. Monosaccharides served as a tool to in detail describe the kinetic behavior and segregate contribution of hydrothermal decomposition and acid catalyzed dehydration at the temperature range of 120-190 °C. Catalyst free aqueous media demonstrated enhanced formation of furanics, while elevated temperatures led to significant saccharide isomerization. The introduction of sulfuric and formic acids maximized furfural yield and significantly reduced HMF concentration by facilitating its rehydration into levulinic acid (46 mol%). Formic acid additionally substantially enhanced formation of anhydrosaccharides. An excellent correlation between modeled and experimental data enabled process optimization to maximize furanic yield in two distinct hemicellulose streams. Sulfuric acid-containing hemicellulose stream achieved the highest furfural yield after 30 minutes at 238 °C, primarily due to the high Ea for pentose dehydration (150-160 kJ mol -1 ). Contrarily, formic acid-containing hemicellulose stream enabled maximal furfural yield at more moderate temperature and extended reaction time due to its lower Ea for the same reaction step (115-125 kJ mol -1 )., (© 2024 The Authors. ChemSusChem published by Wiley-VCH GmbH.)

Levulinic acid, a hydrolysis product of lignocellulose, can be metabolized into important compounds in the field of medicine and pesticides by engineered strains of Saccharomyces cerevisiae. Levulinic acid, as an intermediate product widely found in the conversion process of lignocellulosic biomass, has multiple applications. However, its toxicity to Saccharomyces cerevisiae reduces its conversion efficiency, so screening Saccharomyces cerevisiae genes that can tolerate levulinic acid becomes the key. By creating a whole-genome knockout library and bioinformatics analysis, this study used the phenotypic characteristics of cells as the basis for screening and found the HMX1 gene that is highly sensitive to levulinic acid in the oxidative stress pathway. After knocking out HMX1 and treating with levulinic acid, the omics data of the strain revealed that multiple affected pathways, especially the expression of 14 genes related to the cell wall and membrane system, were significantly downregulated. The levels of acetyl-CoA and riboflavin decreased by 1.02-fold and 1.44-fold, respectively, while the content of pantothenic acid increased. These findings indicate that the cell wall-membrane system, as well as the metabolism of acetyl-CoA and riboflavin, are important in improving the resistance of Saccharomyces cerevisiae to levulinic acid. They provide theoretical support for enhancing the tolerance of microorganisms to levulinic acid, which is significant for optimizing the conversion process of lignocellulosic biomass to levulinic acid., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Tang, Chen, Li, Xin, Xiao, Chen, Yang, Mou, Li, Lu, Fu, Long, Liao, Han, Feng, Li, Zhou, Yang, Yang, Ma and Wang.)

It has been shown that the nature of the metal precursor and the thermal effects during calcination determine the physicochemical properties of the catalysts and their catalytic activity in the levulinic acid (LA) and 5-hydroxymethylfurfural (HMF) hydrogenation reactions. The endothermic effect during calcination of the inorganic nickel precursor promoted higher metal dispersion and stronger interaction with the alumina surface. In contrast, the exothermic effects during the calcination of organic nickel precursors resulted in smaller metal dispersion and lower interaction with the support surface. A clear relationship was found between the size of the metal crystallites and the yield of LA hydrogenation reaction. The smaller crystallites were more active in the LA hydrogenation reaction. In turn, the size of the metal particles and their nature of interaction with the surface of the alumina influence the hydrogenation pathways of the HMF.

Layered double hydroxides (LDH) have significant attention in recent times due to their unique characteristic properties, including layered structure, variable compositions, tunable acidity and basicity, memory effect, and their ability to transform into various kinds of catalysts, which make them desirable for various types of catalytic applications, such as electrocatalysis, photocatalysis, and thermocatalysis. In addition, the upcycling of lignocellulose biomass and its derived compounds has emerged as a promising strategy for the synthesis of valuable products and fine chemicals. The current review focuses on recent advancements in LDH-based catalysts for biomass conversion reactions. Specifically, this review highlights the structural features and advantages of LDH and LDH-derived catalysts for biomass conversion reactions, followed by a detailed summary of the different synthesis methods and different strategies used to tailor their properties. Subsequently, LDH-based catalysts for hydrogenation, oxidation, coupling, and isomerization reactions of biomass-derived molecules are critically summarized in a very detailed manner. The review concludes with a discussion on future research directions in this field which anticipates that further exploration of LDH-based catalysts and integration of cutting-edge technologies into biomass conversion reactions hold promise for addressing future energy challenges, potentially leading to a carbon-neutral or carbon-positive future., (© 2024 Wiley-VCH GmbH.)

Conversion of levulinic acid (LA) to γ-valerolactone (GVL) via catalytic transfer hydrogenation (CTH) using conventional heating (CH) involves long reaction times, and low yields. Microwave (MW) heating seems a solution to address these issues as MW accelerates reactions and enhances yields. In this study, three typical catalysts, Ru/C, Pt/C and Pd/C, are compared for LA conversion using MW heating. In comparison to CH processes, MW-assisted processes significantly enhance LA conversion to GVL with higher yields by Ru/C and Pt/C. While elevated temperatures and secondary alcohols are favorable for LA conversion by these catalysts, Ru/C appears as the most effective catalyst as it can reach LA conversion as 100%, selectivity of GVL as 99% and yield of GVL as 99% at 160 °C. The results of this study confirm that MW was a promising process for enhancing LA conversion and Ru/C shows the highest catalytic activity, followed by Pt/C and Pd/C. [ABSTRACT FROM AUTHOR]

Aim: To evaluate generally recognized as safe (GRAS) liquid wash formulations against hepatitis A virus‐contaminated strawberries and blackberries in order to identify a formulation suitable for reducing virus contamination. Methods and Results: Formulations included the surfactant sodium dodecyl sulfate (SDS; 0·5% w/v) by itself, and in combination, with lactic acid (LA; 0·5% v/v), levulinic acid (LVA; 0·5% v/v) and 3 ppm aqueous chlorine dioxide (ClO2). After contamination and drying overnight, the average total extracted contamination for both untreated strawberries and blackberries was 4·4 log PFU. Three successive distilled H2O only treatments reduced total contamination by up to 1·8 log PFU for both strawberries and blackberries, while wash formulations showed significant (P ≤ 0·05) total reductions ranging from 2·1 to 2·9 log PFU. Conclusions: Considering results for both berry types, the combination of ClO2 and SDS was the most effective. Overall results indicate that adding surfactant and several types of sanitizers to berry wash can enhance HAV reduction on berries. Significance and Impact of the Study: This study indicates that industry could enhance the virologic safety of ready‐to‐eat berries by the combined use of surfactant and sanitizer. [ABSTRACT FROM AUTHOR]

Levulinic acid (LA), a class of important chemical intermediates and new energy chemicals, has been considered one of the top‐12 platform compounds that can be converted from biomass resources. Substantial progress on the conversion of lignocellulose biomass to LA and the further conversion of LA to high value downstream chemicals have been achieved recently. This review summarizes the preparation and separation processes of LA firstly, and then, emphatically discusses the catalytic system for LA conversion to valuable downstream products, including levulinate esters, 2‐methyl tetrahydrofuran (MTHF), Gamma‐valerolactone (GVL), 5‐aminolevulinic acid (DALA), and diphenolic acid (DPA). An outlook is provided at the end of this paper to highlight the challenges and opportunities for the comprehensive utilization of lignocellulose biomass. © 2021 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel bimetallic Ru-Co polymeric catalysts were synthesized. • Hydrogenation of levulinic acid was studied at variation of reaction conditions. • Impregnation of Co resulted in Ru redistribution inside the polymeric support. Levulinic acid (LA) is one of the substances, which can be obtained from cellulosic biomass via acid hydrolysis and serves as a precursor in the synthesis of gamma-valerolactone (GVL) – platform chemical for so-called valeric fuels. This work is devoted to the study of catalytic conversion of LA to GVL using mono- (Ru) and bimetallic (Ru-Co) catalysts based on ruthenium-containing nanoparticles immobilized in hyper-crosslinked polystyrene (HPS). It was shown that RuO 2 nanoparticles are an active phase of HPS-based Ru catalysts, which allow nearly 100 % yield of GVL at 120 °C and 2 MPa of hydrogen partial pressure for the reaction time 60 min. Introduction of cobalt in catalyst composition in a proper amount (Ru-to-Co weight ratio is 30) was found to result in Ru redistribution inside the polymeric support and, in turn, to the increase of reaction rate of LA hydrogenation. [ABSTRACT FROM AUTHOR]

Converting biomass into value‐added chemicals is of significant interest and we report an efficient hydrosilylation to convert levulinic acid to γ‐valerolactone using cost‐effective silanes such as PMHS and TMDS with B(C6F5)3 as catalyst. This metal free methodology works at room temperature reaching TONs and TOFs up to 16000 and 2000 h−1. Insights into the reaction mechanism are reported. [ABSTRACT FROM AUTHOR]

Gamma-valerolactone (GVL) is a highly reactive keto-lactone and a promising platform biomolecule, used as an additive for food and fuels, green solvent, and fuels precursor, among others. Its production from biomass usually involves hydrogenation and subsequent cyclization of levulinic acid or its esters. The process of conventional hydrogenation requires high pressures and temperatures, an external hydrogen source, and scarce noble/precious materials as catalysts. However, it could be produced under mild conditions, using bifunctional metal-acid catalysts with high metal dispersion and meso or microporosity, high surface area, temperatures lower than 200 °C, pressures ≤ 1MPa, and secondary alcohols (such as isopropanol) as hydrogen donors. The catalytic transfer hydrogenation followed by cyclization (CTHC) of levulinic acid (LA) and its esters (LE) to produce GVL using secondary alcohols as H donor is a great alternative. Variables involved in CTHC such as raw material, time, temperature, and type of catalyst, mainly transition metals and their combinations, are reviewed in this work. [ABSTRACT FROM AUTHOR]

The separation of levulinic acid from aqueous solutions is costly and non-ecofriendly in many cases. The major concerns are the low concentration of levulinic acid in fermentation broths and industrial downstreams. In this study, reactive extraction of levulinic acid from aqueous phase is proposed and its efficacy was investigated. Various extractants viz. tri-n-butyl phosphate, trioctylamine, and trioctylmethylammonium chloride along with i-octanol as a diluent were used. The extent of separation was investigated and various performance parameters like extraction efficiency, distribution coefficient, equilibrium complexation constant, and loading ratio were estimated. The number of transfer units, diffusivity, and mass transfer considerations were also discussed in the reactive separation system. Finally, the conceptual method was provided for the separation of levulinic acid using efficient reactive separation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Valeric acid produced from levulinic acid in a single-step using formic acid as H 2 source. • Weak Lewis and strong Brønsted basic sites on Ni-La/TiO 2 surface was responsible for the high selectivity of valeric acid. • 99% selectivity of valeric acid was achieved using aqueous γ-valerolactone. • Surface metallic Ni in conjunction with surface acid-base sites were identified by N 2 O titration and in situ IR study. Titania supported Ni catalyst modified by different lanthanides (La, Ce, Pr and Nd) were evaluated for the one-step conversion of levulinic acid (LA) to valeric acid (VA) using formic acid as a hydrogen source. Among these, the La modified Ni/TiO 2 demonstrated better VA yields with an optimum LA to VA mole ratio of 1:3. Pyridine and/or formic acid adsorbed IR studies revealed that presence of weak Lewis and strong basic sites present on the Ni-La/TiO 2 surface was the reason for higher VA selectivity. The physicochemical characteristics of the modified Ni-M/TiO 2 (M = La, Ce, Pr and Nd) catalysts deduced from H 2 -TPR, N 2 O titration, TPD of NH 3 and catalytic activity data emphasized a combination of metallic Ni with surface acid-base sites were responsible for the formation of VA in single step. Using aqueous γ-valerolactone, 99 % selectivity towards VA was achieved. A plausible reaction mechanism has been proposed based on the kinetic data obtained at moderate temperatures and ambient pressures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Conversion of renewable biomass-derived levulinic acid into value-added ester product. • The conventional synthesis of amyl levulinate was carried out using Immobilized Candida antartica lipase as biocatalyst. • Experimental parameters were optimized and energy of activation, thermodynamic parameters were determined. • The esterification of levilinic acid was performed under the solvent-free system. • The biocatalyst could be reused for at least five times. The current research work focuses on the conventional bio-catalysed synthesis of amyl levulinate with immobilized Candida antarctica lipase B in the absence of a toxic solvent. The green catalyst and solvent free system offered considerable benefits like mild and gentle condition requirement, lesser-energy demand, easy down-streaming and reusability of the biocatalyst. The process parameters were examined, and the maximum conversion (73.2 %) was obtained under the optimum condition of 50℃ temperature, 1:3 M ratio of levulinic acid to amyl alcohol using 0.8 % (w/v) biocatalyst at 250 rpm speed. The immobilized lipase was characterized by SEM, BET, XRD, FTIR and amyl levulinate was characterized by FTIR and GC–MS analysis. The enzyme lipase was effectively reused till 5 cycles for the formation of ester. The thermodynamic parameters (ΔH, ΔG, and ΔS) and energy of activation (Ea) were determined for the assessment of energy requirement. The activation energy was determined to be 48.42 kJ/mol. The research protocol strikes the development of biocatalytic synthetic route of amyl levulinate without using any toxic solvent, which may contribute to green chemistry approach. [ABSTRACT FROM AUTHOR]

Transformation of petrochemical waste oil to sulfonated graphene oxide for efficient conversion of fructose into levulinic acid [Display omitted] • Sulfonated graphene oxide was successfully synthesized from petrochemical waste oil. • sGO has high surface area (246 m2 g−1) due to mesoporosity and many sulfonic groups. • Recyclable sGO was successfully used for fructose conversion to levulinic acid. • Highest yield of levulinic acid (61 %) was obtained at 160 °C, 1 h, and F:C = 6 g g−1. • The sGO derived from petrochemical waste oil is an environmentally benign catalyst. Handling of petrochemical waste oil (PWO) is costly, tedious, and risky to human health and environment. Hence, upcycling of PWO for biomass conversion to platform chemicals would be very advantageous. Herein, a highly porous sheet-like structure of sulfonated graphene oxide (sGO) catalyst was synthesized from PWO. The synthesized sGO possessed high surface area (246.2 m2 g1) due to its mesoporosity and high content of sulfonic groups (2.4 mmol g−1) grafted onto its surface. As its application, the synthesized sGO was employed to convert fructose to levulinic acid (LA) within deionized water. The high yield (61.2 mol %) of LA was obtained under a condition of 160 °C, 1 h, and 6 g g−1 fructose to sGO weight ratio. It can be reused several times (5 runs) with no severe degradation of catalytic activity. Therefore, the sGO derived from petrochemical waste oil would be considered as an environmentally benign catalyst for producing platform chemicals, i.e. LA from fructose and other biomass derivatives. [ABSTRACT FROM AUTHOR]

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As of today, most chemical products are fossil-based. The environmental concerns of fossil resources due to their constant misuse have led to the exploration of bio-based alternatives. Biomass comprising industrial and municipal wastes, agricultural residues, forest residues, and natural herbaceous plants can favorably replace fossil fuel to produce chemicals. In this study, softwood and hardwood pulps were used to synthesize levulinic acid. Prior to a dilute acid hydrolysis step, the wood pulps were decationized overnight with 0.2 M HCl. The effects of the major reaction conditions including reaction temperature, time, and HCl concentration on the yield of levulinic acid was studied via a central composite design. Levulinic acid yields from softwood and hardwood pulps reached 50.30 and 68.85 mol%, respectively, at optimum reaction conditions. When newsprints were tested using the optimized parameters for softwood and hardwood conversion, levulinic acid yields of 66.25 and 79.65 mol% were obtained, respectively. A kinetic model was developed to predict the yields of glucose, hydroxymethylfurfural, and levulinic acid from the HCl-pretreated newsprint. The analysis of the kinetic parameters and the results of the response surface methodology experiments provided optimized conditions for levulinic acid production. [ABSTRACT FROM AUTHOR]

Developing a low-cost and robust catalyst for efficient transformation of biomass-derived platform chemicals plays a crucial role in the synthesis of future transportation fuels. Herein, a post-synthetic strategy was employed to develop a noble metal-free and robust ZrY zeolite catalyst, which is efficient for the hydrogenation of biomass-derived levulinic acid (LA) into biofuel γ-valerolactone (GVL), whereas over 95% yield of GVL was achieved in 10 h at 220°C. The effects of acidic properties from ZrY catalysts and various reaction parameters on the catalytic performance were then discussed in detail. Subsequently, different characterization tools were used to compare the difference and relationship of structure activity between the fresh and spent ZrY catalysts. It was found that acidity and the metal–support interaction were important for the direct synthesis of GVL. This work provides a guideline to design a noble metal-free catalyst for high-value utilization of biomass-derived sources.

Three common solid wastes (waste incineration fly ash, sewage sludge, and polluted soil) were the raw materials used in the synthesis of a geopolymer–type zeolite–like product, which was then used as a catalyst carrier to prepare a nickel hydrogenation catalyst for the catalytic hydrogenation of levulinic acid to γ–valerolactone. Under optimum synthesis conditions, the synthesized geopolymer zeolite has excellent structure and performance. The characterization results show that the composites have a three–dimensional network structure, and the pore structure is homogeneous mesoporous or microporous. In this work, the results of catalytic hydrogenation show that the yield of γ–valerolactone can achieve up to 94% using the synthesized catalyst, which is comparable to that of commercial catalysts and the concentrations of typical polluting heavy metals of Cu, Zn, Pb, and Cd in the reaction solution were all below the emission concentration limit (Class I standard) after five cycles of reaction. In summary, this geopolymer–type zeolite–like catalyst is cheap and has excellent performance; it is, therefore, expected to be widely used in catalysis instead of commercial carriers.

Hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is regarded as the bridge between bio-refinery and the traditional petroleum industry. In recent years, non-precious metal-based catalysts for LA hydrogenation to GVL have attracted much attention owing to their low cost and high efficiency. Metal-involving catalytic hydrogenation of LA is the rate-determining step in the production of GVL, and thus the active site structure of metal-based catalysts governs the overall catalytic performance. Herein, non-precious metal-based catalytic systems including Cu, Zr, Co and Ni are classified into single metal (M = Ni, Cu and Co), bimetallic (Cu–Ni, Ag–Ni, Cu–Co and Co–Zn), metal-heteroatom (M–O and M–N) and heterostructured (CePO4/CoP2 and Ni/NiO) catalysts according to the type of active site structure. The correlation of active site structure with catalytic activity is discussed emphatically, and its relationship with stability is also referred to in terms of strong metal–support interaction, bimetallic synergism, core–shell structure and heterojunction. This review provides an important guide for the rational design of high-performance non-precious metal-based catalysts for the LA-to-GVL process.

Herein, we report a stable catalyst with Ru single atoms anchored on a one-dimensional carbon fiber@graphitic carbon nitride hierarchy, by assembling wet wipes composed of fiber-derived carbon fiber (CF), melamine-derived graphitic carbon nitride (g-C3N4) and RuCl3 before NaBH4 reduction. The atomically dispersed Ru species (3.0 wt%) are tightly attached via N-coordination provided by exterior g-C3N4 nanosheets, and further stabilized by the interior mesoporous CF. The obtained CF@g-C3N4–Ru SAs catalyst can be cycled six times without notable leaching of Ru or loss of GVL yield in the acidic media. This catalyst is more stable than Ru nanoparticles supported on CF@g-C3N4, as well as Ru single atoms anchored on CF and g-C3N4, and proves to be one of the most efficient metal catalysts for aqueous LA hydrogenation to γ-valerolactone (GVL). The isolated Ru atoms by strong N-coordination, and their enhanced electron/mass transfer afforded by the one-dimensional hierarchy, can be responsible for the excellent durability of CF@g-C3N4–Ru SAs under harsh reaction conditions.

Commercial niobium and synthesized zirconium phosphates were tested as water-tolerant heterogeneous acid catalysts in the hydrothermal conversion of different bio-based substrates. Different acid-catalyzed reactions were performed using biomass-derived model compounds and more complex real lignocellulosic biomasses as the substrate. The conversion of glucose and cellulose was preliminarily investigated. Then, a wide plethora of raw lignocellulosic biomasses, such as conifer wood sawdust, Jerusalem artichoke, sorghum, miscanthus, foxtail millet, hemp and Arundo donax, were valorized towards the production of water-soluble saccharides, 5-hydroxymethylfurfural (HMF), levulinic acid (LA) and furfural. The different catalytic performances of the two phosphates were explained on the basis of their acid features, total acidity, Brønsted/Lewis acid sites ratio and strength. Moreover, a better insight into their structure–acidity relationship was proposed. The different acid properties of niobium and zirconium phosphates enabled us to tune the reaction towards target products, achieving from glucose maximum HMF and LA yields of 24.4 and 24.0 mol%, respectively. Remarkably, when real Jerusalem artichoke biomass was adopted in the presence of niobium and zirconium phosphate, maximum yields of furanic compounds and cellulose-derived sugars of 12.7 and 50.0 mol%, respectively, were obtained, after only 1 h of reaction. The synthesized hydrolysates, which were found to be rich in C5 and C6 carbohydrates, can be better exploited for the cascade production of more added-value bio-products.

Levulinates could be used as oxygenated fuel additives or as blending components in biodiesel. In this work, a metallic salt was used for the direct conversion of biomass, ie. (softwood bark), to produce methyl levulinate (ML) and levulinic acid (LA). The experimental data were analyzed through using a response surface methodology (RSM) as well as a central composite design (CCD). Three dependent responses (ML yield, LA yield, and residue production) were studied to determine the optimum combination of the four factors. The total yield of levulinates was 62% at the optimum process parameters, including catalyst concentration (0.067 mol/L), reaction time (5.67 h), and softwood bark concentration (2.5 wt%) at 200 °C. Finally, the results showed that Al2(SO4)3 allowed the production of levulinates probably in light of its good BrØnsted/Lewis acidity while also allowing t to decrease the corrosion inside the reactor (as compared to homogeneous acids such as H2SO4). This shows that the use of these metal salts for this specific application could positively affect the production costs of levulinates (either CAPEX or OPEX) at larger scale.

Levulinic acid (LA) is one of the most prominent biomass‐derived chemical building blocks that can be transformed into specialty chemicals like fuels, solvents, monomers for polymers, plasticizers, surfactants, agrochemicals, and pharmaceuticals. Over the past three decades, an enormous amount of research data have been acquired on the preparation and downstream value addition of LA, and these works have been reviewed. However, considering the astonishing number of publications appearing every year on LA derivatives, the periodical review of recent works focusing on unique aspects of chemistry must be undertaken to critically evaluate the achievements to date, reassess the challenges, and recognize new opportunities. This review discusses the chemical‐catalytic synthesis of various derivatives of LA by focusing on its functionalities and reactivity patterns. Recent literature on some crucial derivatives such as γ‐valerolactone, 4,4'‐diphenolic acid, and ethyl levulinate have been tabulated and discussed. The synthetic interconversion between various derivatives, mechanistic insights, critical analysis of the reaction parameters toward selective preparation of various derivatives, and their potential commercial applications have been elaborated using predominantly heterogeneous catalysts. A critical assessment of the relative advantages and shortcomings of the existing synthetic strategies for various derivatives of LA has been presented to enkindle fresh ideas. [ABSTRACT FROM AUTHOR]

Hydrogenation of bio‐based levulinic acid (LA) to γ‐valerolactone (GVL) was carried out using new cyclopentadienone ruthenium(0) complexes as catalyst precursors. These new complexes were obtained by reaction of cyclopentadione ruthenium(0) with widely available amino, pyridyl and phosphino ligands (L1–L6) using bridging N–N, P–N, or monodentate P or N donor frameworks. The hydrogenation reactions proceeded efficiently using formic acid as a hydrogen source and a low catalyst loading (0.2 mol%) in a benign solvent. At 120°C, up to 1,882 TON and >99% LA conversions and selectivities to GVL were seen, and the catalysts could be recycled up to four times with consistent activity and selectivity. In situ NMR studies show that hydrogen gas was generated from formic acid decomposition with simultaneous release of carbon dioxide. Ru‐hydride species have been detected, by 1H NMR spectroscopy, and the structure of the active catalyst is proposed along with a plausible reaction pathway. [ABSTRACT FROM AUTHOR]