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Epoxyeicosatrienoic acids (EpETrEs) are bioactive lipid mediators of arachidonic acid cytochrome P450 oxidation. In vivo, the free (unbound) form of EpETrEs regulate multiple processes including blood flow, angiogenesis and inflammation resolution. Free EpETrEs are thought to rapidly degrade via soluble epoxide hydrolase (sEH); yet, in many tissues, the majority of EpETrEs are esterified to complex lipids (e.g. phospholipids) suggesting that esterification may play a major role in regulating free, bioactive EpETrE levels. This hypothesis was tested by quantifying the metabolism of intraperitoneally injected free d11-11(12)-Epoxyeicosatrienoic acid (d11-11(12)-EpETrE) in male and female rats. Plasma and tissues (liver, adipose and brain) were obtained 3 to 4 min later and assayed for d11-11(12)-EpETrE and its sEH metabolite, d11-11,12-dihydroxyeicosatrienoic acid (d11-11,12-diHETrE) in both the free and esterified lipid fractions. In both males and females, the majority of injected tracer was recovered in liver followed by plasma and adipose. No tracer was detected in the brain, indicating that brain levels are maintained by endogenous synthesis from precursor fatty acids. In plasma, liver, and adipose, the majority (>54 %) of d11-11(12)-EpETrE was found esterified to phospholipids or neutral lipids (triglycerides and cholesteryl esters). sEH-derived d11-11,12-diHETrE was not detected in plasma or tissues, suggesting negligible conversion within the 3-4 min period post tracer injection. This study shows that esterification is the main pathway regulating free 11(12)-EpETrE levels in vivo.

Sulfonated hierarchical H-ZSM-5 monoliths were synthesized via ice-templating as solid acid catalysts for biodiesel production. Characterization confirmed successful –SO3 group grafting, increasing acid density. The catalysts achieved over 90% conversion of oleic acid in esterification, with easy recovery and reuse, and the relationship between porosity and acid density was explored. [ABSTRACT FROM AUTHOR]

Cellulose is the most abundant and renewable biopolymers on earth. The hydrophilic nature of cellulose endows cellulosic materials with good compatibility with polar matrices, but it also leads to their poor dispersion in non-polar matrices. Regulating the surface hydrophobicity of cellulosic materials via surface esterification can greatly extend their applications. However, the existing surface esterification methods for cellulosic materials are time-consuming and costly, which makes them less attractive for practical application. Here we found that when vinyl esters were used as esterifying agents, various alkalis can be used to catalyze the ultrafast surface esterification of cellulose materials in aqueous media at room temperature within seconds or minutes, which is highly attractive for the surface esterification of nanocellulose in suspension state. Surface acetylated cellulose nanofibers (ACNF) and surface acetylated cellulose nanocrystals (ACNC) with acetyl group content (Ac%) up to 10.7% and 6.5%, respectively, were successfully prepared within 5 min in aqueous diethylamine solution. Additionally, this method can also be used to achieve the rapid acetylation of phenol hydroxy group in aqueous media. [ABSTRACT FROM AUTHOR]

We present a theoretical investigation on the esterification process for boron ester synthesis, considering boric acid and 2(R),4(S)-pentanediol as model boron and diol derivatives, respectively. We report an unprecedented mechanistic pathway, able to rationalise, in contrast with the reported ones, the relatively low Gibbs energies of activation and the pH dependence experimentally observed in the formation of boron esters. We believe that these findings will improve the possibility to predict cross-link reaction rates of boron esters as a fundamental tool in the rational design of functional materials based on boron–oxygen linkages. [ABSTRACT FROM AUTHOR]

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. • Enzymatic route for levulinic acid esterification using biocatalyst. • Araujia sericifera latex-derived biocatalyst demonstrates high activity. • Achieved 65.1 % conversion of levulinic acid in the synthesis of octyl levulinate. • Solvent-free and n-heptane solvent systems investigated. • Studied reaction parameters for optimal conversion. [ABSTRACT FROM AUTHOR]

The objective of this work was to synthesize a new catalyst x-MoO 3 /Ni 0.5 Zn 0.5 Fe 2 O 4 using the combustion reaction method and to evaluate its catalytic potential and reuse in biodiesel production from waste oil, optimizing the process through experimental design. The catalysts were characterized in terms of structure by X-ray diffraction and phase quantification by Rietveld refinement, surface area by the Brunauer-Emmett-Teller technique, experimental density by helium pycnometry, acidity tests by ammonia desorption at programmed temperature, chemical analysis by X-ray fluorescence, morphology by scanning and transmission electron microscopy, and catalytic properties. The products of the simultaneous transesterification and esterification reactions were characterized by gas chromatography and acidity index. The results indicate the formation of catalysts with surface area ranging from 1.5 to 1.7 m2/g and density ranging from 4.5 to 5.1 g/cm3, composed of major crystalline phases of MoO 3 in the orthorhombic configuration and cubic Ni 0.5 Zn 0.5 Fe 2 O 4 ferrite, with total acidity ranging from 70 to 182 μmol/g of NH 3. Morphological characterization revealed that the catalyst comprises irregular plates of various sizes and shapes with a wide range of cluster sizes. In the simultaneous transesterification and esterification reactions of residual oil, the catalysts were active under all conditions tested, with emphasis on the catalyst containing 50 % Mo ions and 50 % Ni 0.5 Zn 0.5 Fe 2 O4 presenting the best catalytic performance with a conversion of 95 % in ethyl esters and a reduction of 71 % in acidity, with a service life of 6 cycles, an average conversion of 90 % and good thermal and structural stability after use. The experimental design was significant and predictive, with a confidence level of 95 %. Statistical analysis identified that all input variables (temperature, time, and amount of catalyst) were significant for the adopted design. The new catalyst composed of molybdenum, iron, nickel, and zinc has a positive impact on biodiesel synthesis from frying oil and ethanol. [ABSTRACT FROM AUTHOR]

The valorization of humins side streams from bio‐refineries holds significant economic and sustainability potential. One plausible strategy involves using them as building blocks to create new materials. However, humins pose conceptual challenges in their natural state due to their high viscosity, processing difficulties, and temperature sensitivity. This article presents a synthetic strategy for modifying humins properties to make them thermally stable and processable. Employing a sequence of esterification reactions and varying the reagent steric length, we showcase the selective transformation of humins into thermally‐stable fine powders and low‐viscosity liquids. We extend this approach by reacting humins with polyesters such as polylactic acids and polycaprolactone. In particular, we detail a one‐pot single‐step synthesis of micro‐phase separated compatibilized blends of polylactic acid and humins capped with the polylactic acid arms. Processed via solution‐casting, the obtained materials behave as high‐strength thermoplastic elastomers having uniform foam morphologies and material characteristics superior to the pure polylactic acid. By varying the content of D‐enantiomers, we demonstrate an additional possibility of manipulating the cellular structures of the foams. Finally, we provide a solution to product circularity by reporting a dissolution recycling method. [ABSTRACT FROM AUTHOR]

Nodupetide, a cyclodepsipeptide with the potential as an antimicrobial agent, was isolated from the fermentation of the fungi Nodulisporium sp strain IFB-A163. It possessed antibacterial activity against Pseudomonas aeruginosa and revealed an insecticidal activity. In our effort to synthesized nodupeptide, the preparation of the (3S,4S)-3-hydroxy-4-methylhexanoic acid (HMHA) as one of the nodupetide residue was found to be challenging, where it is not commercially available and the synthetic trial of the HMHA was not successful. This led us to synthesize nodupetide derivative by replacing HMHA with its α-hydroxy acid to give the analogue [(2S,3S)-Hmp]²-nodupetide. A combination of solid- and solution-phase peptide synthesis was applied in the synthesis nodupetide analogue. Esterification on the resin for synthesis [(2S,3S)-Hmp]²-nodupetide was achieved by placing the reaction at the last stage of the linear peptide synthesis and obtained in overall yield of 4.3%. We also conducted antimicrobial activity screening for [(2S,3S)-Hmp]²-nodupetide and its linear precursor, showing inactive activity. The alter of hydrophobicity on the nodupetide analogue has very important role in the difference of bioactivity compared to their parent compound. [ABSTRACT FROM AUTHOR]

Imidazole is one of the most important heterocyclic rings. This nucleus can be found in a plethora of substances in different knowledge areas such as medicinal, agrochemical, polymer, and dyestuff. N‐alkylation reactions involving N − 1 atom is a remarkable tool to synthesize many imidazole derivatives which can be attached to a great variety of functional groups. In this work, we synthesized 10 new intermediates 4‐chlorobutyl 1‐aryl‐1H‐pyrazole‐4‐carboxylates 3(a–j) from 1‐aryl‐1H‐pyrazole‐4‐carbonyl chlorides, obtained from 1‐aryl‐1H‐pyrazole‐4‐carboxylic acids 4(a–j), and 4‐chlorobutan‐1‐ol 1, generated by THF ring‐opening promoted by hydrochloric acid. Compounds 3(a–j) promoted N‐alkylation of 4(5)‐nitro‐1H‐imidazole to afford the targets 4‐(4‐nitro‐1H‐imidazol‐1‐yl)butyl 1‐aryl‐1H‐pyrazole‐4‐carboxylates 2(a–j) in 18%–85% yields. [ABSTRACT FROM AUTHOR]

AbstractTime-of-flight mass spectrometry (TOF-MS) was used to unravel the composition of commercial polyglycerol polyricinoleate (PGPR) samples, by identifying the various molecular species present. To cover the broad range of molecular weights for the present species, a combination of three ionisation conditions was used. Species exceeding the molecular weight of pentaglycerol hexaricinoleate were difficult to detect. Over 100 molecular species were observed and identified in the analysed samples, including free polyglycerols, ricinoleates, and PGPR-esters. Commercial PGPR samples were shown to be mainly composed of esterification products of di-, tri-, and tetraglycerol, while the esterification degree mainly varied from 1 to 5. The TOF-MS analysis was proven to be reproducible with a relative standard deviation (RSD) below 2.86% for three independent measurements on different days. The method proved to be very suitable to evaluate batch-to-batch variations and to compare the composition of different types of commercial PGPR’s. Moreover, this method can be applied to monitor the quality of PGPR products during the synthesis process. Furthermore, it can also provide fundamental knowledge for optimizing PGPR composition to improve its functionality. [ABSTRACT FROM AUTHOR]

The legal obligation to swiftly adopt renewable energies has been increased because of the continuous usage of fossil fuels. In this perspective, biomass serves as a pillar to improve the current conditions over different heterogeneous catalysts due to their known advantages. This work is focused on the synthesis of a novel catalyst comprising mono lacunary phosphotungstate and zeolite HY. The catalyst was characterized by number of physicochemical techniques and evaluation of the activity of catalyst for the esterification of most promising bio platforms, levulinic acid and succinic acid to produce fuel additives. After a detailed optimization of both reactions, remarkable conversions of levulinic acid (77%) and succinic acid (96%) with turnover numbers of 2749 and 3427 respectively, were obtained. The order of the reaction and activation energy for the said reactions were calculated in the kinetic study. The sustainable nature of the catalyst was confirmed via regeneration and viability towards other bio-based molecules which enhances its industrial importance. [ABSTRACT FROM AUTHOR]

The regularities of extraction of adsorbate from spent bleaching earth (SBE) of sunflower oil by the esteraldehyde fraction (EAF) have been established. The content of the substances adsorbed by SBE was 34.1%, including 19.2% free fatty acids (FFA) and 11.1% moisture. The influence of temperature (50 and 700 C), extraction duration (60 and 120 min), and the mass ratio of EAF to SBE ((2–4):1) on the extraction parameters has been determined. It was found that increasing these process parameters enhances the extraction degree of the adsorbate and FFA from the bleaching earth, reaching 41.9% and 34.4%, respectively, at a temperature of 700 C, extraction duration of 120 min, and a mass excess of EAF to SBC at a ratio of 4:1. Optimal conditions for the removal of FFA from SBE were identified. It was established that strong acidic sites are present on the surface of the bleaching earth, with the acidity of fresh, spent, and EAF-treated bleaching earth being 0.79, 0.77, and 0.74 mmol H+ per gram, respectively. The basicity of fresh bleaching earth was 0.073 mmol OH– per gram, indicating the ability of bleaching earth to catalyze the esterification of FFA with ethanol. The suitability of the obtained extract for the production of FFA ethyl esters was demonstrated. [ABSTRACT FROM AUTHOR]

The Yamaguchi reagent, based on 2,4,6-trichlorobenzoyl chloride (TCBC) and 4-dimethylaminopyridine (DMAP), is an efficient tool for conducting the intermolecular (esterification) reaction between an acid and an alcohol in the presence of a suitable base (Et3N or iPr2NEt) and solvent (THF, DCM, or toluene). The Yamaguchi protocol is renowned for its ability to efficiently produce a diverse array of functionalized esters, promoting high yields, regioselectivity, and easy handling under mild conditions with short reaction times. Here, the recent utilization of the Yamaguchi reagent was reviewed in the synthesis of various natural products such as macrolides, terpenoids, polyketides, peptides, and metabolites. [ABSTRACT FROM AUTHOR]

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The catastrophic ramifications of fossil fuels on the environment have prompted the search for renewable energy sources. Over the recent decades, biodiesel has garnered attention as a promising direct alternative to diesel fuel; however, reliance on homogeneous catalysts and the requirement for refined vegetable oil feedstocks present financial and sustainability concerns. Thus, there exists a need for the development of sustainable and cost‐effective catalytic solutions. Herein, the application of lignin, an abundant and renewable biomass, as an effective heterogeneous catalyst is reported for biodiesel production via the esterification of oleic acid. Lignin is extracted from corn straw using sulfuric acid, which endows sulfonic acid groups (0.85 mmol g−1) to its structure allowing it to act as an acid catalyst without additional post‐treatments. Conversion of oleic oil to biodiesel is achieved at 97% using a 1:3 oleic acid to methanol molar ratio with a 5 wt.% catalyst loading at 90 °C after only 30 min. Moreover, the catalyst exhibits a remarkable turnover frequency of 2.61 min−1 proving its efficiency. These findings demonstrate that heterogeneous catalysts can be prepared from biomass waste offering a significantly cheaper and less intensive synthesis process and allowing for a paradigm shift to non‐edible and waste cooking oils. [ABSTRACT FROM AUTHOR]

Peptides and depsipeptides play a significant role in diverse fields. Solid-phase peptide synthesis (SPPS) is the most renowned protocol for peptide production and can be coordinated with several process intensification techniques such as microwave, ultrasound, and continuous-flow. Until recently, most SPPS was carried out in N,N-dimethylformamide (DMF). However, the use of DMF has been restricted in the European Union since December 2023. Here we introduce a versatile N-formylmorpholine (NFM)/anisole (An) 1 : 1 solvent mixture that meets all green solvent criteria for SPPS. This innovation enables the first green ultrasound-assisted SPPS (US-GSPPS) and uses OxymaB to avoid hazardous benzotriazole-based compounds or OxymaPure coupling additives. Broad feasibility is demonstrated by successful synthesis of challenging peptides and natural products through on-resin esterification and solution/on-resin macrocyclization under ultrasound in NFM/An. Additionally, this mixture also functions as the first green solvent for continuous-flow solid-phase protocols. [ABSTRACT FROM AUTHOR]

Magnusiomyces capitatus A4C, a mycelium‐forming and lipase‐producing yeast‐like fungus, was employed in a five‐level factorial design to optimize the collective and interactive influences of carbon, nitrogen and emulsifying sources and their possible effects on cell‐bound lipase (CBL) and cell biomass production. The cell culture of M. capitatus A4C was incubated along with biomass support particles (BSPs) to immobilize the enzyme while anchoring CBL on their surfaces. Among the BSPs tested, CBL immobilized on loofah sponge under optimized conditions showed a substantial hydrolytic activity of 12.7 U mL−1 and a cell‐loading capacity of 0.61 g g−1 of BSPs. Immobilized CBL was applied for biodiesel production via transesterification and esterification. The conversion percentage of triacylglycerides was approximately 100% at 24 h with the addition of water at 1:1 (v/v). The conversion of oleic acid into biodiesel via esterification was 100% at 48 h in the presence of 15% (v/v) isooctane. Further, biodiesel production was scaled up using a packed bed reactor. The batch production of biodiesel in a packed bed reactor through transesterification was 96.2%, with a circulation flow rate of 5.5 mL min−1 for 18 h. On the other hand, oleic acid conversion into biodiesel via esterification was 99.5%, with a circulation flow rate of 5.5 mL min−1 for 24 h. Further investigation revealed that the immobilized biocatalyst exhibited higher stability with esterification (85.3% fatty acid methyl ester) after ten repeated cycles. [ABSTRACT FROM AUTHOR]

Research on polymer matrix composites has become increasingly important in both the academic and industrial sectors. The study of polymer-natural fiber composites, known for their eco-friendly properties, has gained significance. Sugarcane bagasse fibers, abundant as discarded agricultural byproducts, offer improved properties such as density, rigidity, strength, and cost-effectiveness, enhancing sustainability. As a result, experiments were performed on cellulose fibers pre-treated from sugarcane bagasse using 5% NaOH solution by simply soaking them for 4–5 h followed by washing with water. Further modifications involved esterification using phthalic anhydride and phthaloyl chloride via steam baths at 90 °C and oxidation using sodium percarbonate with a phase transfer catalyst (Adogen) at 80 °C. These chemically altered cellulose fibers exhibited significant peak changes in the FTIR spectra, a reduced crystallinity index in the XRD pattern, increased thermal stability as evidenced by TGA curve, and improved surface roughness in the SEM analysis. This paper emphasizes successful pretreatment procedures for isolating cellulose fibers from sugarcane bagasse and introduces three chemical treatments for surface functionalization which might find applications in the preparation of biocomposites. [ABSTRACT FROM AUTHOR]

Wood modification processes based on citric acid in combination with various copolymers have gained in importance in recent years. These processes also include modification with citric acid (CA) and sorbitol, a sugar alcohol, which is currently in the industrial realisation phase in Germany (SorCA) and Norway (CIOL). The modification of wood with sorbitol and citric acid (SorCA) can significantly improve the dimensional stability and durability of the wood. It is hypothesised that the addition of a copolymer may improve the fixation of the chemicals within as well as the flexibility of the modified wood matrix. In this study, the macroscopic changes, the fixation of the chemicals and the impact bending properties of wood modified with CA and SorCA are compared. Both modifications cause a permanent increase in mass (WPG) and volume (CWB). The fixation of the chemicals was comparable for both modifications; at high chemical concentrations, the SorCA polyester fixed slightly better within the wood matrix. Both modifications led to embrittlement of the wood, measured by a decrease in the impact bending strength (IBS). This embrittlement was clearly concentration-dependent and slightly more pronounced for the modification with CA. [ABSTRACT FROM AUTHOR]

Commercially valuable chenodeoxycholic acid (CDCA) was firstly developed from undesirable allo‐CDCA via multiple reactions: esterification, selective oxidation of C3‐hydroxy, the introduction of 1,4‐dien through IBX and TFA, the stereoselective hydrogenation by Pd/C under basic solution, deprotection, enzymatic reduction of C3‐carbonyl. During the process, highly selective oxidants were found to oxidize the C3‐hydroxy generating allo‐3‐keto bile acid which was used as substrates to investigate the dehydrogenation under IBX, and the possible hydrogenation mechanism under Pd/C had been proposed based on the crystal data. [ABSTRACT FROM AUTHOR]

A highly efficient complex emulsion microreactor has been successfully developed for multiphasic water‐labile reactions, providing a powerful platform for atom economy and spatiotemporal control of reaction kinetics. Complex emulsions, composing a hydrocarbon phase (H) and a fluorocarbon phase (F) dispersed in an aqueous phase (W), are fabricated in batch scale with precisely controlled droplet morphologies. A biphasic esterification reaction between 2‐bromo‐1,2‐diphenylethane‐1‐ol (BPO) and perfluoro‐heptanoic acid (PFHA) is chosen as a reversible and water‐labile reaction model. The conversion reaches up to 100 % under mild temperature without agitation, even with nearly equivalent amounts of reactants. This efficiency surpasses all reported single emulsion microreactors, i. e. 84~95 %, stabilized by various emulsifiers with different catalysts, which typically necessitate continuous stirring, a high excess of one reactant, and/or extended reaction time. Furthermore, over 3 times regulation threshold in conversion rate is attained by manipulating the droplet morphologies, including size and topology, e. g. transition from completely engulfed F/H/W double to partially engulfed (F+H)/W Janus. Addition‐esterification, serving as a model for triple phasic cascade reaction, is also successfully implemented under agitating‐free and mild temperature with controlled reaction kinetics, demonstrating the versatility and effectiveness of the complex emulsion microreactor. [ABSTRACT FROM AUTHOR]

A dual-functional biowaste-derived biochar-supported MIL-100(Fe) catalyst functionalized with p-toluenesulfonic acid (p-TSA) was developed via a facile in-situ coprecipitation and pyrolysis technique and applied for microwave-assisted biodiesel production and solar-light driven degradation of metronidazole (MTZ) from an aqueous stream. Esterification of oleic acid to methyl oleate (FAME) using the p-TSA-MIL-100@SBC catalyst under microwave irradiation resulted in 97.54% conversion efficiency at optimum reaction conditions of 1:20 (mmol) oleic acid to methanol ratio, 7 wt% catalyst loading and 70 °C within 50 min. The results were corroborated by Nuclear Magnetic Resonance (NMR) and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. The catalyst was reusable up to 4 successive esterification cycles with a retention of 89% efficiency. Furthermore, the as-synthesized p-TSA-MIL-100@SBC catalyst demonstrated excellent photocatalytic activity for the degradation of 30 mg/L MTZ, an emerging antibiotic and antiprotozoal pharmaceutical pollutant, with a remarkable efficiency of 97.8% in 150 min of solar irradiation. The catalyst also showed significant degradation of several other emerging organic dyes and pharmaceutical pollutants with more than 70% efficiency. The present research highlights the dual functional role of a sulfonated MOF@biochar composite material and renders the prepared p-TSA-MIL-100@SBC catalyst as a potential candidate for application in the fields of both energy production and environmental remediation. [ABSTRACT FROM AUTHOR]

Biodiesel (methyl esters) has been produced using numerous catalysts to enhance its quality and related productivity. Generally, the raw materials for biodiesel production and its catalysts significantly impact the produced biodiesel's quality. In addition, the heterogeneous catalysts are promising as catalysts in the transesterification for biodiesel production and can be used continuously during this production. In particular, these catalysts are essential for green biodiesel production because of their high activity, thermal stability, and reusability. Hence, several homogeneous and heterogeneous (acidic and alkaline) catalysts for biodiesel production, particularly the naturally derived heterogeneous catalysts, are reviewed in this article. Further, the different heterogeneous catalysts for biodiesel production have been studied extensively as replacements for the respective homogeneous catalyst. Specifically, this replacement is aimed at the simultaneous esterification and transesterification of the nonedible and low-cost biomasses under moderate conditions producing biodiesel. Moreover, this study analyzes biodiesel's impact and long-term performance in various applications. Finally, it also reports the advancements in biodiesel production in terms of the catalysts used in it and its processes to aid further developments in biodiesel production. [ABSTRACT FROM AUTHOR]

The esterification of 1-methoxy-2-propanol (PM) and acetic acid (AA) is an important reaction for the production of 1-methoxy-2-propyl acetate (PMA). Herein, we used the macroporous ion-exchange resin Amberlyst-35 as a catalyst to explore the effects of reaction conditions on the reaction rate and equilibrium yield of PMA. Under the optimized conditions of a reaction temperature of 353 K, using the initial reactant PM/AA with a molar ratio of 1:3, and a catalyst loading of 10 wt%, the PMA equilibrium yield reached 78%, which is the highest equilibrium yield so far. The reaction equilibrium constants and activity coefficients were estimated to obtain reaction thermodynamic properties, indicating the exothermicity of the reaction. Furthermore, pseudo-homogeneous (PH), Eley–Rideal (ER), and Langmuir–Hinshelwood–Hougen–Watson (LHHW) kinetic models were fitted based on experimental reaction kinetic data. The results demonstrate that the LHHW model is the most consistent with experimental data, indicating a surface reaction-controlled process and exhibiting an apparent activation energy of 62.0 ± 0.2 kJ/mol. This work represents a valuable example of calculating reaction thermodynamics and kinetics, which are particularly essential for promising industrial reactor designs. [ABSTRACT FROM AUTHOR]

Transglutaminase enzymes catalyze Ca2+- and thiol-dependent posttranslational modifications of glutamine-residues that include esterification, hydrolysis and transamidation, which results in covalent protein–protein crosslinking. Among the eight transglutaminase family members in mammals, transglutaminase 1 (TG1) plays a crucial role in skin barrier formation via crosslinking and insolubilizing proteins in keratinocytes. Despite this established function in skin, novel functions have begun merging in normal tissue homeostasis as well as in pathologies. This review summarizes our current understanding of the structure, activation, expression and activity patterns of TG1 and discusses its putative novel role in other tissues, such as in vascular integrity, and in diseases, such as cancer and fibrosis. [ABSTRACT FROM AUTHOR]

Microreactors are essential for microchemical reactions owing to their high mass transfer efficiency, precise control of reaction time, easy amplification, and good safety performance. These characteristics provide several advantages, including shortened reaction times and enhanced chemical reaction conversion rates, rendering microreactors particularly significant in chemical production. In this study, a finite-rate model was developed for the esterification of monobutyl chlorophosphate (MCP) and n-butanol in a microchannel reactor. This study investigates the impact of the microchannel's length-to-diameter ratio, the mass ratio of n-butanol to MCP at the inlet, and the inlet flow ratio on the entire reaction system through numerical simulations. The findings indicate that increasing the length-to-diameter ratio and reducing the inlet flow rate effectively prolongs the residence time of materials in the microreactor, thereby enhancing the conversion rate of the reactants. Optimal results are achieved with a moderate n-butanol/MCP mass ratio, which facilitates MCP transformation. Moreover, this study employs response surface analysis to investigate the influence of independent factors, such as the microchannel's length-to-diameter ratio, component ratio, and inlet velocity ratio, on MCP conversion rates. A prediction formula with conversion rate as the dependent variable and microchannel length-to-diameter ratio, component ratio, and inlet velocity ratio as independent variables was established. [ABSTRACT FROM AUTHOR]

The valorization of industrial waste in the production of new products is a growing trend, with food waste showing significant promise as a raw material for various industries. Thus, this research aimed to investigate the production of Geotrichum candidum lipase using industrial waste, such as mozzarella cheese whey (MCW) and corn steep liquor (CSL), and to analyze how effectively it catalyzes the esterification of oleic acid with methanol. Lipase production was carried out in medium containing MCW and CSL, with fermentation conditions optimized using a fractional factorial experimental design and central composite experimental design. The highest activities (16.71 U/mL in 24 h and 17.80 U/mL in 48 h) were found in conditions of 13.6% (%w/v) CSL and 37.1% (%w/v) MCW, with corn oil fixed at 1% (%w/v) and pH fixed at 6,00. Esterification conditions were evaluated at atmospheric pressure, both in a solvent-free environment and using hexane, as well as under high pressures with supercritical carbon dioxide (SC-CO2). The produced lipase demonstrated high catalytic activity for the esterification reaction of oleic acid with methanol under SC-CO2 with an increase of 39.41% in the yield. The yields found confirm the feasibility of producing lipase from industrial waste, thus presenting it as a sustainable and efficient alternative for industrial processes, and show that there is no need to use toxic organic solvents in esterification reactions. [ABSTRACT FROM AUTHOR]

The reliance on wasteful stoichiometric reagents to accomplish dehydration reactions such as esterification, amidation, and alcohol substitution is a longstanding challenge in synthetic chemistry. To address this problem, an electrochemical approach has been developed as a new conceptual platform for dehydration reactions. As a proof-of-concept demonstration, an electrochemical esterification protocol has been described that proceeds at room temperature, without acid or base additives, and without consuming stoichiometric reagents. This approach therefore overcomes key complications of esterification chemistry, and we envision that it will similarly enable improvements to a range of important, related transformations. 1 Introduction 2 An Electrochemical Design for Catalytic Dehydration 3 Electrochemical Esterification 4 Conclusions [ABSTRACT FROM AUTHOR]

Carbohydrates are synthetically challenging molecules with vital biological roles in all living systems. To better understand the biological functions of this fundamentally important class of molecules, novel methodologies are needed, including site-selective functionalization and glycosylation reactions. This account describes our efforts toward the development of novel methodologies for site-selective functionalization of carbohydrates and stereoselective glycosylation through various acylation reactions. [ABSTRACT FROM AUTHOR]

Hyperpolarized13 C magnetic resonance spectroscopy can provide unique insights into metabolic activity in vivo. Despite the advantages of this technology, certain metabolic pathways such as the tricarboxylic acid (TCA) cycle are more challenging to examine due to the limitations associated with currently available hyperpolarized13 C probes. In this report, we systematically employ computational analyses, synthetic techniques, and in vitro studies to facilitate the design of new chemical probes for the TCA cycle. This platform allows for the rapid identification of probe scaffolds that are amenable to hyperpolarized13 C experimentation. Using these results, we have developed two13 C-labeled chemical probes, [1,4-13 C2 ]-dipropyl succinate and [1,4-13 C2 ]-diallyl succinate, which are employed in hyperpolarized13 C metabolic studies. [ABSTRACT FROM AUTHOR]

Bioaromas can be produced by lipases either through their hydrolytic or (trans)esterifying activities. Therefore, this work reports the development of a lipase-catalyzed biotransformed licuri oil, forming volatile ethyl esters with odor notes resembling tropical fruits. Ethyl octanoate formation was promoted when 7.0 % (m/v) Lipozyme 435® was used to convert a grain alcohol:licuri oil mixture (51:49, v/v) at 58ºC and 70 rpm for 6 hours. The biotransformed oil has shown antimicrobial activity against Staphylococcus hominis , S. epidermidis, and Corynebacterium xerosis , bacteria associated with bad skin odor. Finally, this biotransformed oil was used without further treatments (e.g., recovery or purification procedures) to prepare two cosmetic formulations (in a dosage of 1.5 %), aiming for both fragrant and deodorant activity. • Odor-active ethyl esters were formed in lipase-biotransformed licuri oil. • 8.22 g/L ethyl octanoate was formed with 7 % lipase, 51:49 alcohol:oil ratio at 58°C. • Antibacterial activity of biotransformed oil could prevent bad skin odor. • Cosmetic formulations were prepared with 1.5 % biotransformed licuri oil. • No purification procedures were needed to use a natural fragrant mixture. [ABSTRACT FROM AUTHOR]

Alternating‐rich copolymer of vinylboronic acid pinacol ester (VBpin) and maleic anhydride (MAH) was found to catalyze direct dehydrative esterification of carboxylic acid and alcohol. The key to the catalytic function is the activation of the MAH unit by the neighboring Lewis acidic boron directly connected to the backbone through the formation of five‐membered ring. The effects of the side‐chain cooperation were clarified through comparisons with the polymers having similar structures and a conventional titanium catalyst as well as the analyses of reactions with carboxylic acid or alcohol. The catalytic activity was enhanced as the molecular weight was higher, which is owing to the structural feature that boron is directly attached to the backbone. The cooperative catalysis is of interest because of its conceptual similarity with enzyme. [ABSTRACT FROM AUTHOR]

Catalytic esterification in water has been achieved with the aid of a commercially available polymer-supported lipase, Novozym-435. Remarkably, this well-known biocatalyst demonstrates significant activity towards esterification using just water as the reaction medium. This methodology features representative esterifications of complex acids and alcohols, in the presence of unprotected amines. The work disclosed leading to esters typically requires only two equivalents of alcohol, although conversion for water-soluble alcohols appears to require increased loadings. Recycling of both the aqueous medium and catalyst are documented, highlighting the potential of this new technology, especially using directed evolution on the enzyme involved. Pharmaceutically relevant compounds are efficiently esterified (e.g., Ibuprofen, Tolmetin, and Ticagrelor) and multi-step, one-pot chemoenzymatic sequences can be performed to demonstrate the robustness of this catalytic aqueous system. [ABSTRACT FROM AUTHOR]

Mannosylerythritol lipids (MELs), a glycolipid biosurfactant, possess great potential in many high‐value‐added fields. However, its water‐insolubility is an important obstacle to its wide application, especially in home and personal care fields. In this study, a new strategy "killing two birds with one stone" based on the chemical modification of natural MELs was developed for the preparation of hydrophilic MELs. These newly prepared MELs can be efficiently isolated from the reacted solution via stepwise extraction with a methanol/n‐hexane system. 88% of hydrophilic MELs were recovered from natural MELs, with a corresponding yield of 50%. This is mainly attributed to the esterification of fatty acids, representing the main and relatively‐difficult‐to‐remove impurities in fermentative‐produced MELs, facilitating separation from the MEL product via extraction. Moreover, these new MELs presented comparable surface activities to natural MELs while exhibiting enhanced water solubility and biocompatibility. This originates from the generation of MEL‐D, resulting from the deacetylation of natural MELs and the formation of new hydrophilic MELs containing just one hydrophobic chain (named "MEL‐G"). Hence, the present strategy is not only beneficial for the removal of impurities (fatty acids) but also for the preparation of MELs with improved hydrophilicity. [ABSTRACT FROM AUTHOR]

A synthetic method for betulin 3-O-propionate 28-O-acylates via the reaction of betulin 3-O-propionate with melts of benzoic, phthalic, cinnamic, and succinic acids at 185–195°C for 5–6 min was proposed. [ABSTRACT FROM AUTHOR]

Cellulose obtained from oat hulls by bleaching with peracetic acid was modified, employing an ultrasound method that resulted in an esterification reaction with different vegetable oils (soybean, sunflower, and coconut) to produce modified cellulose (MC) with increased hydrophobicity. MC samples were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, scanning electron microscopy, and their wettability and oil and water absorption capacities. FTIR indicated that the reaction occurred with all oils, which was observed by forming a new band associated with ester carbonyl groups at 1747 cm−1. The modification did not affect the crystalline structure or surface morphology of the cellulose. MC samples modified with all oil sources showed a 6 to 9-fold decrease in water absorption capacity, a 3-fold increase in oil absorption capacity, and a higher affinity for nonpolar solvents. The modified samples adsorbed lower amounts of water at a slower rate. Different oil sources did not affect the main properties of MC. The ultrasonication-assisted process was not only effective in modifying cellulose by esterification with vegetable oils but was also an eco-friendly and simple strategy that does not require toxic reagents, providing reassurance of its sustainability. [ABSTRACT FROM AUTHOR]

The inhibition of the hLDHA (human lactate dehydrogenase A) enzyme has been demonstrated to be of great importance in the treatment of cancer and other diseases, such as primary hyperoxalurias. In that regard, we have designed, using virtual docking screening, a novel family of ethyl pyrimidine-quinolinecarboxylate derivatives (13–18)(a–d) as enhanced hLDHA inhibitors. These inhibitors were synthesised through a convergent pathway by coupling the key ethyl 2-aminophenylquinoline-4-carboxylate scaffolds (7–12), which were prepared by Pfitzinger synthesis followed by a further esterification, to the different 4-aryl-2-chloropyrimidines (VIII(a–d)) under microwave irradiation at 150–170 °C in a green solvent. The values obtained from the hLDHA inhibition were in line with the preliminary of the preliminary docking results, the most potent ones being those with U-shaped disposition. Thirteen of them showed IC50 values lower than 5 μM, and for four of them (16a, 18b, 18c and 18d), IC50 ≈ 1 μM. Additionally, all compounds with IC50 < 10 μM were also tested against the hLDHB isoenzyme, resulting in three of them (15c, 15d and 16d) being selective to the A isoform, with their hLDHB IC50 > 100 μM, and the other thirteen behaving as double inhibitors. [ABSTRACT FROM AUTHOR]

Background Accurate determination of active pharmaceutical ingredients and impurities is essential for ensuring the safety and effectiveness of medications. This study focuses on the validation of a high-performance liquid chromatography (HPLC) method for quantifying atorvastatin and its impurities, addressing a critical aspect of pharmaceutical analysis. Objective The primary objective is to conduct a comprehensive validation study for the HPLC method, covering specificity assessment, response function establishment, and a detailed analysis of precision, trueness, and tolerance intervals. The emphasis is on demonstrating the method's precision, accuracy, and stability-indicating capabilities across various concentrations and compounds. Methods The HPLC method is validated through rigorous assessments, including specificity, response function establishment, and analyses of precision, trueness, and tolerance intervals. Induced degradation experiments are conducted to explore atorvastatin's behavior under extreme conditions. Insights into the compound's synthesis and degradation pathways are provided through a proposed mechanism for intramolecular esterification. Results The results affirm the precision, accuracy, and stability-indicating capabilities of the validated HPLC method. The method effectively differentiates between atorvastatin and its impurities, showcasing its suitability for pharmaceutical quality control. Conclusions The validated HPLC method emerges as a robust and reliable tool for atorvastatin analysis, contributing significantly to pharmaceutical research and quality control. Its application ensures the safety and efficacy of medications, reinforcing its role in pharmaceutical analysis. Highlights This study not only validates a crucial HPLC method for atorvastatin analysis but also provides insights into the compound's behavior under extreme conditions and its synthesis and degradation pathways. The validated method serves as a cornerstone in pharmaceutical research and quality control, ensuring medication safety and efficacy. [ABSTRACT FROM AUTHOR]

Petroleum-based food packaging causes environmental problems such as waste accumulation and microplastic generation. In this work, biobased films from stable polyelectrolyte complex suspensions (PECs) of xylan and chitosan (70 Xyl/30 Ch wt% mass ratio), at different concentrations of citric acid (CA) (0, 2.5, 5, 7.5 wt%), were prepared and characterized. Films were treated at two temperatures (135 °C, 155 °C) and times (30 min, 60 min) to promote covalent crosslinking. Esterification and amidation reactions were confirmed by Fourier Transform Infrared Spectroscopy and Confocal Raman Microscopy. Water resistance and dry and wet stress–strain results were markedly increased by thermal treatment, mainly at 155 °C. The presence of 5 wt% CA tended to increase dry and wet stress–strain values further, up to 88 MPa—10% (155 °C for 60 min), and 5.6 MPa—40% (155 °C for 30 min), respectively. The UV-blocking performance of the films was improved by all treatments, as was thermal stability (up to Tonset: 230 °C). Contact angle values were between 73 and 84°, indicating partly wettable surfaces. Thus, thermal treatment at low CA concentrations represents a good alternative for improving the performance of Xyl/Ch films. [ABSTRACT FROM AUTHOR]

Polyglyceryl polyricinoleate (PGPR) is an emulsifier produced by esterification of polyricinoleic acid and polyglycerol. Polyricinoleic acid is derived from ricinoleic acid, which is expensive compared to other fatty acids. Therefore, analogues of polyricinoleic acid should be made from less expensive fatty acids, such as oleic acid. Therefore, oleic acid was converted to polyhydroxy estolide (PE) by a reaction with hydrogen peroxide and acetic acid. The PE was used as a substitute for polyricinoleic acid to produce PGPR analogues by direct esterification with polyglycerol and various fatty acids. The direct reaction between polyglycerol and PE produced a polyglyceryl estolide (PGE) with high viscosity and hydroxyl value, which limited its suitability as an emulsifier for the isopropyl myristate (IPM) and water system. Conversely, PGE prepared from lauric acid, polyglycerol and PE showed lower viscosity and hydroxyl value, resulting in a broad region of emulsion stability on a phase diagram when evaluated as a water-in-oil emulsifier for the IPM/water system. Similarly, other PGE made with oleic acid also displayed good emulsion stability for systems with higher IPM concentrations. In contrast, PGE prepared with stearic acid was a semi-solid at room temperature. Most of the prepared PGEs showed promising potential as emulsifiers for water-in-oil emulsions. [ABSTRACT FROM AUTHOR]

Biodiesel, a promising alternative to traditional petroleum fuels, is a green energy solution. Photocatalysis is a facile, novel, economic, and efficient approach to biodiesel synthesis. Metal sulfides have been used extensively for various photocatalytic applications. The present study demonstrates, for the first time, the photocatalytic production of biodiesel using a novel metal sulfide‐based heterogeneous photocatalyst under visible light irradiation. A nano zero‐valent silver doped hydroxyapatite (Ag/HAp) was synthesized using a green bio‐reductant technique and decorated with tin sulfide nanoparticles (SnS2/Ag/HAp or SAH) for photocatalytic biodiesel synthesis. The hydroxyapatite (HAp) was extracted from waste fish scales to minimize the use of chemicals and to utilize waste for useful applications. The prepared SAH photocatalyst was characterized through X‐ray diffraction, UV‐visible diffuse reflectance spectroscopy, photoluminescence spectroscopy, Fourier transform infrared analysis, energy dispersive X‐ray analysis, scanning electron microscopy, high‐resolution transmission electron microscopy and X‐ray photoelectron spectroscopy analysis. The effect of reaction parameters was optimized, and under optimum conditions of 1 wt% photocatalyst loading, and 8:1 methanol‐to‐oleic‐acid ratio, for 60 min, a high yield of 98.0 ± 0.61% could be achieved using a SAH photocatalyst. Scavenger tests indicated the simultaneous generation of photoinduced electrons and holes necessary for photocatalytic biodiesel synthesis. A mechanism for the photocatalytic esterification reaction of oleic acid is proposed. The synthesized SnS2‐based photocatalyst could be easily recoverable and reusable for five consecutive runs, which can replace traditional industrial heterogeneous catalysts in the near future. [ABSTRACT FROM AUTHOR]

Zeolite imidazolate frameworks (ZIFs) were composited with NaY zeolite using two different approaches to the ship‐in‐bottle method. The two synthesized nanocatalysts showed that the ZIF‐8 composite with NaY zeolite could stabilize their structure as catalysts in an acidic environment. The NaY@ZIF‐8 nanocomposites that were prepared were investigated using Fourier transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), elemental mapping (MAP), thermogravimetric (TGA), temperature‐programmed desorption of ammonia (NH3‐TPD), and inductively coupled plasma analyses. The synthesized composites were used as catalysts for the esterification reaction of acetic acid with four different alcohols and the transesterification reaction of animal fats, vegetable oils, and waste oils. The results show that the efficiency of the esterification reactions for the two catalytic composites was 98.5% and 94.3%, respectively, and 78.1% for the transesterification reaction. [ABSTRACT FROM AUTHOR]

Cerbera odollam oil was extracted from the dried Cerbera odollam seeds by the Soxhlet extraction method. Cerbera odollam seed oil-based alkyd resins were synthesized by the alcoholysis–polyesterification process via reaction of the oil with varying amounts of phthalic and maleic anhydride. Standard evaluation methods were used to analyze the physicochemical features of the resins, including acid value, viscosity, and others. Evaluation tests such as drying times, pencil hardness, adhesion, gloss measurement, and chemical inertness were employed to study the film performance of the produced alkyd resins. Mechanical characteristics such as ultimate tensile strength, strength under impact, elastic modulus, surface hardness, and water absorption were evaluated. Further characterization to study the organic architecture of the oil and alkyd resins was carried out by Fourier transform infrared (FTIR) spectroscopy and gas chromatography–mass spectrometry (1H NMR). The resin with the higher percentage of maleic anhydride showed better surface coating application performance in set-to-touch (88 min), dry-to-touch time (105 min), and pencil hardness (5B) while resin higher in phthalic anhydride shows better results in gloss (92.5) and alkali resistance. On the other hand, the resin with the higher percentage of maleic anhydride showed better mechanical performance in tensile strength, tensile modulus, impact strength, and surface hardness while resin with higher percentage of phthalic anhydride showed better results in water absorption and elongation at break. Overall, the synthesized alkyd resins from the Cerbera odollam seed oil possessed great application potential in both surface coating and polymer composites as matrix. [ABSTRACT FROM AUTHOR]

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One of the most important reactions in organic synthesis is esterification, and the compounds generated using this process are esters with a wide range of applications in various industries. Numerous approaches have been employed to enhance the ester yield and reaction rate and establish equilibrium in esterification reactions. This study uses a non-catalytic thermal esterification method to obtain unbranched aliphatic esters C4–C8. The effect of an audio frequency electric field instead of a catalyst on the esterification reaction between acetic acid and linear C4–C8 aliphatic alcohols was studied. The main goal of this study was to design and implement a lab-scale device for the synthesis of aliphatic esters in an environmentally sustainable manner using only specific raw materials and an audio frequency electric field at 3 and 6 kHz at 20 °C and 50 °C. A mechanism for the esterification reaction using an audio frequency electric field is also suggested. The proposed experimental device is designed to produce esters in a green and cost-effective manner and could be used on a large scale in the food, cosmetics, and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

Bio-oil contains many oxygenated compounds, as well as high acid and water content, which can reduce the stability of its components and have poor overall physicochemical properties. In this study, the quality of bio-oil produced from the pyrolysis of oil palm fronds was enhanced through a hydrodeoxygenation (HDO) reaction that was preceded by esterification as a pre-treatment. The catalyst used in the HDO reaction is mixed metal oxide (Fe2O3-CoO) anchored within zeolite mordenite (Fe2O3-CoO/Mor). The catalysts were characterized using XRD, SEM-EDX, and BET methods. The presence of metal oxides on the surface of mordenite increases the activity of the catalyst in producing liquid products while reducing the formation of coke. Upgrading of bio-oil has improved the physicochemical properties of bio-oil compared to the one-stage upgrading process. The analysis of product showed that the C and H content increased from 11.5 to 23.5 wt% and from 9.76 to 11.2 wt%, respectively. On the other hand, the O content decreased from 78.7 to 65.2 wt% with a degree of deoxygenation of 59.8%. Moreover, higher heating value (HHV) of the bio-oil increased by 38% from 11.6 to 16.0 MJ/kg. [ABSTRACT FROM AUTHOR]

This article discusses the use of perfluorinated sulfamides in various technological processes. The potential of aminotoxane as a catalyst in the cyclohexane oxidation process was studied. The use of aminotoxane significantly shifts the distribution of target products in cyclohexane oxidation, favoring increased alcohol formation. This catalytic system is distinct from those involving crown ethers and polyglycols, suggesting a specific mechanism of influence by perfluorinated sulfamides on the intermediate stages of radical-chain oxidation. For the by-product adipic acid, which is formed in significant amounts, a complex method of utilizing cyclohexane oxidation products is proposed. Specifically, esterification of adipic acid with alcohol was performed, resulting in the production of dibutyl adipinate, a valuable raw material for plasticizer manufacturing. The yield of dibutyl adipinate was 57.6%. The study found that cyclohexane oxidation in the presence of a binary catalyst, cobalt naphthenate–aminotoxane, results in an increased oxidation rate, a threefold reduction in ester and acid selectivity, and a twofold increase in cyclohexanol selectivity compared to oxidation with cobalt naphthenate alone. [ABSTRACT FROM AUTHOR]

Two new compounds, cladospolides I (1) and J (2), together with two new naturally occurring ones, methyl 11-hydroxy-4-oxododecanoate (3) and 11-hydroxy-4-oxododecanoic acid (4), were isolated from the culture extract of the cold-seep sediment-derived fungus Cladosporium cladosporioides 8-1. Their structures and configurations were established by analysis of 1D/2D NMR, MS, ECD, and specific optical rotation data. Compound 3 was possibly formed by methyl esterification of 4 during the purification process due to the utilization of methanol. All compounds were evaluated for inhibition of four marine phytoplankton species and five marine-derived bacteria. [ABSTRACT FROM AUTHOR]

旨在为米糠酸化油的产业化应用提供参考，以米糠酸化油为原料，经丙酮提取预处理后，采用酶法催化制备生物柴油。通过单因素实验考察脂肪酶种类、酶添加量、醇油物质的量比和反应温度对生物柴油产率的影响，结合正交实验对生物柴油制备的工艺条件进行优化，并采用分子蒸馏对生物柴油进行精制，同时对精制生物柴油进行表征。结果表明：米糠酸化油经预处理后，过氧化值、谷维素及不皂化物含量无显著变化，酸值、皂化值显著升高，水分及挥发物含量、磷脂含量、灰分和皂含量显著降低；生物柴油制备的最优工艺条件为醇油物质的量比3∶ 1、液体脂肪酶Lipozyme TL100L添加量4%、反应温度30 ℃、反应时间4 h，在此条件下生物柴油产率达（86.77±0.54）%，经分子蒸馏纯化后脂肪酸甲酯含量达（97.00±0.04）%；精制生物柴油理化指标均符合GB 25199—2017 要求；傅里叶红外光谱分析证实了产物中含脂肪酸甲酯，热重分析表明精制生物柴油在178.0~293.2 ℃区间内失重最快，差示扫描量热分析表明-37.5～-47.2 ℃的峰与不饱和脂肪酸甲酯的晶体有关，-7.9～-3.7 ℃的峰与饱和脂肪酸甲酯的晶体相关，生物柴油的结晶起始温度为-8.87 ℃。综上，以米糠酸化油为原料采用酶法制备生物柴油具有极大的发展潜力。Aiming to provide reference for the industrial application of acidified rice bran oil, biodiesel was prepared by enzyme catalysis of acetone extract of acidified rice bran oil. The effects of lipase type, enzyme dosage, alcohol-oil molar ratio and reaction temperature on biodiesel yield were investigated through single factor experiments. The process conditions for biodiesel preparation were optimized by orthogonal experiments. The biodiesel prepared was refined by molecular distillation, and the refined biodiesel was characterized. The results showed that after the pretreatment of the acidified rice bran oil with acetone extraction, the peroxide value, oryzanol content and unsaponifiable matters content did not change significantly, the acid value and saponification value increased significantly, and the contents of moisture and volatile matter, phospholipid, ash and soap reduced significantly. The optimal process conditions for biodiesel preparation were as follows: alcohol-oil molar ratio 3∶ 1, liquid lipase Lipozyme TL100L dosage 4%, reaction temperature 30 ℃, and reaction time 4 h. Under the optimal conditions, the biodiesel yield reached (86.77±0.54)%, and the content of fatty acid methyl ester reached (97.00±0.04)% after purification by molecular distillation. The physicochemical indexes of refined biodiesel were in accordance with the requirements of GB 25199-2017. Fourier infrared spectroscopy (FTIR) analysis confirmed that the product contained fatty acid methyl ester, thermogravimetric (TG-DTG) analysis showed that the weight loss of refined biodiesel was the fastest in the temperature interval of 178.0-293.2 ℃; differential scanning calorimetry (DSC) analysis showed that the peaks at temperatures from -37.5 ℃ to -47.2 ℃ were related to the crystals of unsaturated fatty acid methyl ester, and the peaks at temperatures from -7.9 ℃ to -3.7 ℃ were related to the crystals of saturated fatty acid methyl ester, and the crystallisation starting temperature of biodiesel was -8.87 ℃. In conclusion, the enzymatic preparation of biodiesel from acidified rice bran oil has great potential for development.

Abstract Research on polymer matrix composites has become increasingly important in both the academic and industrial sectors. The study of polymer-natural fiber composites, known for their eco-friendly properties, has gained significance. Sugarcane bagasse fibers, abundant as discarded agricultural byproducts, offer improved properties such as density, rigidity, strength, and cost-effectiveness, enhancing sustainability. As a result, experiments were performed on cellulose fibers pre-treated from sugarcane bagasse using 5% NaOH solution by simply soaking them for 4–5 h followed by washing with water. Further modifications involved esterification using phthalic anhydride and phthaloyl chloride via steam baths at 90 °C and oxidation using sodium percarbonate with a phase transfer catalyst (Adogen) at 80 °C. These chemically altered cellulose fibers exhibited significant peak changes in the FTIR spectra, a reduced crystallinity index in the XRD pattern, increased thermal stability as evidenced by TGA curve, and improved surface roughness in the SEM analysis. This paper emphasizes successful pretreatment procedures for isolating cellulose fibers from sugarcane bagasse and introduces three chemical treatments for surface functionalization which might find applications in the preparation of biocomposites.