Stereoselective Synthesis of Silylated Vinylboronates by a Boron-Wittig Reaction and Their Application to Tetrasubstituted Olefins.

The highly stereoselective synthesis of a series of tetrasubstituted mono- as well as disilylated vinylboronates is reported by using the boron-Wittig approach. The condensation between acylsilanes and gem-diborylalkanes gave the desired tetrasubstituted olefins in good to excellent yield and high stereoselectivity. Also, a series of trisubstituted silylated vinyl MIDA-boronates was synthesized by using the boron-Wittig reaction followed by a transesterification reaction. This methodology allows direct incorporation of B(pin) and TMS groups in the anti-position of the olefin in a highly stereoselective manner. Further, sequential Suzuki coupling reaction with the silylated vinyl boronic esters generated all-carbon tetrasubstituted alkenes, which have been applied in the total synthesis of the anticancer drug Tamoxifen and aggregation-induced luminogen agent TPE-TF17.

General Construction of Asymmetric Amine Ethers via Efficient Transesterification.

A novel method to prepare asymmetric amine ethers is reported. Tertiary amine alcohol hydrogen sulfate intermediates are prepared through a reactive distillation process, followed by the transesterification process to afford eventually asymmetric amine ethers. Experiments and DFT calculations revealed the essential roles the sulfate group plays in the highly selective monoesterification process. This clean method is tolerant towards various functional groups with good yields under mild condition, which is obviously superior compared to the conventional processes.

Application of Response Surface Methodology (RSM) in the statistical evaluation of biodiesel production from the neutral lipids of the Coelastrella-Nannochloropsis consortium.

The paramount challenge in economically workable microalgal biodiesel production is the selection of a competent catalyst to improve the fatty acid methyl ester yield with desirable fatty acid composition. Though countless researchers have explored different homogeneous and heterogeneous catalysts to improve the transesterification efficacy, achieving greater biodiesel production from the neutral lipids of the microalgal consortium using a statistical tool, response surface methodology is scarce. Thus, the present study applied Response surface methodology to statistically analyze the biodiesel production from the neutral lipids of the indigenous Coelastrella-Nannochloropsis consortium (CNC) on the way to commercial feasibility. Onset of the study, the neutral lipids and acid value of the CNC were determined to be 18.74% and 2.73%, respectively. The transesterification of the neutral lipids of CNC was optimized through the coded factors in the RSM for various reaction parameters as combined influence viz., (i) Catalyst dose: methanol volume, (ii) Catalyst dose: reaction time; (iii) Catalyst dose: reaction temperature, (iv) Time: temperature, (v) time: methanol volume, (vi) temperature: methanol volume. Based on the ANOVA, coefficient determination, 2% KOH, 2 h time, 70 °C temperature, and 9 mL methanol volume were ascertained to be optimal values to accomplish 92% biodiesel production. Further, the biodiesel has desirable palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic acids, with palmitic acid as the prevalent fatty acid contributing 16-18%. In addition, the tested fuel properties of CNC biodiesel satisfy international biodiesel standards.

Advancements in sustainable production of biofuel by Microalgae: Recent insights and future directions.

Microalgae is considered as sustainable and viable feedstock for biofuel production due to its significant advantages over terrestrial plants. Algal biofuels have received significant attention among researchers and energy experts owing to an upsurge in global energy issues emanating from depletion in fossil fuel reserves increasing greenhouse gases emission conflict among agricultural crops, traditional biomass feedstock, and potential futuristic energy security. Further, the exploration of value-added microalgae as sustainable and viable feedstock for the production of variety of biofuels such as biogas, bio-hydrogen, bioethanol, and biodiesel are addressed. Moreover, the assessment of life-cycle, energy balance, and environmental impacts of biofuel production from microalgae are briefly discussed. The present study focused on recent advancements in synthetic biology, metabolic engineering tools, algal bio refinery, and the optimization of algae growth conditions. This paper also elucidates the function of microalgae as bio refineries, the conditions of algae-based cultures, and other operational factors that must be adjusted to produce biofuels that are price-competitive with fossil fuels.

Analyzing the performance of synthesized nano-catalysts for transesterification of waste cooking oil as environment friendly drilling fluid.

Ester-based drilling fluids (EBDF) are preferred over oil-based drilling fluids (OBDF) and water-based drilling fluids (WBDF) because of their great biodegradability, low toxicity, and improved performance. In this work, waste cooking oil methyl ester (WCOME) was used to prepare an environmentally friendly EBDF. Through a transesterification process utilizing a modified calcium oxide based heterogenous catalyst, the waste cooking oil is transformed into waste cooking oil methyl ester. Response surface approach was used to strengthen the transesterification. The optimize conditions for CaO/Al2O3 resulted in the highest yield of 96.56% at a molar ratio of 11.9:1, 3.19 wt % of CaO/Al2O3, 53.79 °C, and 76.86 min. In contrast, CaO/TiO2 yielded 98.15% at a molar ratio of 11.99:1, with a CaO/TiO2 of 2.53 wt % at 59.79 in 68.14 min. Additionally, two separate densities of 9 ppg and 12 ppg EBDF are formulated with two distinct oil-to-water ratios (70:30 and 80:20) using synthesized WCOME. To assess the effectiveness of formulated EBDF thorough rheological investigation is conducted at 150°. Additionally, the filtration loss at HPHT conditions, emulsion stability, and Barite sag analysis of the drilling fluid are all analyzed at before ageing and after dynamic ageing. With better rheological features, less fluid loss, good emulsion stability, and minimal barite sagging, the designed EBDF performs efficiently. The drilling fluid met the API requirement and demonstrated stability even after ageing at 250 °F for 72 h, suggesting that it may be used for extended periods of time in drilling.

Biowaste to bioenergy nexus: Fostering sustainability and circular economy.

Existing fossil-based commercial products present a significant threat to the depletion of global natural resources and the conservation of the natural environment. Also, the ongoing generation of waste is giving rise to challenges in waste management. Conventional practices for the management of waste, for instance, incineration and landfilling, emit gases that contribute to global warming. Additionally, the need for energy is escalating rapidly due to the growing populace and industrialization. To address this escalating desire in a sustainable manner, access to clean and renewable sources of energy is imperative for long-term development of mankind. These interrelated challenges can be effectively tackled through the scientific application of biowaste-to-bioenergy technologies. The current article states an overview of the strategies and current status of these technologies, including anaerobic digestion, transesterification, photobiological hydrogen production, and alcoholic fermentation which are utilized to convert diverse biowastes such as agricultural and forest residues, animal waste, and municipal waste into bioenergy forms like bioelectricity, biodiesel, bio alcohol, and biogas. The successful implementation of these technologies requires the collaborative efforts of government, stakeholders, researchers, and scientists to enhance their practicability and widespread adoption.

Transesterification with CE15 glucuronoyl esterase from Cerrena unicolor reveals substrate preferences.

PURPOSE: Glucuronoyl esterases (GE, family CE15) catalyse the cleavage of ester linkages in lignin-carbohydrate complexes (LCCs), and this study demonstrate how transesterification reactions with a fungal GE from Cerrena unicolor (CuGE) can reveal the enzyme's preference for the alcohol-part of the ester-bond. METHODS: This alcohol-preference relates to where the ester-LCCs are located on the lignin molecule, and has consequences for how the enzymes potentially interact with lignin. It is unknown exactly what the enzymes prefer; either the α-benzyl or the γ-benzyl position. By providing the enzyme with a donor substrate (the methyl ester of either glucuronate or 4-O-methyl-glucuronate) and either one of two acceptor molecules (benzyl alcohol or 3-phenyl-1-propanol) we demonstrate that the enzyme can perform transesterification and it serves as a method for assessing the enzyme's alcohol preferences. CONCLUSION: CuGE preferentially forms the γ-ester from the methyl ester of 4-O-methyl-glucuronate and 3-phenyl-1-propanol and the enzyme's substrate preferences are primarily dictated by the presence of the 4-O-methylation on the glucuronoyl donor, and secondly on the type of alcohol.

Construction of a Pickering interfacial biocatalysis system in skim milk and enzymatic transesterification for enhancement of flavor and quality.

Despite considerable research efforts, lipase catalysis in a fluid milk system with aqueous multi-component mixtures containing multiple microphases, remains challenging. Pickering interfacial biocatalysis (PIB) platforms are typically fabricated with organic solvents/lipids and water. Whether a PIB with excellent catalytic performance can be constructed in complex milk mixtures remains unknown. Here, we challenged PIB with skim milk, and a small amount of flaxseed oil, and phytosterols as a model system for transesterification and lipolysis to enhance quality and flavor. The amino-modified mesoporous silica spheres (MSS-N) were employed as an emulsifier and carrier of lipase AYS (AYS@MSS-N). The conversion of phytosterol esters reached 75.5% at 1.5 h and prepared phytosterol ester-fortified milk with a content of 1.0 g/100 mL. The relative conversion rate remained above 70% after 6 cycles. In addition, the fortified milk showed an intensified and favorable effect on sensory traits through volatile flavor composition analysis. The findings provide a versatile alternative for PIB applications in complex environments, i.e., milk, which might inspire a new bioprocess strategy for dairy products.

Exploration and Development of Nitrone Chemistry.

Nitrones are widely used as 1,3-dipoles in organic synthesis, but control of their reactions is not always easy. This review outlines our efforts to make the reactions of nitrones more predictable and easier to use. These efforts can be categorized into (1) 1,3-nucleophilic addition reaction of ketene silyl acetals to nitrones, (2) geometry-controlled cycloaddition of C-alkoxycarbonyl nitrones, (3) stereo-controlled cycloaddition using double asymmetric induction, and (4) generation of nitrones by N-selective modification of oximes.

Application of Stemphylium lycopersici Extracts Immobilized on MCM-48type Mesoporous Materials as Biocatalysts for Monoacylglycerol Production.

Monoacylglycerols are eco-friendly and inexpensive emulsifiers with a range of applications. The traditional synthetic route is not eco-friendly, while enzymatic catalysis offers milder reaction conditions and higher selectivity. However, its application still is limited due to the costs. In this context, endophytic fungi can be source to new biocatalysts with enhanced catalytic activity. Based on this perspective, the aim of this study was perform the synthesis of MAG's through transesterification reactions of solketal and different vinyl esters, using crude and immobilized lipolytic extracts from the endophytic fungi Stemphylium lycopersici, isolated from Humiria balsamifera. The reactions were conducted using 100 mg of biocatalyst, 1 mmol of substrates, 9 : 1 n-heptane/acetone, at 40 °C, 200 rpm for 96 h. In the reactions using the ILE and stearate, laureate and decanoate vinyl esters it was possible to obtain the correspondent products with conversion rates of 52-75 %. Also, according to the structure drivers used in MCM-48 synthesis, different morphologies and conversions rates were observed. Employing [C16MI] Cl, [C14MI] Cl and [C4MI] Cl, the 1-lauroyl- glycerol conversion was 36 %, 79 % and 44 %, respectively. This is the first work involving the immobilization of an endophytic fungi and its utilization as a biocatalyst in the production of MAG's.

Biodiesel Production by Methanolysis of Rapeseed Oil-Influence of SiO2/Al2O3 Ratio in BEA Zeolite Structure on Physicochemical and Catalytic Properties of Zeolite Systems with Alkaline Earth Oxides (MgO, CaO, SrO).

Alkaline earth metal oxide (MgO, CaO, SrO) catalysts supported on BEA zeolite were prepared by a wet impregnation method and tested in the transesterification reaction of rapeseed oil with methanol towards the formation of biodiesel (FAMEs-fatty acid methyl esters). To assess the influence of the SiO2/Al2O3 ratio on the catalytic activity in the tested reaction, a BEA zeolite carrier material with different Si/Al ratios was used. The prepared catalysts were tested in the transesterification reaction at temperatures of 180 °C and 220 °C using a molar ratio of methanol/oil reagents of 9:1. The transesterification process was carried out for 2 h with the catalyst mass of 0.5 g. The oil conversion value and efficiency towards FAME formation were determined using the HPLC technique. The physicochemical properties of the catalysts were determined using the following research techniques: CO2-TPD, XRD, BET, FTIR, and SEM-EDS. The results of the catalytic activity showed that higher activity in the tested process was confirmed for the catalysts supported on the BEA zeolite characterized by the highest silica/alumina ratio for the reaction carried out at a temperature of 220 °C. The most active zeolite catalyst was the 10% CaO/BEA system (Si/Al = 300), which showed the highest triglyceride (TG) conversion of 90.5% and the second highest FAME yield of 94.6% in the transesterification reaction carried out at 220 °C. The high activity of this system is associated with its alkalinity, high value of the specific surface area, the size of the active phase crystallites, and its characteristic sorption properties in relation to methanol.

The Influence of Basicity/Acidity of Lanthanum Systems on the Activity and Selectivity of the Transesterification Process.

The impact of heterogeneous catalytic systems, which are based on rare earth metals, on the properties of biodiesel produced via the transesterification process in a stationary reactor (autoclave) was thoroughly investigated. The physicochemical attributes, including the specific surface area, were analyzed employing the Brunauer-Emmett-Teller (BET) method. The basicity and acidity levels of the catalytic systems were evaluated through temperature-programmed desorption of ammonia and carbon dioxide (TPD-NH3, TPD-CO2), respectively. Furthermore, High-Performance Liquid Chromatography (HPLC) analysis facilitated the assessment of triglyceride conversion and the determination of methyl ester (FAME) selectivity within these processes. Our findings indicate that catalytic systems augmented with lanthanum showcased superior performance. A significant correlation was discerned between the conversion and selectivity to methyl esters and both the specific surface area and the acidity and basicity properties of the catalytic systems under study. These results underscore the crucial role that the physicochemical characteristics of catalytic systems play in optimizing the transesterification process, thereby enhancing the quality of the produced biodiesel. This study contributes valuable insights into the development of more efficient and effective biodiesel production methodologies, highlighting the potential of rare earth metal-based catalysts in renewable energy technologies.

Kinetic Aspects of Esterification and Transesterification in Microstructured Reactors.

Microstructured reactors offer fast chemical engineering transfer and precise microfluidic control, enabling the determination of reactions' kinetic parameters. This review examines recent advancements in measuring microreaction kinetics. It explores kinetic modeling, reaction mechanisms, and intrinsic kinetic equations pertaining to two types of microreaction: esterification and transesterification reactions involving acids, bases, or biocatalysts. The utilization of a micro packed-bed reactor successfully achieves a harmonious combination of the micro-dispersion state and the reaction kinetic characteristics. Additionally, this review presents micro-process simulation software and explores the advanced integration of microreactors with spectroscopic analyses for reaction monitoring and data acquisition. Furthermore, it elaborates on the control principles of the micro platform. The superiority of online measurement, automation, and the digitalization of the microreaction process for kinetic measurements is highlighted, showcasing the vast prospects of artificial intelligence applications.

Optimization of Biodiesel Production Process Using MoO3 Catalysts and Residual Oil: A Comprehensive Experimental 23 Study.

The study aimed to utilize MoO3 catalysts, produced on a pilot scale via combustion reaction, to produce biodiesel from residual oil. Optimization of the process was conducted using a 23 experimental design. Structural characterization of the catalysts was performed through X-ray diffraction, fluorescence, Raman spectroscopy, and particle size distribution analyses. At the same time, thermal properties were examined via thermogravimetry and differential thermal analysis. Catalytic performance was assessed following process optimization. α-MoO3 exhibited a monophasic structure with orthorhombic phase, whereas α/h-MoO3 showed a biphasic structure. α-MoO3 had a larger crystallite size and higher crystallinity, with thermal stability observed up to certain temperatures. X-ray fluorescence confirmed molybdenum oxide predominance in the catalysts, with traces of iron oxide. Particle size distribution analyses revealed polymodal distributions attributed to structural differences. Both catalysts demonstrated activity under all conditions tested, with ester conversions ranging from 93% to 99%. The single-phase catalyst had a long life cycle and was reusable for six biodiesel production cycles. The experimental design proved to be predictive and significant, with the type of catalyst being the most influential variable. Optimal conditions included α-MoO3 catalyst, oil/alcohol ratio of 1/15, and a reaction time of 60 min, resulting in high biodiesel conversion rates and showcasing the viability of MoO3 catalysts in residual oil biodiesel production.

Bis(2,2,2 trifluoroethyl) Phosphonate as a Convenient Precursor for the Synthesis of H-Phosphonates.

A microwave-assisted synthesis of dialkyl and cyclic H-phosphonates via bis(2,2,2 trifluoroethyl) phosphonate (BTFEP) is described. This method enables the synthesis of various cyclic H-phosphonates and hetero-substituted dialkyl H-phosphonates by simple alcoholysis under non-inert and additive-free conditions. Short reaction times and the requirement for only stoichiometric amounts of alcohol render this method attractive for synthetic applications.

Lipase-Catalyzed Preparation and Optimization of Structured Phosphatidylcholine Containing Nervonic Acid.

This study investigated the incorporation of nervonic acid into the chemical structure of phosphatidylcholine via a lipase-catalyzed acidolysis reaction to obtain a functional phospholipid. Lipase immobilization was conducted, and Amberlite XAD7-HP was selected as a carrier to immobilize phospholipase A1 (PLA1) for subsequent experiments. The main acidolysis reaction parameters, including enzyme load, substrate ratio, temperature, and water content, were studied against the reaction time. The optimum reaction conditions obtained were enzyme load, 20%; reaction temperature, 55 °C; water content, 1%; and reaction time, 9 h. The maximum incorporation of nervonic acid into phosphatidylcholine was 48 mol%, with PC recovery at 61.6 mol%. The positional distribution of structured phosphatidylcholine shows that nervonic acid was found in the sn-1 position due to enzyme specificity and in the sn-2 position, possibly due to acyl migration.

Enhanced Enzymatic Performance of Immobilized Pseudomonas fluorescens Lipase on ZIF-8@ZIF-67 and Its Application to the Synthesis of Neryl Acetate with Transesterification Reaction.

In this study, hybrid skeleton material ZIF-8@ZIF-67 was synthesized by the epitaxial growth method and then was utilized as a carrier for encapsulating Pseudomonas fluorescens lipase (PFL) through the co-precipitation method, resulting in the preparation of immobilized lipase (PFL@ZIF-8@ZIF-67). Subsequently, it was further treated with glutaraldehyde to improve protein immobilization yield. Under optimal immobilization conditions, the specific hydrolytic activity of PFL@ZIF-8@ZIF-67 was 20.4 times higher than that of the free PFL. The prepared biocatalyst was characterized and analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR). Additionally, the thermal stability of PFL@ZIF-8@ZIF-67 at 50 °C was significantly improved compared to the free PFL. After 7 weeks at room temperature, PFL@ZIF-8@ZIF-67 retained 78% of the transesterification activity, while the free enzyme was only 29%. Finally, PFL@ZIF-8@ZIF-67 was applied to the neryl acetate preparation in a solvent-free system, and the yield of neryl acetate reached 99% after 3 h of reaction. After 10 repetitions, the yields of neryl acetate catalyzed by PFL@ZIF-8@ZIF-67 and the free PFL were 80% and 43%, respectively.

Enzymatic Synthesis of Structured Lipids Enriched with Medium- and Long-Chain Triacylglycerols via Pickering Emulsion-Assisted Interfacial Catalysis: A Preliminary Exploration.

Medium- and long-chain triacylglycerol (MLCT), as a novel functional lipid, is valuable due to its special nutritional properties. Its low content in natural resources and inefficient synthesis during preparation have limited its practical applications. In this study, we developed an effective Pickering emulsion interfacial catalysis system (PE system) for the enzymatic synthesis of MLCT by trans-esterification. Lipase NS 40086 served simultaneously as a catalyst and a solid emulsifier to stabilize the Pickering emulsion. Benefitting from the sufficient oil-water interface, the obtained PE system exhibited outstanding catalytic efficiency, achieving 77.5% of MLCT content within 30 min, 26% higher than that of a water-free system. The Km value (0.259 mM) and activation energy (14.45 kJ mol-1) were 6.8-fold and 1.6-fold lower than those of the water-free system, respectively. The kinetic parameters as well as the molecular dynamics simulation and the tunnel analysis implied that the oil-water interface enhanced the binding between substrate and lipase and thus boosted catalytic efficiency. The conformational changes in the lipase were further explored by FT-IR. This method could give a novel strategy for enhancing lipase activity and the design of efficient catalytic systems to produce added-value lipids. This work will open a new methodology for the enzymatic synthesis of structured lipids.

Chemical transesterification of coconut and corn oils using different metal hydroxides as catalysts to determine the chemical and physiochemical changes to the oils.

BACKGROUND: The transesterification of butteroil has been shown to alter its lipid chemistry and thus alter the crystallization of the fat. The reaction kinetics and resulting crystallization of the butteroil differ depending on the nature of the catalyst used. Modeling the reaction with vegetable oils is a simpler method for the analysis of resulting products to understand the chemical and physiochemical changes that occur based on catalyst selection. The objective of this work is to perform a chemical transesterification of coconut and corn oil using monovalent and divalent catalysts to investigate the chemical and crystal changes that occur. RESULTS: Coconut and corn oil were subjected to chemical transesterification using both Ca(OH)2 and KOH as catalysts. In both the coconut and corn oil samples, transesterification caused monoglycerides (MAGs) and diacylglycerides (DAGs) to form from the most abundant fatty acid found in each sample. Coconut oil's melting temperature, solid fat content (SFC), and storage modulus decreased as a result of the transesterification, and crystals began to form in the corn oil causing melting thermograms to be evident, higher SFC, and a more viscous oil as a result. Using Ca(OH)2 as a catalyst resulted in more MAG formation, and a higher SFC and melting temperature than when KOH was used as a catalyst. CONCLUSION: The results demonstrate that the chemical changes that result from transesterification of plant-based oils change the crystallization behavior of the oils and can therefore be used for different applications in the food industry. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Hyperbranched Vitrimer for Ultrahigh Energy Dissipation.

Polymers are ideally utilized as damping materials due to the high internal friction of molecular chains, enabling effective suppression of vibrations and noises in various fields. Current strategies rely on broadening the glass transition region or introducing additional relaxation components to enhance the energy dissipation capacity of polymeric damping materials. However, it remains a significant challenge to achieve high damping efficiency through structural control while maintaining dynamic characteristics. In this work, we propose a new strategy to develop hyperbranched vitrimers (HBVs) containing dense pendant chains and loose dynamic crosslinked networks. A novel yet weak dynamic transesterification between the carboxyl and boronic acid ester was confirmed and used to prepare HBVs based on poly (hexyl methacrylate-2-(4-ethenylphenyl)-5,5-dimethyl-1,3,2-dioxaborinane) P(HMA-co-ViCL) copolymers. The A B n ${{AB}_{n}}$ -type of macromonomers, the crosslinking points formed by the dynamic covalent connection via the associative exchange, and the weak yet dynamic exchange reaction are the three keys to developing high-performance HBV damping materials. We found that P(HMA-co-ViCL) 20k-40-60 HBV exhibited ultrahigh energy-dissipation performance over a broad frequency and temperature range, attributed to the synergistic effect of dense pendant chains and weak dynamic covalent crosslinks. This unique design concept will provide a general approach to developing advanced damping materials.