Search Results (30)

Non-cephem drugs with 1,3-thiazine-derived rings are very rare, although a number of bioactive 1,3-thiazine derivatives are known. Similarly, 1,4-thiazepine-derived drugs are rare, but many 1,4-thiazepine derivatives show interesting biological activities. Therefore, our aim was the synthesis of such N,S-heterocycles using a versatile and short (1–3 steps) literature method. First, a three-component reaction of a cycloalkene, a thioamide, and an aldehyde provided 5,6-dihydro-4H-1,3-thiazines. Afterwards, Staudinger ketene–imine cycloaddition with chloroketene resulted in β-lactam-fused 1,3-thiazinanes. Finally, treatment with sodium methoxide induced ring expansion, yielding 4,5,6,7-tetrahydro-1,4-thiazepines. This synthetic pathway generates 3–5 new chiral centers with the help of pericyclic reactions, and almost every cycloaddition proceeded in a diastereoselective manner. Two-dimensional NOESY as well as single-crystal X-ray diffraction enabled unequivocal determination of the stereochemistry of all synthesized compounds. Full article

The growing problem of antibiotic resistance and associated side effects underscores the need for exploring novel therapeutic strategies. The utilization of insect resources is being investigated as one potential avenue in this context. The effective utilization of insect resources represents a promising pathway to this end. This study focuses on investigating the glycerolysis of black soldier fly (Hermetia illucens) larvae (BSFL) oil, which is rich in lauric acid, to optimize the production of antimicrobial monoglycerides. Response surface optimization yielded the following optimal conditions: 35.5 min, 219 °C, 0.72% sodium methoxide catalyst, and a 1:4 molar ratio of triglyceride to glycerol. Under these conditions, monoglycerides accounted for 55.86% of the product, specifically glycerol monolaurate, accounting for 29.47%; this mixture showed notable antimicrobial activity against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. After purification via the solvent crystallization method, the monoglyceride content rose to 69.64%, while the glycerol monolaurate content increased to 35.24%, resulting in enhanced antimicrobial efficacy. Notably, monoglycerides were more effective against Gram-positive than Gram-negative bacteria, consistent with their known membrane-targeting specificity. Importantly, the potent activity against MRSA highlights the potential of these MAGs to combat antibiotic-resistant strains. These findings indicate that BSFL oil is a sustainable feedstock for producing antimicrobial agents with in vitro efficacy. This work supports the further investigation of MAGs derived from BSFL oil as potential candidates to complement existing antibiotics, particularly against resistant strains such as MRSA. Full article

The importance of 1,2,4-triazole derivatives in modern pharmaceuticals is very high. They find their application in drug therapy as antifungal, antifungal agents (fluconazole, intraconazole). It is worth noting that some 1,2,4-triazole compounds are used in therapy for the treatment of Alzheimer’s disease, and new, more effective pharmacophores are being sought to create drugs for neurodegenerative diseases. We propose a modernized method for obtaining a new bis(1,2,4-triazole) derivative using the recyclization reaction of 4-hydroxy-2,5-disubstituted-1,3-6H-oxazin-6-ones with a bisnucleophilic reagent, which was m-phenylenedihydrazine. The method of preparation described in the literature did not lead to the expected products, so it was necessary to select new reaction conditions. 1,1′-(benzene-1,3-diyl)bis[5-benzyl-3-(4-nitrophenyl)-1H-1,2,4-triazole] was obtained by recyclization of 4-hydroxy-2-(4-nitrophenyl)-5-phenyl-6H-1,3-oxazin-6-one with m-phenylenedihydrazine dihydrochloride in absolute methanol in the presence of sodium methoxide for 48 h. The structure of the compound was confirmed by ¹H, ¹³C NMR spectroscopy, and mass spectrometry. Antifungal and antibacterial activities were determined by serial dilutions using meat-peptone broth and Sabouraud medium. The yield based on 4-hydroxy-2-(4-nitrophenyl)-5-phenyl-6H-1,3-oxazin-6-one was 76%. The obtained compound exhibited antimicrobial activity against Staphylococcus aureus with a minimum inhibitory concentration of 62.5 μg/mL and 125 μg/mL against Candida albicans. Full article

A comprehensive techno-economic assessment was undertaken to determine the viability of bioethanol production from sugarcane bagasse in Thailand through organosolv fractionation, incorporating three distinct catalytic systems: sulfuric acid, formic acid, and sodium methoxide. Rigorous process simulations were executed using Aspen Plus, facilitating the derivation of detailed mass and energy balances, which served as the foundational input for downstream cost modeling. Economic performance metrics, including the total annualized cost and minimum ethanol selling price, were systematically quantified for each scenario. Among the evaluated configurations, the formic acid-catalyzed organosolv system exhibited superior techno-economic attributes, achieving the lowest unit production costs of 1.14 USD/L for ethanol and 1.84 USD/kg for lignin, corresponding to an estimated ethanol selling price of approximately 1.14 USD/L. This favorable outcome was attained with only moderate capital intensity, indicating a well-balanced trade-off between operational efficiency and investment burden. Conversely, the sodium methoxide-based process configuration imposed the highest economic burden, with a TAC of 15.27 million USD/year, culminating in a markedly elevated MESP of 5.49 USD/kg (approximately 4.33 USD/L). The sulfuric acid-driven system demonstrated effective delignification performance. Sensitivity analysis revealed that reagent procurement costs exert the greatest impact on TAC variation, highlighting chemical expenditure as the key economic driver. These findings emphasize the critical role of solvent choice, catalytic performance, and process integration in improving the cost-efficiency of lignocellulosic ethanol production. Among the examined options, the formic acid-based organosolv process stands out as the most economically viable for large-scale implementation within Thailand’s bioeconomy. Full article

This study evaluates the production of base oils for biolubricants using fatty acid methyl esters (FAMEs) derived from sunflower oil as the raw material. The production process involved the synthesis of oleochemical esters through a single-step alkaline transesterification reaction with a high-molecular-weight polyol, such as trimethylolpropane (TMP). To assess the effectiveness of the developed catalytic system in conducting the transesterification reactions and its impact on the properties of the final product, two types of alkaline catalysts were used. Specifically, the reactions were carried out using either Ca/TEA alkoxide or sodium methoxide as catalysts in various configurations and concentrations to determine the optimal catalyst concentration and reaction conditions. Sodium methoxide served as the commercial benchmark catalyst, while the Ca/TEA alkoxide was prepared in the laboratory. The optimal concentration of Ca/TEA was determined to be 3.0% wt. in the presence of iso-octane and 3.5% wt. under vacuum, while the corresponding concentrations of CH₃ONa for both cases were determined to be 2.0% wt. The synthesized biolubricant esters exhibit remarkable performance characteristics, such as high kinematic viscosities and low pour points—ranging from 33–48 cSt at 40 °C, 7.68–10.03 cSt at 100 °C, to −14 to −7 °C, respectively—which are comparable to or improved over those of mineral oils such as SN-150 or SN-500, with the Ca/TEA alkoxide-catalyzed systems showing superior oxidation stability and reduced byproduct formation. Full article

Background: Fatty acids (FAs) represent a ubiquitous class of nonpolar alkyl carboxylate metabolites with diverse biological functions. Nutrition, metabolism, and endogenous and exogenous stress influence the overall FA metabolic status and transport via the bloodstream. FAs esterified in lipids are of particular interest, as they represent promising biomarkers of pathological diseases and nutritional status. Methods: Here, we report a validated gas chromatographic-mass spectrometric (GC-MS) method for the quantitative analysis of 32 FAs exclusively bound in esterified lipids. The developed sample preparation protocol comprises three steps using only 5 µL of human serum for Folch extraction, sodium methoxide-catalyzed transesterification in tert-butyl methyl ether, and re-extraction in isooctane prior to a quantitative GC-MS analysis with positive ion chemical ionization (PICI) and selected ion monitoring (SIM). Results: The base-catalyzed transmethylation step was studied for 14 lipid classes and was found to be efficient under mild conditions for all major esterified lipids but not for free FAs, lipid amides, or sphingolipids. To minimize matrix effects and instrument bias, internal fatty acid trideuteromethyl esters (D3-FAME) standards were prepared through isotope-coded derivatization with D3-labeled methylchloroformate/methanol medium mixed with each transmethylated serum extract for the assay. The method was validated according to FDA guidelines and evaluated by analyzing NIST SRM 2378 Serum 1 and sera from three healthy donors. Conclusions: The measured quantitative FA values are consistent with the reference data of SRM 2378, and they demonstrate the application potential of the described method for general FA analysis in esterified lipids as a novel complementary tool for lipidomics, as well as for the analysis of membrane FAs in dry blood spots and red blood cells. Full article

In the current environmental scenario, the proposal of alternatives for petroleum-based products has considerably increased, with the aim of looking for bioproducts with interesting properties such as biodegradability, sustainability and efficiency, among others. In this sense, the role of biolubricants is promising, offering a wide range of possibilities through different methods and operating conditions. Specifically, double transesterification could be a suitable process in a biorefinery context. The aim of this work was to produce a biolubricant through double transesterification with methanol and neopentyl glycol (NPG) under different reaction conditions by using homogeneous catalysis (sodium methoxide). Different catalyst concentrations, among other changes in reaction conditions (temperature ranging between 100 and 140 °C and NPG/FAME ratios between 0.5 and 2), were used, obtaining high conversion values (96%) and a final product with a high viscosity (20.7 cSt), which allows for its use as engine oil (SAE 5W). In conclusion, biodiesel and biolubricant production was feasible through homogeneous catalysis, proving the feasibility of this process at the laboratory scale. Further studies, including the use of different heterogeneous catalysts, as well as the implementation of this process at a semi-industrial scale, are recommended. Full article

Biodiesel is a renewable and sustainable alternative fuel to petrol-derived diesel. Decreasing the operating costs by improving the catalyst’s characteristics is an effective way to increase the competitiveness of biodiesel in the fuel market. An aqueous solution of sodium methoxide (CH₃ONa), which is a traditional alkaline catalyst, was immersed in nanometer-sized particles of titanium dioxide (TiO₂) powder to prepare the strong alkaline catalyst TiO₂/CH₃ONa. The immersion method was used to enhance the transesterification reaction. The mixture of TiO₂ and CH₃ONa was calcined in a high-temperature furnace in a range between 150 and 450 °C continuously for 4 h. The heterogeneous alkaline catalyst TiO₂/CH₃ONa was then used to catalyze the strong alkaline transesterification reaction of palm oil with methanol. The highest content of fatty acid methyl esters (FAMEs), which amounted to 95.9%, was produced when the molar ratio of methanol to palm oil was equal to 6, and 3 wt.% TiO₂/CH₃ONa was used, based on the weight of the palm oil. The FAMEs produced from the above conditions were also found to have the lowest kinematic viscosity of 4.17 mm²/s, an acid value of 0.32 mg KOH/g oil, and a water content of 0.031 wt.%, as well as the highest heating value of 40.02 MJ/kg and cetane index of 50.05. The lower catalyst amount of 1 wt.%, in contrast, resulted in the lowest cetane index of 49.31. The highest distillation temperature of 355 °C was found when 3 wt.% of the catalyst was added to the reactant mixture with a methanol/palm oil molar ratio of 6. The prepared catalyst is considered effective for improving the fuel characteristics of biodiesel. Full article

A strong alkaline catalyst, sodium methoxide (CH₃ONa), is commonly used to catalyze the transesterification reaction for biodiesel production. Meanwhile, titanium dioxide (TiO₂) anatase with a bandgap of 3.2 eV is a highly competitive photocatalyst after the absorption of sufficient energy from ultraviolet light. There has been no published report on the synergistic catalyst effects of CH₃ONa and TiO₂ on further facilitating the transesterification reaction. Hence, an impregnating method was used in this study to prepare the heterogeneous photocatalyst comprising TiO₂ nanoparticles embedded with a CH₃ONa catalyst. The TiO₂ nanoparticles were first immersed in an aqueous solution of CH₃ONa so that CH₃ONa could diffuse into the interior surfaces of the TiO₂ porous structure. The mixture of TiO₂ and CH₃ONa was then calcined in the temperature range from 150 °C to 450 °C for 4 h to produce the TiO_2/CH₃ONa photocatalyst. Various characteristics of the catalyst were analyzed to determine the optimum preparation conditions. The Fourier transform infrared spectroscopy spectra revealed that the absorption peaks of CH₃ONa appeared in the wavelength range of 600 cm⁻¹ and 1500 cm⁻¹. The X-ray diffractometer analysis showed that the calcined CH₃ONa did not alter the crystal structure of the catalyst carrier TiO₂. At the calcined temperatures between 100 °C and 800 °C, no intermediate or pyrolyzed product of CH₃ONa was detected, as revealed by the thermogravimetric analyzer spectra. In addition, about 5~9 wt.% elemental calcium in the CH₃ONa solution could be calcined onto the surface of TiO₂. In addition, the FTIR spectra confirmed the successful sintering and bonding of CH₃ONa onto the TiO₂ nanoparticles. The energy dispersive spectrometry result revealed that the interior surface of the TiO₂ nanoparticles was filled with the CH₃ONa compound. Full article

Replacing petroleum-based polymers with biopolymers such as polysaccharides is essential for protecting our environment by saving fossil resources. A research field that can benefit from the application of more sustainable and renewable materials is photochemistry. Therefore, cellulose-based photoresists that could be photocrosslinked via UV irradiation (λ = 254 nm and λ = 365 nm) were developed. These biogenic polymers enable the manufacturing of sustainable coatings, even with imprinted microstructures, and cellulose-based bulk materials. Thus, herein, cellulose was functionalized with organic compounds containing carbon double bonds to introduce photocrosslinkable side groups directly onto the cellulose backbone. Therefore, unsaturated anhydrides such as methacrylic acid anhydride and unsaturated and polyunsaturated carboxylic acids such as linoleic acid were utilized. Additionally, these cellulose derivatives were modified with acetate or tosylate groups to generate cellulose-based polymers, which are soluble in organic solvents, making them suitable for multiple processing methods, such as casting, printing and coating. The photocurable resist was basically composed of the UV-crosslinkable biopolymer, an appropriate solvent and, if necessary, a photoinitiator. Moreover, these bio-based photoresists were UV-crosslinkable in the liquid and solid states after the removal of the solvent. Further, the manufactured cellulose-based architectures, even the bulk structures, could be entirely regenerated into pure cellulose devices via a sodium methoxide treatment. Full article

In this work we demonstrate one-pot glycidol synthesis, via trans-esterification between glycerol and dimethyl carbonate, by making use of commercially available sodium methoxide as a catalyst. An excellent glycerol conversion (99%) and remarkable glycidol yield (75%) was obtained using dimethyl carbonate/glycerol (molar ratio 2:1) in the presence of 3 wt% catalyst amount (with respect to glycerol weight) at 85 °C for a reaction time of 120 min. Sodium methoxide was recycled and reused twice with only a slight decrease in glycerol conversion. The water content of the glycerol reached 2.5 wt%; this did not reduce the glycerol conversion efficiency of the catalyst. A plausible mechanism for the trans-esterification involved in the preparation of glycidol was proposed. Full article

This study aims to prepare a supported catalyst based on zeolite Y doped with NaOMe (sodium methoxide) for the transesterification of waste cooking oil (WCO). The catalytic screening data showed that NaOMe/zeolite is a prominent catalyst for the transesterification of WCO prepared by a solvent-free, ball-milling process. We initially tested 5–20% of sodium methoxide loading onto zeolite Y and found that 20% is the optimum loading for the reaction. The transesterification reaction required a comparatively lower methanol-to-oil mole ratio of 16:1 with the reaction temperature as 60 °C. The ball-milled NaOMe/zeolite catalyst was characterized by BET surface area analysis, FE-SEM, TEM, FT–IR, and XRD. The BET surface analysis revealed that the surface area for zeolite Y was substantially decreased in the NaOMe/zeolite catalyst. The ball-milling process dropped the crystallinity of zeolite Y, which can be seen from the XRD and FE-SEM images of both zeolite Y and the NaOMe/zeolite catalyst. Finally, the transesterification reaction product was fully characterized by ${}^1$H-NMR and viscosity analysis for biodiesel, glycerol, and the WCO. The chemical shifts for the biodiesel and glycerol are found accordingly. This is also supported by the FT–IR characterization of biodiesel, glycerol, and WCO. It is noteworthy that a very high mass ratio of 250 g oil/g NaOMe is obtained when converting WCO to biodiesel, indicating very high catalytic activity for the aforementioned catalyst. Full article

Non-fullerene acceptors have recently attracted much attention as components of organic solar cells. 1H-indene-1,3(2H)-dione is a key compound for the synthesis of the end-capping component of non-fullerene acceptors. In this communication, an intermediate for the synthesis of this compound, tert-butyl (E)-3-oxo-2-(3-oxoisobenzofuran-1(3H)-ylidene)butanoate, was prepared by the reaction between phthalic anhydride and tert-butyl acetoacetate. Further treatment with sodium methoxide in methanol led to the formation of 1H-indene-1,3(2H)-dione in a high yield. The structure of the newly synthesized compound was established by means of elemental analysis, high-resolution mass spectrometry, ¹H, ¹³C NMR, IR spectroscopy, mass spectrometry and X-ray analysis. Full article

Glycolysis of post-consumer polyethylene terephthalate (PET) waste is a promising chemical recycling technique, back to the monomer, bis(2-hydroxyethyl) terephthalate (BHET). This work presents sodium methoxide (MeONa) as a low-cost catalyst for this purpose. BHET product was confirmed by gas chromatography-mass spectrometry (GCMS), Nuclear Magnetic Resonance (NMR) Spectroscopy, melting point, and Differential Scanning Calorimetry (DSC). It was shown, not surprisingly, that PET conversion increases with the glycolysis temperature. At a fixed temperature of 190 °C, the response surface methodology (RSM) based on the Box-Behnken design was applied. Four independent factors, namely the molar ratio of PET: MeONa (50–150), the molar ratio of ethylene glycol to PET (EG: PET) (3–7), the reaction time (2–6 h), and the particle size (0.25–1 mm) were studied. Based on the experimental results, regression models as a function of significant process factors were obtained and evaluated by analysis of variance (ANOVA), to predict the depolymerization performance of MeONa in terms of PET conversion. Coefficient of determination, R² of 95% indicated the adequacy for predicted model. Afterward, the regression model was validated and optimized within the design space with a prediction of 87% PET conversion at the optimum conditions demonstrating a deviation of less than 5% from predicted response. A van ‘t Hoff plot confirmed the endothermic nature of the depolymerization reaction. The ceiling temperature (T_C = 160 °C) was calculated from Gibbs’ free energy. A kinetic study for the depolymerization reaction was performed and the activation energy for MeONa was estimated from the Arrhenius plot (E_A = 130 kJ/mol). The catalytic depolymerization efficiency of MeONa was compared under similar conditions with widely studied zinc acetate and cobalt acetate. This study shows that MeONa’s performance, as a glycolysis catalyst is promising; in addition, it is much cheaper and environmentally more benign than heavy metal salts. These findings make a valuable contribution towards the chemical recycling of post-consumer PET waste to meet future recycling demands of a circular economy. Full article

N-Arylmaleimides are universal substrates for the synthesis of various heterocyclic compounds with a wide spectrum of biological activity. However, their reactions with thioacetamides have not been comprehensively studied. We studied the reactions of thioacetamide with N-arylmaleimides under various conditions. We established for the first time that three types of products: epithiopyrrolo[3,4-c]pyridines, pyrrolo[3,4-c]pyridines and 3,3′-thiobis(1-arylpyrrolidine-2,5-diones) can be obtained in different conditions. In all cases, two maleimide molecules are involved in the reaction. 3,3′-Thiobis(1-arylpyrrolidine-2,5-diones) are the major products when the reaction is conducted at boiling in acetic acid. When thioacetamide and N-arylmaleimide are kept in dioxane at 50 °C, epithiopyrrolo[3,4-c]pyridines can be isolated, which, when heated in dioxane, in acetic acid or in methanol in the presence of catalytic amounts of sodium methoxide, are converted into pyrrolo[3,4-c]pyridines by eliminating hydrogen sulfide. The reaction of thioacetamide and N-arylmaleimide in dioxane at boiling temperature with the portioned addition of N-arylmaleimide leads predominantly to the formation of pyrrolo[3,4-c]pyridines. The reaction of thioacetamide with N-alkylmaleimides under all the above conditions leads predominantly to the formation of the corresponding sulfides. The structure of the compounds obtained was characterized by a set of spectral analysis methods and X-ray diffraction (XRD) data. Full article