Production Of Esters Research Articles

Transesterification reactions as a means to produce esters: A critical review

AbstractEsters are important chemicals used in fine and bulk chemical industry with numerous applications: solvents, paints, varnishes, dyes, and cosmetics. Ester formation is dominated mainly by Fischer esterification and transesterification. Fischer reaction is generally used for ester production, but in certain cases, transesterification can be used with advantage. It is useful when the acid is less soluble in the alcohol or in the solvent used, thus forming two layers. Water formation creates purification problems during esterification reactions due to azeotrope formation and transesterification can be useful in such cases. Commercially, cheaply available methyl and ethyl esters can be conveniently used as raw materials for value added ester production by transesterification. Transesterification is also useful when the parent acids are highly reactive and pose difficulty in separation. Transesterifications are slow reactions and a catalyst is used: acids and bases, ion exchange resins, zeolites, and clays. Homogeneous catalysts were used in the past which are now replaced by their heterogeneous counterparts. Heterogeneous catalysts offer added advantages like reusability, lesser corrosion, and ease of separation. Transesterification can be commercially used to produce a number of esters of industrial importance like acrylics and biodiesel. This review considers all these aspects in considerable detail. A large literature set was scanned and its judicious extract is presented.

Modification of Growth Media for Scenedesmus and Nitchzer Species for Fatty Acid Methyl Esters Production in Raceway Pond

The aim of this study was to modify the growth media for Scenedesmus and Nitchzia species for fatty acid methyl esters production in raceway pond. Native Scenedesmus and Nitchzia species were cultivated in raceway pond in three different growth media (Nitrogen-sufficient, Nitrogen-deficient and Blue Green 11) media at different periods to assess their quantitative parameters (biomass concentration (g/L), biomass productivity (g/L/d), lipid content (%), and lipid productivity (mg/L/d) as well as their fatty acid methyl esters composition. The quantitative parameters were determined following standard methods and the fatty acid methyl esters composition was analysed by Gas Chromatography Mass Spectrometry (GC-MS). The results of the quantitative parameters obtained from Scenedesmus species were highest in the Blue Green 11 (control) media as compared to the experimental media. Statistically, there is significant difference (p<0.05) in the lipid content obtained from Scenedesmus species between the Blue Green 11 media and the experimental media. The biomass concentration and lipid content obtained from Nitchzia species were also found to be highest in Blue Green 11 media as compared to the other two media. However, the lipid content obtained from Nitchzia species in the three different media showed insignificant difference (p>0.05). Scenedesmus and Nitchzia species did not respond to nitrogen deficiency condition. The Gas Chromatography Mass Spectrometry analysis of the fatty acid methyl esters composition revealed the presence of similar compounds in different proportion. The dominant compound of the fatty acid methyl esters of the two species in the three different media are Hexadecanoic acid methyl ester ((palmitic acid)), 9-octadecenoic acid (Z) methyl ester ((oleic acid) and 9, 12-octadecadienoic acid methyl ester (linolenic acid) among others. The Carbon16-Carbon18 (C16-C18) chain in Scenedesmus and Nitchzia species ranges from 74.14-61.84% and 63.81-61.98% respectively. These could suggest that both species have a great potential for the production of fatty acid methyl esters in large scale cultivation.

Resveratrol Propionate Ester Supplement Exerts Antihypertensive Effect in Juvenile Rats Exposed to an Adenine Diet via Gut Microbiota Modulation.

Resveratrol, acting as a prebiotic, and propionate, functioning as a postbiotic, hold promise for preventing hypertension in chronic kidney disease (CKD). Previously, we employed propionate to enhance the bioavailability of resveratrol through esterification, resulting in the production of a resveratrol propionate ester (RPE) mixture. In this study, we purified 3-O-propanoylresveratrol (RPE2) and 3,4'-di-O-propanoylresveratrol (RPE4) and investigated their protective effects in a juvenile rat adenine-induced CKD model. To this end, male Sprague Dawley rats aged three weeks (n = 40) were divided into five groups: control; CKD (rats fed adenine); CKRSV (CKD rats treated with 50 mg/L resveratrol); CDRPE2 (CKD rats treated with 25 mg/L RPE2); and CKRPE4 (CKD rats treated with 25 mg/L RPE 4). RPE2 and PRE4 similarly exhibited blood pressure-lowering effects comparable to those of resveratrol, along with increased nitric oxide (NO) availability. Furthermore, RPE2 and RPE4 positively influenced plasma short-chain fatty acid (SCFA) levels and induced distinct alterations in the gut microbial composition of adenine-fed juvenile rats. The supplementation of RPE2 and RPE4, by restoring NO, elevating SCFAs, and modulating the gut microbiota, holds potential for ameliorating CKD-induced hypertension.

Impact of sequential inoculation timing on the quality of wine fermented by indigenous Lachancea thermotolerans and Saccharomyces cerevisiae

Lack of acidity in wine is one of the main challenges in warm wine-producing regions. The non-Saccharomyces yeast, Lachancea thermotolerans (LT), is well known for its great potential in wine acidification through the production of lactic acid. In this study, an indigenous LT strain was sequentially inoculated with S. cerevisiae (SC). The influence of the timing of SC inoculation on wine quality was extensively studied. Inoculating SC 72 h after the inoculation of LT delayed the peak of fermentation rate, but had no significant influence on the duration of fermentation. The late inoculation (72 h) of SC effectively increased the production of lactic acid, which consequently increased the total wine acidity and decreased the pH. Higher levels of esters were also achieved by the late inoculation. Pilot-scale fermentations were carried out with both Chardonnay and Cabernet Sauvignon to verify the effect of late inoculation. Lactic acid produced in sequential fermentation was 2.73 g/L for Chardonnay wine and 5.35 g/L for Cabernet Sauvignon wine, and the production of ethyl esters was also enhanced. Overall, the results demonstrated that the late inoculation of SC in sequential fermentation with LT improved wine quality by increasing acidity and producing more balanced and aromatic wines.

Production of biodiesel (isopropyl ester) from coconut oil by microwave assisted transesterification: parametric study and optimization

Biodiesel, a renewable fuel for diesel vehicle engines, has been commonly produced from transesterification process involving triglycerides from vegetable oil with alcohol. One of the most promising candidates for vegetable oil due to its abundance in Indonesia is coconut oil. However, the short carbon chain present in coconut oil necessitates the use of longer-chain alcohol types to adjust to the biodiesel carbon chain, such as isopropanol. Therefore, this research focused on producing biodiesel (isopropyl ester) from coconut oil using isopropanol and NaOH catalyst through a transesterification process. To enhance this process, microwave technology was utilized for its ability to lower the biodiesel production reaction time from the conventional one-hour timeframe to less than ten minutes, increase energy efficiency, and improve biodiesel quality. The primary objective was to investigate the impact of reaction time, catalyst concentration, and microwave power on the isopropyl ester yield. Further optimization was conducted using Response Surface Methodology (RSM) with Box-Behnken Design (BBD) to illustrate the model's effectiveness and applicability. Based on BBD optimization simulation, the optimal condition for producing isopropyl ester from coconut oil using microwave technology is a 1-minute reaction time, 0.2 wt.% NaOH catalyst concentration, and 443.9 W microwave power, maximizing the yield to 99.89%. This research highlights the potential of microwave assisted transesterification and the reliability of this innovative approach, contributing to the development of isopropyl ester production with enhanced quality that meets the specifications of the Indonesian National Standard (SNI).

Nano-CaO as a heterogeneous catalyst for biodiesel synthesis by transesterification of Jatropha oil

BackgroundThis research employs response surface methodology, specifically Central Composite Design (CCD), to optimize the process parameters for the effective production of biodiesel. Jatropha oil was utilized as the raw material to minimize expenses. A nanocatalyst was utilized as a solid catalyst, developed from CaCO3 via waste snail shells, offering advantages such as recyclability and improved catalytic activity during a transesterification process. The developed nanocatalyst was analyzed using various techniques, including dynamic light scattering (DLS), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, and Fourier-transform infrared (FTIR). The BET analysis revealed a surface area of 5.1m2/g and the Barrett-Joyner-Halenda (BJH) analysis provided insights into the pore volume and diameter of the synthesized nano-CaO, showing values of 0.002556 cc/g and 1.1 nm, respectively, indicating the presence of both microspores and active sites on the external surface of the nano-CaO catalyst. Biodiesel conversion was controlled by adjusting factors like the methanol to oil ratio, catalyst weight, reaction time, reaction temperature, and agitation speed. A quadratic model was established to explore the correlation between the independent variables and the biodiesel conversion rate. The results showed a maximum biodiesel conversion rate of 96.73% under the optimal conditions: methanol to oil ratio (6:1), catalyst weight (1.4 wt%), reaction time (60 min), reaction temperature (55 °C), and agitation speed (250 rpm). These parameters were determined through 32 experimental trials. The RSM technique yielded impressive results with a determined coefficient of determination (R2) of 0.9834, adjusted R2 of 0.8503, predicted R2 of 0.8309, and a coefficient of variance (CV) 0.75%. Based on the analysis of variance (ANOVA) findings, the model exhibits a high level of significance (p<0.0001), which is less than 0.05 and F- Value 29.71.The study aims to enhance the yield and efficiency of the transesterification process, thereby increasing the overall production of fatty acid methyl ester from Jatropha oil. This innovative approach efficiently generates biodiesel from renewable resources, in a manner that is both environmentally friendly and maximizes the effectiveness of the process parameters. The evaluation conform that the quality of the biodiesel met the standards set by ASTM D 6751 and EN 14214.

Production of Esters in Escherichia coli Using Citrate Synthase Variants.

Acetate esters comprise a wide range of products including fragrances and industrial solvents. Biosynthesis of esters offers a promising alternative to chemical synthesis because such routes use renewable carbohydrate resources and minimize the generation of waste. One biochemical method for ester formation relies on the ATF1 gene from Saccharomyces cerevisiae, which encodes alcohol-O-acyltransferase (AAT) which converts acetyl-CoA and an exogenously supplied alcohol into the ester. In this study, the formation of several acetate esters via AAT was examined in Escherichia coli chromosomally expressing citrate synthase variants, which create a metabolic bottleneck at acetyl-CoA. In shake flask cultures, variant strains generated more acetate esters than the strains expressing the wild-type citrate synthase. In a controlled bioreactor, E. coli GltA[A267T] generated 3.9 g propyl acetate in 13 h, corresponding to a yield of 0.155 g propyl acetate/g glucose, which is 18% greater than that obtained by the wild-type GltA control. These results demonstrate the ability of citrate synthase variants to redistribute carbon from central metabolism into acetyl-CoA-derived biochemicals.

[formula omitted] -catalyzed trans-esterification of brassica carinata seed oil for biodiesel production

Brassica carinata seed is a non-edible oil containing crop grown for oil-based product development like biodiesel synthesis. However, recently technical challenges such as availability of feedstock, type of catalyst, cost, and quality of biodiesel hindered the feasibility and utilization of biodiesel. Thus, this study addressed those problems under the production of fatty acid methyl ester through trans-esterification reaction in the presence of heterogeneous catalyst (CaO), and methanol alcohol from Ethiopian brassica carinata seed oil. The synergetic and antagonistic effects of selected parameters (temperature, methanol to oil molar ratio, and amount of catalyst) on the yield of FAME were analyzed. Box-Behnken response surface methodology statistical analysis was applied to examine the parametric interaction effect, and optimization of reaction conditions. Accordingly, 90 % of fatty acid methyl ester (FAME) yield was achieved at the optimum value of 65 °C temperature, 14.85: 1 methanol to oil molar ratio, and 13.77 % catalyst load. The fuel properties of the resulted biodiesel were determined following standard procedures, and the results were within the standard limits (ASTM D6751). This implies that brassica carinata oil over heterogeneous catalyzed reaction medium under optimum reaction conditions provides higher biodiesel yield.

Effects of Heterologous Expression of Genes Related L-Malic acid Metabolism in Saccharomyces uvarum on Flavor Substances Production in Wine.

During malolactic fermentation (MLF) of vinification, the harsh L-malic acid undergoes transformation into the milder L-lactic acid, and via decarboxylation reactions it is catalyzed by malolactic enzymes in LAB. The use of bacterial malolactic starter cultures, which usually present challenges in the industry as the suboptimal conditions after alcoholic fermentation (AF), including nutrient limitations, low temperatures, acidic pH levels, elevated alcohol, and sulfur dioxide concentrations after AF, lead to "stuck" or "sluggish" MLF and spoilage of wines. Saccharomyces uvarum has interesting oenological properties and provides a stronger aromatic intensity than Saccharomyces cerevisiae in AF. In the study, the biological pathways of deacidification were constructed in S. uvarum, which made the S. uvarum carry out the AF and MLF simultaneously, as different genes encoding malolactic enzyme (mleS or mleA), malic enzyme (MAE2), and malate permease (melP or MAE1) from Schizosaccharomyces pombe, Lactococcus lactis, Oenococcus oeni, and Lactobacillus plantarum were heterologously expressed. For further inquiry, the effect of L-malic acid metabolism on the flavor balance in wine, the related flavor substances, higher alcohols, and esters production, were detected. Of all the recombinants, the strains WYm1SN with coexpression of malate permease gene MAE1 from S. pombe and malolactic enzyme gene mleS from L. lactis and WYm1m2 with coexpression of gene MAE1 and malate permease gene MAE2 from S. pombe could reduce the L-malic acid contents to about 1 g/L, and in which the mutant WYm1SN exhibited the best effect on the flavor quality improvement.

Hexa-Fe(III) Carboxylate Complexes Facilitate Aerobic Hydrocarbon Oxidative Functionalization: Rh Catalyzed Oxidative Coupling of Benzene and Ethylene to Form Styrene.

Fe(II) carboxylates react with dioxygen and carboxylic acid to form Fe6(μ-OH)2(μ3-O)2(μ-X)12(HX)2 (X = acetate or pivalate), which is an active oxidant for Rh-catalyzed arene alkenylation. Heating (150-200 °C) the catalyst precursor [(η2-C2H4)2Rh(μ-OAc)]2 with ethylene, benzene, Fe(II) carboxylate, and dioxygen yields styrene >30-fold faster than the reaction with dioxygen in the absence of the Fe(II) carboxylate additive. It is also demonstrated that Fe6(μ-OH)2(μ3-O)2(μ-X)12(HX)2 is an active oxidant under anaerobic conditions, and the reduced material can be reoxidized to Fe6(μ-OH)2(μ3-O)2(μ-X)12(HX)2 by dioxygen. At optimized conditions, a turnover frequency of ∼0.2 s-1 is achieved. Unlike analogous reactions with Cu(II) carboxylate oxidants, which undergo stoichiometric Cu(II)-mediated production of phenyl esters (e.g., phenyl acetate) as side products at temperatures ≥150 °C, no phenyl ester side product is observed when Fe carboxylate additives are used. Kinetic isotope effect experiments using C6H6 and C6D6 give k H/k D = 3.5(3), while the use of protio or monodeutero pivalic acid reveals a small KIE with k H/k D = 1.19(2). First-order dependencies on Fe(II) carboxylate and dioxygen concentration are observed in addition to complicated kinetic dependencies on the concentration of carboxylic acid and ethylene, both of which inhibit the reaction rate at a high concentration. Mechanistic studies are consistent with irreversible benzene C-H activation, ethylene insertion into the formed Rh-Ph bond, β-hydride elimination, and reaction of Rh-H with Fe6(μ-OH)2(μ3-O)2(μ-X)12(HX)2 to regenerate a Rh-carboxylate complex.

OPTIMIZATION OF YELLOW OLEANDER BIODIESEL PRODUCTION PARAMETERS USING CENTRAL COMPOSITE DESIGN RESPONSE SURFACE METHODOLOGY

Response surface methodology was used for optimization of methyl ester production parameters with the two-step trans- esterification of Yellow oleander seed oil. The model equation obtained with R2, 0.877 and coefficient of variation (CV), 3.21% shows the reliability of the model and adequately captured the correlation between the biodiesel yield and process parameters. The result suggested the best combination of the process variables for optimum biodiesel yield of 91.42% are: reaction temperature (46.61 °C); reaction time (90.52 min); amount of methanol (5.90 cm3/g oil) and catalyst concentration (11.44gm). Validation results show close agreement between the actual (90.85%) and predicted (91.42%) biodiesel yields.

Heterogeneous Calcium Oxide Catalytic Filaments for Three-Dimensional Printing: Preparation, Characterization, and Use in Methyl Ester Production.

This study aimed to investigate heterogeneous catalytic filaments of calcium oxide (CaO) for fused deposition modeling three-dimensional (3D) printers. The CaO catalysts were blended with acrylonitrile butadiene styrene (ABS) plastic to form catalytic filaments. A single-screw filament extruder was used to prepare the filaments, following which their mechanical properties, thermal properties, morphology, catalytic characteristics in biodiesel production, and reusability were evaluated. In accordance with the results, a maximum CaO catalyst content of 15 wt % was recommended to be blended in the ABS pellet. The hardness and compressive strength of these catalytic filaments were shown to be improved. Subsequently, the catalytic filaments with the highest CaO content (15 wt %) were used to produce methyl ester from pretreated sludge palm oil through the transesterification process. To determine the recommended conditions for achieving the highest purity of methyl ester in biodiesel, the process parameters were optimized. A methyl ester purity of 96.58 wt % and a biodiesel yield of 79.7 wt % could be achieved under the recommended conditions of a 9.0:1 methanol to oil molar ratio, 75.0 wt % catalytic filament loading, and 4.0 h reaction time. Furthermore, the reusability of the 15 wt % CaO catalytic filaments was evaluated in a batch process with multiple transesterification cycles. The results indicated that the purity of methyl ester dropped to 95.0 wt % only after the fourth cycle. The method used in this study for preparing and characterizing CaO catalytic filaments can potentially serve as a novel approach for constructing biodiesel reactors using 3D printing technology.

Enhancing Erucic Acid and Wax Ester Production in Brassica carinata through Metabolic Engineering for Industrial Applications

Metabolic engineering enables oilseed crops to be more competitive by having more attractive properties for oleochemical industrial applications. The aim of this study was to increase the erucic acid level and to produce wax ester (WE) in seed oil by genetic transformation to enhance the industrial applications of B. carinata. Six transgenic lines for high erucic acid and fifteen transgenic lines for wax esters were obtained. The integration of the target genes for high erucic acid (BnFAE1 and LdPLAAT) and for WEs (ScWS and ScFAR) in the genome of B. carinata cv. ‘Derash’ was confirmed by PCR analysis. The qRT-PCR results showed overexpression of BnFAE1 and LdPLAAT and downregulation of RNAi-BcFAD2 in the seeds of the transgenic lines. The fatty acid profile and WE content and profile in the seed oil of the transgenic lines and wild type grown in biotron were analyzed using gas chromatography and nanoelectrospray coupled with tandem mass spectrometry. A significant increase in erucic acid was observed in some transgenic lines ranging from 19% to 29% in relation to the wild type, with a level of erucic acid reaching up to 52.7%. Likewise, the transgenic lines harboring ScFAR and ScWS genes produced up to 25% WE content, and the most abundant WE species were 22:1/20:1 and 22:1/22:1. This study demonstrated that metabolic engineering is an effective biotechnological approach for developing B. carinata into an industrial crop.

Nickel (II) complex supported on amino-functionalized magnetic nanoparticles: A active magnetically recoverable catalyst for the synthesis of esters and thioesters

Esters and thioesters are of great interest to chemists from a biological and medicinal point of view, that's why the synthesis of these compounds is always a popular research field in organic chemistry. In this method, we first synthesized Fe3O4@BA/Pyrim-Carboxamide-NiCl2 nanocatalyst, then studied its catalytic application in the preparation of esters and thioesters through carbonylation and thiocarbonylation of aryl iodides. The results of these experiments showed that the Fe3O4@BA/Pyrim-Carboxamide-NiCl2 catalyst in the presence of KOAc in ChCl-Urea solvent can easily conducted a wide range of reactions and the desired ester and thioester products were synthesized with very good yields. The structure of the Fe3O4@BA/Pyrim-Carboxamide-NiCl2 catalyst before use and after recovery was well confirmed by a series of techniques. Among the features of this method, the following can be mentioned: the synthesis of esters and thioesters with very good yields, using mild conditions, simple separation of the catalyst, high reusability of the catalyst, providing NMR analysis for all the obtained products.

Whole-cell Lipase Catalytic Synthesis of Short-chain Fragrance Esters using Aspergillus flavus

Background: Fragrances are the collection of unlike functional assemblies, most likely alcohols, esters, aldehydes, ketones, and acids in organic products/hydrocarbons. Short-chain aliphatic fragrance esters have immense applications as flavors in the food, pharmaceutical and cosmetic industries and also have remarkable commercial significance in cosmetics and personal care products like perfumes, face creams, shampoos, soaps, lotions, jams, jellies, etc. Objective: This study aimed to synthesize short-chain fragrance esters using a whole-cell lipase catalyst from Aspergillus flavus (RBD-01). Method: The present study emphasizes the synthesis of artificial flavoring compounds by using a wholecell biocatalytic process, which can have wide significance. Herein, the preparation of ethyl alkanoates (ethyl propanoate to ethyl decanoate) was performed to investigate the flavors and fragrance excellence. The biomass from Aspergillus flavus (RBD-01) was used as a catalyst to facilitate the remarkable esterification activities towards the synthesis of important aroma esters with the help of a series of short-chain acids and alcohols. Result: The ethyl hexanoate (4) among all synthesized alkanoates was found to have a fruity fragrance with a good conversion rate. Further synthesized alkyl hexanoates (4A-4I) were found to have good fruity/pineapple/berry flavors and significant aroma quality. Conclusion: These results implied that whole-cell lipase of Aspergillus flavus (RBD-01) is a promising biocatalyst in the production of flavor aroma esters and can boost production in the food/cosmetic manufacturing industries.

Microbial cell factory for butyl butyrate production: Knowledges and perspectives.

Butyl butyrate is a short-chain fatty acid ester (C8) with a fruity aroma. It has broad prospects in the fields of foods, cosmetics and biofuels. At present, butyl butyrate is produced by chemical synthesis in the industry, but it is highly dependent on petroleum-based products. The growing concerns regarding the future scarcity of fossil fuels have been strongly promoted the transition from traditional fossil fuels and products to renewable bioenergy and biochemicals. Therefore, it is necessary to develop a green biochemical technology to replace traditional petroleum-based materials. In recent years, microorganisms such as Escherichia coli and Clostridium have been engineered to serve as cell factories for the sustainable one-pot production of short-chain fatty acid esters, including butyl butyrate. This opinion highlights the recent development in the use of lipases and alcohol acyltransferases (AATs) for butyl butyrate production in microbial fermentation, as well as future perspectives.

Formulation of Body Lotion with Sucrose Ester Emulsifier

Abstract Sucrose ester is synthesized from palm fatty acid methyl ester and sucrose using a base catalyst. Emulsifiers that replace palm oil with sucrose esters are biodegradable and potentially non-toxic to the skin. The efficiency of sucrose ester production was obtained by using water as a solvent for sucrose, with a mass ratio of 3:5 for water and sucrose. Dilution of sucrose with water reduces caramelization during reaction. Based on laboratory research, sucrose ester has good emulsion stability from sucrose myristate ester, sucrose palmitate ester, and sucrose laurate ester. The design used a random block design with three levels of variation in sucrose ester concentration, namely 2%, 6%, and 10%. Based on ANOVA, there is a very significant effect between variations in concentration on specific gravity, pH, viscosity and surface tension. Verification tests were carried out on consumer references in the form of organoleptic tests on 35 respondents. Then, microbial tests are carried out based on Indonesian National Standards, namely the maximum number of total plates (10−2 colonies), negative tests for fungi, Staphylococcus aureus, Pseudomonas aeruginosa, and Coliform (maximum 3). Determining the best combination uses the Composite Performance Index (CPI) and Analytical Hierarchy Process (AHP). Based on organoleptic tests, the best sample is 10% myristate. The analysis of organoleptic results is consistent with the analysis of laboratory results which states that the lotion sample made from 10% sucrose myristate ester is the best sample. The best lotion samples have good emulsion stability and are not contaminated by microbes.

Synthesis of microalgae-based methyl ester using calcium glyceroxide catalyst derived from duck eggshells and crude glycerol in the n-hexane co-solvent system

Abstract The synthesis of microalgae-based methyl ester has attracted the interest of researchers since microalgae have a high lipid content and can proliferate. Chlorella vulgaris, with its 63% lipid content on a dry basis, holds promise for methyl ester production. Heterogeneous catalysts, particularly calcium glyceroxide (Ca[O(OH)2C3H5]), play a crucial role in ester manufacturing due to their high catalytic activity. The synthesis of the calcium glyceroxide catalyst involves duck eggshells as a calcium source and crude glycerol. Optimal methyl ester production is achieved by employing n-hexane as a co-solvent for efficient microalgae oil dissolution. This research focuses on synthesizing and characterizing the calcium glyceroxide catalyst derived from duck eggshells and crude glycerol, emphasizing its application in manufacturing microalgae-based methyl esters with n-hexane as the co-solvent. Methyl ester synthesis variables include a 55°C reaction temperature, a 1.5% microalgae-derived catalyst, and a 9:1 methanol to microalgae ratio. FTIR functional group analysis identifies hydroxyl (O-H) groups from crude glycerol bound to calcium at 3345.71 cm−1, along with C-H group vibrations from crude glycerol bound to calcium at 2941.80 cm−1. SEM morphological analysis reveals aggregate formation on the calcium glyceroxide catalyst, indicating potential active sites. Utilizing the calcium glyceroxide catalyst for methyl ester synthesis yields a promising 62.42% yield. GC characterization demonstrates a methyl ester purity of 72.09%, with methyl palmitate as the predominant component at 30.927%. This study underscores the efficient use of the synthesized calcium glyceroxide catalyst for microalgae-based methyl ester production, showcasing its potential for sustainable biodiesel synthesis.

Analyte protectant approach to protect amide-based synthetic cannabinoids from degradation and esterification during GC–MS analysis

The forensic analysis of amide-based synthetic cannabinoids (SCs) in seized materials is routinely performed using gas chromatography-mass spectrometry (GC–MS); however, a major challenge associated with GC–MS is the thermolytic degradation of substances with sensitive functional groups. Herein, we report the comprehensive thermal degradation and ester transformation of amide-based SCs, such as AB-FUBINACA, AB-CHMINACA, and MAB-CHMINACA, during GC–MS analysis and their treatment with analyte protectants (APs). These SCs were found to undergo thermolytic degradation during GC–MS in the presence of non-alcohol solvents. Using methanol as an injection solvent resulted in the conversion of the amide group to an ester group, producing other SCs such as AMB-FUBINACA, MA-CHMINACA, and MDMB-CHMINACA. Degradant and ester product formation has been interpreted as the adsorption of target SCs on glass wool via hydrogen bonding interactions between the active silanol and amide groups of the SCs, followed by an addition and/or elimination process. The factors found to influence the thermal degradation and/or esterification of the amide functional group include residence time, activity of glass wool, and injection volume. This report presents the fragmentation patterns of all compounds that were produced by degradation and esterification. Using 0.5 % sorbitol (AP) in MeOH as an injection solvent resulted in complete protection and improvement of the chromatographic shape of the compounds. This method has been successfully confirmed in terms of sensitivity, linearity, accuracy, and precision for standard solutions and tablet extraction using 0.5 % sorbitol in MeOH. Using AP increased the sensitivity by ten times or more compared to the use of only MeOH. The limit of detection for all analytes was determined as 25 ng/mL, and the calibration curves were linear over the concentration range of 50–2000 ng/mL. The values of accuracy error were below 11 %, and precision was less than 13 %. The effects of phytochemicals of herbal products, tablet ingredients, and biological matrices on the degradation and/or esterification and APs performance have also been evaluated in this work.

Cyclometalated half‐sandwich iridium complexes: Synthesis, characterization, and catalytic activity in preparation of esters from halides by using formate as both CO source and coupling partner

A highly efficient carbonylation of aryl halides using half‐sandwich iridium catalysis was developed, providing a new avenue for synthesizing carboxylic ester derivatives and yielding consistently impressive results. These iridium complexes demonstrated remarkable catalytic performance in the coupling reaction using phenyl formate derivatives as the source of CO, phenol, and aryl halides as the starting material in the presence of air and possessed good air and moisture stability properties. Ester products with different substituents were synthesized at low reaction temperatures without the need for an inert atmosphere, leading to high yields. The broad substrate scope, impressive catalytic activity, and mild reaction conditions suggest promising industrial applications for this catalytic system. The desired metal complexes 1–4 have been well proven by attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR), nuclear magnetic resonance (NMR), and elemental analysis (EA). The molecular structure of the cyclometalated iridium complexes 2 and 3 was proven through X‐ray crystallography. Additionally, the possible mechanism of this Ir‐catalyzed process is further supported by the density functional theory (DFT) study.