Transesterification Of Esters Research Articles

Visible Light-Promoted Oxidative Cross-Coupling of Alcohols to Esters

Ester is one of the most significant functional groups in organic chemistry and is enclosed in several valued molecules. Usually, esters are prepared through the acid-catalyzed esterification reaction of carboxylic acids with alcohols, transesterification of esters with alcohols, or via activation of carboxylic acids followed by the addition of alcohols. However, these procedures typically imply the excess use of reactants and harsh reaction conditions. Visible light-mediated photoreactions have been disclosed to display a safe, sustainable, and accessible alternative to traditional methods, and to lead new reactivity modes in organic procedures. In this context, we propose a transition metal-based and organic-based photocatalyst-free synthesis of esters from alcohols induced by visible light. The methodology can be carried out using sunlight or artificial visible light as a solar simulator or a blue LED source.

Room-temperature self-healable and recyclable polythiourethane film with excellent mechanical properties based on double dynamic covalent bonds

Currently, it remains a challenge to find an appropriate dynamic interaction to prepare elastomers which perfectly match the general properties of the target material with self-healing and recyclability properties. Herein, a room-temperature self-healable polythiourethane with excellent mechanical properties and recyclability has been development. Based on the boronic ester transesterification and thiourethane exchange macrophase separation, polythiourethane can achieve complete self-healing at room temperature after 36 h in the absence of external stimuli. More importantly, PTU-B7 has a good tensile strength of 9.58 MPa, a toughness of 35.8 MJ/m3 as well as a fracture strain of up to 735 %. At a relatively low temperature (60 °C), small pieces can be hot pressed for a short time to form a homogeneous block for reprocessability. The ability to self-repair under mild conditions while still having good mechanical strength makes the material a promising application and provides new ideas for the study of self-healing polymers.

Self-healing and robust polymer-based protective interlayer containing boronic esters for stabilizing lithium metal anode

Lithium (Li) metal batteries have attracted wide research interests due to the ultrahigh theoretical capacity of Li anode. However, lithium metal anodes suffer from the inhomogeneous Li deposition, resulting in capacity fade and unacceptable safety hazards. More importantly, the huge volume change of the mechanically fragile solid electrolyte interphase (SEI) further induces the dendrite growth during repeated Li plating. Therefore, it is critical to protect Li metal anodes and inhibit the growth of Li dendrites for stabilizing the Li plating process. Herein, we fabricated a novel polymer-based protective interlayer (LBP) with a stable cross-linked network containing abundant boron moieties via the thiol-ene click reaction. The polymer-based protective interlayer obtains self-healing properties through the boronic ester transesterification and enhances the safety of lithium batteries. Besides, the dense layer with a cross-linked network effectively retards the air corrosion when the Li metal was exposed to the air environment. Furthermore, the vacant p orbital in the boron atoms of boronic ester can trap anions of Li salt and regulate a homogeneous Li deposition, enhancing the interface stability of Li metal. Consequently, the Li|Li symmetric cell with LBP protective interlayer shows stable stripping/plating voltage over 3500 h at 1.0 mA cm−2. The LBP-Li|LFP cell maintains a high capacity of 142.2 mAh/g after 300 cycles, demonstrating the cell with LBP-Li exhibits excellent cycling stability. The design of this advanced protective interlayer with multiple capabilities is potential to shed a light for high-performance lithium metal batteries.

Fluorescent and Catalytic Properties of a 2D Lamellar Zn Metal-Organic Framework with sql Network Structure.

A two-dimensional (2D) lamellar Zn metal-organic framework (Zn-MOF, 1) with a fluorescent 1,6-di(pyridin-3-yl)pyrene (3-DPPy) and 1,4-benzenedicarboxylate (BDC2-) bridging linkers was prepared and structurally characterized. The chemical formula of 1 is [Zn(μ-3-DPPy)(μ-BDC)]n. The mononuclear Zn(II) ion, acting as a node, is tetrahedrally coordinated with two 3-DPPy and two BDC linkers. The coordination environment of Zn(II) is a distorted tetrahedral geometry. The Zn-MOF is the sql network structure based on topology analysis. The undulated 2D sheets of 1 tightly pack together to form a lamellar structure. The pyrene moieties are parallelly oriented to each other. The Zn-MOF is not porous, possibly because the mononuclear Zn(II) node did not form cluster-based secondary building units due to the less symmetric 3-DPPy. The steady-state fluorescence measurements indicate that the fluorescence signal of the 1 is slightly blue-shifted compared to the free 3-DPPy in the solid state. The excimer emission band at 463 nm for crystalline 3-DPPy is shifted to 447 nm for 1. The value of 447 nm is also a blue-shift value compared to nonsubstituted pyrene crystals (470 nm). Despite its nonporosity, the surface Lewis acidic sites of 1 could catalyze the transesterification of esters. Surface defect sites are responsible for this catalytic activity.

Two-Stage Conversion of Used Cooking Oil to Biodiesel Using Ion Exchange Resins as Catalysts

This study focuses on the development of a novel two-stage (esterification–transesterification) synthesis of biodiesel from used cooking oil (UCO) using ion exchange resins as catalysts. Esterification of the UCO has been conducted using various types of ion exchange resin catalysts. Purolite D5081, a hyper cross-linked resin, showed the best catalytic performance among all the catalysts investigated, with 92% of free fatty acid (FFA) conversion. The transesterification of pre-treated used cooking oil (P-UCO) was carried out sequentially using several acidic and basic ion exchange resin catalysts. In the screening process, the Diaion PA306s catalyst showed the best catalytic performance and was selected for the optimisation study. A triglyceride conversion of ca. 75% was recorded at the optimum reaction conditions (9% (w/w) catalyst loading, 328 K reaction temperature, 18:1 methanol to P-UCO feed mole ratio, and 350 rpm stirring speed). Furthermore, the reusability study of the Diaion PA306s catalyst gave a similar triglyceride conversion after a couple of cycles without losing its catalytic activity. A dry purification technique was found to give the lowest percentage of glycerides and glycerine content and, therefore, was chosen as the best biodiesel purification route.

Statistical optimization of ultrasound‐assisted biodiesel production from Moringa oleifera oil – waste cooking oil mixture using modified conch shell catalyst

AbstractBiodiesel is a potential alternative fuel that offers several environmental benefits and can be used in conventional engines. However, high feedstock cost poses a challenge for its commercial viability. This study focuses on producing biodiesel using waste cooking oil (WCO) and Moringa oleifera oil (MOO) as feedstock, with a specific emphasis on the use of modified conch shell as solid catalyst under ultrasonic conditions. Different mixtures of WCO and MOO were evaluated for their suitability in a two‐stage esterification transesterification process, and the acid value of the WCO‐MOO blend was reduced through an ultrasound‐assisted esterification process. Additionally, a calcium oxide‐based catalyst was developed from conch shells (CS) through calcination for 3 h at 900°C and further modified using water and methanol. The characterization studies confirm the successful development and modification of the CS catalyst and also demonstrates excellent catalytic activity. The ultrasound assisted transesterification process parameters were optimized using response surface methodology (RSM) based Box–Behnken design (BBD). By employing a catalyst loading of 5.8 wt%, methanol to esterified oil volumetric ratio of 0.37:1, and an ultrasonication time of 57 min, a maximum predicted methyl ester conversion of 94.7% was achieved. Therefore, this work provides valuable insights into the use of modified conch shell catalyst for biodiesel production from WCO and MOO mixtures thereby contributing to the advancement of cost‐effective and environmentally friendly biodiesel production methods.

Biodiesel production from rice bran oil fatty acid distillate via supercritical hydrolysis–esterification–transesterification in a microreactor

Rice bran oil fatty acid distillate (RBOFAD), a by-product from rice bran oil production, was used as feedstock for the production of biodiesel. The hydrolysis–esterification–transesterification of RBOFAD with ethanol was performed in a microreactor under supercritical conditions. The biodiesel product in the form of fatty acid ethyl ester (FAEE) was obtained. The operating conditions, including the sulfuric acid content (0.2–0.6%), water content (0–7.5%), ethanol-to-oil molar ratio (5:1–16:1), and reaction temperature (260–320 °C), were optimized. The water content could affect the reaction system via both hydrolysis of triglycerides and reverse esterification of fatty acids. Biodiesel with the FAEE content of 93% was obtained at the optimal conditions (sulfuric acid content of 0.4%, water content of 2.5%, ethanol-to-oil molar ratio of 7:1, residence time of 19 min, and reaction temperature of 280 °C). The properties of the biodiesel, including density, viscosity, acidity, oxidation stability, freezing point, and pour point, were compared with standards. The properties such as viscosity, acid value, heating value, and oxidation stability were suitable as biodiesel according to EN14213, except for the contents of ester, monoglyceride, and diglyceride.

Boronic Ester Transesterification Accelerates Ion Conduction for Comb-like Solid Polymer Electrolytes

Polyether is a kind of ideal polymer matrix for solid polymer electrolytes (SPEs), but its inherent drawbacks (such as the semi-crystalline nature and strong complexation of lithium ions) still hinder their commercial application. The construction of comb-like SPEs effectively increases their functionalities and improves the comprehensive performance. Herein, we apply a dynamic boronic ester exchange strategy to simultaneously enhance the lithium-ion conduction and self-healing ability of the SPEs, thus effectively solving the current problems of polyether. The copolymer (GPA) containing side chains with poly(ethylene glycol) (PEG) and diol groups was obtained through reversible addition–fragmentation chain-transfer (RAFT) polymerization and hydrolysis, and PBA-M2070 containing the boronic acid group and flexible polyether segments was obtained via Schiff base reaction. Boronic ester bonds were formed by dehydration of the diol groups of GPA and the boronic acid groups of PBA-M2070. Dynamic exchange of the boronic ester bonds at the branched sites enhanced the side-chain motion, thus increasing the self-healing ability and electrochemical performance of the SPEs, as well as the cycling stability of assembled batteries. Benefiting from the dynamic boronic ester exchange and enhanced side-chain mobility, the SPEs exhibited self-healing within 10 min and an ionic conductivity of 1.58 × 10–5 S cm–1 at 30 °C. The assembled lithium metal batteries (LMBs) were operated stably at 0.5C for 300 cycles. The dynamic boronic ester exchange strategy used to enhance the LMBs properties provides new insight into the design of comb-like polymer electrolytes.

Self‐Healing and Recyclable Polymer Electrolyte Enabled with Boronic Ester Transesterification for Stabilizing Ion Deposition

AbstractDamage to solid polymer electrolytes can lead to mechanical degradation, short circuits, or functional failures. Therefore, introducing a self‐healing function to solid polymer electrolytes is an ideal strategy to improve the safety and reliability of electrolyte systems. Herein, dynamic boronic ester‐based self‐healing polymer electrolytes (DB‐SHPEs) with excellent mechanical properties and interfacial stability are developed via a thermally initiated ring‐opening reaction between thiol and epoxy groups. The DB‐SHPEs containing boronic ester bonds can not only alter the topologies via boronic ester transesterification and exhibit good self‐healing capability but also enable homogeneous deposition of Li ions on the Li metal through the Lewis acid–base interactions between boron atoms and salt anions. Furthermore, the boronic ester bonds can endow the DB‐SHPE with reprocessability and recyclability taking advantage of associative transesterification reaction. More significantly, the Li/DB‐SHPE/Li symmetric cells exhibit a stable voltage plateau after cycling for 1200 h and the LiFePO4/DB‐SHPE/Li batteries present excellent cycling performance, suggesting that high‐performance self‐healing polymer electrolytes with multiple functions are promising materials for the next‐generation lithium metal batteries.

Experimental and theoretical feasibility study of methanol application for Echium oil-based biodiesel production

In this study, the effect of ultrasound waves on biodiesel production from methanol and Echium oil is evaluated experimentally under different operating conditions. A two-step esterification–transesterification process was applied to improve the biodiesel quality, and, in order to optimize the reaction conditions, the effect of variables such as methanol to oil molar ratio, KOH catalyst concentration and temperature were experimentally investigated. The results showed that the optimum biodiesel yield (97.2%) could be obtained at a catalyst concentration of 1.875% w.t, feed molar ratio equal to 9.65, and at 50 °C of operating temperature. The acid value, saponification numbers, iodine value, density, kinematic viscosity, fire point, cloud point and flash point were measured and compared with ASTM D6751 and EN 14214 standards. The results of the analysis showed that the produced biodiesel is a good alternative to fossil fuels. The results demonstrate that methanol and Echium Oil can be used as a proper feedstock for biofuel production. Furthermore, the kinetic study of transesterification is carried out for Echium oil production and the reaction rate constant and activation energy were determined. Finally, the sizing calculations and cost estimation of the Echium oil-based biodiesel production were investigated.

Kinetic study of ethyl ester transesterification using a hybrid silica catalyst

Kinetic study of ethyl ester transesterification using a hybrid silica catalyst

Pongamia pinnata biodiesel production using cobalt doped ZnO nanoparticles—An analytical study

AbstractKaranja is second most popular non‐edible oil, in Indian sub‐continent, for Biodiesel production; with current plantation, almost 55,000 ton/year of oil can be extracted. Also, studies in past two decades have elucidated that use of heterogeneous solid catalyst has been commercially most viable, economical, produces almost pure biodiesel, easy to use, recycle and environment friendly. In this paper, we have used cobalt doped zinc oxide (CZO) nanoparticles for dual step esterification—transesterification processes, which has not been studied for Karanja oil, additionally, the detailed analytical study such as X‐ray diffraction, field emission scanning electron microscope, Brunauer–Emmett–Teller and energy‐dispersive analysis of X‐rays on catalyst unavailable in literature, has also been incorporated here. The CZO particles are synthesized using co‐precipitation method and yields particles of size ~75 nm, the reusability of catalyst is also included. The optimum process parameters where experimentally determined and compositional analysis of oil and biodiesel is done using Fourier transformed infrared. The economic and technical aspects of CZO synthesis, the benefits of easy separation of glycerol and reduced impurities in final product, make this process commercially more suitable for Karanja oil biodiesel synthesis, and study will promote use of CZO nanoparticles for other oil biodiesel production too. Result shows that under optimized condition of transesterification, 1:25 M ratio of oil:methanol, 0.3 wt% catalytic concentration, 70°C reaction temperature, 180 min time of reaction and 500 rpm of stirring speed fatty acid methyl ester (biodiesel) conversion was 98.5 ± 0.5%.

A Strong and Rigid Coordination Adaptable Network that Can Be Reprocessed and Recycled at Mild Conditions

A Strong and Rigid Coordination Adaptable Network that Can Be Reprocessed and Recycled at Mild Conditions

Two-Stage Biodiesel Synthesis from Used Cooking Oil with a High Acid Value via an Ultrasound-Assisted Method

In this study, ultrasound was used to accelerate two-stage (esterification–transesterification) catalytic synthesis of biodiesel from used cooking oil, which originally had a high acid value (4.35 mg KOH/g). In the first stage, acid-catalyzed esterification reaction conditions were developed with a 9:1 methanol/oil molar ratio, sulfuric acid dosage at 2 wt %, and a reaction temperature of 60 °C. Under ultrasound irradiation for 40 min, the acid value was effectively decreased from 4.35 to 1.67 mg KOH/g, which was decreased to a sufficient level (<2 mg KOH/g) to avoid the saponification problem for the subsequent transesterification reaction. In the following stage, base-catalyzed transesterification reactions were carried out with a 12:1 methanol/oil molar ratio, a sodium hydroxide dosage of 1 wt %, and a reaction temperature of 65 °C. Under ultrasound-assisted transesterification for 40 min, the conversion rate of biodiesel reached 97.05%, which met the requirement of EN 14214 standard, i.e., 96.5% minimum. In order to evaluate and explore the improvement of the ultrasound-assisted two-stage (esterification–transesterification) process in shortening the reaction time, additional two-stage biodiesel synthesis experiments using the traditional mechanical stirring method under the optimal conditions were further carried out in this study. It was found that, under the same optimal conditions, using the ultrasound-assisted two-stage process, the total reaction time was significantly reduced to only 80 min, which was much shorter than the total time required by the conventional method of 140 min. It is worth noting that compared with the traditional method without ultrasound, the intensification of the ultrasound-assisted two-stage process significantly shortened the total time from 140 min to 80 min, which is a reduction of 42.9%. It was concluded that the ultrasound-assisted two-stage (esterification–transesterification) catalytic process is an effective and time-saving method for synthesizing biodiesel from used cooking oil with a high acid value.

ANALYSIS OF POLYESTERS STRUCTURE BASED ON MALIC ACID AND ITS ESTER

Four polyesters based on malic acid and its dibutyl ester were obtained. Ethylene glycol and 1,4-butanediol were used as comonomers. The reaction of polycondensation was carried out without a catalyst, and the transesterification of glycol esters was carried out in the presence of tetrobutoxytitanium in an amount of 1wt%. The malic acid during polycondensation we melted and dissolved in glycols at a temperature of 100 °C to prevent the reaction of intramolecular dehydration. The reactions were carried out for 3 hours with stirring and gradual heating of the reaction mass. The processes were carried out in a flow of nitrogen to remove the formed low-molecular products. These products were condensed and analyzed by gas-liquid chromatography. The control of the polycondensation reaction was carried out by the molecular weight determined by the viscometric method. The structure of the obtained polyesters was determined using IR and (1H, 13C) NMR spectroscopy. The obtained polymer samples represent a resinous mass from light yellow to light brown with average molecular weights from 2000 to 4000 g/mol. Analysis of IR spectra showed that in the samples obtained by ester transesterification, the intensity of the hydroxyl group band is more than that of acid and diol based polymers. This difference can be explained by the presence of polymer chain branches obtained as result of the reaction of self-condensation. Analysis of (1H, 13C) NMR spectra confirms that in the process of polycondensation of malic acid with diols, a side reaction of self-condensation of the acid occurs with the formation of branched polymer units. In the case of the use of an ester as a monomer, polyester of a linear structure is obtained. In all obtained samples of polyesters, the presence of unsaturated bonds in the structure was also observed. This confirms that a side reaction of internal malic acid dehydration took place under the synthesis conditions. To reduce the unsaturation of polyesters, the polycondensation process must be carried out at a lower temperature.

Simultaneous Formation of a Fully Organic Triply Dynamic Combinatorial Library.

Here we report the simultaneous formation of doubly and triply dynamic libraries as a result of exchange reactions between functionalized organic building blocks. A combination of three different reversible covalent linkages involving a boronate ester transesterification along with an imine and disulfide exchange was employed to generate a new type of fully organic triply dynamic molecular assembly.

Biodiesel production from milk thistle seed oil as nonedible oil by cosolvent esterification–transesterification process

AbstractThe crude oil extracted from milk thistle seeds was employed as a precursor for creating biodiesel (BD) via the cosolvent esterification–transesterification process. The high acid value of the extracted oil (11.90 mg KOH/g) encouraged its pre‐esterification in the occurrence of hexane as a cosolvent. The cosolvent esterification of oil diminished its acidity index to below 2.0 mg KOH/g using 1.5:1 hexane:methanol volume ratio, 50°C, 60‐min reaction time, 6:1 methanol:oil molar ratio, and 0.75 wt.% HCl. Alcoholysis reaction of the esterified oil with methanol and a blend of methanol:ethanol to synthesize, respectively, methylic BD and methylic/ethylic BD was accomplished in the presence of hexane as a cosolvent as well. Under the ideal reaction conditions, methylic BD yield and methylic/ethylic BD yield were 96.23% and 95.63%, respectively. The Fourier‐transform infrared (FTIR) and 1H nuclear magnetic resonance (NMR) spectra affirmed the lipid transformation from milk thistle seeds into BD. The attained samples of BD exhibited properties conforming to those specified by ASTM D6751. Also, the cosolvent methanolysis kinetic obeyed the pseudo‐first‐order with 35.94 KJ/mol activation energy and 6.32‐s frequency factor.

Investigating the Effects of Ultrasonic Frequency and Membrane Technology on Biodiesel Production from Chicken Waste

In this study, the experiments were carried out under different operating conditions to evaluate the effect of ultrasound waves on biodiesel production from chicken feet oil. A two-step esterification–transesterification mechanism was employed to improve the biodiesel quality. The continuous (methanol-to-oil molar ratio and KOH catalyst amount) and discrete (frequencies, 25 and 45 kHz) variables were investigated using the experimental design method. The five-level three-factor response surface method (RSM) was assisted to optimize the biodiesel synthesis variables. Applying RSM based on the central composite design (CCD), a polynomial equation was fitted to the experimental data with the aid of Design-Expert software. The model accuracy was checked by analysis of variance (ANOVA). The results showed the highest yield of 89.74% could be achieved by using an M/O molar ratio of 12, a KOH concentration of 1 wt%, and an ultrasound frequency of 45 kHz. Finally, a mathematical model of biodiesel production in a membrane system was developed. The reaction rate constant was calculated as a function of ultrasonic frequency. Compared with the conventional method, the membrane system has significantly improved chicken feet biodiesel production’s reaction rate. The membrane is more effective at higher frequencies than at lower ones.

Effect of Temperature and Concentration of Zeolite Catalysts from Geothermal Solid Waste in Biodiesel Production from Used Cooking Oil by Esterification–Transesterification Process

The production of biodiesel using zeolite catalysts from geothermal solid waste has been studied. This study aims to make zeolite catalysts as catalysts in biodiesel production, assessing the effect of catalyst concentration, and temperature in the esterification–transesterification process on the biodiesel yield produced. The results showed that the synthesized zeolite catalyst was an analcime zeolite catalyst (Al1.9Na1.86O12Si4). The biodiesel yield of 98.299% with 100% fatty acid alkyl ester (FAAE) content was achieved at a catalyst concentration of 5%wt and a reaction temperature of 300 °C for one-hour reaction time. The yield of biodiesel decreased with repeated catalysts, which experienced morphological changes before and after three usage times. Consequently, in this case, the catalyst cannot be regenerated.

Biodiesel Waste Cooking Oil is Environmentally Friendly Alternative Fuels and More Feasible than Fossil Fuels

The use of diesel engines is increasing at the moment, the other hand, supplies of petroleum base diesel oil in the market decreasing. Therefore we need alternative fuels to use as supplement fuel for diesel engines. Biodiesel processing can be done with the process of esterification and transesterification. Biodiesel is processed from used cooking oil can be done only by the transesterification process. Ester transesterification is the process of converting into esters in another form by reacting carboxylic esters and alcohols with an alkaline catalyst (NaOH), in processing biodiesel transesterification process is the process of converting triglycerides of cooking oil into methyl or ethyl ester as biodiesel. According to various studies, biodiesel derived from waste cooking oil proved to be more environmentally friendly fuels than the results are known and used today. Nitrogen Monoxide emission levels (NOx) in the biodiesel from used cooking oil to produce emissions 12% lower than emissions produced by diesel oil. Another advantage, the exhaust emissions of the unburned form of carbohydrates produced biodiesel used cooking oil turned out to be 25% lower than on diesel oil. The diesel engine durability test, performance analysis, analysis of the degree of damage is indicated by the metal content in lubricants, and test the properties of each lubricating it can be some conclusions as follows.