Direct Esterification Research Articles

Crystal Facet Structure Dependence and Promising Pd-Based Catalytic Materials for Resistance toward Deactivation and Catalytic Performance in Direct Oxidative Esterification.

Designing an effective Pd-based catalytic material with higher stability and catalytic performance for direct oxidative esterification is a great challenge. In this work, a systematic study on the activation mechanism of H2O on the different crystal facets of monometallic Pd, bimetallic Pd-Pb(Bi), and trimetallic Pd-Pb-Bi catalysts was first performed, which showed that the (111) crystal facet of Pd-Pb-Bi had stronger stability of resistance toward deactivation induced by H2O. Further, a detailed direct oxidative esterification mechanism on the screened crystal facet was investigated, where Pd-Pb-Bi catalytic materials showed higher stability and intrinsic catalytic performance for direct oxidation esterification, which was attributed to a dimer Pd-active unit and the synergistic effect of Pb and Bi compared to that of Pd-Pb(Bi) and Pd and also applied to other aldehydes with electron-donating groups producing corresponding esters. Meanwhile, the essential relationship between structures of Pd-based catalytic materials and catalytic performance for direct oxidation esterification was obtained. This work opens up a new simultaneous path for improving the stability of resistance toward deactivation and catalytic performance for direct oxidative esterification of Pd-based catalytic materials, which can be realized by regulating the surface-active unit with dimer Pd adsorbed more O-preadsorbed using Pb and Bi promoters.

Solvent-free direct esterification of acrylic acid with 2-ethylhexyl alcohol using simple Zn(II) catalysts

Direct esterification of acrylic acid with 2-ethylhexyl alcohol was investigated using low toxic and cheap Zn(II) salts as catalysts. An initial screening using Zn(ClO4)2, ZnCl2, Zn(OAc)2 and ZnO disclosed that the most effective was the perchlorate, which was used for the subsequent refining of the study. In optimized conditions (0.5 % mol of polymerization inhibitor, 0.1 % mol of catalyst, 170 °C, 4 h) the product was obtained in 99 % yield. A kinetic model was proposed to quantify the contribution of each chemical reaction of the network, allowing a quantitative comparison of the effect of the inhibitors on the acrylic acid esterification side-reactions.

Enantioselective Flow Synthesis of Rolipram Enabled by a Telescoped Asymmetric Conjugate Addition-Oxidative Aldehyde Esterification Sequence Using in Situ-Generated Persulfuric Acid as Oxidant.

A novel approach is reported for the enantioselective flow synthesis of rolipram comprising a telescoped asymmetric conjugate addition–oxidative aldehyde esterification sequence followed by trichlorosilane-mediated nitro group reduction and concomitant lactamization. The telescoped process takes advantage of a polystyrene-supported chiral organocatalyst along with in situ-generated persulfuric acid as a robust and scalable oxidant for direct aldehyde esterification. This approach demonstrates significantly improved productivity compared with earlier methodologies while ensuring environmentally benign metal-free conditions.

Esterification of 1-hexene and acetic acid catalyzed by a modified resin with a Lewis acid

1-Methylpentyl acetate was synthesized by direct esterification between 1-hexene and acetic acid using modified resin catalysts, and Zn0.8/A15 showed excellent catalytic activity.

One-pot synthesis of 2-bromopropionyl esterified cellulose nanofibrils as hydrophobic coating and film.

Hydrophobic 2-bromopropionyl esterified cellulose nanofibrils (Br-CNFs) have been facilely produced via one-pot esterification of cellulose with 2-bromopropionyl bromide (BPB) then in situ disintegrated by ultrasonication in the same reaction media. Br-CNFs optimally produced by this robust esterification-ultrasonication approach, i.e., 5 : 1 BPB to anhydroglucose (AGU) molar ratio, 23 °C, 6 h and ultrasonication (50% amplitude, 30 min), were 4.6 nm thick, 29.3 nm wide, and 1 μm long in 71% yield and 48% crystallinity. Successful 2-bromopropionyl esterification of cellulose was confirmed by FTIR and 1H NMR. The degree of substitution (DS) of surface hydroxyl to 2-bromopropanoate was determined to be between 0.53 (DSs) based on XRD and Br-CNF dimensions and 0.56 (DSNMR) from solution-state 1H NMR. Br-CNF dispersions in DMF exhibited Newtonian behaviors at concentrations below and shear thinning behaviors above 0.5%, enabling homogeneous deposition at dilute concentrations up to 0.01% into a few nm ultra-thin layers as well as blade coating of gel into ca. 100 μm thick film, all similarly hydrophobic with surface water contact angles (WCAs) in the range of 70–75°. The ultra-high modulus and strength film from gel coating further showed the potential for dual high-strength and hydrophobic applications of Br-CNFs.

Strategies for the direct oxidative esterification of thiols with alcohols.

This review paper provides an overview of the main strategies for the oxidative esterification of thiols with alcohols. The review is divided into two major parts according to final products. The first includes the methods for the synthesis of sulfinic esters, while the second contains the procedures for the fabrication of sulfonic ester derivatives.

Enhancing the activity of Pd/Zn–Al–O catalysts for esterification of CO to dimethyl oxalate via increasing oxygen defects by tuning the Zn/Al ratio

The enhancement of oxygen defects in the spinel support is the essential reason for the improvement of catalytic activity, which reveals the support effect of catalyst for CO direct esterification to dimethyl oxalate.

Gas chromatography method to quantify α-monobenzoate glycerol in methanolic solutions using methyl benzoate as internal standard and a Rxi-1ms column

The 2,3-dihydroxypropyl benzoate, also known as α-monobenzoate glycerol (α-MBG), is an important building block used in the organic chemistry industry and its synthesis can be performed by the direct esterification of glycerol and benzoic acid. On the other hand, gas chromatography is a powerful laboratory tool applied for the quantification of known and unknown molar concentrations of chemical compounds. Under those conditions, I developed a method and a calibration curve for the analysis of unknown concentrations of α-MBG in methanolic solutions using a gas chromatograph equipped with a Rxi-1ms column and methyl benzoate (MBe) as an internal standard. Thus, by a suitable chromatograph setup, such as injector temperature and column oven temperature program, it was achieved a good resolution of the chromatographic peaks of each individual compound (MBe and α-MBG). Additionally, it was possible to generate an appropriated calibration curve with a corresponding equation for the calculation of unknow molar concentrations of α-monobenzoate glycerol in methanolic solutions. The highlights of the method described are:•There were no derivatization steps in this method, only dilution of the α-monobenzoate glycerol in methanol.•The calibration curve was made using only four calibration mixtures.•This method also promotes the appropriate separation of glycerol, benzoic acid, and methyl benzoate, which can be useful for the analysis of the progress of an esterification reaction of glycerol and benzoic acid for the synthesis of α-MBG.

Vatrootporni kompoziti na bazi akril-funkcionalizovanog lignina i poliesterske smole dobijene od otpadnog poli(etilen tereftalata)

This paper investigates the using potential of acryl-functionalized kraft lignin (AKL) in reducing the flammability of polymer composites based on recycled unsaturated polyester resins (UPR). Acryl functionalization of kraft lignin was performed by direct esterification of free polyphenolic groups with acryloyl chloride, after what, the AKL was blended in UPR resin synthesized from the polyols obtained by catalytic depolymerization of waste poly(ethylene terephthalate). The AKL was homogenized in UPR resin in different weight ratios: 2.5, 5.0, 7.5, and 12.5 wt.%. Structural and dynamic-mechanical characteristics of acryl-functionalized kraft lignin and composites were determined using FTIR spectroscopy, dynamicmechanical analysis (DMA), and tensile tests. The influence of functionalization and mass fraction of AKL on tensile and thermal properties of UPR resin was studied. The thermal properties of the composite were tested according to the standard UL-94 method, based on which the highest category of heat-resistant materials is a composite with 12.5 wt.% acylfunctionalized lignin.

Ester crosslinking on cellulose with pyromellitic acid for anti-wrinkle finishing

Aromatic carboxylic acids were investigated for anti-wrinkle finishing on cotton fabrics as it caused less damage to fibers. However, its application was limited to its poor water solubility. In this study, pyromellitic acid (PMA) was applied for anti-wrinkle finishing on fabric in 30%(w/w) ethanol solution instead of water. The optimum process parameters, such as concentration, bath pH, catalyst dosage, curing condition, were analyzed by orthogonal test for crosslinking cellulose. The surface morphology changes of treated fibers were recorded by scanning electron microscope (SEM). The possible reactive mechanism between PMA and cellulose was discussed by means of Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyses (TGA), in-situ temperature-dependent Fourier transform infrared spectroscopy (FTIR). The results demonstrated that the optimized process for PMA crosslinking cellulose was PMA 0.3 mol/L, bath pH 1.5, sodium hypophosphite (SHP, NaH2PO2) 0.10 mol/L, baking condition 180 °C*1.5 min. The bath pH and curing temperature were the primary factors for fabric wrinkle resistance and strength lose, respectively. After repeated laundering, the strength loss of treated samples with PMA was obviously lower than that of aliphatic carboxylic acid and dimethylol dihydroxy ethylene urea (DMDHEU, 2 D resin). Meanwhile, PMA had less effect on fiber surface morphology and the fiber strength lose was mainly from the damage accumulation of macromolecular chains in fibers. The SHP catalytic action in PMA was much lower than that in aliphatic carboxylic acids for esterification. Moreover, the ortho carboxylic groups on PMA not only esterified with cellulose directly, but also dehydrated into anhydride and further reacted with cellulose. The crosslinking between PMA and cellulose was mainly by direct esterification rather than indirect esterification by anhydride intermediate. The results provided new insights for the application of insoluble crosslinker on cellulose.

Design and control of novel reaction–separation–recycle processes for the production of 4-hydroxybutyl acrylate

Two chemistry routes are known for 4-hydroxybutyl acrylate production: the direct esterification of acrylic acid with 1,4-butanediol, and the transesterification of methyl acrylate with 1,4-butanediol. However, very scarce information in the literature is available about industrial production, or design and operation of production processes. In this study, we propose three novel reaction–separation–recycle processes for 4-hydroxybutyl acrylate production by direct esterification based on solid catalyst. Use of solid catalysts may avoid well-known issues of the liquid catalysts like recovery and re-use of the catalyst, difficult product recovery, and corrosion. Due to the nature of the chemical system and reactions conditions, the chemistry is not 100% selective towards the acrylate, important amounts of diacrylate by-product being formed. All processes use fixed-bed tubular reactors to perform the reactions and distillation-based equipment to achieve the required separations. While all processes have a similar separation sequence, each has its key particularities: the RSR-A process accepts the loss of reactants due to formation and elimination from the process of the diacrylate, RSR-B converts the diacrylate into its reactants in the esterification reactor, while RSR-C converts the diacrylate in a dedicated hydrolysis reactor. A key element in the separation sequence is the use of pressure-swing distillation to make the difficult split of the alcohol/acrylate/diacrylate ternary mixture. All processes are capital and energy intensive. The economic analysis shows that the RSR-A process has the most favorable economics: a total annualized cost of 2 million $/y and a specific annualized cost of 100 $/t of product. A control structure for the RSR-C process is presented, the dynamic simulations showing its efficiency in rejecting various disturbances.

Convenient Synthesis of Benziodazolone: New Reagents for Direct Esterification of Alcohols and Amidation of Amines.

Hypervalent iodine heterocycles represent one of the important classes of hypervalent iodine reagents with many applications in organic synthesis. This paper reports a simple and convenient synthesis of benziodazolones by the reaction of readily available iodobenzamides with m-chloroperoxybenzoic acid in acetonitrile at room temperature. The structure of one of these new iodine heterocycles was confirmed by X-ray analysis. In combination with PPh3 and pyridine, these benziodazolones can smoothly react with alcohols or amines to produce the corresponding esters or amides of 3-chlorobenzoic acid, respectively. It was found that the novel benziodazolone reagent reacts more efficiently than the analogous benziodoxolone reagent in this esterification.

The synthesis of functionalized graphene oxide by polyester dendrimer as a pH-sensitive nanocarrier for targeted delivery of venlafaxine hydrochloride: Central composite design optimization

In this study, a new type of polyester dendrimer was synthesized through direct esterification reaction between phloroglucinol (PG) and terephthalic acid (TPA) in the presence of a catalyst. Graphene oxide (GO) functionalized with polyester dendrimer, decorated with 3,4-dihydroxybenzoic acid (DHB), was used to sustain delivery of venlafaxine hydrochloride (VH) as an antidepressant drug. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET), and thermogravimetric analysis (TGA) confirmed the attachment of polyester dendrimer onto the GO. Different variables, including pH, contact time, and temperature were optimized to evaluate the adsorption of VH on the PAH-GO/PGTPA/DHB Dendr using a central composite design (CCD). The highest adsorption percentage was obtained at pH of 7, contact time of 20 min, and temperature of 30 °C. The sorption mechanism was determined via the Langmuir isotherm model (R2 = 0.9965), representing the monolayer adsorption with the adsorption capacity of 19.72 mg g−1. PAH-GO/PGTPA/DHB Dendr displayed a fast sorption rate, and the pseudo-second-order kinetic model confirmed the best correlation between experimental data with R2 = 0.9995. The release of the VH from nanocarrier in simulated intestinal fluid (SIF) and in simulated gastric fluid (SGF) was studied. The release mechanism was considered by applying various mathematical models to the in vitro release curves. Nearly 40% and 99% of VH were released in SIF (pH = 7.4) and SGF (pH = 1.2) at 6 h, respectively. The cytotoxicity of PAH-GO/PGTPA/DHB Dendr was investigated via 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and apoptosis methods using PC-12 cell lines.

Controlled Metal-Support Interactions in Au/CeO2-Mg(OH)2 Catalysts Activating the Direct Oxidative Esterification of Methacrolein with Methanol to Methyl Methacrylate.

The strong metal–support interaction (SMSI) between the three components in Au/CeO2–Mg(OH)2 can be controlled by the relative composition of CeO2 and Mg(OH)2 and by the calcination temperature for the direct oxidative esterification of methacrolein (MACR) with methanol to methyl methacrylate (MMA). The composition ratio of CeO2 and Mg(OH)2 in the catalyst affects the catalytic performance dramatically. An Au/CeO2 catalyst without Mg(OH)2 esterified MACR to a hemiacetal species without MMA production, which confirmed that Mg(OH)2 is a prerequisite for successful oxidative esterification. When Au/Mg(OH)2 was used without CeO2, the direct oxidative esterification of MACR was successful and produced MMA, the desired product. However, the MMA selectivity was much lower (72.5%) than that with Au/CeO2–Mg(OH)2 catalysts, which have an MMA selectivity of 93.9–99.8%, depending on the relative composition of CeO2 and Mg(OH)2. In addition, depending on the calcination temperature, the crystallinity of the CeO2–Mg(OH)2 and the surface acidity/basicity can be remarkably changed. Consequently, the Au-nanoparticle-supported catalysts exhibited different MACR conversions and MMA selectivities. The catalytic behavior can be explained by the different metal–support interactions between the three components depending on the composition ratio of CeO2 and Mg(OH)2 and the calcination temperature. These differences were evidenced by X-ray diffraction, X-ray photoelectron spectroscopy, and CO2 temperature-programmed desorption. The present study provides new insights into the design of SMSI-induced supported metal catalysts for the development of multifunctional heterogeneous catalysts.

Lipid extraction from sewage sludge using green biosolvent for sustainable biodiesel production

Sewage sludge is a type of urban waste generated as a byproduct of wastewater treatment in quantities ranging from 9 to 9.5 million tons (dry substance) in Europe. This waste can be considered a source of lipids, which can be converted into biofuels. Recovery of lipids from sludge is a critical step in the overall process, and the choice of the extracting solvent should satisfy efficiency as well as sustainability criteria. This study reports experimental optimisation of lipid extraction from sewage sludge using ethyl butyrate, a green bio-derivable solvent. Extraction conditions were optimised using the desirability function applied to the response surface methodology analysis of a Box–Behnken factorial design of experiments. By carrying out the extraction at 70 °C for 7 h, using an amount of solvent equal to the wet sludge, and without using any acids, 93.7% of the starting lipids were recovered. The extracted lipids were then efficiently converted into biodiesel (fatty acid methyl esters) through direct esterification promoted by AlCl3∙6H2O (catalyst). Furthermore, the residual sludge obtained after the extraction, different to that obtained using hexane, was found to be anaerobically digestible without any inhibition.

A novel methodology for direct esterification of olives optimized through design of experiments

A novel methodology was proposed, and optimized using the Design Expert software, aiming to enable characterization of the fatty acid profile of olives whilst abolishing the lipid extraction step. Furthermore, the proposed method was proven more efficient whereas requiring less time, and sample and solvent amounts, consequently improving process yield. Optimum conditions obtained after experimental design were as follows: sonication temperature and time of 60 ºC and 8 minutes, respectively, and concentrations for alkaline and acid reactions of 0.70 and 1.5 mol L-1, respectively. Total fatty acid content for olive sample was 172.0 mg g-1, the predicted value was and is in the coefficient of variation range of 11.52%

Improved synthesis of the antifungal isobutyl o-coumarate catalyzed by the Aspergillus terreus type B feruloyl esterase

Hydroxycinnamic acids and some of their derivatives are molecules with interesting biological activities; for instance, hydroxylated hydroxycinnamic esters have proved to have antifungal properties, and thus the generation of these molecules is of industrial importance. In this study, the direct esterification capacity of the pure recombinant type B feruloyl esterase from Aspergillus terreus (AtFAE B) was evaluated by its ability to catalyze the synthesis of isobutyl o- coumarate, an interesting antifungal molecule. A ternary solvent system (isooctane/isobutanol/water) was employed to improve the synthesis of isobutyl o- coumarate, assessing different substrate concentrations, enzyme load, water percentages and pH and temperature values. AtFAE B showed the highest initial rate at 18% (v/v) isobutanol and 50 mM o- coumaric acid, 0.04 mg/ml of enzyme, 4% (v/v) water without buffer and 40°C. AtFAE B half-lives at 30°C, 40°C and 50°C were 16.5 h, 1.75 h and 3.5 min, respectively. Thus, we decided to evaluate the bioconversion yield at 30°C, where the enzyme showed the highest operational stability. At this temperature, we obtained a yield of ~80% after only 8 h of reaction, using a 78:18:4 isooctane:isobutanol:water ternary solvent system, with 50 mM of o- coumaric acid. Under these improved conditions, the productivity was 1.06 g isobutyl o -coumarate/L*h with a biocatalyst yield of 209.6 kg isobutyl o -coumarate/kg free AtFAE B, demonstrating the promising potential of AtFAE B to accept the non-canonical o- coumaric acid as the substrate and to achieve the synthesis of isobutyl o- coumarate. How to cite: Vega-Rodríguez AD, Armendáriz-Ruiz MA, Grajales-Hernández DA, et al. Improved synthesis of the antifungal isobutyl o -coumarate catalyzed by the Aspergillus terreus type B feruloyl esterase. Electron J Biotechnol 2021;54. https://doi.org/10.1016/j.ejbt.2021.08.001

Transition Metal-Based Nanoparticles Catalyzed Esterification Reactions

Esters are an important source of aroma due to which they are widely used in cosmetics and food industries. Apart from their fragrance, they are used in textile industries, lubricants, and many other fields. This review paper mainly introduces the overview of research about oxidative esterification using metal nanoparticles. Traditional esterification fundamentally proceeds between carboxylic acid derivatives and alcohols and is regularly a multistep process. Also, research interest in the area of nanotechnology using transition metal nanoparticles is of great interest for application in catalysis for direct esterification of alcohols and aldehydes under oxidative conditions. Transition metal nanoparticles catalyzed esterification process has paved the way to the efficient, sustainable, and environmentally friendly direct oxidative esterification of alcohols and aldehydes.

Microwave-assisted esterification of P-acids

The possibilities for the preparation of dialky phenylphosphonates were evaluated. On the one hand, the oxidation of phenyl-H-phosphinates gave the corresponding phenylphosphonic acid monoesters. On the other hand, phenylphosphonates may be prepared by MW-assisted direct esterification of phenylphosphonic acid. The reaction with alcohols was performed under MW irradiation in the presence of an ionic liquid as the catalyst. The second ester function was established by alkylating esterification carried out with alkyl halides in the presence of triethylamine under MW conditions.

Citric acid functionalized cellulose monolith for continuous‐flow removal of cationic dye in water

AbstractDeveloping efficient yet cost‐effective material from bioresources for dye removal is promising in both economic and environmental protection aspects. Here, a monolithic cellulose material functionalized with citric acid is reported as an absorbent for continuous‐flow removal of cationic dye. The functionalization process is realized by a direct esterification reaction between citric acid and cellulose without any other additions. The obtained monolithic absorbent possesses a 3D connected porous structure, which enables the application of the product in a continuous‐flow fashion. Results indicate that the produced monolith has a good adsorption ability to methylene blue. Moreover, the product can be reused after a fast desorption process by flowing with a salt solution. This work provides a simple strategy for fabricating green absorbents based on biofriendly cellulose and citric acid, which exhibits a potential of industrial application for water treatment.