Synthesis Of Acetate Research Articles

Promotional Role of Acid Sites on Aluminosilicate-Supported PdAu for Vinyl Acetate Synthesis

Promotional Role of Acid Sites on Aluminosilicate-Supported PdAu for Vinyl Acetate Synthesis

TO ISSUE INCREASING THE EFFICIENCY OF THE MASS TRANSFER PROCESS IN AGITATORS

This study investigates the impact of impeller design on the rate of esterification reaction in a batch reactor. Different impeller designs were tested and compared, including Backswept impeller, C-shaped, Double Blade impeller, and Pitched impeller. The results showed that the choice of impeller design has a significant effect on the rate of esterification reaction, with the Backswept impeller proving to be the most effective. In this work, it is aimed to investigate the esterification of acetic acid and methanol in a batch stirred reactor for the synthesis of methyl acetate. The temperature range of 303.15 K is examined, with sulphuric acid used as the homogeneous catalyst in varying concentrations of 0.0633 mol·L1 to 0.3268 mol·L-1. The feed molar ratio of acetic acid to methanol also varied from 1:1 to 1:4 to observe its influence on the reaction rate. The research delves into the effects of temperature, catalyst concentration, and reactant concentration on the reaction rate. The experimental data is correlated using a second-order kinetic rate equation, and the forward and backward reaction rate constants and activation energies are determined from the Arrhenius plot. The developed kinetic model is compared with previous models in literature. In order to find the most effective impeller for esterification reaction, diameter of impellers was accepted same in the constant volume and dimension of batch reactor. The obtained kinetic equation proves useful for the simulation of a reactive distillation column for the synthesis of methyl acetate. Keywords: the batch reactor, impeller, esterification, effectivity, mass transfer, mixing, mechanical mixers, Logarithmic Shear Rate, Eddy Diffusivity.

Green catalysis for the production of n-butyl acetate over phosphotungstic acid-encapsulated metal-organic framework UiO-67 catalyst: Catalyst preparation, characterization and reaction kinetics

In the present study, a composite of Keggin-type phosphotungstic acid encapsulated in sized-matched metal-organic framework UiO-67 (HPW@UiO-67) was successfully fabricated via a facile hydrothermal synthesis method and utilized for the preparation of n-butyl acetate. The as-synthesized composite catalyst was comprehensively characterized using FT-IR, PXRD, ICP-OES, N2 adsorption-desorption, SEM, TEM, NH3-TPD, TGA-DTG and XPS techniques. The characterization results confirmed that HPW was successfully immobilized in metal-organic framework without changing the structure of UiO-67. The asprepared HPW@UiO-67 catalyst exhibited higher esterification activity compared to the UiO-67 catalyst due to its suitable surface area and total volume, high dispersion of phosphotungstic acid and high total acidity. The kinetic study indicated that the process followed the second-order kinetic with the activation energy Ea = 53.1 kJ/mol. The catalyst exhibited good recovery and catalytic performance in the reuse study, maintaining the conversion of acetic acid above 63.1% after four reaction cycles. Moreover, the reaction mechanism for the synthesis of n-butyl acetate via esterification over HPW@UiO-67 was proposed.

Synthesis and characterisation of copper acetate mediated oxidative coupled product of naturally occurring hydroxy benzoquinone, embelin and its in vitro and in vivo cytotoxic studies in Dalton Lymphoma ascites tumour cells

Embelin is an active phytoconstituent known to exhibit a variety of biological activities, especially active against various cancer and tumour cell lines. In the present work, embelin was extracted and isolated from Embelia ribes and was structurally modified by incorporating different fluoro substituted aniline in the quinone motif with a view of enhancing the biological activity. The synthesis was carried out in presence of copper acetate catalyst in a protic solvent, glacial acetic acid to obtain EDFA, ETFA and EOCF and were characterised by various spectral techniques. Embelin and its derivatives were then subjected to in vitro studies in DLA cell lines. Antiangeogenic activities were tested using CAM assay. EOCF was identified as the most active derivative and hence subjected to in vivo studies in tumour induced albino mice. The activity was compared with currently used anticancer drug, cyclophosphamide. The study revealed that EOCF was effective in inhibiting tumour growth.

Facile Synthesis of Ethyl Acetate over ZrO2.TiO2 Mixed Oxide Supported Vanadium Boasted Phosphomolybdic Acid Catalyst at Room Temperature

Initially, mixed oxide of ZrO2.TiO2 support was synthesized by the sol-gel method, and then after vanadium was incorporated, phosphomolybdic acid (VPMA) was synthesized by the hydrothermal method. VPMA supported on ZrO2.TiO2 support of various VPMA loadings that were synthesized by the impregnation method. The structure, surface area, acidity, and morphology of the materials were analysed by X-ray diffraction, BET surface area, ammonia TPD studies, and SEM analysis, respectively. The XRD result shows crystallites of zirconia, titania, and Keggin ion of VPMA catalysts, and also, below 20 wt% of VPMA loading, crystallites of Keggin ion are not observed. BET surface area analysis reveals that increase of VPMA loading, surface area was sharply declined at higher loadings. Ammonia TPD analysis finds that acidity is inclined with VPMA loadings. SEM studies reveal that bulk formation of the active phase is observed at higher loadings. Esterification of acetic acid was tested over VPMA/ZrO2.TiO2 catalyst that exhibited higher activity during reaction than pure VPMA catalyst. These findings were well correlated with surface area and acidity loadings.

Synthesis of diallyl acetals from allyl alcohol and paraformaldehyde or 1,3,5-trioxanes

Synthesis of diallyl acetals from allyl alcohol and paraformaldehyde or 1,3,5-trioxanes

Comprehensive risk assessment for the esterification processes based on Dempster-Shafer evidence theory and cloud model

As a typical chemical process, esterification is usually exothermic and has a high risk of fire and explosion. To recognize and control the risk, it is vital to conduct risk assessment. Therefore, a comprehensive risk assessment method for the esterification process was proposed in this study. By analyzing the characteristics and hazards of the esterification process, a comprehensive evaluation index system was established. It covers four aspects including risk of materials, risk of reaction, possibility of thermal runaway inhibition and risk of process conditions. The improved Dempster-Shafer evidence theory integrates the Hellinger distance and the Pignistic vector angle. It effectively deals with the conflicts between different experts when determining weights. And the cloud model was used to grade index criteria, converting qualitative and quantitative assessment results. This was done to deal with the randomness and ambiguity in the assessment process. Syntheses of butl acetate and tert-butyl peroxyacetate were adopted as case study to validate the proposed method. The assessment results are generally consistent with the Dow's Fire and Explosion Index (F&EI) and the Inherent Benign⁃ness Indicator (IBI). This work will provide a new method for comprehensive risk assessment of the esterification process and can be further used for process optimization.

Optimization of Autoclave Reactors to Improve Bearing Life Using the Taguchi Method and the Response Surface Methodology

Plastic pervasiveness in daily life has increased in tandem with population growth. Ethylene–vinyl acetate (EVA) is emerging as a popular compound for manufacturing plastic, which is obtained from ethylene and vinyl acetate synthesis. EVA is produced using autoclave reactors, which often encounter bearing damage under specific operating conditions. This research aims to optimize the parameters in autoclave reactors to enhance bearing life. The study focuses on two crucial factors: the number of impellers and the temperature, with bearing life as the response variable. Simulations using finite-element analysis were conducted to obtain the fatigue life of bearings and validated using real-time company data stating the damage of bearings within 80 days. The optimization process employed the Taguchi method (TM) and the response surface methodology (RSM). A comparison of these techniques revealed that temperature had the most significant influence on the response. Interestingly, both methods yielded the same optimal parameters: seven impellers and a temperature of 150 °C. The simulation results using these optimized parameters demonstrated a noteworthy 3.095% increase in bearing life compared to the initial design. The RSM outperformed the Taguchi method in accurately predicting response values with minimum prediction error under optimal conditions.

Expression of ATP-binding cassette transporter proteins AatA or MdlB facilitates butyric acid production in Clostridium tyrobutyricum

ATP-binding cassette (ABC) transporters, one of the largest super families of membrane-associated microbial proteins involved in the transport of a wide range of substrates, play a vital role in bacterial physiology. In this study, we investigated the utility of heterologous expression of the ABC transporter AatA from Acetobacter pasteurianus AC2005 and homologous overexpression of the ABC transporter protein MdlB to improve butyric acid production in Clostridium tyrobutyricum. Compared to the starting wild-type strain C. tyrobutyricum ATCC 25755, recombinant strains of C. tyrobutyricum/aatA and C. tyrobutyricum/mdlB showed increased butyrate yield, productivity, selectivity, and titer during fed-batch fermentation. qRT-PCR revealed that AatA and MdlB upregulated the expression levels of ack, the gene encoding a key enzyme in the acetate synthesis pathway. This result was consistent with the observed increase in acetate titer in the recombinant strains. Moreover, overexpression of AatA or MdlB promoted the synthesis and secretion of acetic acid. An assay of cellular ATPase activities established that the two recombinant strains demonstrated two-folder higher ATPase activities compared to the wild-type strain. This increase in ATPase activity is proposed to accelerate sugar utilization, induce extracellular secretion of acetate for butyrate production, and shorten fermentation periods to improve butyrate productivity.

Effectiveness of Cellulose Acetate Nanofiber from Banana Leaf Waste (Musa paradisiaca L.) as an Antibacterial Filter in Masks

The COVID-19 pandemic requires all people in Indonesia to comply with health protocols, from washing hands to wearing masks. Cloth masks are one of the masks that are widely used by the community. However, the public needs to pay attention to the rules of the cloth masks used. The purposes of this study were to produce an antibacterial filter on masks and to find out the effective and efficient processing of banana stems as an antibacterial filter on masks. Banana stems were chosen as the raw material because it is easy to obtain, has a cellulose content of ± 63%, and has antibacterial compounds in it. The stages of this research were sample preparation, phytochemical screening of banana stems, isolation of α-cellulose and synthesis of cellulose acetate from α-cellulose which were further characterized by using FTIR, manufacture of dop solution, manufacture of nanofiber membranes by electrospinning, and product application. The resulting product was then tested by pressure drop test, contact angle test, antibacterial activity test, SEM test, and porosity test. The test results showed that the resulting product was a nanofiber with a fiber diameter of ± 220.74075 nm, had antibacterial activity which was indicated by the formation of inhibition zone with a diameter of ± 14.8 mm in Escherichia coli and ± 9.8 mm in Staphylococcus. aureus, the filter is hydrophilic with an average contact angle of 60°. From the observations, it can be concluded that banana stems have the potential as an antibacterial filter on masks.

Synthesis and Characterization of Isopropylidene Glycerol Acetate and Isopropylidene Glycerol Propanoate Compounds

Isopropylidene Glycerol Acetate (IGA) and Isopropylidene Glycerol Propanoate (IGP) as ester compounds using acetic and propanoic acids have been synthesized, characterized, and studied for their antibacterial properties. The IGA was synthesized from ethyl acetate (EtOAc) and 1,2-O-isopropyliden glycerol (IPG) with a mole ratio of 1:8 through a transesterification reaction. Meanwhile, the IGP was synthesized using ethyl propanoate (EP) with the same ratio and method as IGA. All materials in this study were identified using FT-IR, GC-MS, 1H-NMR, and 13C-NMR. The characterization results indicated that the compounds of EP, IPG, IGA, and IGP had been successfully formed and identified. It was also revealed that the compounds of EP, IPG, IGA, and IGP were successfully synthesized with yields of 37.72, 27.78, 70.11, and 63.83%, respectively. The antibacterial activity test revealed that neither IGA nor IGP inhibited the growth of Staphylococcus aureus or Escherichia coli at concentrations of 62.5; 125; 250; 500; and 1000 ppm. Therefore, it was asserted that ester compounds synthesized with short-chain carboxylic acids, such as propanoic and acetic acids, lacked antibacterial properties.

Nickel-Catalyzed Decarbonylation of α-Oxyacetic Acid Thioesters: Hydroxymethylation of Mercaptans

AbstractA strategy for the Ni-catalyzed decarbonylation of α-oxyacetic acid thioesters is described, providing a new pathway for the synthesis of monosulfide acetals, and further proving that oxygen atoms can stabilize an α-carbocation and promote a decarbonylation reaction. This method has good functional-group compatibility and can tolerate a wide range of electron-withdrawing, electron-neutral, and electron-donating substituents. In addition, this method complements the conventional cross-coupling reactions.

Sintesis Selulosa Asetat dari Ampas Tebu sebagai Bahan Baku Biodegradable Foam

The high cellulose content of bagasse allows it to be developed into a variety of valuable products, one of them is cellulose acetate which will be used to make biodegradable foam. The purpose of this research is to determine the best conditions for the synthesis of cellulose acetate from bagasse and test how cellulose acetate can be used to make biodegradable foam. This study used phosphoric acid as a solvent and glacial acetic acid as an acetylating agent to make cellulose acetate through the acetylation process. The variations in acetylation time in this study were 15, 30, and 45 minutes and the volume of glacial acetic acid as acetylating agent was 20, 40, 60, 80, and 100 ml. The results of this study indicated that the optimum conditions for the synthesis of cellulose acetate are 15 minutes of acetylation with a volume of 100 ml of glacial acetic acid, with a yield of 79.31% cellulose acetate, 36.19% acetyl content and a degree of substitution of 2.11. The test for the application of cellulose acetate to make biodegradable foam obtained a water absorption of 18.81%, the biodegradation test obtained was 24.53% in 14 days. In the biodegradable foam leak test for 10 minutes, no leakage occurred. This indicated that the biodegradable foam obtained was suitable to use because it complied with SNI.

Theoretical insights into the dissociation and oxidation of ethylene during vinyl acetate synthesis

Gas phase synthesis of vinyl acetate from ethylene over Pd-Au catalyst is one of the mainstream processes. During the synthesis of vinyl acetate, the surface C generated by the dissociation of ethylene can be doped into the lattice of Au to form interstitial C. The synergistic effect of interstitial C and Au can promote the production of vinyl acetate. However, the formation mechanism of surface C is not clear. In addition, CO2 is formed during the dissociation and oxidation of ethylene. In order to reduce carbon emissions, it is also necessary to clarify the formation mechanism of CO2. In this study, the reaction mechanism for the dissociation and oxidation of ethylene on the PdAu(100) surface was investigated by density functional theory and kinetic Monte Carlo, and the formation pathways of surface C and CO2 were clarified.The results show that the generation pathway of surface C is CH2CH2→ CH2CH→ CHCH→ CHC→ CC→ CCO→ C+CO. The rate control step is CCO→C + CO with energy barrier of 1.39 eV and reaction heat of 0.52 eV. The generation pathway of CO2 is C → COH → CO → CO2. The rate control step is C+OH→COH with energy barrier of 0.71 eV and reaction heat of -1.12 eV. Clarification of the reaction mechanism for dissociation and oxidation of ethylene on the PdAu(100) surface and the formation pathways of surface C and CO2 can more specifically reduce the consumption of ethylene for by-products, better construct the synergism of surface C and Au, and reduce the emission of CO2 in the process of catalyst improvement and optimization.

A Designed Chemoenzymatic Route for Efficient Synthesis of 6-Dehydronandrolone Acetate: A Key Precursor in the Synthesis of C7-Functionalized Steroidal Drugs

A Designed Chemoenzymatic Route for Efficient Synthesis of 6-Dehydronandrolone Acetate: A Key Precursor in the Synthesis of C7-Functionalized Steroidal Drugs

Identification, Characterization, and Computer-Aided Rational Design of a Novel Thermophilic Esterase from Geobacillus subterraneus, and Application in the Synthesis of Cinnamyl Acetate.

Investigation of a novel thermophilic esterase gene from Geobacillus subterraneus DSMZ 13552 indicated a high amino acid sequence similarity of 25.9% to a reported esterase from Geobacillus sp. A strategy that integrated computer-aided rational design tools was developed to select mutation sites. Six mutants were selected from four criteria based on the simulated saturation mutation (including 19 amino acid residues) results. Of these, the mutants Q78Y and G119A were found to retain 87% and 27% activity after incubation at 70°C for 20min, compared with the 19% activity for the wild type. Subsequently, a double-point mutant (Q78Y/G119A) was obtained and identified with optimal temperature increase from 65 to 70°C and a 41.51% decrease in Km. The obtained T1/2 values of 42.2min (70°C) and 16.9min (75°C) for Q78Y/G119A showed increases of 340% and 412% compared with that in the wild type. Q78Y/G119A was then employed as a biocatalyst to synthesize cinnamyl acetate, for which the conversion rate reached 99.40% with 0.3M cinnamyl alcohol at 60°C. The results validated the enhanced enzymatic properties of the mutant and indicated better prospects for industrial application as compared to that in the wild type. This study reported a method by which an enzyme could evolve to achieve enhanced thermostability, thereby increasing its potential for industrial applications, which could also be expanded to other esterases.

Synthesis of Phase‐Selective Ionic Liquid Gels and Application to the Synthesis of Ethyl Acetate

AbstractNovel and environment‐friendly ionic liquid gels (ILG) were synthesized based on polymers, phenylboronic acid, and [BMIM]HSO4, in order to solve the problems in esterification, such as poor selectivity, difficult separation of product and catalyst, and catalyst recycling. The stability and structures of the ILG were characterized by rheology, thermogravimetric analysis, Fourier transform infrared and 1H nuclear magnetic resonance spectroscopy, and energy calculation. The solubility data proved that the ILG had phase selectivity, which could enable a homogeneous reaction. The synthesis of ethyl acetate was chosen to evaluate the catalytic activity, with the product yields being higher than 80 %. The catalyst could be recycled directly, without any post‐treatment. Thus, the ILG could enhance the industrial application of esterification.

Process design and optimization of enzymatic reaction distillation

Driven by global environmental awareness, biocatalysts are playing an increasingly important role in industrial chemistry. Enzymatic reactive distillation (ERD) combines the high efficiency of enzymatic reaction and distillation separation to reduce the limiting effects of reaction equilibrium, product inhibition, and the difficulty of product recovery due to its thermodynamic constraints. The lipase CALB was immobilized and coated on the θ-ring by sol-gel method. The synthesis of n-butyl acetate by transesterification reaction was selected as the model reaction in the ERD process, and a laboratory scale column was constructed. The Rate-based RadFrac model in Aspen Plus was used to describe the ERD. The results showed that the enzyme-loaded packing showed high long-term stability after 120 days in the reaction system. The deviation of the ERD experiment and simulation results was less than 10 %, which verifies the reliability of simulation. After the parameter sensitivity optimization on the simulation, compared with the batch reactor, the ERD process increased the reactant conversion from 60 % to 94.74 %. This study established a complete process from enzyme immobilization to ERD process, which provided a theoretical basis for the establishment and optimization of ERD process.

Bio-green synthesis of calcium acetate from oyster shell waste at low cost and reducing the emission of greenhouse gases

Biological wastes obtained from food, oyster shells, were recycled to calcium carbonate and then used as bio-green raw material to replace limestone/carbonate stone for calcium acetate (Ca(CH3COO)2·H2O) production. The conditions (ambient temperature occurred in an exothermic reaction, drying time, yield, and solubility) of the reaction between the bio-green CaCO3 and three different acetic (CH3COOH) concentrations (8, 10, and 12 M) were investigated. The product's maximum yield (93%) with a shorter drying time (18 h) was obtained from the reaction between the bio-green CaCO3 with 12 M acetic acid revealing a lower cost. The chemical compositions without any toxic metal impurity revealed by the X-ray fluorescence technique would be useful to suggest use in the specific application. The X-ray diffraction, Fourier Transform Infrared, and Thermogravimetric analysis data of Ca(CH3COO)2·H2O prepared by the bio-green CaCO3 obtained from oyster shell wastes in this work and those in previous works used other calcium sources were consistent. The morphologies with different sizes of the obtained Ca(CH3COO)2·H2O depend on the CH3COOH concentrations reported in this work and were different from those reported in previous works because of different calcium sources. According to the observation, it can be concluded that the low-cost and bio-green technique without the environmental effects was successfully applied to produce cheap Ca(CH3COO)2·H2O and reduce greenhouse gas emissions, which can be used in the specific industry.

A DFT study on the mechanism of acetaldehyde generation during vinyl acetate synthesis from gas-phase ethylene acetoxylation on Pd/Au (100) surface

Acetaldehyde (CH3CHO) is an important by-product in the reaction of ethylene to vinyl acetate (VAC). However, the mechanism of the generation of CH3CHO has been little studied. In this paper, we designed a reaction network for the possible generation of acetaldehyde from intermediate species on Pd/Au catalysts, including three reaction paths. Stable adsorption configurations of the species involved in each elementary reaction were identified by Density Functional Theory (DFT) calculations and the charge changes on the catalyst surface during the adsorption process as well as the structural parameter changes of the adsorption configurations were compared. Based on this, we calculated the kinetic parameters on three reaction paths and combined with Kinetic Monte Carlo (KMC) simulations to found the dominant path and rate-determining step to help understand the mechanism of acetaldehyde generation on the surface of Pd/Au (100). Results suggest that species involved in the reactions are adsorbed mainly on Pd-Au bridge sites, Pd top sites, and Pd-Pd intermediate vacancies and species structure changes after adsorption. CHCH, CH2CH, and CH3CH could all generate CHxCHO by reacting with O species or OH species, and the energy barrier for reactions with O species are all lower than those for reactions with OH species. The dominant pathway for acetaldehyde generation on Pd/Au (100) surface is CH2CH2 → CH2CH→ CH2CHO → CH3CHO and the ethylene dehydrogenation elementary reaction is the rate-determining step.