Synthesis Of Ethyl Acetate Research Articles

Effect of vitamin concentration on the synthesis of lactate, ethanol, pyruvate, and ethyl acetate in cells of the yeast Dipodascus magnusii

In the yeast Dipodascus magnusii, which is auxotrophic for thiamine and biotin, during cultivation on glucose with excessive thiamine concentration, pyruvate metabolism was shown to result in the synthesis of fermentation products, namely, ethanol and, to a lesser extent, lactate. Substantial synthesis of ethyl acetate was also observed under these conditions. Introduction of nicotinic acid (NA) into the medium resulted in time separation of ethanol and lactate production. It was shown that cultivation of the yeast under biotin deficiency resulted in nearly complete suppression of aerobic production of ethanol and cessation of ethyl acetate synthesis, whereas lactate synthesis was activated as early as in the first hours of cultivation. Upon introduction of NA under these conditions, lactate concentration sharply increased. These results show that the combination of thiamine and biotin with other vitamins can stimulate utilization of the pyruvate pool in yeasts towards formation of considerable amounts of lactate, which is typical only of cells of higher eukaryotes and bacteria.

Dynamic Simulation of Reactive Batch Distillation Column for Ethyl Acetate Synthesis

A detailed mathematical dynamic model of reactive batch distillation column is formulated for ethyl acetate synthesis and presented in terms of differential and algebraic equations (DAEs). These DAEs are solved using fourth order Runge-Kutta method in MATLAB® to obtain the detailed column dynamics. The simulation results provide the dynamics of reboiler and distillate compositions, reboiler temperature, ethyl acetate purity in the accumulated distillate and conversion of the reactants. These results are analyzed to derive the optimum operating policy, i.e., reflux ratio and batch time.

Transport of Small Molecules through Polyphenylene Oxide Membranes Modified by Fullerene

Homogeneous membranes based on fullerene‐polyphenylene oxide compositions containing up to 2 wt% fullerene C60 were prepared. The effect of fullerene addition on PPO transport properties was studied in gas separation and pervaporation processes. Permeability coefficients of H2, O2, N2, CH4, and CO2 were measured; a correlation between gas transport properties and membrane free volume was established. Pervaporation properties were studied for the system with ethyl acetate synthesis reaction: quaternary system ethanol—acetic acid—water—ethyl acetate and some constituent binary and ternary mixtures. Pervaporation in binary systems, ethanol–water and ethyl acetate–water was considered with the use of the data on sorption capacities and interaction parameters. In pervaporation of a quaternary reacting mixture, the permeate containing essentially ethyl acetate was obtained. Results show that membranes with fullerene additives exhibit improved transport properties.

The effect of increased yeast alcohol acetyltransferase and esterase activity on the flavour profiles of wine and distillates

The fruity odours of wine are largely derived from the synthesis of esters and higher alcohols during yeast fermentation. The ATF1- and ATF2-encoded alcohol acetyltransferases of S. cerevisiae are responsible for the synthesis of ethyl acetate and isoamyl acetate esters, while the EHT1-encoded ethanol hexanoyl transferase is responsible for synthesizing ethyl caproate. However, esters such as these might be degraded by the IAH1-encoded esterase. The objectives of this study were: (a) to overexpress the genes encoding ester-synthesizing and ester-degrading enzymes in wine yeast; (b) to prepare Colombard table wines and base wines for distillation using these modified strains; and (c) to analyse and compare the ester concentrations and aroma profiles of these wines and distillates. The overexpression of ATF1 significantly increased the concentrations of ethyl acetate, isoamyl acetate, 2-phenylethyl acetate and ethyl caproate, while the overexpression of ATF2 affected the concentrations of ethyl acetate and isoamyl acetate to a lesser degree. The overexpression of IAH1 resulted in a significant decrease in ethyl acetate, isoamyl acetate, hexyl acetate and 2-phenylethyl acetate. The overexpression of EHT1 resulted in a marked increase in ethyl caproate, ethyl caprylate and ethyl caprate. The flavour profile of the wines and distillates prepared using the modified strains were also significantly altered as indicated by formal sensory analysis. This study offers prospects for the development of wine yeast starter strains with optimized ester-producing capability that could assist winemakers in their effort to consistently produce wine and distillates such as brandy to definable flavour specifications and styles.

Influence of glucose and oxygen on the production of ethyl acetate and isoamyl acetate by a Saccharomyces cerevisiae strain during alcoholic fermentation

The effect of glucose and dissolved oxygen in a synthetic medium simulating the standard composition of grape juice on the production of ethyl acetate and isoamyl acetate by a Saccharomyces cerevisiae strain during alcoholic fermentation was studied. The specific in vitro activity of alcohol acetyltransferase (AATase, EC 2.3.1.84) and esterases (ESase, EC 3.1.1.1; hydrolysis and synthesis of esters) in cell-free extracts was also examined. The specific activity of AATase for ethyl acetate was found to peak at the beginning of the exponential growth phase and that for isoamyl acetate at its end. While the glucose concentration only affected the maximum specific activity of AATase, and only slightly, oxygen inhibited such activity, to a greater extent for isoamyl acetate than for ethyl acetate. On the other hand, esterases were found to catalyse the synthesis of ethyl acetate only at a low or medium glucose concentration (50 or 100 g l-1, respectively), and to reach their maximum hydrolytic activity on isoamyl acetate during the stationary growth phase. The highest ethyl acetate and isoamyl acetate concentrations in the medium were obtained with a glucose concentration of 250 g l-1 and semianaerobic conditions.

Biochemical characterization of recombinant acetyl xylan esterase from Aspergillus awamori expressed in Pichia pastoris: Mutational analysis of catalytic residues

We engineered an acetyl xylan esterase ( AwaxeA) gene from Aspergillus awamori into a heterologous expression system in Pichia pastoris. Purified recombinant AwAXEA (rAwAXEA) displayed the greatest hydrolytic activity toward α-naphthylacetate (C2), lower activity toward α-naphthylpropionate (C3) and no detectable activity toward acyl-chain substrates containing four or more carbon atoms. Putative catalytic residues, Ser 119, Ser 146, Asp 168 and Asp 202, were substituted for alanine by site-directed mutagenesis. The biochemical properties and kinetic parameters of the four mutant enzymes were examined. The S119A and D202A mutant enzymes were catalytically inactive, whereas S146A and D168A mutants displayed significant hydrolytic activity. These observations indicate that Ser 119 and Asp 202 are important for catalysis. The S146A mutant enzyme showed lower specific activity toward the C2 substrate and higher thermal stability than wild-type enzyme. The lower activity of S146A was due to a combination of increased K m and decreased k cat. The catalytic efficiency of S146A was 41% lower than that of wild-type enzyme. The synthesis of ethyl acetate was >10-fold than that of ethyl n-hexanoate synthesis for the wild-type, S146A and D168A mutant enzymes. However, the D202A showed greater synthetic activity of ethyl n-hexanoate as compared with the wild-type and other mutants.

Synthesis of Ethyl Acetate by Coupling a Heterogeneous Catalytic System with a Pervaporation Unit

The synthesis of ethyl acetate was investigated using a heterogeneous catalyst and a pervaporation unit. Shifting the reaction equilibrium by selective water removal increased the ethyl acetate productivity. Commercial acid resin, Amberlyst 15 (Rohm and Haas), and commercial hydrophilic composite membrane, PERVAP 1000 and 1001 (Le Carbone Lorraine), were used. The effects of catalyst mass, reaction temperature, and initial reactants ratio were studied. The kinetic parameters, such as activation energy and apparent reaction order, were determined. The water production and removal rates obtained in reaction and pervaporation experiments, respectively, were used in a computational code to simulate the behavior of the coupled system. The highest conversion was observed when an initial ethanol/acetic acid molar ratio of 9:1 was used. At this condition, the water production was reduced turning the water removal process more selective, increasing the acetic acid conversion from 51.0% to 63.9%.

Optimisation of Ethyl(2-phthalimidoethoxy)acetate Synthesis with the Aid of DOE

We investigated the reaction of alkylation of 2-phthalimidoethanol with ethyl chloroacetate leading to ethyl(2-phthalimidoethoxy)acetate. The synthesis was successfully optimised by applying factorial design. Major side products have been separated, identified, and characterised. The yield level was increased from 25% to 52%, and a method of decreasing the amount of side products has been proposed.

Rate-based modelling and simulation of reactive separations in gas/vapour–liquid systems

In this paper, rigorous modelling of reactive separations is considered. Focus is set to gas/vapour–liquid systems, namely reactive distillation and reactive stripping. The paper describes the modelling framework and the process simulator PROFILER developed within the European research project Intelligent Column Internals for Reactive Separations (INTINT). The application is illustrated by two heterogeneously catalysed esterification processes: the synthesis of ethyl acetate from ethanol and acetic acid via reactive distillation and the synthesis of octyl hexanoate from octanol and hexanoic acid via reactive stripping. For both processes, the simulation results are in satisfactory agreement with the experimental data. A comparison of different model complexities is presented.

Investigation of different column configurations for the ethyl acetate synthesis via reactive distillation

The ethyl acetate synthesis via reactive distillation is studied theoretically and experimentally using different catalytic packings. Experiments are carried out at laboratory scale in a 50 mm diameter column with a packing height of 3 m, and at semi-industrial scale in a 162 mm diameter column with a packing height of 12 m. The experimental set-up is similar for both cases. The commercially available packings studied are KATAPAK ®-S and two different variants of MULTIPAK ®. Modelling is performed with a rate-based stage model. The simulation environment ASPEN Custom Modeler™ is used for the implementation and solution of the model equations. The results of the rate-based simulations agree well with the corresponding experimental results. In addition, suitable operating conditions and the influence of the selected catalytic internal on conversion and product purity are investigated. The developed model enables the scale-up from laboratory to industrial size columns, based on the respective packing characteristics.

Monitoring of chemical reactions within microreactors using an inverted Raman microscopic spectrometer.

An inverted Raman microscope spectrometer has been used to profile the spatial evolution of reactant and product concentrations for a chemical reaction within a microreactor operating under hydrodynamic flow control. The Raman spectrometer was equipped with a laser source at wavelength of 780 nm, confocal optics, a holographic transmission grating, and a charge-coupled device (CCD) detector. The microreactor consisted of a T-shaped channel network etched within a 0.5 mm thick glass bottom plate that was thermally bonded to a 0.5 mm thick glass top plate. The ends of the channel network were connected to reagent reservoirs that were linked to a syringe pump for driving the solutions by hydrodynamic pumping within the channels. The microchannels were 221 micro m wide and 73 micro m deep. The synthesis of ethyl acetate from ethanol and acetic acid was investigated as a model system within the microreactor as Raman scattering bands for each reactant and product species were clearly resolved. Raman spectral intensities of each band were proportional to concentration for each species and hence all concentrations could be quantitatively measured after calibration. By scanning specific Raman bands within a selected area in the microchannel network at given steps in the X-Y plane, spatially resolved concentration profiles were obtained under steady-state flow conditions. Under the flow conditions used, different positions within the concentration profile correspond to different times after contact and mixing of the reagents, thereby enabling one to observe the time dependence of the product formation. Raman microscopy provides a useful complementary technique to UV/VIS absorbance and fluorescence methods for the in situ monitoring and analysis of chemical reaction species having their lowest S(0)-S(1) absorption bands too far in the UV to be of use, due to their probable overlap with the bands from other reactant, product and solvent molecules.

Direct Synthesis of Ethyl Acetate from Ethanol Carried Out under Pressure

Direct synthesis of ethyl acetate from ethanol over a Cu–Zn–Zr–Al–O catalyst was investigated under pressured conditions between 473 and 533 K. Both the selectivity to ethyl acetate and the space-time yield of ethyl acetate increase with increasing reaction pressure, whereas ethanol conversion decreases. The highest space-time yield of ethyl acetate is attained at a reaction pressure of about 0.8 MPa with maximum selectivity of 93 wt%. During the process, ethanol is first dehydrogenated to acetaldehyde and is then coupled with another ethanol molecule to form hemiacetal, which is further dehydrogenated to ethyl acetate. The concentration of by-products such as 1-butanol and butanone, which form after the aldol addition of acetaldehyde, decreases with increasing reaction pressure. Since the equilibrium of the dehydrogenation of ethanol to acetaldehyde shifts to an ethanol-rich composition at high pressure, the decrease in the partial pressure of acetaldehyde explains the suppression of the by-products formed through acetaldol.

Polycondensed Heterocycles. Part 12. An Approach to the Synthesis of 2‐Acetyl‐1′‐methyl‐1,2,3,4‐tetrahydrospiro [isoquinoline‐1,4′‐pyrrolidine]‐2′‐one.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Direct synthesis of ethyl acetate from ethanol over Cu-Zn-Zr-Al-O catalyst

Direct synthesis of ethyl acetate from ethanol is investigated over several copper catalysts. We clarified the role of additive metal oxides such as ZrO 2, ZnO and Al 2O 3. An additive ZrO 2 gives ester-formation activity to the pure copper catalyst. ZnO suppresses the formation of undesirable products such as methyl ethyl ketone (MEK) under the co-existence of ZrO 2. Al 2O 3 enhances not only the conversion of ethanol but also the catalytic activity for the side reaction of aldol addition of acetaldehyde. Ethanol is converted into ethyl acetate with high selectivity over Cu-ZnO-ZrO 2-Al 2O 3 catalyst, together with low selectivity to methyl ethyl ketone. Then we investigated the influence of copper content in the quaternary copper catalysts containing ZrO 2, ZnO and Al 2O 3 on the catalytic performance. The ethyl acetate production ability of catalyst is roughly proportional to the Cu surface area of the Cu-ZnO-ZrO 2-Al 2O 3 catalyst. The highest ethanol conversion, the highest ethyl acetate selectivity, and the highest space-time yield of ethyl acetate were achieved at Cu content of 70 mol%.

Polycondensed heterocycles. Part 12: An approach to the synthesis of 2-acetyl-1′-methyl-1,2,3,4-tetrahydrospiro[isoquinoline-1,4′-pyrrolidine]-2′-one

The synthesis of ethyl (2-acetyl-1-cyano-1,2,3,4-tetrahydro-1-isoquinolyl)acetate was accomplished by cyanation/acylation of the dihydroquinoline ring system. The selective cobalt boride catalyzed reduction of the cyano group of the cyanoester intermediate was the key step to obtain the corresponding ethyl (1-aminomethyl-2-acetyl-1,2,3,4-tetrahydro-1-isoquinolyl)acetate which was cyclized by exposure to trimethylaluminum catalysis, leading to the novel spiro-polycondensed heterocyclic system.

Acetate technology using reactive distillation

Acetates are products frequently used in the chemical industry. They have a wide range of applications, especially as a solvent in the cellulose, paint, coating and rubber industry. Together with various partners, Sulzer Chemtech has developed processes for the synthesis of ethyl and butyl acetate, as well as for the hydrolysis of methyl acetate, and now offers this acetate technology for licensing. The key feature of the processes, for which patent protection has been applied, is a reactive distillation column.

Investigation of ethyl acetate reactive distillation process

In this paper, an extensive study of ethyl acetate synthesis by homogeneously catalyzed reactive distillation is presented. Reactive distillation is a promising operation whereby reaction and separation take place within a single distillation column. The synergistic effect of this combination has the potential to increase conversion, improve selectivity and facilitate separation tasks. The feasibility of ethyl acetate synthesis is examined using the reactive distillation lines diagram. A completely rate-based simulator DESIGNER developed within the framework of a large European research project is used in order to predict concentrations, temperatures and other important process variables. In order to validate theoretical predictions, a set of reactive distillation experiments is performed in a glass tray column with 80 bubble cap trays. The concentrations and temperature profiles computed by DESIGNER agree well with the experimental data.

One-step synthesis of ethyl acetate from ethene and oxygen

A one-step synthesis of ethyl acetate from a feed mixture of ethene, oxygen, and water using a supported Pd and silicotungstic acid catalyst was demonstrated. At about 180°C and 25% ethene conversion, ethyl acetate could be produced with up to 46% selectivity, together with 34% acetic acid and ethanol that could be recycled. The catalyst was believed to be bifunctional, with Pd providing the oxidation function and the silicotungstic acid providing the acidic function.

Formation of a strong, high-porosity spinodal silica and its impregnation with a perfluoro ionomer to obtain a high performance solid acid catalyst composite

Spinodal silicas, with similar properties to phase-separated glasses but showing high mechanical strength, with large pore sizes and porosities (total pore volume to total particle volume) of 0.7 or more have been produced by adding monobasic sodium phosphate and ammonium molybdate to a silica sol, drying to obtain particles, baking at about 700°C, and washing in hot water. The porosity was governed mainly by the monobasic sodium phosphate and ammonium molybdate addition, and the microstructure and pore size by the baking temperature and time, with short low-temperature baking yielding a spheroidal silica similar in properties to silica gels and high-temperature baking resulting in the spinodal microstructure. Spinodal silica particles of 1.1 µm average pore size and 0.74 porosity were filled with perfluoro ionomer solution and heat treated at 250°C after solvent removal, to obtain composite particles of 0.7 µm average pore size and 0.51 meq g−1 exchange capacity. The composite particles exhibited high mechanical strength and resistance to chemical desorption of the perfluoro ionomer, and strong catalytic activity as shown by the reaction rate constant of 0.98 L mol−1 min−1 eq(H+)−1 for the synthesis of ethyl acetate at 60°C and ambient pressure, which was 1.4 to several times the rate obtained under the same conditions with commercially available catalysts.

Reaction monitoring using Raman spectroscopy and chemometrics

The synthesis and hydrolysis of ethyl acetate was monitored with a Raman spectrometer equipped with a 785-nm laser, confocal optics, an optical fiber, a holographic transmission grating, and a charge coupled device (CCD) detector. In the Raman spectra, the signals were seen to vary in proportion to the concentrations of ethanol, acetic acid and ethyl acetate. First-order reaction, rate constants were determined for the hydrolysis reaction, under different experimental conditions according to a full factorial experimental design. The rate constants were determined either by using the peak height at one single wavelength, or by using score values from principal components analysis (PCA) or partial least squares (PLS). The rate constants determined agree well with literature values. It is shown that the single wavelength and the PCA/PLS approaches give similar reaction profiles, where the standard normal variate (SNV) transformation was used for spectral pretreatment. The use of Raman spectroscopy for reaction monitoring in opalescent mixtures is also shown and discussed.