Methyl Acetate Research Articles

Exploring the freshness biomarker and volatiles formation in stored pork by means of lipidomics and volatilomics

Raw pork is prone to oxidation and rancidity as it contains a high level of unsaturated lipid molecules. Reliable biomarkers to benchmark pork freshness and their formation have not been systematically investigated. The results indicated that the peroxide values, TVB-N and rancid volatiles dramatically increased in pork during the storage period (4 °C, 0–9 d). Concentrations of most volatile compounds with carbonyl groups were increased markedly in pork during storing, including hexanal, acetic acid, and hexadecanoic acid methyl ester. Lipidomics, volatilomics and chemometrics methods were used to discriminate the freshness of pork, among which acetic acid and PC O-20:3 emerged as the most reliable freshness biomarkers. Phospholipids and neutral lipids, including phosphatidylcholines (PC), triglycerides (TG), and phosphatidylethanolamine (PE), played a crucial role in the formation of rancid volatiles and the decreased freshness. This work will provide technical supports for the efficient storage and preservation of raw meat.

Direct conversion of syngas into methyl acetate by relay catalysis: From fabrication of active sites to process control

AbstractThe direct and selective conversion of syngas into C2+ oxygenates is challenging due to the complex reaction network. Here, we report a robust relay system for the direct synthesis of methyl acetate (MA) from syngas, which combines CuZnAlOx/H‐ZSM‐5 for syngas to dimethyl ether (DME) with modified H‐MOR for DME carbonylation. The dehydration of methanol to DME on H‐ZSM‐5 significantly enhanced the hydrogenation of CO on CuZnAlOx, because of high DME equilibrium yields. Blocking of Brönsted acid sites with basic molecules or selective dealumination of 12‐membered rings in H‐MOR suppressed the zeolite coking. Besides, reaction temperatures above 240°C avoided H2O poisoning of carbonylation sites inside 8‐MR side pockets of H‐MOR, further benefiting the catalytic stability. Eventually, this relay system provided a high MA selectivity of 75% and an acetic acid selectivity of 13% at a CO conversion of 65%, outperforming reported catalysts.

Confinement and synergy effect of bimetallic Cu-Ni clusters encapsulated in Beta zeolite for methyl acetate formation from methanol alone

The direct synthesis of methyl acetate (MA) from methanol is an appealing and green approach, but an efficient catalyst is urgently needed. Herein, Cu-Ni bimetallic clusters, with a diameter of ∼1.2 nm, have been successfully encapsulated within BEA zeolite by an in-situ two-step encapsulation method (Cu-Ni@Beta), which significantly favors the dispersion of metals compared to the ion-exchanging (Cu/Ni@Beta) and wet impregnation approach (Cu-Ni/Beta). The as-synthesized Cu-Ni@Beta catalyst shows a MA formation rate of 1.46 mmol s−1 g(Cu+Ni)−1, which is much higher than Cu/Ni@Beta of 0.02 mmol s−1 g(Cu+Ni)−1 and Cu-Ni/Beta of 0.12 mmol s−1 g(Cu+Ni)−1. Characterization studies reveal that zeolite constraints could not only provide the spatial confinement for metal clusters but also induce an electronic interaction between confined Cu and Ni species in Cu-Ni@Beta. This interaction can increase and stabilize Cu+ sites as well as Lewis acid sites, which are crucial for improving catalytic performance. In-situ FTIR experiments indicate that the formation of formaldehyde (CH2O*) is the critical step for methanol to MA, and the CH2O* further couples with methoxy (CH3O*) to form acetate species (CH3CHO*), which subsequently couples with CH3O* to produce MA.

Effects of electron beam irradiation on the sensory qualities and bioactive compounds of broccoli sprout juice

This study investigates the effects of electron beam irradiation at varying doses on the bioactive compounds and sensory qualities and of broccoli sprout juice (BSJ). A comprehensive analysis of volatile flavor components using GC-IMS and GC–MS identified 49 compounds, including esters, aldehydes, and olefins. Notably, the sulforaphane content exhibited a strong negative correlation with irradiation intensity (R2 = 0.9596), which is critical for predicting the impact of irradiation dose on sulforaphane degradation. Statistical analysis confirmed that 34 volatile compounds, like methyl acetate, 2-methylbutanal, hexanoic acid ethyl ester, etc., exhibited significant difference in different irradiation doses groups (P < 0.05). Sensory evaluation revealed that 6 kGy was the optimal irradiation dose, enhancing the sweetness and mushroom aroma while reducing undesirable spicy flavors. These findings provide valuable insights for balancing preservation techniques, sensory qualities, and nutritional integrity in BSJ, offering potential applications in both food and medicinal industries.

Solubility behavior of Rosiglitazone in ten pure solvents: Model correlation, thermodynamic calculations, and molecular simulation

Rosiglitazone is an oral antidiabetic medication primarily used to treat type 2 diabetes. Herein, the single crystal structure of Rosiglitazone (a = 14.0613(7) Å, b = 8.4675(4) Å, c = 29.8841(16) Å, space group Pbca, Z = 8, V = 3558.1(3) Å3) was analyzed for the first time. Through solubility measurements, model correlation, thermodynamic calculations, and molecular simulations, the dissolution of Rosiglitazone in ten pure solvents was comprehensively investigated. The solubility order at 298.15 K is acetone > methyl acetate > ethyl acetate > butyl acetate > acetonitrile > alcoholic solvents (methanol, ethanol, n-propanol, iso-propanol, n-butanol). Rosiglitazone exhibits higher solubility in non-alcoholic solvents, whereas its solubility in alcoholic solvents is similar and relatively low. Subsequently, the correlation between the experimentally measured solubility of Rosiglitazone and the Modified Apelblat model, λh model, NRTL model, and Van’t Hoff model was examined. The Van’t Hoff equation calculations proved that the dissolution of Rosiglitazone was an endothermic process driven by entropy and characterized by non-spontaneity. The calculation of solvent polarity and Hansen solubility parameters (HSP) reveals that the primary factor influencing the solubility of Rosiglitazone is polarity in highly polar solvents, while the dominant factor is molecular volume in low-polarity solvents. Furthermore, the molecular interactions of solute and solvents were investigated by molecular simulation, including the calculation of electrostatic potential, 2D fingerprint plots and solvation free energy, which provided insights into the mechanism of Rosiglitazone dissolution behavior in different solvents.

Electron scattering study on acetic acid and methyl formate

Abstract In this work we report the results of a theoretical calculation of the elastic, differential scattering, and excitation cross-sections on electron interactions with the C2H4O2 isomers (methyl formate and acetic acid) using the ab initio R-matrix method in the energy range of 0.1-20 eV. The computations were performed using static exchange (SE), static exchange plus polarization (SEP) and Close-Coupling (CC) models with electronic structure calculation for these molecules performed using GAMESS. In the electron scattering cross section we have identified π* type resonance in both the isomers. Ionization cross-sections for both the molecules from ionization threshold to 500 eV using BEB method are also presented here. We endeavoured to explore the isomeric effect on various cross sections among these two isomers and included the third isomer, namely glycolaldehyde, as reported in our previous publication.&amp;#xD;

Caesium-Iodide-Assisted Synthesis of High-Quality, Stable, and Robust Lead-Free Perovskite Quantum Dots.

The poor morphology, and susceptibility to oxidation of tin-based perovskite quantum dots (TQDs) have posed significant challenges, limiting their application potential. This study presents a straightforward method for synthesizing high-quality CsSnI3-based perovskite quantum dots (TQDs) by incorporating a mixed Cs source of Cs2CO3 and CsI. The addition of CsI increased the I:Sn ratio while maintaining Sn:Cs, resulting in TQDs with smaller size and improved uniformity. X-ray photoelectron spectroscopy (XPS), and Nuclear magnetic resonance (NMR) analyses confirmed enhanced crystallinity, photoluminescence intensity, and antioxidation ability of CsI-TQDs. Remarkably, these TQDs exhibit exceptional stability, enduring over 1 h in air and more than 24 h before complete oxidation, surpassing the previously reported longest lifetime in air for TQDs with conventional oleic acid (OA) and oleylamine (OAm) ligands. Furthermore, these TQD films retain robustness after ligand exchange with methyl acetate (MeOAc) and formamidinium iodide (FAI), representing the first successful short-ligand exchange of TQDs and enabling further electronic device applications. These findings suggest that CsI in the Cs source plays a crucial role in facilitating the formation of surface complexes, regulating TQD growth and suppressing iodine vacancies.

Hierarchical Intercalation of Solvated Tetrafluoroborate Anions into Graphite Electrodes: The Case Studies of Methyl Acetate and γ-Butyrolactone Solutions.

Intercalation of anions unlocks graphite as a positive material in energy storage devices, and the performance could be affected by solvents in solutions. In this context, it is vital to investigate the role of solvents in anion intercalation. Herein, a hierarchical intercalation phenomenon, in which different graphite intercalation compounds are generated in the same solution, is studied in lithium tetrafluoroborate (LiBF4) solutions of carboxylate ester solvents γ-butyrolactone (GBL) and methyl acetate (MA). The evolution modes of the graphite cathode structure during electrochemical intercalation and deintercalation are discussed via in situ X-ray diffraction (XRD) measurements. Based on this, the relationship between GICs and potentials, together with concentrations, is compared in detail. Furthermore, various graphite materials with different surface properties are applied to adjust the anions' solvation status inside graphite sheets.

Molecular Synergistic Effects Mediate Efficient Interfacial Chemistry: Enabling Dendrite-Free Zinc Anode for Aqueous Zinc-Ion Batteries.

The primary cause of the accelerated battery failure in aqueous zinc-ion batteries (AZIBs) is the uncontrollable evolution of the zinc metal-electrolyte interface. In the present research on the development of multiadditives to ameliorate interfaces, it is challenging to elucidate the mechanisms of the various components. Additionally, the synergy among additive molecules is frequently disregarded, resulting in the combined efficacy of multiadditives that is unlikely to surpass the sum of each component. In this study, the "molecular synergistic effect" is employed, which is generated by two nonhomologous acid ester (NAE) additives in the double electrical layer microspace. Specifically, ethyl methyl carbonate (EMC) is more inclined to induce the oriented deposition of zinc metal by means of targeted adsorption with the zinc (002) crystal plane. Methyl acetate (MA) is more likely to enter the solvated shell of Zn2+ and will be profoundly reduced to produce SEI that is dominated by organic components under the "molecular synergistic effect" of EMC. Furthermore, MA persists in a spontaneous hydrolysis reaction, which serves to mitigate the pH increase caused by the hydrogen evolution reaction (HER) and further prevents the formation of byproducts. Consequently, the 1E1M electrolyte not only extends the cycle life of the zinc anode to 3140 cycles (1 mA h cm-2 and 1 mA cm-2) but also extends the life of the Zn//MnO2 full battery, with the capacity retention rate still at 89.9% after 700 cycles.

Evaluation of the phytochemical, bioactive compounds and descriptive sensory of encapsulated lingzhi (Ganoderma lucidum) extracts with combined wall materials for masking effect on the perception of off-flavour and bitterness

Lingzhi mushroom (Ganoderma lucidum) is known as a medicinal mushroom that can be utilized in various functional foods available in the market, including powders, dietary supplements, and tea. However, its use is limited due to factors such as bitterness, flavour, and astringency. The objective of this study is to characterize and quantify the sensory profile of Lingzhi mushroom samples (fresh, dried and Lingzhi extracts) using quantitative descriptive analysis and investigate the physicochemical and sensory properties of encapsulated Lingzhi extracts using different ratios of wall material (maltodextrin, gum Arabic and modified starch from rice flour). The optimal ratio for encapsulation involved 32.75 % maltodextrin, 42.25 % gum Arabic, and 25 % modified starch w/w. Three parallel experiments were performed under practical conditions, resulting in average encapsulation efficiencies of 88.39 ± 0.09 % for flavonoids 89.53 ± 0.06 % for polysaccharides and 0.31 ± 0.01 of water activity. The sensory descriptive analysis indicated the following ratings: brown sugar aroma (4.36 ± 0.17), earthy aroma (22.04 ± 0.12), nutty aroma (2.00 ± 0.01), fresh mushroom aroma (11.18 ± 0.19), dried Lingzhi aroma (3.08 ± 0.13), black tea aroma (4.50 ± 0.19), salty taste (1.00 ± 0.01), earthy flavour (23.14 ± 0.22) and Mushroomy (after taste) (2.06 ± 0.09), respectively. The flavour identified of Lingzhi extracts and encapsulated by gas chromatography electronic nose (GC-E-Nose). The result showed ten flavour compounds (Acetaldehyde, Methanethiol, Propanal, propane-2-one, Methyl acetate, 2-methyl propanal, Ethyl Acetate, Heptane, 1-Butanamine, 2-methyl butanal, Thiophene). Optimizing the encapsulation conditions has a significant impact on reducing off-flavours and bitterness. Comparing the flavour profiles of Lingzhi extracts with encapsulated Lingzhi extracts using gas chromatography electronic nose (GC-E-Nose). Encapsulation technology represents a burgeoning field that holds immense potential in ensuring the stability of functional ingredients and facilitating their incorporation into instant beverage products.

Organometallic Compound Stabilizes All-Inorganic Tin-Based Perovskite Nanocrystals Against Antisolvent Post-Treatment.

The isolation and purification of all-inorganic Sn-based perovskite nanocrystals (PNCs) remain troublesome, as common antisolvents accelerate the collapse of the optically active perovskite structure. Here, we mitigate such instabilities and endow strong resistance to antisolvent by incorporating the organometallic compound zinc diethyldithiocarbamate, Zn(DDTC)2, during the solution-based synthesis of all-inorganic CsSnI3 nanocrystals. Thiourea is shown to form through the thermal-driven conversion of Zn(DDTC)2 during synthesis, which binds to un-passivated Sn sites on the crystal surface and shields it from irreversible oxidation reactions. The CsSnI3 PNCs capped with thiourea show great stability after two purification cycles using methyl acetate, with negligible change in morphology, phase, and optical properties. Moreover, the modified PNCs are resistant to other commonly used antisolvents, like ethyl acetate, 1-pentanol, and isopropanol, offering a platform to explore all-inorganic Sn-based nanocrystalline thin films and optoelectronics.

Enhanced heat transfer in two-phase closed thermosyphons with external liquid-vapor separation

Two-phase closed thermosyphons (TPCTs) are highly efficient heat transfer devices that leverage natural convection to transport heat over substantial distances with minimal temperature gradients. This study investigates the thermal performance of a novel TPCT equipped with an external liquid-vapor separator, compared to a conventional TPCT. The innovative design incorporates an external pathway connecting the condenser and evaporator sections. A comprehensive evaluation was conducted using three working fluids (water, methyl acetate, and ethanol) across a spectrum of heat inputs (50 ≤ Q ≤ 300 W) and filling ratios (25 %, 40 %, 55 %, 70 %, and 85 %). Optimal performance was consistently observed at a 70 % filling ratio for all fluids tested. While the conventional TPCT exhibited superior performance with methyl acetate, the novel TPCT demonstrated enhanced thermal efficiency when charged with water or ethanol. Notably, the novel TPCT using water reduced thermal resistance by approximately 63 % and 60.5 % compared to ethanol and methyl acetate, respectively, at a 50 W heat input and the optimal filling ratio. These findings underscore the critical influence of working fluid selection and offer valuable insights into the thermal characteristics of the novel TPCT. The results contribute significantly to the optimization and design of TPCTs for diverse applications.

Homogeneous reactive distillation: The influence of pressure drop on separation and reaction kinetics

This study investigates the Total Annual Cost (TAC) optimization of a reactive distillation (RD) process for methyl acetate (MA) production as a function of tray pressure drop, focusing on the trade-off between chemical reaction kinetics and separation efficiency. The analysis examines how variations in column diameter and weir height influence the TAC across different liquid hold-ups with and without incorporating a tray pressure drop in the simulations. Results indicate that for larger liquid hold-ups, the decrease in separation efficiency predominates over kinetic advantages, leading to higher energy costs when pressure drop is considered. Despite the loss in separation efficiency with a high weir height, a pressure drop-incorporated column design featuring a high weir height and small diameter is shown to achieve lower TAC due to the comparatively lower installed costs. A reduction of tray liquid hold-up of more than 50 % is found for the optimal column design in the considered case study when the tray pressure drop is considered. A sensitivity analysis towards a hypothetical infinite fast reaction is conducted to illustrate how the energy costs are affected by the kinetic rate of the chemical reaction.

Enhancement of Low-Temperature Cycling Performance of Lithium-Ion Batteries by use of Dual Cosolvent

Lithium-ion batteries (LIBs) based on conventional electrolyte suffer from poor cycling performance at low temperatures due to the reduced ionic conductivity of electrolytes, sluggish charge transfer reaction, and Li plating during the charging process. Herein, we propose a dual cosolvent composed of methyl acetate (MA) and ethyl fluoroacetate (EFA). MA effectively reduced the viscosity of the electrolyte, improving the ionic conductivity at low temperatures. EFA facilitated the de-solvation of Li+ ions and formed an anion-derived solvation structure, enabling the formation of an inorganic-rich solid electrolyte interphase on the graphite anode. Due to the synergistic effect of MA and EFA, the graphite/LiFePO4 cell employing a dual cosolvent exhibited good cycling performance at low temperatures, delivering a discharge capacity of 68.7 mAh g−1 at −20 °C and 0.2 C and showing a capacity retention of 99.7% after 100 cycles at −20 °C and 0.33 C. Additionally, the cell exhibited an initial discharge capacity of 131.2 mAh g−1 at 25 °C and 1.0 C, with a capacity retention of 99.4% after 300 cycles. Our results demonstrate that liquid electrolytes containing dual cosolvent with various beneficial roles can be a promising solution for improving the low-temperature cycling performance of LIBs.

Rigorous design and economic optimization of reactive distillation column considering real liquid hold-up and hydraulic conditions of industrial device

The liquid hold-up in a reactive distillation (RD) column not only has a significant impact on the extent of reactions, but also affects the pressure drop and hydraulic conditions in the column. Therefore, the liquid hold-up would be a critical design factor for RD columns. However, the existing design methods for RD columns typically neglect the influence of considerable amount of liquid hold-up in downcomers owing to the difficulties of solving a large-scale nonlinear model system by considering downcomer hydraulics, resulting in significant deviations from actual situation and even operation infeasibility of the designed column. In this paper, a pseudo-transient (PT) RD model based on equilibrium model considering tray hydraulics was established for rigorous simulation and optimization of RD plate columns considering the liquid hold-up both in downcomers and column trays, and a steady-state optimization algorithm assisted by the PT model was adopted to robustly solve the optimization problem. The optimization results of either ethylene glycol RD or methyl acetate RD demonstrated that assuming all the liquid hold-up of a stage belonged to the tray will cause significant deviations in the column diameter, weir height, and the number of stages, which leads to not meeting the separation requirements and even operation hydraulic infeasibility. The rigorous model proposed in this study which considers the liquid hold-up both on trays and in downcomers as well as hydraulic constraints can be applied to systematically design industrial RD plate columns to simultaneously obtain optimal operating variables and equipment structure variables.

Production of Biodiesel Without Catalyst Separation with Palm Oil Interesterification Process Using Essential Oil Biocatalyst

The transesterification is a method commonly used in the production of biodiesel. Therefore, this study aimed to investigate interesterification reaction of palm oil with methyl acetate using essential oil biocatalyst, specifically focusing on eugenol and cajuput oil. The operating parameters were: 250 g of palm oil, a molar ratio of palm oil:methyl acetate of 1:6, a reaction temperature of 60ºC, a stirring speed of 300 rpm, a biocatalyst of 0.75 wt. % in relation to oil, and reaction times of 15, 30, 45, 60, and 75 min. The palm oil, methyl acetate and biocatalyst reacted in a three-necked flask as a reactor under operating conditions. Additionally, simulations were performed using ChemDraw Professional 15.0 to analyze the molecular behavior of the reacting compounds.

Electrochemical radiofluorination using a split-bipolar electrode

Electrochemical (radio)fluorination (ECF) is a versatile approach for nucleophilic radiofluorination of electron-rich compounds such as thioether derivatives. However, ECF generally requires high concentrations of supporting salts, which leads to low molar activity (Am) of the final product due to undesired contamination with [19F]F– ions. Here, we demonstrate the first example of radiofluorination using a split bipolar electrode (s-BPE) platform with low concentration of supporting salt. Under optimal reaction conditions, the ECF of methyl (methylthio)acetate (MMTA) using s-BPEs provided [18F]F-MMTA with radiochemical conversion of up to 70 % and high molar activities (28–43 GBq/μmol; 0.74–1.1 Ci/μmol), with approximately 5 mM of tetrabutylammonium perchlorate as supporting electrolyte.

Absolute Configuration of the Invasive Mealybug Delottococcus aberiae (De Lotto) Sex Pheromone: Synthesis and Bioassay of Both Enantiomers.

The mealybug Delottococcus aberiae (De Lotto) (Hemiptera: Pseudococcidae) is an invasive pest reported in Europe at the end of the first decade of the 2000s, causing severe damage to citrus production in eastern Spain. In a previous work, (4,5,5-trimethyl-3-methylenecyclopent-1-en-1-yl)methyl acetate was identified as the sex pheromone emitted by females, a new compound with an unusual β-necrodol skeleton possessing one stereocenter. This compound was assigned to the (-)-enantiomer but the absolute configuration was then not reported. In the present study, enantiomeric pure samples of both enantiomers were synthesized. X-ray diffraction analysis allowed the (-)-enantiomer, identical to the one emitted by virgin D. aberiae females, to be unequivocally identified as (-)-(R)-(4,5,5-trimethyl-3-methylenecyclopent-1-en-1-yl)methyl acetate. Bioassays carried out to test the activity of both enantiomers under field conditions suggest that the presence of the (+)-(S)-enantiomer has detrimental effects on the activity of the racemates.

O2-Dependence of reactions of 1,2-dimethoxyethanyl and 1,2-dimethoxyethanylperoxy isomers

Reaction mechanisms of R˙ and ROO˙ radicals derived from low-temperature oxidation of 1,2-dimethoxyethane (CH3O(CH2)2OCH3) were investigated using speciation from multiplexed photoionization mass spectrometry (MPIMS) measurements via Cl-initiated oxidation, in conjunction with electronic structure calculations. The experiments were conducted at 5 bar, from 450 K – 650 K, and O2 concentrations from 1 · 1014 cm–3 – 6 · 1018 cm–3 to probe the effects on competing reaction channels of 1,2-dimethoxyethanyl (R˙) and 1,2-dimethoxyethanylperoxy (ROO˙) isomers. Several species were detected with photoionization spectral fitting – ethene, formaldehyde, methyl vinyl ether, and 2-methoxyacetaldehyde – and, as determined by electronic structure calculations, may form via unimolecular decomposition of 1,2-dimethoxyethanyl or 1,2-dimethoxyethanylperoxy. O2-dependent yield ratios show that the formation pathways for all species undergo a competition between O2-addition and unimolecular decomposition. Adiabatic ionization energies were also calculated and utilized along with exact mass determinations to infer contributions for other species derived exclusively from first- and second-O2-addition, including 1,2-dimethoxyethene, cyclic ethers, and dicarbonyls.In addition to species formed from conventional low-temperature oxidation pathways, an important conclusion is derived from the detection of species produced from an O2-addition step involving ĊH2CH2OCH3 (R˙′), which forms via prompt dissociation of the primary 1,2-dimethoxyethanyl radical (ĊH2O(CH2)2OCH3). Species derived from R˙′ + O2 – 1,3-dioxolane and methyl acetate – were detected at [O2] = 1.2 · 1017 cm–3 and formed on timescales parallel to the main R˙ + O2 reactions. In addition, ion signal at m/z 106 was detected and increased with O2 concentration from which connections are drawn to ketohydroperoxides produced by Q˙′OOH + O2. Detection of such species indicate that β-scission of 1,2-dimethoxyethanyl is sufficiently facile such that timescales of R˙′ + O2 compete with conventional R˙ + O2 pathways.

Temperature and Composition Dependence of the Densities, Speed of Sound, and Viscosities of Binary Liquid Mixtures of Tetrahydrofuran with Methyl Acetate, Propyl Acetate, and Pentyl Acetate

Temperature and Composition Dependence of the Densities, Speed of Sound, and Viscosities of Binary Liquid Mixtures of Tetrahydrofuran with Methyl Acetate, Propyl Acetate, and Pentyl Acetate