Aromatic Esters Research Articles

Citrus Peel Extract Starch-Based Bioplastic: Effect of Extract Concentration on Packed Fish and Bioplastic Properties

An environmentally friendly packaging material was produced from starch with the incorporation of citrus lemon peel ethanol extract. Gas chromatography-mass spectrometry of the citrus lemon extract revealed the presence of compounds such as fatty acid, terpenes, aromatic esters, aldehyde, and polyphenolics. Bioplastic films produced with different percentages of the citrus lemon ethanol extract are designated as film0%, film5%, film10%, film15%, and film20%. From the physico-tensile properties of the bioplastics, the density ranges from 0.12 to 0.20 g cm−3, thickness, 0.25 to 0.74 mm, moisture content, 12.00 to 14.86, water-solubility, 1.23 to 2.84%, opacity, 0.36 to 0.67% and, tensile strength, 9.94 to 25.60 MPa. The 2,2-diphenyl-2-picrylhydrazyl anti-oxidant radical activities of the biofilms range from 1.44 to 6.19% and total phenol content, 0.01 to 0.32%. Proximate analysis of the fish after packaging revealed a decrease in moisture content from 38.69% ( $${\text{film}}_{{{{o\% }}}}$$ ) to 12.01% ( $${\text{film}}_{{20{{\% }}}}$$ ) and an increase in fat (20.93%— $${\text{film}}_{{0{{\% }}}}$$ to 24.92%— $${\text{film}}_{{20{{\% }}}}$$ ), and protein (30.19%— $${\text{film}}_{{0{{\% }}}}$$ to 37.06%— $${\text{film}}_{{20{{\% }}}}$$ ). Biochemical results revealed closeness of the peroxide, saponification, and total volatile basic nitrogen values of the fresh Pp fish and packed fish with film20%. The fatty acid analysis results showed that bioplastic with the highest amount of added citrus lemon extract had the best result; lowest saturated fatty acid, highest unsaturated fatty acid, and polyunsaturated fatty. Thus, good active packaging films have been produced from this research using waste citrus peel ethanol extract additive.

Removal of the Methylene Blue Dye (MB) with Catalysts of Au-TiO<sub>2</sub>: Kinetic and Degradation Pathway

Au-TiO2 catalysts were used in the photocatalytic degradation of the methylene blue dye (MB). The synthesis of titanium oxide (TiO2) was carried out by sol-gel method. Subsequently, particles of Au were deposited on the surface of the semiconductor by photo-deposition, thus modifying the surface of the semiconductor. For the characterization of the catalyst obtained, the techniques of X-ray Diffraction (DRX), Scanning Electron Microscopy (SEM), Spectroscopy with Diffuse Reflectance (DR) and Surface Area by the BET (Brunauer, Emmett y Teller) were used. The solid obtained was tested experimentally as a catalyst in the photocatalytic degradation of a solution of MB. The data obtained were analyzed by UV-vis Spectroscopy and Total Organic Carbon (TOC) and the results indicated conversions were greater than 80%. The intermediate products were evaluated by mass coupled gas chromatography (GC-MS) and the MB decomposition route was by hydroxylation, obtaining aromatic intermediates, esters and products of the chemical degradation of the molecule.

Carboxyboronate as a Versatile In Situ CO Surrogate in Palladium-Catalyzed Carbonylative Transformations.

The application of carboxy-MIDA-boronate (MIDA=N-methyliminodiacetic acid) as an in situ CO surrogate for various palladium-catalyzed transformations is described. Carboxy-MIDA-boronate was previously shown to be a bench-stable boron-containing building block for the synthesis of borylated heterocycles. The present study demonstrates that, in addition to its utility as a precursor to heterocycle synthesis, carboxy-MIDA-boronate is an excellent in situ CO surrogate that is tolerant of reactive functionalities such as amines, alcohols, and carbon-based nucleophiles. Its wide functional-group compatibility is highlighted in the palladium-catalyzed aminocarbonylation, alkoxycarbonylation, carbonylative Sonogashira coupling, and carbonylative Suzuki-Miyaura coupling of aryl halides. A variety of amides, esters, (hetero)aromatic ynones, and bis(hetero)aryl ketones were synthesized in good-to-excellent yields in a one-pot fashion.

Self-adhesive PMIA membranes with virus-like silica immobilized lipase for efficient biological aging of Chinese liquor

Excellent separation and biocatalysis performance of novel CALB@virus-like silica/Poly (m-phthaloyl-m-phenylenediamine) (CALB@VLS/PMIA) membranes were fabricated by the self-adhesion method via introducing the immobilized biological enzyme (CALB@VLS) on the surface of PMIA membrane, in which the interconnection of CALB@VLS and PMIA was able to improve the ability of one-step refining Chinese liquor and catalytic synthesis of aromatic esters. The outcomes stated clearly that the increment of dosage of CALB@VLS and ratio of ethanol/water coagulation bath led a raise of the lipase loading on the surfaces of membrane yet overdose caused an abatement in the lipase activity. With the optimal conditions of 0.5 g L−1 dosage and 60 %v/v ratio, the CALB@VLS decorated PMIA membrane achieved the supreme lipase relative activity at 95.3% of its initial activity. Meanwhile, the rejection rate of turbid advanced fatty acid ethyl esters attached the highest 92.5% under satisfactory liquor flux (432.5 L m−2 h−1). The pH, thermal, organic solvent and storage stability of the lipase immobilized on the membrane were markedly enhanced. The effect of CALB@VLS dosage, liquor concentration and operating temperature on the efficiency of catalytic esterification was explored. Additionally, the immobilized lipase on the membrane could be readily maintained at 75.7% after repeated use ten times. Consequently, the PMIA membrane promised to be an excellent carrier for lipase, and the bioactive membrane could have broad applications in food, medicine, etc.

Chemoenzymatic Synthesis of New Aromatic Esters of Mono- and Oligosaccharides

An efficient and convenient chemoenzymatic route for the synthesis of novel phenolic mono-, di- and oligosaccharide esters is described. Acetal derivatives of glucose, sucrose, lactose and inulin were obtained by chemical synthesis. The fully characterized pure sugar acetals were subjected to enzymatic esterification with 3-(4-hydroxyphenyl) propionic acid (HPPA) in the presence of Novozyme 435 lipase as a biocatalyst. The aromatic esters of alkyl glycosides and glucose acetal were obtained with good esterification yields, characterized by mass spectrometry (MALDI-TOF MS), infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR). The synthesis of aromatic esters of disaccharide acetals was successful only for the enzymatic esterification of sucrose acetal. The new chemoenzymatic route allowed the synthesis of novel aromatic esters of inulin as the inulin monoacetal monoester and diester and the inulin diacetal monoester with a polymerization degree of two, as well as the inulin monoacetal monoester with a degree of polymerization of three, were obtained by enzymatic acylation of inulin acetals with HPPA. These compounds could represent a new class of sugar ester surfactants with enhanced bioactivity, antioxidative and antimicrobial properties and with potential application in drug delivery systems.

Instrumental and thermal characterization of the sludge generated after bio-coagulation treatment (GSABT) of petroleum produced water (PW)

A study on the instrumental, thermal and settling characteristics of generated sludge after bio-coagulation treatment (GSABT) of petroleum produced water (PW) was undertaken. SEM-EDAX, FTIR, XRD and TGA/DSC were conducted to respectively investigate the structure, composition and thermal stability of GSABT. Settling characteristics of GSABT and its filterability were also studied. The wave numbers (peaks) for the GSABT show the finger prints regions of aromatic aldehyde, alkane, azo and ester groups. The atomic structure and thermal characterization of GSABT depict primitive crystalline structure and thermal stability. The sludge sedimentation studies showed four zones of settling (lag, hindered, transition and compression zones). The sludge filtration characteristics of GSABT indicated specific cake resistance (SCR) (α) of 1.265×1010mkg and filter medium resistance (Rm) of 5.89×102m−1 at determination coefficient (R2) of 0.9838. The settling velocity models tested show that Cho exponential model fitted the data adequately and satisfactorily. GSABT contains essential elements (P, Ca, Mg, Na) and could be beneficiated further for economic uses.

Study of assessment of green tea’ grades in GC‐MS determination of aromatic components based on principal component analysis (PCA)

Aroma compounds are one of the most important components in tea, as well as an important indicator for its quality. In this paper, using HS-SPME/GC-MS method, we established the fingerprint for aromatic components in green tea produced in Guizhou Province, China. In this fingerprint, there are nine volatile aromatic components which have significant correlation with the quality scores of green teas’ aroma (p < .05). They contain ethers and aldehydes (dimethyl sulfide and phenylacetaldehyde) of aromatic compounds, and alcohols and esters (1-penten-3-ol, linalool, phenethyl alcohol, geraniol, and Methyl salicylate) of aliphatic compounds, and pyrrole compounds of heterocyclic compounds (3-ethyl-1-pyrrole and 1-ethyl-2-carbaldehyde-1-pyrrole). The Regression Model has been established for predicting evaluation scores of green teas’ aroma. A good result was obtained via verification, indicating that GC-MS is a feasible way to analyze key volatile aromatic components in green tea, which also can be used to predict quality scores aroma and different grades. Practical applications The aromatic components of tea are considered as the important indicator for evaluating the quality of green tea. We can use GC-MS and other technologies to determine the representative aroma substances in green tea that can evaluate the quality of green tea. In this way, we can use the instrumental analysis method of the aromatic components to assist the traditional sensory evaluation, which make the green tea quality evaluation results more scientific.

Integrating amino acid oxidase with photoresponsive probe: A fast quantitative readout platform of amino acid enantiomers

Low-cost, high-throughput, broadly useful photoresponsive enantiomeric excess (ee) sensing of amino acids remains challenging to date. Herein, based on the selective oxidation reaction of amino acid oxidase (AAO) to amino acid enantiomers (D/L-AA) and the oxidation reaction of substrate (H2O2) with aromatic boronic ester, we put forward a photoresponsive strategy for the determination of D/L-AA at a certain concentration. In this scheme, the substrate H2O2 produced by the enzyme-catalyzed reaction was determined by sensitive fluorescent and colorimetric response of ethyl-3-(3-(benzothiazol-2-yl)-5-methyl-2-((4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)oxy)phenyl)-2-cyanoacrylate (HBT-PB) to reflect the enantiomeric content at a certain concentration. The photoresponsive probe HBT-PB was readily available and inexpensive with sensitive long-wavelength red fluorescence and colorimetric light response to H2O2, the detection limit (LOD) was estimated as 2.91 μM. The operation of the sensing method was simple and data collection and processing are straightforward. The practicability of the scheme was favorably confirmed by accurate and scientific analysis of methionine and Dopa samples. As a result, the scheme was not only suitable for high-throughput screening but also adaptable to low-cost and sensitive RGB colorimetric analysis platform (LOD of methionine and Dopa was calculated as 9.23 μM and 8.34 μM respectively) with modern plate readers, and possessed extremely high enantioselectivity and wide applicability which benefited from the specificity and efficiency of enzyme catalytic reaction.

Enological Repercussions of Non-Saccharomyces Species 2.0

Non-Saccharomyces yeast species are currently a biotechnology trend in enology and broadly used to improve the sensory profile of wines because they affect aroma, color, and mouthfeel. They have become a powerful biotool to modulate the influence of global warming on grape varieties, helping to maintain the acidity, decrease the alcoholic degree, stabilize wine color, and increase freshness. In cool climates, some non-Saccharomyces can promote demalication or color stability by the formation of stable derived pigments. Additionally, non-Saccharomyces yeasts open new possibilities in biocontrol for removing spoilage yeast and bacteria or molds that can produce and release mycotoxins, and therefore, can help in reducing SO2 levels. The promising species Hanseniaspora vineae is analyzed in depth in this Special Issue in two articles, one concerning the glycolytic and fermentative metabolisms and its positive role and sensory impact by the production of aromatic esters and lysis products during fermentation are also assessed.

Methyl jasmonate alleviates the reduced release of aroma‐related esters in ‘Nanguo’ pears by regulating ethylene biosynthesis and signal transduction

SummaryCryopreserved fruits usually develop symptoms, which affects the release of aroma. Our study investigated the impact of exogenous methyl jasmonate (MeJA) upon the synthesis of aromatic esters in ‘Nanguo’ pears after cold storage. It found that exogenous MeJA enhanced ethylene accumulation via improving the activity of 1‐aminocyclopropane‐1‐carboxylic‐acid (ACC) synthase (ACS) and ACC oxidase (ACO) and the expression levels of PuACS1 and PuACO1. After cryopreservation for 90 days, the ester aroma of ‘Nanguo’ pears was effectively improved by MeJA during normal temperature shelf life. In addition, the expression of PuERS1, PuETR1, PuEIN4, PuEIN2 and PuERF1 in MeJA‐treated fruits were obviously increased. Therefore, we infer that the influence of MeJA on production of aroma‐related esters in ‘Nanguo’ pears is closely connected with ethylene biosynthesis and signal transduction, namely increase activity of ACS and ACO, and upregulation of the expression level of PuACS1, PuACO1, PuERS1, PuETR1, PuEIN2, PuEIN4 and PuERF1.

A Multi-Enzyme Cascade for the Production of High-Value Aromatic Compounds

Cascade reactions are the basis of life in nature and are adapted to research and industry in an increasing manner. The focus of this study is the production of the high-value aromatic ester cinnamyl cinnamate, which can be applied in flavors and fragrances. A three-enzyme cascade was established to realize the synthesis, starting from the corresponding aldehyde with in situ cofactor regeneration in a two-phase system. After characterization of the enzymes, a screening with different organic solvents was carried out, whereby xylene was found to be the most suitable solvent for the second phase. The reaction stability of the formate dehydrogenase (FDH) from Candida boidinii is the limiting step during cofactor regeneration. However, the applied enzyme cascade showed an overall yield of 54%. After successful application on lab scale, the limitation by the FDH was overcome by immobilization of the enzymes and an optimized downstream process, transferring the cascade into a miniplant. The upscaling resulted in an increased yield for the esterification, as well as overall yields of 37%.

Decarbonylative Synthesis of Aryl Nitriles from Aromatic Esters and Organocyanides by a Nickel Catalyst

AbstractA decarbonylative cyanation of aromatic esters with aminoacetonitriles in the presence of a nickel catalyst was developed. The key to this reaction was the use of a thiophene-based diphosphine ligand, dcypt, permitting the synthesis of aryl nitrile without the generation of stoichiometric metal- or halogen-containing chemical wastes. A wide range of aromatic esters, including hetarenes and pharmaceutical molecules, can be converted into aryl nitriles.

Reductive Deuteration of Aromatic Esters for the Synthesis of α,α-Dideuterio Benzyl Alcohols Using D2O as Deuterium Source

Abstractα,α-Dideuterio benzyl alcohols are important building blocks for the synthesis of deuterium-labeled medicines and agrochemicals. We have developed the first general single-electron transfer reductive deuteration of readily commercially available aromatic esters for the synthesis of α,α-dideuterio benzyl alcohols using benign D2O and a mild single-electron donor SmI2. This operationally convenient method features very good functional group tolerance and high deuterium incorporations (&gt;95% D2). The potential impact has been exemplified by the synthesis of numerous deuterium labeled building blocks of important bioactive compounds. Most crucially, the method represents the first example of selective reductive deuteration of benzylic-type ketyl radicals using mild and highly chemoselective lanthanide(II) reagents.

Assessment of the Thermal Properties of Aromatic Esters as Novel Phase Change Materials

In the quest for a decarbonized energy system, the development of highly efficient technologies that allow the integration of renewables is of the utmost importance. Latent Heat Storage systems with Phase Change Materials (PCM) can contribute to solving the issue of the mismatch between demand and supply brought forward by renewable energies. Despite possessing promising thermal properties, organic PCMs and esters in particular have rarely been investigated. In the present study, eight commercial aromatic esters are assessed as possible PCM candidates. To do so, their thermal properties, such as phase change temperature, enthalpy of fusion, density, and thermal conductivity, alongside sustainability and toxicity issues, are considered. The aromatic esters are found to possess phase change temperatures between −16 ∘C and 190 ∘C and maximum enthalpies of fusion of 160 J/g. This, alongside densities above 1 g/mL, makes them interesting candidates for high-temperature applications, where, typically, salts and ceramics or metals dominate as PCMs.

Measurement and Modeling of Liquid–Liquid Equilibria for Water–Phosphoric Acid–Aromatic Esters

Ternary liquid–liquid equilibrium (LLE) data were measured for the {water + phosphoric acid + aromatic esters (benzyl acetate, benzyl benzoate, dimethyl phthalate, and diethyl phthalate)} systems a...

The Effect of 4,4′-Methylene-bis-(2,6-di-tert-butylphenol) on Properties of Polyvinyl Alcohol/Chlorinated Polyethylene Composites

A series of damping composites were prepared by adding 4,4′-Methylene-bis-(2,6-di-tert-butylphenol) (AO 4426) to a mixture of chlorinated polyethylene (CPE) and polyvinyl alcohol (PVA) with a mass ratio of 80:20. The damping properties and molecular structure of the composites were measured, characterized and analyzed by means of DMTA, DSC and FT-IR. The results show that there is only one damping peak in the PVA/CPE composite. However, a new damping peak appeared above the glass transition temperature of CPE with the addition of AO 4426 because of phase separation which caused by the aggregation of AO 4426 microcrystal under the action of hydroxyl hydrogen bonds. The corresponding temperature of this new damping peak is determined by glass transition temperature of AO 4426. Fourier infrared spectrum show aromatic ether and aromatic ester formed by dehydration between PVA and AO 4426.

Decarboxylative Borylation of Stabilized and Activated Carbon Radicals.

Redox-active esters (RAEs) as active radical precursors have been extensively studied for C-B bond formations. However, the analogous transformations of stabilized radicals from the corresponding acid precursors remain challenging owing to the strong preference towards single-electron oxidation to the stable carbocations. This work describes a general strategy for rapid access to various aliphatic and aromatic boronic esters by mild photoinduced decarboxylative borylation. Both aryl and alkyl radicals could be generated from the leaving group-assisted N-hydroxybenzimidoyl chloride esters, even α-CF3 substituted substrates could be activated for further elaboration.

Mechanism of the Ir/Pd catalyzed photocarboxylation of aryl halides

The recent Ir/Pd co-catalyzed photo carboxylation of aromatic halides with CO2 has shown high efficiency and excellent functional group tolerance for preparing aromatic carboxylic acids and esters. With the aid of density functional theory (DFT) calculations, the carboxylation starts with two parallel steps, i.e., oxidative addition of aromatic halides on Pd0 and reductive quenching of the photocatalyst Ir(ppy)2(dtbpy)+ with amine. Thereafter, a successive oxidation of PdII with the amine radical (generated by the reaction of cationic radical amine and Cs2CO3) and IrII species occurs to generate Pd0, from which the carboxylation occurs easily via a coordination, Pd-C insertion step. The release of the carboxylate product then regenerates the catalyst.

Decarboxylative Borylation of Stabilized and Activated Carbon Radicals

AbstractRedox‐active esters (RAEs) as active radical precursors have been extensively studied for C−B bond formations. However, the analogous transformations of stabilized radicals from the corresponding acid precursors remain challenging owing to the strong preference towards single‐electron oxidation to the stable carbocations. This work describes a general strategy for rapid access to various aliphatic and aromatic boronic esters by mild photoinduced decarboxylative borylation. Both aryl and alkyl radicals could be generated from the leaving group‐assisted N‐hydroxybenzimidoyl chloride esters, even α‐CF3 substituted substrates could be activated for further elaboration.

In Situ Carbonylative Synthesis of Aromatic Esters and Formation of Quinazoline‐2,4(1H,3H)‐diones by Chemical Fixation of CO2 in Assistance of Polymer‐Supported Palladium Catalyst

AbstractIn this work, a functionalized chloromethylated polystyrene supported polymer complex of palladium was designed and synthesized in the three‐step process. The synthesized heterogeneous Pd(DAP‐DEAS‐MERF) catalyst was characterized by Field emission scanning electron microscopy, Energy dispersive analysis of X‐rays, Elemental mapping, Atomic absorption spectroscopy, N2‐BET adsorption‐desorption isotherm, High‐resolution transmission electron microscopy, Thermogravimetric analysis‐Differential thermal analysis, Powder X‐Ray diffraction and Fourier‐transform infrared spectroscopy. The calculated surface area of the synthesized Pd(DAP‐DEAS‐MERF) catalyst is 4.018 m2/g and palladium content is found to be 5.16 % from AAS analysis. After this, the synthesized catalyst was successfully applied for the synthesis of aromatic esters and quinazoline‐2,4(1H,3H)‐diones in high efficiency. Aromatic esters were synthesized by the in‐situ carbonylative coupling reaction of iodobenzenes and phenols using chlorofirmand KOH as CO source.In the case of quinazoline‐2,4(1H,3H)‐diones synthesis, CO2 fixation reaction was performed with 2‐iodoaniline derivatives and tert‐butyl isocyanide/cyclohexyl isocyanide under atmospheric CO2 pressure. The synthesized products were identified by 1HNMR spectroscopy after purifying by coloum chromatography technique. In this report, Pd(DAP‐DEAS‐MERF) catalyst proved its efficiency by providing a comparatively better reaction condition than the other reported homogeneous and heterogeneous catalytic systems. Additionally, the catalyst isrecyclable up to six times and thermally stable up to 319 °C.