Ethyl Acetates Research Articles

DABCO‐Mediated [4+1] Annulation of Cyclopropane‐1,1‐dicarbonitriles with Ethyl Glycinate to Access Ethyl (2‐Amino‐1H‐pyrrol‐1‐yl)acetates

AbstractAn effective DABCO‐promoted (4+1) annulation reaction for the synthesis of ethyl (2‐amino‐1H‐pyrrol‐1‐yl)acetate derivatives from 2‐aroyl‐3‐arylcyclopropane‐1,1‐dicarbonitriles and ethyl glycinate was developed. This strategy is characterized by the readily accessible starting materials, mild conditions, and simplicity of operation.

Discovering the volatilome fingerprint of selected traditional Cuban wines elaborated with native grapes, tropical fruits, and rice using DHS-TD-GC-MS.

Cuban wine is a traditional alcoholic beverage elaborated with a wide variety of raw materials, such as native grapes, tropical fruits, and rice, and different winemaking processes. Research on Cuban wines is almost nonexistent, and therefore, a study of these wines is necessary to improve their quality. Dynamic headspace (DHS)-TD-gas chromatography-mass spectrometry (GC-MS) analysis was carried out to establish the different aroma fingerprints of different Cuban wines. A total of 42 volatile aroma metabolites (VAMs) were identified, including esters, alcohols, aldehydes, acids, volatile phenols, terpenes, and lactones. The odorant activity values (OAV) of each VAM were obtained, and the esters were the most relevant group due to their highest OAV. Ethyl octanoate, hexanoate, and butanoate stand out and are considered key odorants in the aromatic fingerprint. The VAMs were grouped into seven aromatic series. Fruity series showed the highest OAVs due to the contribution of ethyl esters and acetates. Principal component analysis was used to identify the specific parameters most accurately reflecting the differences between the wines. Showing that fruity, spicy, and chemical aromatic series allow distinguishing the wines into three aroma types. These results may provide useful information for the selection of raw materials and optimization of the traditional winemaking processes of Cuban wines. PRACTICAL APPLICATION: This research contributes to knowledge of the aroma and the oenological parameters of traditional and selected Cuban wines (rice wine, tropical fruit wine, and native grape varieties). The establishing of the aroma fingerprint of these wines provides useful information for the industrial development of a quality product that may then be promoted in other areas of the world.

Dissolution dynamics of zirconia nanocluster resist

The metal oxide resists are promising materials for the high numerical aperture EUV lithography. In the metal oxide resists, the bridging ligands are generated upon exposure to radiations, which results in the formation of a pattern insoluble in developers. In this study, the dissolution dynamics of zirconia nanocluster resist was investigated using a quartz crystal microbalance method. The ligand was methacrylate. The developers used were ethyl, butyl, amyl, hexyl, 2-methylbutyl, and 3-methylbutyl acetates. The zirconia nanocluster resist showed characteristic dissolution dynamics. After the immersion into developers, the frequency slowly decreased with approximately constant impedance (no viscosity change of the film) for a while and then rapidly dissolved with the softening of resist film. The dependences of dissolution dynamics on the molecular structures of acetates and post exposure baking were clarified. The effect of branched structure at the third position of butyl was, in particular, remarkable.

Screening and characterization of indigenous non-Saccharomyces cerevisiae with high enzyme activity for kiwifruit wine production

To explore the diversity and fermentation potential of non-Saccharomyces cerevisiae associated with kiwifruit, indigenous yeasts isolated from kiwifruit and natural fermentation were comprehensively analyzed. A total of 166 indigenous yeasts were isolated, of which 54 representative strains were used for subsequent enzyme activity characterization. Different colorimetric methods were used to verify the ability of these strains to secrete hydrolytic enzymes, and then six strains were selected for sequential fermentation by specific activity assay. The performance of indigenous yeasts in improving organic acids, polyphenols, volatile compounds and sensory characteristics of wines was evaluated holistically. Results indicated that most sequential fermentations exhibited significant improvements in vitamin C and polyphenols. Remarkably, the involvement of Zygosaccharomyces rouxii, Meyerozyma guilliermondii, and Pichia kudriavzevii increased the concentrations of ethyl esters, acetates and alcohols, enhancing floral and tropical fruit odors and ultimately achieving the highest overall sensory acceptability, thereby highlighting their potential in kiwifruit wine fermentation.

Enhancing lipases reactivity in benzylic acetates hydrolysis: impact of kosmotropic salts under non-conventional conditions

The effect of four kosmotropic salts additives, namely Na2CO3, Na2SO4, Na2HPO4, and NaCl, on the reactivity and selectivity of immobilized Candida antarctica lipase B (CAL-B) and a free lipase of Pseudomonas cepacia (PCL) during the hydrolysis of rac-4-(1-methoxyphenyl) ethyl and rac − 1-phenyl ethyl acetates (1a-2a) was investigated in this study. The study was carried out in two different mediums: non-aqueous conditions and in low water content media. The impact of the anionic counter-ions was examined in four solvents: nonpolar, semipolar, protic, and aprotic, with and without the aforementioned salts. In non-aqueous media, the addition of Na2CO3 significantly enhanced CAL-B hydrolysis rates, resulting in a conversion of 50% for 1a and 44% for 2a, with high enantioselectivities (E > 200). These effects were independent of the solvent hydrophobicity. In contrast, PCL required the presence of external water for effective hydrolysis of both acetates. The addition of salt additives had an adverse impact on PCL activity during the hydrolysis of 1a in hexane, toluene, and TBME solvents. However, when 2M2B was used, the inclusion of salt additives had a notable positive effect on the conversion rates, except for NaCl, which resulted in a lower conversion rate with a value of 15.5%. The presence of Na2CO3 improved the conversion rate during the hydrolysis of 2a in both hexane and TBME. Na2HPO4 further enhanced the conversion rate, reaching 44% in TBME. However, in 2M2B solvent, the addition of Na2HPO4 significantly reduced the enantioselectivity.

Bioactive Secondary Metabolites Extracted from Some Species of Candida Isolated from Women Infected with Vulvovaginal Candidiasis

Candida spp. are well known for their impact on our life as opportunistic pathogens and can produce secondary metabolites, which are an interesting source of high-value chemicals and are often diffi cult to synthesize chemically. Some of these metabolites are already being used as active antimicrobials or pharmaceuticals. GC-MS analysis of chemical compounds was conducted in ethyl acetate of fi ve Candida species (C. parapsilosis, C. albicans, C. krusei, C. glabrata and C. kefyr). The results showed that about 249 chemical compounds were detected from all tested Candida species. Fifteen bioactive compounds identifi ed in secondary metabolites of all tested species. Benzene, pentamethyl, n-hexadecanoic acid, 1-docosene and bis(2-ethylhexyl) produced by C. parapsilosis, C. albicans, C. krusei and C. glabrata. All tested Candida except C. krusei produced 3buten- 1-ol and ethyl acetoacetate ethylene acetal. Benzen, 2-ethenyl-1,3-dimethyl- a compound found in four tested Candida except C. albicans, benezene, (1-ethyl-1-propenyl)- produced by all species except C. glabrata, acetic acid, cyclohexyl ester produced by C. parapsilosis, C. albicans and C. glabrata.

Total Synthesis of Aculenes B and D

AbstractThe first total synthesis of aculene D, a structurally rare nordaucane‐type natural product exhibiting quorum sensing inhibitory activity, has been accomplished from a known five‐membered hydroxy carboxylic acid. Nucleophilic addition of methallylzinc bromide to a β‐keto aldehyde intermediate under Barbier conditions to install the secondary hydroxy group on the seven‐membered ring of aculene D gave the corresponding alcohol with an undesired configuration predominantly. On the other hand, the protection of its keto group as the ethylene acetal induced a reversal of diastereoselectivity, affording a desired diastereomer in a selective manner. The construction of the seven‐membered ring was realized by ring‐closing metathesis using a triethylsilyl‐protected monocyclic diene ester precursor. An additional five‐step manipulation on the cyclization product including the installation of an ethyl group on the five‐membered ring completed the synthesis of aculene D, whose esterification with an N‐protected l‐proline followed by deprotection also achieved the first total synthesis of aculene B.

Theoretical study of the side reactions of ethanol-to-butadiene conversion on MgO catalyst: formation of diethyl ether, ethyl acetal, 1,3-butanediol, methyl ethyl ketone, n-butanol, butanal, and acetone

Theoretical study of the side reactions of ethanol-to-butadiene conversion on MgO catalyst: formation of diethyl ether, ethyl acetal, 1,3-butanediol, methyl ethyl ketone, n-butanol, butanal, and acetone

Structure and cytotoxic properties of 1-hydroxy-5-methyl-7-phenylpyrido[3,4-d]pyridazin-4(3H)-one and its mono- and disubstituted ethyl acetates.

Derivatives of pyrido[3,4-d]pyridazine, namely, 1-hydroxy-5-methyl-7-phenylpyrido[3,4-d]pyridazin-4(3H)-one dimethylformamide monosolvate, C14H11N3O2·C3H7NO (2), ethyl [1-(2-ethoxy-2-oxoethoxy)-5-methyl-4-oxo-7-phenyl-3,4-dihydropyrido[3,4-d]pyridazin-3-yl]acetate, C18H17N3O4 (3), and ethyl [(5-methyl-4-oxo-7-phenyl-3,4-dihydropyrido[3,4-d]pyridazin-1-yl)oxy]acetate, C22H23N3O6 (4), were synthesized with the aim of discovering new potential biologically active agents. The properties of all three derivatives were characterized by 1H NMR, 13C NMR and FT-IR spectroscopic analysis. All the crystals were obtained by a solvent diffusion method from dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) and characterized by single-crystal X-ray diffraction. The collected X-ray data revealed that the crystals of 2 and 4 belong to the triclinic space group P-1, whereas the crystal of 3 belongs to the monoclinic space group P21/c. The presented derivatives crystallized with one molecule in the asymmetric unit, but only compound 2 crystallized as a solvate with DMF. Structure analysis showed that the molecule of 2 exists as its amide-imidic acid tautomer and that O-alkylation occurred before N-alkylation during the synthesis of the mono- and disubstituted derivatives, i.e. 3 and 4, respectively. The molecular geometries of the 5-methyl-7-phenylpyrido[3,4-d]pyridazine core within the studied derivatives differ in the mutual orientation of the rings. The interplanar angles between the heterocyclic ring and the bound aromatic ring are 1.71 (7), 18.16 (3) and 3.1 (1)° for 2, 3 and 4, respectively. The potential cytotoxicity of these compounds was evaluated against one normal (HaCat) and four human cancer cell lines (A549, DU145, MDA-MB-231 and SKOV-3).

Adsorption equilibria of ester VOCs (ethyl and butyl acetates) on activated carbon in supercritical CO2: Measurement and modeling by the Dubinin–Astakhov equation

The adsorption equilibria of ethyl and butyl acetates, the main volatile organic compounds (VOCs) used in the printing industry, on activated carbon were measured in supercritical CO2 at 10–20 MPa and 313–353 K. The measured adsorption equilibria of the VOCs decreased with increasing pressure and decreasing temperature. The amount of butyl acetate adsorption was greater than that of ethyl acetate, owing to differences in the affinities of the VOCs for the adsorbent and in their volatilities in supercritical CO2. The measured adsorption equilibria were correlated using the Dubinin–Astakhov equation to within an average relative deviation of 3.1 %. Furthermore, the parameters determined by this correlation strongly depended on the CO2 density and VOC properties. These analyses enabled us to evaluate the adsorption phenomena of the ester VOCs in supercritical CO2, including the effects of the interaction between the VOC and adsorbent, and the CO2 density.

RIFM fragrance ingredient safety assessment, formaldehyde cyclododecyl ethyl acetal, CAS Registry Number 58567-11-6

• Formaldehyde cyclododecyl ethyl acetal; a safety assessment based on RIFM's criteria. • A safety assessment based on 7 human health endpoints plus environmental. • All endpoints were cleared using target data, read-across, and/or TTC.

Immobilization of Rh(I)-N-Xantphos and Fe(II)-C-Scorpionate onto Magnetic Nanoparticles: Reusable Catalytic System for Sequential Hydroformylation/Acetalization

Two heterogeneous catalysts, MNP@SiO2-N-Xantphos/Rh(I) and MNP@SiO2-NH-C-scorpionate/Fe(II), were prepared by reaction of chloro-functionalized MNP@SiO2 with N-Xantphos and amino-functionalized MNP@SiO2 with iron(II)/C-allyl-scorpionate through nucleophilic substitution and hydroaminomethylation reactions, respectively. All catalysts were characterized using standard spectroscopic means, transmission electron microscopy (TEM), thermogravimetry (TG), and inductively coupled plasma optical emission spectrometry (ICP-OES). An active and highly selective one-pot hydroformylation/acetalization homogeneous system for the transformation of terminal and highly substituted olefins (including terpenes) onto ethyl acetals is described. A synergic effect of bimetallic Rh(I)/P and Fe(II)/C-scorpionate catalysts is disclosed for the first time. The further sequential use of the heterogeneous catalysts, MNP@SiO2-N-Xantphos/Rh(I) and MNP@SiO2-NH-C-scorpionate/Fe(II) in hydroformylation/acetalization reactions allows the direct transformation of olefin onto ethyl acetals, keeping the activity and selectivity. Both catalysts were easily recovered by magnetic separation and reused with negligible loss of activity/selectivity, after six reutilization cycles.

Aromatic and Sensory Characterization of Maturana Blanca Wines Made with Different Technologies

Vitis vinífera L. cv. Maturana Blanca is an autochthonous minor variety recently recovered in the Rioja Qualified Denomination of Origin (D.O.Ca Rioja, Spain) for the production of monovarietal white wines with singular and differentiated characteristics. In this paper, Maturana Blanca wines made with different technologies were analyzed by sensory analysis and aromatic profile by gas chromatography-mass detector. Maturana Blanca wines were characterized by low pH, high acidity, and yellowish tonalities. The compounds that most influenced the aroma of Maturana Blanca wines were those related to fruity (acetates and ethyl esters), floral aromas (2-phenylethanol), and spicy notes (γ-decalactone). These wines were mainly characterized by volatile compounds of fruity aromas of banana and apple. The use of pre-fermentative maceration increased the concentration of ethyl esters and acetates and produced wines with higher odor activity values, indicating a greater aromatic intensity. The aromatic profile of Maturana Blanca wines fermented in oak barrels showed a greater complexity as they were also characterized by the presence of important amounts of furfural, whiskey lactone, and eugenol. The sensory analysis confirmed the results obtained in the aromatic analysis, and described the wines as fresh and balanced in mouth, with notes of acidity and medium to high persistence. These results will contribute to a better knowledge of this white variety.

DTBP-promoted site-selective α-alkoxyl C-H functionalization of alkyl esters: synthesis of 2-alkyl ester substituted chromanones.

The direct C-H functionalization of ethyl acetates was developed, delivering a variety of 1-(4-oxochroman-2-yl)ethyl acetate derivatives by reacting with chromones. This reaction has a wide substrate scope with excellent site-selective C-H activation at the inactive α-hydrogen of the alkoxyl group instead of the α-hydrogen of the carbonyl group under radical conditions. Compared with other protocols for the α-alkoxyl C-H functionalization of alkyl esters, a distinguishing feature of this reaction is that no metal catalyst was required, with DTBP as the sole oxidant.

Influence of tetraconazole on the proteome profile of Saccharomyces cerevisiae Lalvin T73™ strain

This work aimed to evaluate the modifications on the proteome profile of Saccharomyces cerevisiae T73™ strain as a consequence of its adaptive response to the presence of tetraconazole molecules in the fermentation medium. Pasteurised grape juices were separately supplemented with tetraconazole or a commercial formulation containing 12.5% w/v of tetraconazole at two concentration levels. In addition, experiments without fungicides were developed for comparative purposes.Proteome profiles of yeasts cultured in the presence or absence of fungicide molecules were different. Independently of the fungicide treatment applied, the highest variations concerning the control sample were observed for those proteins involved in metabolic processes, especially in the metabolism of nitrogen compounds. Tetraconazole molecules altered the abundance of several enzymes involved in the biosynthesis of amino acids, purines, and ergosterol. Moreover, differences in the abundance of several enzymes of the TCA cycle were found. Changes observed were different between the active substance and the commercial formulation. SignificanceThe presence of fungicide residues in grape juice has direct implications on the development of the aromatic profile of the wine. These alterations could be related to changes in the secondary metabolism of yeasts. However, the molecular mechanisms involved in the response of yeasts to fungicide residues remains quite unexplored. Through this exhaustive proteomic study, alterations in the amino acids biosynthesis pathways due to the presence of the tetraconazole molecules were observed. Amino acids are precursors of some important higher alcohols and ethyl acetates (such as methionol, 2-phenylethanol, isoamyl alcohol or 2-phenylacetate). Besides, the effect of tetraconazole on the ergosterol biosynthesis pathway could be related to a higher production of medium-chain fatty acids and their corresponding ethyl acetates.

Synthesis, Structure, Reactivity and Catalytic Implications of a Cationic, Acetylide-Bridged Trigold-JohnPhos Species.

The cationic complex [(JohnPhos-Au)3 (acetylide)][SbF6 ] (JohnPhos=(2-biphenyl)di-tert-butylphosphine, L1) has been characterised structurally and features an acetylide-trigold(I)-JohnPhos system; the trinuclear-acetylide unit, coordinated to the monodentate bulk phosphines, adopts an unprecedented μ,η1 ,η2 ,η1 coordination mode with an additional interaction between distal phenyl rings and gold centres. Other cationic σ,π-[(gold(I)L1)2 ] complexes have also been isolated. The reaction of trimethylsilylacetylene with various alcohols (iPrOH, nBuOH, n-HexOH) catalysed by cationic [AuI L1][SbF6 ] complexes in CH2 Cl2 at 50 °C led to the formation of acetaldehyde acetals with a high degree of chemo- and regioselectivity. The reaction mechanism was studied, and several organic and inorganic intermediates have been characterised. A comparative study with the analogous cationic [CuI L1][PF6 ] complex revealed different behaviour; the copper metal is lost from the coordination sphere leading to the formation of cationic vinylphosphonium and copper nanoparticles. Additionally, a new catalytic approach for the formation of this high-value cationic vinylphosphonium has been established.

Синтез и биологическая активность этиловых эфиров 2-[8-арилметилиденгидразино-3-метил-7-(1-оксотиетанил-3)-ксантинил-1]уксусных кислот

Этиловые эфиры 2-[8-арилметилиденгидразино-3-метил-7-(1-оксотиетанил-3)ксантинил-1]уксусных кислот (IV) синтезированы реакцией этилового эфира 2-[8-гидразино-3-метил-7-(1-оксотиетанил-3)ксантинил-1]уксусной кислоты (III) с различными бензальдегидами и ацетофенонами. Структура соединений установлена с помощью ИК-, ЯМР спектроскопии и элементного анализа. Исследования in vitro и на лабораторных животных для оценки антиагрегантной, антикоагулянтной, антиоксидантной и противовоспалительной активности выявили перспективные соединения, проявляющие антиагрегантные (гидразон IVd) и антиоксидантные (гидразон IVb) свойства. По расчётам in silico оба соединения IVb, d характеризуются отсутствием токсических рисков (мутагенности, онкогенности, репродуктивной токсичности и местного раздражающего действия) и приемлемой площадью топологической полярной поверхности (TPSA), поэтому эти соединения перспективны.

Grape water: reclaim and valorization of a by-product from the industrial cryoconcentration of grape (Vitis vinifera) must.

The term 'grape (Vitis vinifera) water' refers to a by-product from the cryoconcentration of must that, if not reclaimed, would be considered as wastewater. In this study, the nutraceutical potential of waters reclaimed from the cryoconcentration of Grillo and Moscato musts was evaluated. Both waters showed physicochemical parameters in agreement with Italian regulation for drinking water, and interesting levels of F- (3.02-8.02 mg L-1 ) and SO4 - (52.85-49.34 mg L-1 ). Inorganic elements, including Mg (5.54-7.78 mg L-1 ), K (47.12-59.87 mg L-1 ), Fe (219.09-205.32 μg L-1 ), and Zn (189.65-127.30 μg L-1 ), and phenolic contents <35 mg GAE L-1 contributed to determine moderate antioxidant activities. Considering fatty acid composition, oleic and linoleic acids predominated, being higher in Moscato than Grillo samples (64.42% versus 58.22%, and 5.42% versus 6.07%). Grape waters displayed also rich aroma profiles, including mainly esters, alcohols and terpenoids. The latter components (i.e. linalool and α-terpineol) were more abundant in Moscato than in Grillo (13% versus 8%). Interestingly, some minor volatiles, characterized the vine of provenance (e.g. benzaldehyde and 3-methylbutylacetate in Moscato). All grape waters showed also a considerable fraction of ethyl lactate, six-carbon compounds and acetates, reflecting the proximity of samples to the grapes of origin. In a growing scenario of environmental decay and resource depletion, results from this study support an innovative and profitable waste recycling strategy for the wine industry. © 2020 Society of Chemical Industry.

Densities, viscosities and excess parameters of octanol with alkyl(C1 – C4) acetates at varying temperatures

The density and viscosity of binary mixtures of octanol with methyl, ethyl, propyl and butyl acetates were experimentally measured (T = 298.15, 303.15, 308.15and 313.15 K) at 1 atm over the complete range of mixture composition. Based on the measurements, excess molar volume, viscosity deviation, and excess Gibbs free energy were evaluated. The calculated excess properties were then fitted to the Redlich-Kister polynomial to obtain the coefficients. All the experimental values for the pure components were comparable with the existing research values. The consequences were discussed in terms of molecular interactions prevailing in the mixtures. 15 different approaches especially some recently developed ones have been employed, both predictive and correlative, for predicting viscosity values and a comparative study carried out thereof.

Synthesis of Benzo[1,2‐b:4,5‐b’]dithiophene and Benzocondensed Thiaheterocycles

AbstractA two‐step synthesis of benzo[1,2‐b:4,5‐b’]dithiophene (BDT) was carried out starting from 3‐thiophene carbaldehyde as the sole thiophene precursor. This method involves the selective lithiation of the 2‐position of 3‐thiophenecarbaldehyde ethylene acetal, followed by the condensation with 3‐thiophenecarbaldehyde and subsequent dehydrative cycloaromatization of the dithienylmethanol intermediate to give BDT. This synthetic pathway was extended to other thiophene benzocondensed heterocycles.