Journal articles: 'Ethers'

1

Kim, Yong-Hak, and Karl-Heinrich Engesser. "Degradation of Alkyl Ethers, Aralkyl Ethers, and Dibenzyl Ether by Rhodococcus sp. Strain DEE5151, Isolated from Diethyl Ether-Containing Enrichment Cultures." Applied and Environmental Microbiology 70, no. 7 (July 2004): 4398–401. http://dx.doi.org/10.1128/aem.70.7.4398-4401.2004.

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ABSTRACT Twenty strains isolated from sewage sludge were found to degrade various ethers, including alkyl ethers, aralkyl ethers, and dibenzyl ether. In Rhodococcus strain DEE5151, induction of ether degradation needed substrates exhibiting at least one unsubstituted Cα-methylene moiety as the main structural prerequisite. The cleavage reaction observed with anisole, phenetole, and dibenzyl ether indicates that the initial oxidation occurs at such respective Cα positions. Diethyl ether-induced strain DEE5151 degraded dibenzyl ether via intermediately accumulated benzoic acid. Phenetole seems to be subject also to another ether-cleaving enzyme. Other strains of this group showed different enzymatic activities towards the substrate classes investigated.

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Zmysłowski, Adam, Jerzy Sitkowski, Katarzyna Bus, Katarzyna Michalska, and Arkadiusz Szterk. "Synthesis of Oxidized 3β,3′β-Disteryl Ethers and Search after High-Temperature Treatment of Sterol-Rich Samples." International Journal of Molecular Sciences 22, no. 19 (September 27, 2021): 10421. http://dx.doi.org/10.3390/ijms221910421.

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It was proven that sterols subjected to high-temperature treatment can be concatenated, which results in polymeric structures, e.g., 3β,3′β-disteryl ethers. However, it was also proven that due to increased temperature in oxygen-containing conditions, sterols can undergo various oxidation reactions. This study aimed to prove the existence and perform quantitative analysis of oxidized 3β,3′β-disteryl ethers, which could form during high-temperature treatment of sterol-rich samples. Samples were heated at 180, 200 and 220 °C for 0.5 to 4 h. Quantitative analyses of the oxidized 3β,3′β-disteryl ethers were performed with liquid extraction, solid-phase extraction and liquid chromatography coupled with mass spectrometry. Additionally, to perform this analysis, the appropriate standards of all oxidized 3β,3′β-disteryl ethers were prepared. Eighteen various oxidized 3β,3′β-disteryl ethers (derivatives of 3β,3′β-dicholesteryl ether, 3β,3′β-disitosteryl ether and 3β,3′β-distigmasteryl ether) were prepared. Additionally, the influence of metal compounds on the mechanism of ether formation at high temperatures was investigated.

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Dachavaram, Soma Shekar, Narsimha R. Penthala, Julie L. Calahan, Eric J. Munson, and Peter A. Crooks. "Highly sulphated cellulose: a versatile, reusable and selective desilylating agent for deprotection of alcoholic TBDMS ethers." Organic & Biomolecular Chemistry 16, no. 33 (2018): 6057–62. http://dx.doi.org/10.1039/c8ob01438h.

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A mild, effcient protocol was developed for the deprotection of alcoholic TBDMS ethers using highly sulphated HS-cellulose sulphate catalyst, which selectively cleaves alcoholic TBDMS ethers in bis-TBDMS ethers containing both alcoholic and phenolic TBDMS ether moieties.

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Palanychamy, Prakas, Steven Lim, Yeow Hong Yap, and Loong Kong Leong. "Critical Review of the Various Reaction Mechanisms for Glycerol Etherification." Catalysts 12, no. 11 (November 21, 2022): 1487. http://dx.doi.org/10.3390/catal12111487.

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This review provides in-depth coverage of numerous mechanisms available for the etherification process of glycerol, including alcohol solvent, olefin solvent and solvent-free routes along with products that are formed at various stages of the reaction. Mono tert-butyl glycerol ether (MTBG), di tert-butyl glycerol ether (DTBG), and tri tert-butyl glycerol ether (TTBG) are the three general ether compounds obtained through tert-butyl alcohol (TBA) etherification. Glycerol etherification with n-butanol results in the formation of glycerol ether products that are linked to the substituted butyl groups. These products include two mono-butyl glycerol ethers, two di-butyl glycerol ethers and a tri-butyl glycerol ether. Two mono-benzyl glycerol ether isomers, two di-benzyl glycerol ether isomers and tri-benzyl glycerol ether are the most reported results when benzyl alcohol is used as a solvent in the etherification reaction. The etherification of glycerol with 1-butene involves a series of equilibrium reactions to produce mono-ethers, di-ethers, and tri-ethers, whereas the etherification of glycerol with isobutene is carried out via tert-butylation of glycerol, yielding similar glycerol ether products when TBA is used as a solvent. As the by-product may be easily removed, the solvent-free glycerol etherification approach may have several advantages over the other conventional methods. Therefore, further studies on base-catalyzed glycerol etherification that employs a solvent-free reaction route may reveal a method for improving the conversion, selectivity, and yield of reaction products. This review study is crucial in improving knowledge of numerous mechanisms and how they relate to the effectiveness of the product’s catalytic process.

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Modrzakowski, Malcolm C., and William R. Finnerty. "Intermediary metabolism of Acinetobacter grown on dialkyl ethers." Canadian Journal of Microbiology 35, no. 11 (November 1, 1989): 1031–36. http://dx.doi.org/10.1139/m89-171.

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The microbial dissimilation of long-chain dialkyl ethers by Acinetobacter sp. H01-N involved a terminal methyl group oxidation of the dialkyl ether substrates, resulting in the formation of ether oxygen containing fatty acids of corresponding chain length. An internal carbon–carbon scission of the dialkyl ethers resulted in the formation of end-product ether fatty acids and corresponding dicarboxylic acids. Cellular carbon and energy were derived from the subsequent metabolism of the dicarboxylic acids. Dicarboxylic acid oxidation, activation, and identification of cellular dicarboxylic acids indicated dibasic acids as intermediates in the metabolism of dialkyl ethers.Key words: dialkyl ethers, dicarboxylic acids, fatty acids, Acinetobacter.

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Ragauskas, Arthur J., and J. B. Stothers. "13C magnetic resonance studies. 120. The Simmons–Smith reaction with some silyl enol ethers. Unusual ring expansions of some norcamphorsti." Canadian Journal of Chemistry 63, no. 11 (November 1, 1985): 2969–74. http://dx.doi.org/10.1139/v85-492.

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Unexpected difficulties with Simmons–Smith cyclopropanation of the trimethylsilyl enol ether of exo-tricyclo[3.2.1.02,4]-octan-6-one led to a reexamination of this reaction with the parent norcamphor derivative which under "concentrated" conditions gave ring-expanded allylic ethers in low yield. With the tert-butyldimethylsilyl ethers, however, the allylic product is formed in high yield in the norcamphor and exo-trimethylenenorcamphor (tricyclo[5.2.1.02,6]decan-8-one) systems. The tert-butyldimethylsilyl enol ethers of bicyclo[3.2.1]octan-6-one and nopinone do not undergo ring expansion under similar conditions but the silyl ether of 3-methylenenopinol is a major product in the latter case.

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Sireesha, Reddymasu, Reddymasu Sreenivasulu, Choragudi Chandrasekhar, and Mannam Subba Rao. "A Facile, Efficient and Selective Deprotection of P - Methoxy Benzyl Ethers Using Zinc (II) Trifluoromethanesulfonate." Letters in Organic Chemistry 16, no. 12 (October 9, 2019): 955–58. http://dx.doi.org/10.2174/1570178616666190222151934.

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: Deprotection is significant and conducted over mild reaction conditions, in order to restrict any more side reactions with sensitive functional groups as well as racemization or epimerization of stereo center because the protective groups are often cleaved at last stage in the synthesis. P - Methoxy benzyl (PMB) ether appears unique due to its easy introduction and removal than the other benzyl ether protecting groups. A facile, efficient and highly selective cleavage of P - methoxy benzyl ethers was reported by using 20 mole% Zinc (II) Trifluoromethanesulfonate at room temperature in acetonitrile solvent over 15-120 min. time period. To study the generality of this methodology, several PMB ethers were prepared from a variety of substrates having different protecting groups and subjected to deprotection of PMB ethers using Zn(OTf)2 in acetonitrile. In this methodology, zinc triflate cleaves only PMB ethers without affecting acid sensitivity, base sensitivity and also chiral epoxide groups.

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8

Mireles, Raul, Joaquin Ramirez-Ramirez, Miguel Alcalde, and Marcela Ayala. "Ether Oxidation by an Evolved Fungal Heme-Peroxygenase: Insights into Substrate Recognition and Reactivity." Journal of Fungi 7, no. 8 (July 28, 2021): 608. http://dx.doi.org/10.3390/jof7080608.

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Ethers can be found in the environment as structural, active or even pollutant molecules, although their degradation is not efficient under environmental conditions. Fungal unspecific heme-peroxygenases (UPO were reported to degrade low-molecular-weight ethers through an H2O2-dependent oxidative cleavage mechanism. Here, we report the oxidation of a series of structurally related aromatic ethers, catalyzed by a laboratory-evolved UPO (PaDa-I) aimed at elucidating the factors influencing this unusual biochemical reaction. Although some of the studied ethers were substrates of the enzyme, they were not efficiently transformed and, as a consequence, secondary reactions (such as the dismutation of H2O2 through catalase-like activity and suicide enzyme inactivation) became significant, affecting the oxidation efficiency. The set of reactions that compete during UPO-catalyzed ether oxidation were identified and quantified, in order to find favorable conditions that promote ether oxidation over the secondary reactions.

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Ghosh, Arun, Anthony Tomaine, and Kelsey Cantwell. "Lewis Acid Mediated Cyclizations: Diastereoselective Synthesis of Six- to Eight-Membered Substituted Cyclic Ethers." Synthesis 49, no. 18 (July 25, 2017): 4229–46. http://dx.doi.org/10.1055/s-0036-1589054.

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Cyclic ethers are widely abundant in natural products. Cyclic ether templates are also utilized in drug design and medicinal chemistry. Although the synthetic processes for this class of compounds have been studied extensively with respect to five- and six-membered rings, medium-sized cyclic ethers are synthetically more challenging due to a variety of factors. Herein, we report our results on the Lewis acid catalyzed synthesis of medium-sized cyclic ethers in a diastereoselective manner.

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Verevkin, Sergey P., and Aleksandra A. Zhabina. "Platform Chemicals from Ethylene Glycol and Isobutene: Thermodynamics “Pays” for Biomass Valorisation and Acquires “Cashback”." Chemistry 5, no. 2 (May 9, 2023): 1171–89. http://dx.doi.org/10.3390/chemistry5020079.

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Ethylene glycol (EG) produced from biomass is a promising candidate for several new applications. In this paper, EG derivatives such as mono- and di-tert-butyl ethers are considered. However, accurate thermodynamic data are essential to optimise the technology of the direct tert-butyl ether EG synthesis reaction or reverse process isobutene release. The aim of this work is to measure the vapour pressures and combustion energies for these ethers and determine the vaporisation enthalpies and enthalpies of formation from these measurements. Methods based on the First and Second Law of Thermodynamics were combined to discover the reliable thermodynamics of ether synthesis reactions. The thermochemical data for ethylene glycol tert-butyl ethers were validated using structure–property correlations and quantum chemical calculations. The literature results of the equilibrium study of alkylation of EG with isobutene were evaluated and the thermodynamic functions of ethylene glycol tert-butyl ethers were derived. The energetics of alkylation determined according to the “First Law” and the “Second Law” methods agree very well. Some interesting aspects related to the entropy of ethylene glycol tert-butyl ethers were also revealed and discussed.

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11

Iranpoor, Nasser, Habib Firouzabadi, and Mohammad Gholinejad. "4-Aminophenyldiphenylphosphinite (APDPP), a new heterogeneous and acid scavenger phosphinite — Conversion of alcohols, trimethylsilyl, and tetrahydropyranyl ethers to alkyl halides with halogens or N-halosuccinimides." Canadian Journal of Chemistry 84, no. 7 (July 1, 2006): 1006–12. http://dx.doi.org/10.1139/v06-120.

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A new heterogeneous phosphinite, 4-aminophenyldiphenylphosphinite (APDPP), is prepared and used for the efficient conversion of alcohols, trimethylsilyl ethers, and tetrahydropyranyl ethers to their corresponding bromides, iodides, and chlorides in the presence of molecular halogens or N-halosuccinimides. The amino group in this phosphinite acts as an acid scavenger and removes the produced acid. A simple filtration easily removes the phosphinate by-product.Key words: 4-aminophenyldiphenylphosphinite, alcohol, trimethylsilyl ether, tetrahydropyranyl ether, alkyl halide.

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12

Navarro, Jaume. "Killed by its own obituaries: Explaining the demise of the ether." Science in Context 34, no. 2 (June 2021): 209–25. http://dx.doi.org/10.1017/s0269889722000175.

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ArgumentIn this paper I follow the demise of the ether in the first half of the twentieth century to show how the first obituaries of the ether were instrumental in creating an object with specific and largely simplified properties related to, but different from, nineteenth-century ethers. I suggest that writing the history of dead objects (or objects an author wants to be dead) is not epistemologically neutral but, on the contrary, it involves a reformulation of the object itself. I show that this was indeed the case with the ether: those arguing for its demise in the early twentieth century tended to overlook as irrelevant one of the ether’s most important properties, namely being the seat for the transmission of electromagnetic waves. Instead, they emphasized the contradictions between other properties of previous ether(s), so as to advocate for its disappearance.

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13

Hajko, J., G. Szabovik, J. Kerekgyarto, M. Kajtar, and A. Liptak. "Hydrogenolysis of the 4,6-O-Ketals of Glucopyranosides. Configuration-Dependent High Regio- and Stereo-Selectivity of the Diastereoisomeric Acetophenone Derivatives." Australian Journal of Chemistry 49, no. 3 (1996): 357. http://dx.doi.org/10.1071/ch9960357.

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Hydrogenolysis (reductive cleavage) of the (R) isomers of the acetophenone 4,6-O-derivatives of glucopyranosides with LiAlH4/AlCl3 gives the 4-O-(1'-phenylethyl) ethers with (R) configuration; the corresponding (S) isomers produce the respective (R) 6-O-(1'-phenylethyl ) ethers are produced. The hydrogenolysis of other 4,6-O-ketals affords O 4 ether derivatives; the two diastereoisomeric 4,6-O-s-butylidene derivatives (cyclic ketals ) give O 4-ethers with the opposite absolute configuration. The stereoselectivity of these reactions is explained by the development of a four-centre transition state. The absolute configuration of the ethers has been determined by means of circular dichroism measurements.

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14

Andersen, F. Alan. "Special Report: Reproductive and Developmental Toxicity of Ethylene Glycol and Its Ethers." International Journal of Toxicology 18, no. 2_suppl (March 1999): 53–67. http://dx.doi.org/10.1177/109158189901800208.

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Polymers of Ethylene Glycol are linked via ether linkages with various alcohols or via ester linkages to various fatty acids in many cosmetic ingredients. Ethylene Glycol, when reacted with an alkyl alcohol, forms an ethylene glycol monoalkyl ether. These compounds are metabolized in the human body by alcohol dehydrogenase and aldehyde dehydrogenase to form corresponding acetaldehyde and acetic acid derivatives. Data are presented that show reproductive and developmental toxicity is associated with metabolites of ethylene glycol monoalkyl ethers, but not with the monoalkyl ethers themselves. Further, it is suggested that the toxicity of these metabolites is inversely proportional to the length of the alkyl chain in the original alkyl ether. In the case of the compounds used in cosmetics, most have alcohols or fatty acids linked to polyethylene glycol chains, not a single Ethylene Glycol moiety. Where Ethylene Glycol is linked to a fatty acid by an ester linkage, the resulting compound is chemically different from the monoalkyl ethers. Where Ethylene Glycol is linked to an alcohol via an ether linkage, the alkyl chain is large and complex, suggesting little or no potential toxicity. Overall, it was found that metabolites of ethylene glycol monoalkyl ethers are reproductive and developmental toxins. In general, however, the metabolites of concern are not expected to be formed in cosmetic formulations that contain polymers of ethylene glycol.

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Fronczek, Frank R., Richard D. Gandour, Thomas M. Fyles, Philippa J. Hocking, Susan J. McDermid, and P. Daniel Wotton. "Polycarboxylate crown ethers from meso-tartaric acid." Canadian Journal of Chemistry 69, no. 1 (January 1, 1991): 12–19. http://dx.doi.org/10.1139/v91-003.

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The synthesis of crown ethers derived from meso-tartaric acid was investigated. The sodium salt of the bis(dimethylamide) of meso-tartaric acid reacted with diethylene glycol ditosylate to give a mixture of 18-crown-6 tetraamide and 27-crown-9 hexaamide crown ethers. The 2R,3S,11S,12R 18-crown-6 isomer crystallized in triclinic space group [Formula: see text] (a = 7.557(2), b = 8.866(2), c = 10.4133(13) Å, α = 94.13(2), β = 95.86(2), γ = 99.26(2)°, R = 0.040 for 2090 observed of 3129 unique reflections). The structures of the remaining products were then assigned from the NMR spectra. The solution conformations of the amide crown ethers were examined by NMR, and provide a rationale for the product distribution obtained. One of the 18-crown-6 isomers and a mixture of the two 27-crown-9 isomers were hydrolyzed to the respective crown ether carboxylic acids, and the stability constants for complexation of cations were determined by potentiometric titration. The meso tetra- and hexacarboxylates are remarkably nonselective and inefficient cation complexing agents, compared to related crown ethers from R,R-(+)-tartaric acid, due to the unfavorable conformational control exerted by the tartaro units. Key words: crown ether synthesis, complexation, crown ether conformation, meso-tartaric acid, crystal structure.

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Sang, Dayong, Jiahui Wang, Yun Zheng, Jianyuan He, Caili Yuan, Qing An, and Juan Tian. "Carbodiimides as Acid Scavengers in Aluminum Triiodide Induced Cleavage of Alkyl Aryl Ethers." Synthesis 49, no. 12 (March 14, 2017): 2721–26. http://dx.doi.org/10.1055/s-0036-1588755.

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A practical procedure for the cleavage of alkyl aryl ethers containing labile functional groups has been developed using aluminum triiodide as the ether cleaving reagent. Carbodiimides, typically used as dehydration reagents for the coupling of amines and carboxylic acids to yield amide bonds, are found to be effective hydrogen iodide scavengers that prevent acid-labile groups from deterioration. The method is applicable to variant alkyl aryl ethers such as eugenol, vanillin, ortho-vanillin and methyl eugenol. Suitable substrates are not limited to alkyl o-hydroxyphenyl ethers.

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Pranowo, Harno Dwi, and Chairil Anwar. "INTERACTION BETWEEN Li⁺ CATION WITH CROWN ETHERS OF Bz15C5, DBz16C5 AND DBz18C6: MOLECULAR MODELING BASE ON MNDO/d SEMIEMPIRICAL METHOD." Indonesian Journal of Chemistry 3, no. 1 (June 7, 2010): 55–66. http://dx.doi.org/10.22146/ijc.21906.

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The aim of this research is to find information about the substituent effect to the structure of crown ether benzo-15-crown-5 (Bz15C5), dibenzo-16-crown-5 (DBz16C5) and dibenzo-18-crown-6 (DBz18C6), and also crown ether selectivity to coordinate a Li+ metal cation. The presence of substituent could change the conformations flexibility of crown ether during interact with metal cation. In this research semi empirical MNDO/d method was used for calculations. Firstly, geometry optimization was conducted to crown ethers structure using MNDO/d methods. The next steps were running the geometry optimization of complexes between cation Li+ with crown ethers. Data were produced from these calculation are the parameter of crown ether structures, structures of the complexes, and the binding energy of the cation-crown ethers. The presence of electron-withdrawing substituents decreased the binding energy while that of electron-donating one increase the binding energy (value of ΔE more negative). The substituents which are increase the degree of symmetry of the cation-crown ether complexes could give the increase of crown ether selectivity to bind the cation. Selectivity of crown ether to bind the cation depends on the structural match between ionic radii of crown ether cavity (the ion-cavity size concept). Bz15C5 what has higher selectivity to bind Li+ than DBz16C5 and DBz18C6. Keywords: selectivity, crown ether, MNDO/d.

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18

Szemenyei, Balázs, Balázs Novotny, Sarolta Zsolnai, Zsombor Miskolczy, László Biczók, Attila Takács, László Kollár, László Drahos, Ildikó Móczár, and Péter Huszthy. "Push or Pull for a Better Selectivity? A Study on the Electronic Effects of Substituents of the Pyridine Ring on the Enantiomeric Recognition of Chiral Pyridino-18-Crown-6 Ethers." Symmetry 12, no. 11 (October 30, 2020): 1795. http://dx.doi.org/10.3390/sym12111795.

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Seven dimethyl-substituted optically active pyridino-18-crown-6 ethers containing various substituents at position 4 of the pyridine ring were studied with regards to the electron-donating and -withdrawing effects of substituents on enantiomeric recognition. In order to compile this set of compounds, we prepared four novel pyridino-18-crown-6 ethers, including an intermediate of a new synthetic route for a formerly reported crown ether. The discriminating ability of these pyridino-crown ethers with C2-symmetry toward the enantiomers of protonated primary amines was examined by isothermal titration calorimetry.

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Ollevier, Thierry, and Topwe M. Mwene-Mbeja. "Diastereoselective bismuth triflate catalyzed Claisen rearrangement of 2-alkoxycarbonyl-substituted allyl vinyl ethers." Canadian Journal of Chemistry 86, no. 3 (March 1, 2008): 209–12. http://dx.doi.org/10.1139/v07-149.

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In the presence of a catalytic amount of bismuth triflate, 2-alkoxycarbonyl-substituted allyl vinyl ethers as a mixture of enol ether double bond isomers were smoothly converted into the β,γ-alkyl-substituted α-keto esters. The isomerization reaction proceeded rapidly to afford smoothly the α-keto esters in good to excellent yields using catalytic amounts of Bi(OTf)3·4H2O (1 mol%). (Z,Z)-2-iso-Propyloxycarbonyl-substituted allyl vinyl ethers 3Z,Z afforded the corresponding β,γ-alkyl-substituted α-keto esters 4 with very good syn diastereoselectivity.Key words: bismuth; bismuth(III) triflate; Claisen rearrangement; allyl vinyl ethers.

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Hosoya, Akihiro, Tadashi Narita, and Hiroshi Hamana. "Radical Additions of Heptafluoropropyl Trifluorovinyl Ether." Collection of Czechoslovak Chemical Communications 73, no. 12 (2008): 1663–70. http://dx.doi.org/10.1135/cccc20081663.

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The radical addition reactions of heptafluoropropyl trifluorovinyl ether (CF2=CF-O-C3F7) with cyclic ethers such as tetrahydrofuran, tetrahydropyran, 1,4-dioxane and 1,3-dioxolane were investigated to afford the corresponding one to one addition products in fairly high yields in the presence of dibenzoyl peroxide at 60 °C. The method provides a facile way to prepare cyclic ethers possessing fluoroalkyl substituents.

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Schuster, Judith, Jessica Purswani, Uta Breuer, Clementina Pozo, Hauke Harms, Roland H. Müller, and Thore Rohwerder. "Constitutive Expression of the Cytochrome P450 EthABCD Monooxygenase System Enables Degradation of Synthetic Dialkyl Ethers in Aquincola tertiaricarbonis L108." Applied and Environmental Microbiology 79, no. 7 (January 25, 2013): 2321–27. http://dx.doi.org/10.1128/aem.03348-12.

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ABSTRACTInRhodococcus ruberIFP 2001,Rhodococcus zopfiiIFP 2005, andGordoniasp. strain IFP 2009, the cytochrome P450 monooxygenase EthABCD catalyzes hydroxylation of methoxy and ethoxy residues in the fuel oxygenates methyltert-butyl ether (MTBE), ethyltert-butyl ether (ETBE), andtert-amyl methyl ether (TAME). The expression of the IS3-type transposase-flankedethgenes is ETBE dependent and controlled by the regulator EthR (C. Malandain et al., FEMS Microbiol. Ecol. 72:289–296, 2010). In contrast, we demonstrated by reverse transcription-quantitative PCR (RT-qPCR) that the betaproteobacteriumAquincola tertiaricarbonisL108, which possesses theethABCDgenes but lacksethR, constitutively expresses the P450 system at high levels even when growing on nonether substrates, such as glucose. The mutant strainA. tertiaricarbonisL10, which is unable to degrade dialkyl ethers, resulted from a transposition event mediated by a rolling-circle IS91-type element flanking theethgene cluster in the wild-type strain L108. The constitutive expression of Eth monooxygenase is likely initiated by the housekeeping sigma factor σ70, as indicated by the presence in strain L108 of characteristic −10 and −35 binding sites upstream ofethAwhich are lacking in strain IFP 2001. This enables efficient degradation of diethyl ether, diisopropyl ether, MTBE, ETBE, TAME, andtert-amyl ethyl ether (TAEE) without any lag phase in strain L108. However, ethers with larger residues,n-hexyl methyl ether, tetrahydrofuran, and alkyl aryl ethers, were not attacked by the Eth system at significant rates in resting-cell experiments, indicating that the residue in the ether molecule which is not hydroxylated also contributes to the determination of substrate specificity.

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Taniguchi, Takashi, Yasuaki Taketomo, Mizuki Moriyama, Noritada Matsuo, and Yoo Tanabe. "Synthesis and Stereostructure-Activity Relationship of Novel Pyrethroids Possessing two Asymmetric Centers on a Cyclopropane Ring." Molecules 24, no. 6 (March 14, 2019): 1023. http://dx.doi.org/10.3390/molecules24061023.

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2-Methylcyclopropane pyrethroid insecticides bearing chiral cyanohydrin esters or chiral ethers and two asymmetric centers on the cyclopropane ring, were synthesized. These compounds were designed using a “reverse connection approach” between the isopropyl group in Fenvalerate, and between two dimethyl groups in an Etofenprox analogue (the methyl, ethyl form), respectively. These syntheses were achieved by accessible ring opening reactions of commercially available (±)-, (R)-, and (S)-propylene oxides using 4-chlorobenzyl cyanide anion as the crucial step, giving good overall yield of the product with >98% ee. The insecticidal activity against the common mosquito (Culex pipiens pallens) was assessed for pairs of achiral diastereomeric (1R*,2S*)-, (1R*,2R*)-cyanohydrin esters, and (1R*,2S*)-, (1R*,2R*)-ethers; only the (1R*,2R*)-ether was significantly effective. For the enantiomeric (1S,2S)-ether and (1R,2R)-ether, the activity was clearly centered on the (1R,2R)-ether. The present stereostructure‒activity relationship revealed that (i) cyanohydrin esters derived from fenvalerate were unexpectedly inactive, whereas ethers derived from etofenprox were active, and (ii) apparent chiral discrimination between the (1S,2S)-ether and the (1R,2R)-ether was observed. During the present synthetic study, we performed alternative convergent syntheses of Etofenprox and novel 4-EtO-type (1S,2S)- and (1R,2R)-pyrethroids from the corresponding parent 4-Cl-type pyrethroids, by utilizing a recently-developed hydroxylation cross-coupling reaction.

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Aikawa, Haruo, Tetsuro Kaneko, Naoki Asao, and Yoshinori Yamamoto. "Gold-catalyzed alkylation of silyl enol ethers with ortho-alkynylbenzoic acid esters." Beilstein Journal of Organic Chemistry 7 (May 20, 2011): 648–52. http://dx.doi.org/10.3762/bjoc.7.76.

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Unprecedented alkylation of silyl enol ethers has been developed by the use of ortho-alkynylbenzoic acid alkyl esters as alkylating agents in the presence of a gold catalyst. The reaction probably proceeds through the gold-induced in situ construction of leaving groups and subsequent nucleophilic attack on the silyl enol ethers. The generated leaving compound abstracts a proton to regenerate the silyl enol ether structure.

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Štěpánek, Petr, Ondřej Vích, Lukáš Werner, Ladislav Kniežo, Hana Dvořáková, and Pavel Vojtíšek. "Stereoselective Preparation of Precursors of α-C-(1→3)-Disaccharides." Collection of Czechoslovak Chemical Communications 70, no. 9 (2005): 1411–28. http://dx.doi.org/10.1135/cccc20051411.

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The stereoselectivity of cycloaddition of sugar-containing substituted 1-(thiazol-2-yl)but-2-en-1-ones 1 and vinyl ethers was studied using the achiral vinyl ether/chiral catalyst as well as the chiral vinyl ether/achiral catalyst combinations. It has been shown that Eu(fod)3-catalyzed cycloaddition of oxadienes 1a-1e with the chiral vinyl ethers 9 and 10 affords stereoselectively almost pure cycloadducts 11a-11e and 12a-12e, respectively. The obtained cycloadducts are suitable precursors for the synthesis of α-C-(1→3)-disaccharides, containing 2-deoxy-arabino-hexopyranose moiety of D- or L-configuration.

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Masiunas, John B. "Tomato (Lycopersicon esculentum) Tolerance to Diphenyl Ether Herbicides Applied Postemergence." Weed Technology 3, no. 4 (December 1989): 602–7. http://dx.doi.org/10.1017/s0890037x00032887.

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Tolerance of tomato cultivars to diphenyl ether herbicides applied postemergence was determined in greenhouse and field experiments. In greenhouse experiments, tomato cultivar tolerance differed, but acifluorfen injured all genotypes. ‘Carmen’, ‘PetoPride 2’ and ‘Heinz 1350’ tolerated acifluorfen while ‘Advantage’, and ‘Red Plum’ were susceptible. Growth habit and tolerance to 1.1 kg ae/ha acifluorfen was significantly correlated (r2= 0.24). Field-planted tomato cultivars' tolerance to diphenyl ether herbicides applied postemergence differed. Heinz 1350 and ‘Veeroma’ tolerated diphenyl ethers, while Advantage and Red Plum were susceptible. Potency of diphenyl ethers also varied with oxyfluorfen the most injurious and acifluorfen and fomesafen the least injurious.

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26

Samoylov, V. O., T. I. Stolonogova, D. N. Ramazanov, E. V. Tyurina, V. A. Lavrent'ev, Yu I. Porukova, E. A. Chernysheva, and V. M. Kapustin. "tert-Butyl Ethers of Renewable Diols as Oxygenated Additives for Motor Gasoline. Part I: Glycerol and Propylene Glycol Ethers." Нефтехимия 63, no. 2 (April 15, 2023): 220–30. http://dx.doi.org/10.31857/s0028242123020065.

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The study investigates tert-butoxy alkanols (otherwise defined as polyol tert-butyl ethers) that have vicinal tert-butoxy and hydroxy groups in their molecules from the perspective of their usability as oxygenated additives for motor gasoline. A series of propylene glycol mono-tert-butyl ether (PTBE) and glycerol di-tert-butyl ether (di-GTBE) samples were prepared: PTBE by direct acid-catalytic alkylation of diols with tert-butanol, and di-GTBE by alkylation of epichlorohydrin. Adding PTBE and di-GTBE to base motor gasoline was found to improve its antiknock performance: the average blending research octane number to blending motor octane number ratios (bRON/bMON) equaled 120/111 and 124/104 for PTBE and di-GTBE, respectively. Furthermore, the effects of the ether additives on the properties of ethanol-blended base gasoline were characterized. Finally, the study describes the effect of polyol tert-butyl ether additives on the cloud point depression of ethanol-blended gasoline (low-temperature phase stabilization) and demonstrates a positive synergistic effect of adding the ethers mixed with ethanol

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27

Schaefer, Ted, Kerry J. Cox, Cherrie L. Morier, Christian Beaulieu, Rudy Sebastian, and Glenn H. Penner. "Motion about the bond in benzyl OR (R = CH3, CH2CH3, CH(CH3)2, C(CH3)3). Solvent and substituent dependence." Canadian Journal of Chemistry 68, no. 9 (September 1, 1990): 1553–58. http://dx.doi.org/10.1139/v90-240.

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The 1H nuclear magnetic resonance spectral parameters of benzyl alkyl ethers (CH3, CH2CH3, CH(CH3)2, and C(CH3)3) in CS2 and acetone-d6 solutions are obtained, as are those for the 3,5-dichloro derivatives (CH3, CH2CH3, and CH(CH3)3) in acetone-d6 solution. The long-range coupling constants between the methylene and para ring protons show that the apparent twofold barrier to rotation about the [Formula: see text] bond is solvent and ring-substituent dependent. The apparent twofold barrier ranges from a vanishing value for benzyl methyl ether in CS2 solution to as much as 4.6 kJ/mol for 3,5-dichlorobenzyl isopropyl ether in acetone-d6 solution. The data imply that, for the free molecules, the conformation of highest energy has the CH2—O bond in a plane perpendicular to that of the phenyl group. Molecular orbital computations with a minimal Gaussian basis set agree that, for benzyl methyl ether in the exo form (the methyl group pointing away from the phenyl moiety), this conformation is the least stable. However, geometry optimization procedures imply that the CH2—O bond is twisted out of the ring plane by 30.3° in the most stable geometry of the exo form. Such procedures for the (distorted) endo form locate another stable conformer, in which the CH2—O bond is twisted out of the phenyl plane by 45°, only 0.25 kJ/mol less stable than the most stable conformer of the exo form. These results, together with some computations for the tert-butyl derivative, are discussed in terms of the theoretical potentials for rotation about the [Formula: see text] bond. The approximate potential surface is rather flat compared to kT at ambient temperatures for the free molecules, consistent with its sensitivity to the medium and to ring substituents. Keywords: 1H NMR, benzyl alkyl ethers; long-range coupling constants in benzyl alkyl ethers; conformations, benzyl alkyl ethers; internal motion, benzyl alkyl ethers; MO computations on benzyl methyl ether.

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28

Esseffar, M'hamed, Mohamed El Mouhtadi, José-Luis M. Abboud, José Elguero, and Daniel Liotard. "Étude théorique (AM1) de l'affinité protonique des polyéthers cycliques (éthers couronnes) et non cycliques (glymes)." Canadian Journal of Chemistry 69, no. 12 (December 1, 1991): 1970–75. http://dx.doi.org/10.1139/v91-283.

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Semi-empirical calculations at the AM1 level have been used to study the proton affinity (PA) of polyether compounds (dioxane, glymes, and crown ethers). The calculated values, although systematically lower than the experimental ones, are linearly correlated with eight experimental PA's (r = 0.993). Taking into account the considerable conformational changes that take place upon protonation, the result is highly satisfactory and provides an estimate of proton affinity for 9-ether-crown-3 (206.5 kcal mol−1) and glyme-5 (231.1 kcal mol−1). Moreover, this work provides a rationale for the fact that, for the same number of oxygen atoms, glymes are more basic than crown ethers. For the crown ethers, the proton affinity depends on angular strain in the base and on intramolecular hydrogen bonds in the cation. Key words: protonation, reactivity, glymes, crown ethers, coordination.

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29

Li, Yiting, Song Sun, Jiang Cheng, and Jin-Tao Yu. "Alkylarylation of N-allylbenzamides and N-allylanilines with simple ethers for the direct construction of ether substituted dihydroisoquinolinones and indolines." Organic & Biomolecular Chemistry 18, no. 4 (2020): 650–54. http://dx.doi.org/10.1039/c9ob02565k.

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30

Anantanarayan, Ashok, and Thomas M. Fyles. "Polycarboxylate diaza crown ethers derived from R,R-(+)-tartaric acid: synthesis and complexation of metal ions." Canadian Journal of Chemistry 68, no. 8 (August 1, 1990): 1338–51. http://dx.doi.org/10.1139/v90-206.

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The synthesis and complexation properties of polycarboxylate diaza crown ethers based on R,R-(+)-tartaric acid are described. Cesium carbonate mediated macrocyclization of a bis-tosylamide precursor with a bis-tosylate precursor provided the protected crown ethers. Photochemical deprotection of the tosylamides and hydrolysis of the carboxamides yielded dicarboxylic and tetracarboxylic acid derivatives of 1,10-diaza-18-crown-6. N-Methylenecarboxylate (N-acetate) derivatives were prepared by N-alkylation with bromoacetic acid. The synthetic and purification procedures developed provide samples of the ligands in a metal-free form. Acidity and stability constants for complexation of alkali metal, alkaline earth, late- and post-transition metal cations were determined by potentiometric titration. The ligands form complexes which show enhancement of stability by charge–charge and chelate interaction with the carboxylates. In comparison with crown ether polycarboxylates these aza crown ethers showed a selectivity for softer metal ions relative to alkali and alkaline earth metal ions. N-Methylenecarboxylate chelate ligands were found to bind almost all types of metal ions, due to a highly co-operative array of charge–charge, chelate and crown ether interactions. Keywords: aza crown ether synthesis, tartaric acid, potentiometric titration, cation complexation, aminocarboxylate complexone.

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31

Metzger, Pierre, and Eliette Casadevall. "Botryococcoid ethers, ether lipids from Botryococcus braunii." Phytochemistry 30, no. 5 (January 1991): 1439–44. http://dx.doi.org/10.1016/0031-9422(91)84181-q.

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32

Perrott, A. L., H. J. P. De Lijser, and D. R. Arnold. "The importance of conformational effects on the carbon–carbon bond cleavage of β-phenethyl ether radical cations." Canadian Journal of Chemistry 75, no. 4 (April 1, 1997): 384–97. http://dx.doi.org/10.1139/v97-044.

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The photosensitized (electron transfer) bond cleavage of some β-phenylethyl ether radical cations has been investigated. In previous studies the feasibility of the bond cleavage was thought to depend on the bond dissociation energy (BDE). However, this simple hypothesis led to several incorrect predictions and therefore additional criteria, conformational effects, were added to the hypothesis. This study has now been extended and additional examples of the importance of the conformation on the carbon–carbon bond cleavage of radical cations are provided. The four β-phenylethyl ethers studied are 2-methoxy-3-phenylbutane (9, both diastereomers), and cis- and trans-2-methyl-3-phenyltetrahydropyran (10c, 10t). Generally, bond cleavage will occur if the (calculated) BDE in the radical cation is less than 55 kJ/mol, and if there is significant overlap between the singly occupied molecular orbital (SOMO) and the vulnerable (C—C or C—H) bond. In the case of a β-phenylethyl ether radical cation, the alkoxy group must also be oriented so that an oxygen lone pair of electrons can overlap with the C—C sigma antibonding (σ*) orbital. The calculated BDE values of the vulnerable C—C bond in the radical cations of the four ethers studied here are well below the threshold value, 55 kJ/mol, and C—C cleavage will therefore be governed by conformational effects. Molecular mechanics (MM3) calculations were used to identify the most stable conformers of the neutral molecules. Based on the calculated angles and overlap between orbitals it was predicted that the global-minimum conformers of the ethers 9 and 10c would not give C—C bond cleavage products or deprotonation to any significant extent. The global minimum of ether 10t is well oriented for C—C cleavage but not for deprotonation. Irradiation of an electron-accepting photosensitizer, 1,4-dicyanobenzene (2), in the presence of the ethers showed that the ethers 9 did not cleave efficiently; no deprotonation or isomerization was observed. This is in good agreement with the predictions based on the MM3 calculations. Both ethers 10c and 10t gave reasonable yields of the C—C cleavage products; in fact, ether 10c cleaved more efficiently than 10t. This can be explained by the fact that a conformer of 10c, only 4.35 kJ/mol higher in energy than the global minimum, is perfectly aligned for cleavage. Ether 10t did not show any evidence for deprotonation whereas 10c did. This is also in good agreement with the calculations. Keywords: photoinduced electron transfer, radical cations, bond cleavage, conformation, molecular mechanics calculations.

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33

Saengarun, Chakrapong, Amorn Petsom, and Duangamol Nuntasri Tungasmita. "Etherification of Glycerol with Propylene or 1-Butene for Fuel Additives." Scientific World Journal 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/4089036.

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The etherification of glycerol with propylene over acidic heterogeneous catalysts, Amberlyst-15, S100, and S200 resins, produced mono-propyl glycerol ethers (MPGEs), 1,3-di- and 1,2-di-propyl glycerol ethers (DPGEs), and tri-propyl glycerol ether (TPGE). The propylation of glycerol over Amberlyst-15 yielded only TPGE. The glycerol etherification with 1-butene over Amberlyst-15 and S200 resins produced 1-mono-, 2-mono-, 1,2-di-, and 1,3-di-butyl glycerol ethers (1-MBGE, 2-MBGE, 1,2-DBGE, and 1,3-DBGE). The use of Amberlyst-15 resulted in the propylation and butylation of glycerol with higher yields than those obtained from the S100 and S200 resins. The PGEs, TPGE, and BGEs were evaluated as cold flow improvers and octane boosters. These alkyl glycerol ethers can reduce the cloud point of blended palm biodiesels with diesel. They can increase the research octane number and the motor octane number of gasoline.

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34

Taguchi, Hiroyasu, Bela Paal, and Wilfred L. F. Armarego. "Glyceryl-Ether Monooxygenase [EC 1.14.16.5J Part VIII. Probing the Nature of the Active Site." Pteridines 6, no. 2 (May 1995): 45–57. http://dx.doi.org/10.1515/pteridines.1995.6.2.45.

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Summary The V /K kinetic parameters for glyceryl-ether monooxygenase with 3-1 '-n-alkoxypropane-I,2-diols having alkyl sidechains varying from Cll to C22 (lb-k, 2a and b, and 3d) were determined. Maximum activity was found with the CI6 ethers, dropping almost to zero with ethers that have sidechains shorter than Cl2 and longer than C19. The thioether analogues with C16 and CI8 sidechains were poorer substrates than the respective oxygen ethers by one order of magnitude. The kinetic parameters for 2-1 '-n-hexadecyloxy- (6a) and 2-1 '-n-octadecyloxy- (6d) ethanol revealed that they were also better substrates than the respective thio-ethers by one order of magnitude and with these compounds those with C16 sidechains were better substrates than the C 18 analogues. L2-bis-3-1 '-n-Hexadecyloxypropan-3-01 (3c) and 1,3-bis-3- 1'-n-hexadecyloxypropan-3-01 and 2- 01 (4a) were inactive but 3-1'-n-hexadecyloxy- 2-methoxypropan-I-ol (3b) and 3-1'-n-hexadecyloxy-l-methoxypropan-2-01 (4b) which have one long fatty chain were viable substrates because they possessed a free hydroxy group, but the ethers (6b, c and e), (7c and d) and (5) which do not have a free hydroxy group were inactive. These data, taken with those reported previously, have allowed us to postulate a model for the active site of the alkyl-ether substrates of the monooxygenase and to define the contours of the hydrophobic and hydrophilic pockets.

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35

Mao, Ying, Min Cao, Xiaoguang Pan, Jiancheng Huang, Jing Li, Liren Xu, and Lei Liu. "Bimolecular oxidative C–H alkynylation of α-substituted isochromans." Organic Chemistry Frontiers 6, no. 12 (2019): 2028–31. http://dx.doi.org/10.1039/c9qo00352e.

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36

Han, Jianhua, Kuanyu Yuan, Cheng Liu, Jinyan Wang, and Xigao Jian. "Donor–acceptor copolymers containing the phthalazinone–thiophene structure synthesized by classical nucleophilic aromatic polymerization." RSC Advances 5, no. 39 (2015): 30445–55. http://dx.doi.org/10.1039/c5ra03771a.

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37

Mulero, A., I. Cachadiña, and A. Becerra. "Recommended Correlations for the Surface Tension of Ethers." Journal of Physical and Chemical Reference Data 52, no. 1 (March 1, 2023): 013103. http://dx.doi.org/10.1063/5.0139446.

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Surface tension values for 82 ethers have been compiled from databases, books, and papers in the literature. The data were carefully screened, and finally, 2122 values were selected. Each fluid dataset has been fitted with the Guggenheim–Katayama correlation with two, four, or six adjustable parameters, except diphenyl ether, for which the data taken from different sources clearly disagree. Thus, recommended correlations are proposed for 81 ethers. The proposed correlations provide mean absolute deviations equal to or below 0.5 mN/m and mean absolute percentage deviations below 2.6% for 79 ethers. Moreover, percentage deviations below 9.5% are obtained for all the selected data of 78 ethers. The highest deviations found are due to the disagreement between the data obtained from different sources and not to an inadequate mathematical form of the correlation model. These correlations are added to the collection of those previously proposed for different fluids, including common substances, alcohols, refrigerants, organic acids, n-alkanes, and esters.

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38

Jiang, Dandan, Jun Xiao, Yingzhen Zhang, Kunming Liu, Juanhua Li, and Jinbiao Liu. "Lewis Acid-Initiated Ring-Opening Reactions of Five- and Six-Membered Cyclic Ethers Based on the Oxonium Ylide Intermediates." Organics 5, no. 3 (July 22, 2024): 219–36. http://dx.doi.org/10.3390/org5030011.

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In light of the small ring strain of five/six-membered cyclic ethers, constructing complex molecules via ring-opening reactions has consistently been a highly challenging topic in organic synthesis. Induced by Lewis acids, the charge redistribution in cyclic ethers forms oxonium ylide intermediates, thereby activating the C–O bond and subsequently facilitating nucleophilic attack for ring opening. In recent years, a variety of novel Lewis acids, encompassing those with new metal centers and frustrated Lewis pairs (FLPs), have been effectively utilized to induce the formation of oxonium ylides, offering a diverse array of methods for the ring opening of five/six-membered cyclic ethers. This review conveys the extensive application advancements of diverse Lewis acid types for cyclic ether ring-opening reactions over the past two decades, originating from the perspective of the classification of Lewis acids. Furthermore, the substrate applicability and chemical transformation efficiency of these Lewis acids in the ring-opening reactions of cyclic ethers have also been discussed herein.

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39

Jin, Qingwu, and Robert M. Coates. "Synthesis of Methoxynor Polyisoprenoid Alcohols by Alkylation of (3-Methoxyallyl)lithium Reagents." Collection of Czechoslovak Chemical Communications 67, no. 1 (2002): 55–74. http://dx.doi.org/10.1135/cccc20020055.

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A series of six methyl enol ether analogs 8-13 of geraniol, (E,E)-farnesol, and (E,E,E)-geranylgeraniol was synthesized from a group of three allylic methyl ethers and three allylic chlorides. Lithiation of the 1-methyl-, or 1-alkenylvinyl ethers with sec-butyllithium at -78 °C followed by alkylations of the resulting (Z)-(3-methoxyallyl)lithium reagents afforded the six possible Z-configured(trans) methoxynor polyprenyl benzyl ethers bearing the methoxy substituent at the internal and terminal double bonds with high Z/E ratios (5 : 1-31 : 1) and 47-80% yields. Reductive cleavage of the benzyl groups with lithium in liquid ammonia gave the corresponding methoxynor polyprenols. 11-Methoxy-18-nor and 7-methoxy-19-nor geranylgeraniols (13 and 12) were converted to the corresponding diphosphates, 7 and 32, by the Poulter displacement method. The stability of the enol ether in 7 in aqueous solution at pH 8 was verified by NMR analyses. The diphosphates of the methoxynor polyprenols may prove useful as substrate analogs for terpene synthases to capture transient intermediates in cyclization reactions catalyzed by these enzymes.

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40

Li, Jianxiao, Dan He, Zidong Lin, Liying Cen, Wanqing Wu, and Huanfeng Jiang. "NHC–palladium-catalyzed ionic liquid-accelerated regioselective oxyarylation of alkynes with diaryl ethers." Green Chemistry 24, no. 5 (2022): 1983–88. http://dx.doi.org/10.1039/d1gc04556c.

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41

Zaharani, Lia, and Nader Ghaffari Khaligh. "Recent Developments in Catalytic Reductive Etherifications." Malaysian Catalysis-An International Journal 2, no. 1 (October 21, 2022): 21–31. http://dx.doi.org/10.22452/mcij.vol2no1.2.

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Ether derivatives are versatile organic compounds and have been applied in various fields of academia and the chemical industry. Therefore, it is highly desirable to create procedures for their manufacture that are more efficient and sustainable. Catalytic reductive etherification with carbonyl moiety such as ketones/ aldehydes and carboxylic acid derivatives has recently been recognized as a possible tool among the several techniques reported for ether production. These procedures offer promising methods to selectively produce ethers with higher molecular structures, both symmetrical and asymmetrical. This Review provides an update on current developments in the field of catalytic reductive etherification, which synthesize ethers utilising an alcohol and an aldehyde substrate. Applications for organic synthesis and catalyst design are given special attention.

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42

Zimnicka, Magdalena M. "Crown ethers as shift reagents in peptide epimer differentiation –conclusions from examination of ac-(H)FRW-NH2 petide sequences." International Journal for Ion Mobility Spectrometry 23, no. 2 (October 2020): 177–88. http://dx.doi.org/10.1007/s12127-020-00271-2.

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Abstract Crown ethers with different ring sizes and substituents (18-crown-6, dibenzo-18-crown-6, dicyclohexano-18-crown-6, a chiral tetracarboxylic acid-18-crown-6 ether, dibenzo-21-crown-7, and dibenzo-30-crown-10) were evaluated as shift reagents to differentiate epimeric model peptides (tri-and tetrapeptides) using ion mobility mass spectrometry (IM-MS). The stable associates of peptide epimers with crown ethers were detected and examined using traveling-wave ion mobility time-of-flight mass spectrometer (Synapt G2-S HDMS) equipped with an electrospray ion source. The overall decrease of the epimer separation upon crown ether complexation was observed. The increase of the effectiveness of the microsolvation of a basic moiety - guanidine or ammonium group in the peptide had no or little effect on the epimer discrimination. Any increase of the epimer separation, which referred to the specific association mode between crown substituents and a given peptide sequence, was drastically reduced for the longer peptide sequence (tetrapeptide). The obtained results suggest that the application of the crown ethers as shift reagents in ion mobility mass spectrometry is limited to the formation of complexes differing in stoichiometry rather than it refers to a specific coordination mode between a crown ether and a peptide molecule.

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43

Tian, Juan, Dayong Sang, Xiaodong Tu, Zhoujun He, and Ming Yao. "Cleavage of Catechol Monoalkyl Ethers by Aluminum Triiodide–Dimethyl Sulfoxide." Synthesis 51, no. 03 (September 26, 2018): 704–12. http://dx.doi.org/10.1055/s-0037-1610996.

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Using eugenol and vanillin as model substrates, a practical method is developed for the cleavage o-hydroxyphenyl alkyl ethers. Aluminum oxide iodide (O=AlI), generated in situ from aluminum triiodide and dimethyl sulfoxide, is the reactive ether cleaving species. The method is applicable to catechol monoalkyl ethers as well as normal phenyl alkyl ethers for the removal of methyl, ethyl, isopropyl, and benzyl groups. A variety of functional groups such as alkenyl, allyl, amide, cyano, formyl, keto, nitro, and halogen are well tolerated under the optimum conditions. Partial hydrodebromination was observed during the demethylation of 4-bromoguaiacol, and was resolved using excess DMSO as an acid scavenger. This convenient and efficient procedure would be a practical tool for the preparation of catechols.

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44

Baumstark, Alfons L., Franci Kovac, and Pedro C. Vasquez. "Oxidation of secondary alcohols and ethers by dimethyldioxirane." Canadian Journal of Chemistry 77, no. 3 (March 1, 1999): 308–12. http://dx.doi.org/10.1139/v99-011.

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The oxidation of several series of secondary alcohols 2-9, ethers 10-17, and related derivatives 18 and19, by dimethyldioxirane, 1, in acetone at 25°C produced the corresponding ketones in good to excellent yields for all but two cases. (The exceptions: oxidation of 1-methoxy-2-methyl-1-phenylpropane (48%) and 1-methoxy-2,2-dimethyl-1-phenylpropane (24%).) The oxidation of the secondary alcohols was found to yield k2 values that were roughly 10-fold greater than those of the corresponding methyl ethers. The rate constant for oxidation of a silyl ether was slightly lower than that for the corresponding methyl ether while that for the ester derivative was roughly half the value. For oxidation of alcohols and methyl ethers, the k2 values became smaller as the R " series (Me, Et, nPr, iPr, and tBu) increased in steric bulk (ρ* = 1.7; r = 0.998 and ρ* = 3.2; r = 0.95, respectively). The Hammett study for the oxidation of the methyl ethers of α-methyl-p-benzyl alcohols (10, 20-25) yielded a ρ value of -0.74. The activation parameters for oxidation of the parent compound of the ether series (1-methoxy-1-phenylethane) were ΔH = 14.8 ± 0.5 kcal/mol, ΔS = -21.9 eu, ΔG = 21.3 kcal/mol, k2 (25°C) = 1.6 × 10-3 M-1 s-1. The mechanistic aspects of the oxidation are discussed in relation to two mechanistic extremes: (a) direct insertion of the oxygen atom into the CH bond and (b) direct abstraction of the H by dimethyldioxirane to yield a caged-radical pair, with subsequent coupling to hemi-ketal intermediates that fragment to yield acetone, alcohol or water, and ketone as the final products.Key words: dimethyldioxirane, oxidation.

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45

Browning, Randall G., and Steven C. Curry. "Effect of Glycol Ethers on Plasma Osmolality." Human & Experimental Toxicology 11, no. 6 (November 1992): 488–90. http://dx.doi.org/10.1177/096032719201100608.

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1 Glycol ethers and their alkoxyacetic acid metabolites produce a linear increase in plasma osmolality with increasing plasma concentration. 2 This change in osmolality may be too small to be clinically useful at concentrations expected in cases of acute human glycol ether poisoning.

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46

Ragauskas, Arthur J., and J. B. Stothers. "13C magnetic resonance studies. 119. Tricyclo[3.3.0.0] and [3.2.1.0]octanones from substituted norbornenones via cyclopropanation and homoketonization." Canadian Journal of Chemistry 63, no. 11 (November 1, 1985): 2961–68. http://dx.doi.org/10.1139/v85-491.

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Simmons–Smith cyclopropanation of the trimethylsilyi enoi ethers of 7-isopropylidene- and two 7-spirocyclopropyl-norbomenones leads directly to the 8-substituted 2-trimethylsilyl ethers of homoquadricyclene. Homoketonization of the unsaturated ether proceeds regiospecifically to the corresponding tricyclo[3.3.0.02.8]octan-4-one while the others give the tricyclo[3.2.1.02.6]octan-4-ones exclusively, all with high stereoselectivity favoring inversion of configuration. This difference in the regiochemistry of homoketonization can be attributed to a directive effect of β-functionalization overcoming thermodynamic control of cleavage.

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47

Oh, Young-Ho, Ju Gyeong Jeong, Dong Wook Kim, and Sungyul Lee. "Nucleophilic Reactions Using Alkali Metal Fluorides Activated by Crown Ethers and Derivatives." Catalysts 13, no. 3 (February 27, 2023): 479. http://dx.doi.org/10.3390/catal13030479.

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We review crown ether-facilitated nucleophilic reactions using metal salts, presenting the studies using kinetic measurements and quantum chemical methods. We focus on the mechanistic features, specifically on the contact ion-pair (CIP) mechanism of metal salts for nucleophilic processes promoted by crown ethers and derivatives. Experimental verification of the CIP form of the metal salt CsF complexed with [18-Crown-6] by H-NMR spectroscopy is described. The use of chiral crown ethers and derivatives for enantioselective nucleophilic processes is also discussed.

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48

Dian, Longyang, Qingyu Xing, Daisy Zhang-Negrerie, and Yunfei Du. "Direct functionalization of alkyl ethers to construct hemiaminal ether skeletons (HESs)." Organic & Biomolecular Chemistry 16, no. 24 (2018): 4384–98. http://dx.doi.org/10.1039/c8ob00793d.

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49

Vaughn, Steven F., and Gayland F. Spencer. "Synthesis and Herbicidal Activity of Modified Monoterpenes Structurally Similar to Cinmethylin." Weed Science 44, no. 1 (March 1996): 7–11. http://dx.doi.org/10.1017/s0043174500093474.

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The preemergence herbicide cinmethylin is a benzyl ether derivative of the monoterpene 1,4-cineole. Other oxygenated monoterpenes (carvone, citronellol, fenchone, geraniol, and pulegone) were previously found to inhibit the germination and growth of several weed species while exhibiting low phytotoxicity to soybean. Benzyl ether derivatives of these oxygenated monoterpenes were synthesized and examined for preemergence and postemergence activity towards corn, soybean, wheat, and velvetleaf. Benzyl pulegyl ether exhibited the most preemergence activity when applied directly to the soil, completely inhibiting wheat and velvetleaf emergence at 1.0 kg ha−1while reducing soybean emergence 80%. Several of the benzyl ethers were more inhibitory to velvetleaf radicle elongation relative to cinmethylin but less inhibitory to corn and wheat radicle elongation in petri dish bioassays. Several of the benzyl ethers exhibited limited postemergence activity when applied at 1.0 kg ha−1to seedlings of the test species 10 d after emergence. The benzyl ether derivatives demonstrated altered selectivity and sensitivity as compared to the parent compounds and cinmethylin.

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50

PLOTNIKOVA, R. N., V. I. KORCHAGIN, and L. V. POPOVA. "Evaluation of the possibility of using brominated phthalates from production waste as a plasticizer-flame retardant for cellulose ethers." Plasticheskie massy 1, no. 5-6 (August 9, 2022): 50–52. http://dx.doi.org/10.35164/0554-2901-2022-5-6-50-52.

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Abstract:

The possibility of using brominated phthalates obtained from wastes of butyl alcohol production by oxosynthesis as a plasticizerflame retardant in composites based on cellulose ethers is considered. A regression equation has been obtained for the quantitative description of the cellulose compositions flammability depending on the type of cellulose ether, the type of plasticizer-flame retardant and its content in the composite. It has been shown that the flammability of plasticized compositions based on various cellulose ethers depends only on the content of the flame retardant element in the composition. An indicator to assess the degree of inhibition of the flame propagation in compositions based on cellulose ethers from the content of brominated phthalate plasticizer from waste production is proposed, which can be used to evaluate the effectiveness of various flame retardants in such compositions.

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Journal articles on the topic 'Ethers'

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