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Artykuły w czasopismach na temat "Ether linkage":
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Andersen, F. Alan. "Special Report: Reproductive and Developmental Toxicity of Ethylene Glycol and Its Ethers". International Journal of Toxicology 18, nr 2_suppl (marzec 1999): 53–67. http://dx.doi.org/10.1177/109158189901800208.
Streszczenie:
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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Zhou, Jinghui, Xinjin Sui i Haiqiang Shi. "Study on the structural change of lignin during auto-catalyzed ethanol-water pulping of aspen by 1H-NMR". BioResources 4, nr 3 (1.06.2009): 979–85. http://dx.doi.org/10.15376/biores.4.3.979-985.
Streszczenie:
This study concerns the structural change of lignin during auto-catalyzed ethanol-water pulping of aspen by 1H-NMR. The results showed that the linkages of alkyl-aryl ether of lignin, such as the α-ether linkages (α-O-4) and the β-ether linkages (β-O-4), were broken and the alkyl part formed carbenium at the Cα and Cβ of the aliphatic branch. Meanwhile, the aryl part of ether accepted one H+ and formed phenol. Because of the electronegative effect originating from the electron cloud of phenyl, partial carbenium of Cβ was rearranged. Due to its ether or hydroxyl linkage, rearranging to Cβ, the Cα was changed into carbenium and formed a new β-O-4 alkyl-aryl ether. The β-O-4 alkyl-aryl ether was not stable and broken further. So the large molecule of lignin was disintegrated into a smaller one and dissolved into ethanol. Finally, the α+ carbenium reformed α-O-4 linkages of ether with phenol.
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Duvva, Naresh, A. R. Ramya, Govind Reddy i L. Giribabu. "Intramolecular electron transfer in porphyrin-anthraquinone donor–acceptor systems with varying molecular bridges". Journal of Porphyrins and Phthalocyanines 23, nr 06 (28.05.2019): 628–38. http://dx.doi.org/10.1142/s1088424619500287.
Streszczenie:
Photoinduced electron transfer has been investigated in porphyrin anthraquinone (ZnTTP-AQ) donor–acceptor dyads having either ester (ZnTTP-AQ1) or ether (ZnTTP-AQ2) linkages. Both dyads were characterized by spectroscopic and electrochemical methods. Absorption spectra show absence of any ground state interaction between the porphyrin and anthraquinone moieties. The quenched fluoresence and lifetime indicate electron transfer from the porphyrin to the anthraquinone moiety. The quenching is more pronounced in ZnTTP-AQ1 with ester linkage, suggesting efficient electronic coupling compared to the ether linkage in ZnTTP-AQ2. Computational analysis and frontier molecular orbitals confirmed the formation of charged separated state por[Formula: see text]AQ[Formula: see text]. The electron transfer rates ([Formula: see text] of these triads are found in the range 0.43 × 108 to 10.52 × 109 s[Formula: see text] and are found to be solvent polarity dependent.
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Bang, Moon-Soo. "Synthesis and Properties of Liquid Crystalline Copolymers with Ether-ether-ester Linkage in Main Chain". Journal of the Korea Academia-Industrial cooperation Society 11, nr 4 (30.04.2010): 1367–72. http://dx.doi.org/10.5762/kais.2010.11.4.1367.
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Zhao, Rui, Pan Shi, Junyou Chen, Shuaishuai Sun, Jingnan Chen, Jibin Cui, Fangming Wu i in. "Chemical synthesis and biological activity of peptides incorporating an ether bridge as a surrogate for a disulfide bond". Chemical Science 11, nr 30 (2020): 7927–32. http://dx.doi.org/10.1039/d0sc02374d.
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Ni, Zhi-Yu, Yi-Bing Wu, Mei Dong, Man-Li Zhang, Yu-Fang Wang, Françoise Sauriol, Chang-Hong Huo i in. "Diabietane Ether, a New Dimeric Abietane with an Ether Linkage from Taxus cuspidata Needles". Zeitschrift für Naturforschung B 66, nr 10 (1.10.2011): 1083–86. http://dx.doi.org/10.1515/znb-2011-1015.
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Kikuchi, Shuhei, Yugo Iwasaki, Mina Yoshioka, Kodai Hino, Shin-ya Morita, Ryu Tada, Yasuhiro Uchimura i in. "Solitary and Synergistic Effects of Different Hydrophilic and Hydrophobic Phospholipid Moieties on Rat Behaviors". Pharmaceutics 16, nr 6 (4.06.2024): 762. http://dx.doi.org/10.3390/pharmaceutics16060762.
Streszczenie:
Glycerophospholipids have hydrophobic and hydrophilic moieties. Previous studies suggest that phospholipids with different moieties have different effects on rodent behavior; however, the relationship between chemical structures and behavioral effects remains unclear. To clarify the functions of phospholipid moieties, we injected male rats with phospholipids with different moieties and conducted behavioral tests. Exploratory activity was reduced by phosphatidylethanolamine (PE)(18:0/22:6) but not PE(18:0/18:0) or PE(18:0/20:4). Conversely, exploratory activity was increased by plasmanyl PE(16:0/22:6), which harbors an alkyl–ether linkage, but not by phosphatidylcholine (PC)(16:0/22:6) or plasmanyl PC(16:0/22:6). Docosahexaenoic acid (DHA)(22:6) and an alkyl–ether linkage in PE were thus postulated to be involved in exploratory activity. Anxiety-like behavior was reduced by plasmenyl PC(18:0/20:4), which harbors a vinyl–ether linkage, but not by PC(18:0/20:4) or plasmanyl PC(18:0/20:4), suggesting the anxiolytic effects of vinyl–ether linkage. The activation of social interaction was suppressed by PE(18:0/18:0), PE(18:0/22:6), PC(16:0/22:6), plasmanyl PE(16:0/22:6), and plasmanyl PC(16:0/22:6) but not by PE(18:0/20:4), plasmenyl PE(18:0/20:4), or plasmanyl PC(18:0/22:6). DHA may suppress social interaction, whereas arachidonic acid(20:4) or a combination of alkyl–ether linkage and stearic acid(18:0) may restore social deficits. Our findings indicate the characteristic effects of different phospholipid moieties on rat behavior, and may help to elucidate patterns between chemical structures and their effects.
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Lundquist, Knut, Vratislav Langer i Jim Parkås. "The structure and conformation of lignin as judged by X-ray crystallographic investigations of lignin model compounds: Arylglycerol beta-syringyl ethers". BioResources 4, nr 2 (5.03.2009): 529–36. http://dx.doi.org/10.15376/biores.4.2.529-536.
Streszczenie:
Structural elements of the arylglycerol b-syringyl ether type are very frequent in hardwood lignins. A variety of crystalline dimeric lignin models representing different diastereomeric forms of structural elements in lignin of this type have been studied using X-ray crystallography. Bond distances and bond angles in the model compounds are in all probability nearly identical with those of the corresponding structural elements in lignins. Special attention was paid to the geometry of the b-O-syringyl linkage, since the reactivity of this linkage is of particular interest in connection with pulping reactions. The crystal structures of the model compounds suggest that two types of conformations are predominating; in both of them the aromatic rings are separated by ca. 4.5 Å (maximal distance 4.9-5 Å). Based on X-ray crystallographic data from four compounds a sequence of units (5 aromatic rings, 8 chiral C-atoms) attached to each other by b-syringyl ether linkages was constructed. The appearance of the resulting oligomer illustrates that stereoisomerism can be expected to influence the shape of the lignin molecules to a great extent.
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Xie, Yimin, Xudong Chen, Kai Zhang, Sheng Cui i Gongxia Zhang. "Elucidation of lignin and polysaccharide linkages in wheat straw by 2H/13C isotopic tracer". BioResources 18, nr 1 (17.11.2022): 550–69. http://dx.doi.org/10.15376/biores.18.1.550-569.
Streszczenie:
To elucidate chemical linkages between lignin and polysaccharides, the aqueous mixed solutions of coniferin-[α-13C], syringin-[α-13C], D-glucose-[6-2H], and phenylalanine ammonia-lyase inhibitor were injected into a living wheat stalk. Internode tissues with high abundance of 2H-13C were collected. The milled wood lignin, lignin-carbohydrate complex (LCC), and residual LCC (R-LCC) with enrichment of 2H-13C were isolated. The 13C and 2H abundances showed that the lignin and polysaccharides of internode tissues were labeled by 13C and 2H, respectively. Analysis with carbon-13 nuclear magnetic resonance (13C-NMR) showed that ketal and benzyl ether bonds were formed between α-C of lignin and carbohydrates. The R-LCC and LCC were further treated with enzymes to obtain enzymatic degraded R-LCC (ED-R-LCC) and enzymatic degraded LCC (ED-LCC). 13C-NMR spectra of ED-LCC showed that the α-C of lignin side chain was combined with 6-C of carbohydrates by ether, ester, and ketal linkages. 1H-NMR differential spectra of ED-LCCs revealed an LC linkage of benzyl ether bond. Glucan-lignin (En-R-GL) and xylan-lignin (En-R-XL) complexes were separated from ED-R-LCC by ionic liquid. A part of lignin α-C was linked to cellulose 6-C by benzyl ether and α-ketal linkages. 13C-NMR spectra of En-R-XL showed there were α-benzyl ether and α-ketal bonds between lignin and xylan.
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Grainger, James, V. Vikram Reddy i Donald G. Patterson. "Pentachlorodibenzo-p-dioxin Isomer Differentiation by Capillary Gas Chromatography Fourier Transform Infrared Spectroscopy". Applied Spectroscopy 42, nr 5 (lipiec 1988): 800–806. http://dx.doi.org/10.1366/0003702884429166.
Streszczenie:
Reference infrared vapor-phase spectra of the 14 pentachlorodibenzo-p-dioxin (PnCDD) isomers were recorded at low microgram concentrations. A unique infrared spectrum corresponding to each chromatographically separated or spectrally subtracted mixture component was observed. The structures for individual isomers in each isomer pair were assigned by qualitative valence-bond evaluations and empirically derived quantitative estimations of ether linkage asymmetric stretching frequencies [ vcoc(asym)] Correlations between calculated ether linkage (C-O-C) bond angles and vcoc(asym) indicate the existence of buttressed 1,6 and 1,9 nonbonded interactions not observed in tetrachlorodibenzo- p-dioxin (TCDD) isomers.
Rozprawy doktorskie na temat "Ether linkage":
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Badami, Anand Shreyans. "Morphological and Structure-Property Analyses of Poly(arylene ether sulfone)-Based Random and Multiblock Copolymers for Fuel Cells". Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29469.
Streszczenie:
The commercialization of proton exchange membrane (PEM) fuel cells depends largely upon the development of PEMs whose properties are enhanced over current perfluorinated sulfonic acid PEMs. Understanding how a PEMâ s molecular weight and morphology affect its relevant performance properties is essential to this effort. Changes in molecular weight were found to have little effect on the phase separated morphologies, water uptake, and proton conductivities of random copolymers. Changes in block length, however, have a pronounced effect on multiblock copolymers, affecting surface and bulk morphologies, water uptake, proton conductivity, and hydrolytic stability, suggesting that multiblock copolymer PEM properties may be optimized by changes in morphology.
A major goal of current proton exchange membrane fuel cell research involves developing high temperature membranes that can operate at ~120 °C and low humidites. Multiblock copolymers synthesized from 100% disulfonated poly(arylene ether sulfone) (BPSH100) and naphthalene polyimide (PI) oligomers may be an alternative. At block lengths of ~15 kg/mol they displayed no morphological changes up to 120 °C or even higher. Water desorption was observed to decrease with increasing block length. The copolymers exhibited little to no water loss during a 200 °C isotherm in contrast to random BPSH copolymers and Nafion. A BPSH100-PI multiblock copolymer with large block length appears to have morphological stability and retain water at temperatures exceeding 120 °C, suggesting its candidacy as a high temperature PEM.
A growing number of alternative PEM research efforts involve multiblock copolymer chemistries, but little emphasis is placed on the methods used to couple the oligomers. Fluorinated linkage groups can help increase block efficiency during coupling, but their effect on a PEM is not well-known. The choice of linkage type, hexafluorobenzene (HFB) vs. decafluorobiphenyl (DFBP), appears to have small but observable influences on multiblock copolymers with disulfonated and unsulfonated poly(arylene ether sulfone) oligomers. DFBP linkages promote greater phase separation than HFB linkages, resulting in increased stiffness, decreased ductility, and increased proton conductivity at low humidities. DFBP linkages also promote more surface enrichment of fluorine, causing changes in surface morphology and slightly increased water desorption, but determining the impact on actual fuel cell performance requires further research.Ph. D.
2
Azevedo, Rafael Raphaela. "Development of catalysts for the valorization of lignin : hydrodeoxygenation of dimeric aryl ethers". Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILR041.
Streszczenie:
Cette thèse a pour but d'étudier le rôle du support et de la taille des particules métalliques sur les réactions d'hydrodésoxygénation (HDO) du benzyl phényl éther (BPE), du phenethoxybenzène (PEB) et du diphényl éther (DPE) choisis comme molécules modèles représentatives des principales liaisons éther présentes dans la biomasse lignocellulosique. Les réactions ont été réalisées en phase liquide à 230 °C et sous 18 bar de H2. Les catalyseurs au Pd supporté sur différents oxydes (SiO2, TiO2, Nb2O5, Al2O3, ZrO2 et HZSM5) ont été synthétisés par imprégnation par voie humide et par dépôt de particules métalliques préparées par voie colloïdale. Les sites acides du support favorisent le craquage de la liaison éther C-O du BPE mais pour le PEB et le DPE, cet effet est moins prononcé en raison de l'énergie plus élevée requise pour rompre ces liaisons. L'hydrogénolyse de la liaison éther C-O a lieu sur les particules de Pd métallique, produisant les arènes respectifs. Cependant, la taille des particules de Pd peut directement affecter la distribution des produits après le clivage de la liaison C-O. En raison de la taille plus importante des particules de Pd, les catalyseurs imprégnés favorisent l'hydrogénolyse et présentent une sélectivité plus élevée pour les produits alkylés, tandis que la taille plus petite des particules de Pd, obtenue pour les catalyseurs préparés par voie colloïdale, augmente la sélectivité pour les produits désoxygénés. Sur ces catalyseurs, la formation de produits alkylés est supprimée, mais l'hydrogénation du cycle aromatique des BPE, PEB et DPE se produit parallèlement à l'hydrogénolyse, également favorisée par les particules de Pd. La performance des catalyseurs à base de Ru a également été évaluée dans les mêmes conditions de réaction. En présence de Ru, des produits alkylés ont été produits même en l'absence de sites acidesThe present thesis aims at studying the role of the support and metal particle size on the hydrodeoxygenation reactions (HDO) of benzyl phenyl ether (BPE), phenethoxybenzene (PEB), and diphenyl ether (DPE) chosen as model molecules representative of the main ether linkages present in the lignocellulosic biomass. The reactions were carried out in liquid phase at 230 °C and 18 bar of H2. Pd supported on different oxides (SiO2, TiO2, Nb2O5, Al2O3, ZrO2, and HZSM5) were synthesized by incipient wetness impregnation and deposition of metal particles prepared by colloidal method. The acidic sites of the support promote the cracking of the C-O ether bond of BPE, but for PEB and DPE, this effect is less pronounced due to the higher energy required to break these linkages. The hydrogenolysis of the C-O ether bond takes place on the metallic Pd particles, producing the respective arenes. However, the Pd particle size can directly affect the product distribution after C-O cleavage. Due to the larger Pd particle size, impregnated catalysts favor the hydrogenolysis and exhibit a higher selectivity to alkylated products, whereas a smaller Pd particle size, obtained for catalysts prepared by the colloidal route, increases the selectivity to deoxygenated products. Over these catalysts, the formation of alkylated products is suppressed, but the hydrogenation of BPE, PEB, and DPE aromatic rings occurs in parallel to hydrogenolysis also promoted by Pd particles. The performance of Ru-based catalysts was also evaluated in the same reaction conditions. In the presence of Ru, alkylated products are produced even in the absence of acidic sites
3
Kaurich, Kevin Joseph. "Segmented Aromatic Polymers Containing Thermally Reversible Linkages". Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/87533.
Streszczenie:
This dissertation describes a general synthetic platform for segmented polymers that have main-chain reversible linkages based on cyclopentadiene-maleimide Diels-Alder chemistry. Research in the area of thermally reversible (self-healing) polymers has been an ever-expanding area of interest in the current scientific literature. However most of the emphasis has been on systems containing furan-maleimide linkages. While inexpensive and synthetically accessible, furan chemistry is mostly limited to crosslinked and hyperbranched architectures due to its relatively weak binding with maleimides at suitable propagation temperatures.
Following a general review of the literature in this area (Chapter 1) the first stage of our research (Chapter 2) entails the synthesis of 2-substituted hydroquinones, which are needed as monomers in the later stages. The novelty of our hydroquinone synthesis stems from the use of allylic and other alkenyl ethers as the source of the ring substituent, and from the utilization of catalytic hydroboration to improve atom-efficiency. We showed that hydroquinones with widely varying functionality can be prepared efficiently by our method; these findings were published in the journal Tetrahedron in 2018.
The second stage (Chapter 3) involves the use of the new hydroquinones in step-growth syntheses of hydroquinone-terminated telechelic and chain-extension of these telomers via Diels-Alder chemistry to form segmented polymers having thermally reversible linkages. The novelty of our approach rests with the use of cyclopentadiene-maleimide chemistry for the linkages, while the overall physical properties such as the glass transition temperature were established by using well-defined aromatic polymers �" poly(ether ether ketones) or PEEK and poly(aryl ether sulfones) or PAES �" as segments. This approach represents an important departure from earlier work in our group in which reversible linkages were present in every repeat unit of a step-growth Diels-Alder polymer that showed thermal reversibility in solution but not in the bulk, owing to glass transition temperatures that were too high. Using scratch-healing and mechanical (tensile) tests, we show that our new segmented polymers exhibit self-healing characteristics that are competitive with or superior to previously reported systems based on different Diels-Alder chemistry.
The third stage (Chapter 4) aims to explore new application areas for some of the more novel functionalized hydroquinones reported in Chapter 2. First we developed an efficient synthesis of a PAES derivative bearing 5-phenoxypentyl groups on the hydroquinone moiety. Then we showed that the 5-phenoxy group can be cleanly cleaved, post-polymerization, to afford a PAES having 5-bromopentyl substituents. The promise of our method rests with the potential of the pendant electrophiles to undergo reactions with nucleophilic reagents to post-modify these polymers further. As proof of concept, we showed that substitution of the pendant bromides with furfuryloxy groups enabled thermally reversible crosslinking with a bis-maleimide reagent to form a polymeric material that demonstrates partial scratch healing. Finally we are exploring the synthesis of new ion-containing polymers by substituting the pendant bromides with tertiary amines.PHD
This dissertation describes a new synthetic approach to polymeric materials that can heal themselves (for example, repair small cracks that may have formed due to stress or aging) simply by heating the damaged area. Our approach uses a thermally reversible chemical reaction (called the Diels-Alder reaction) to connect several shorter polymer segments into longer chains. Upon heating, the segments can come apart, diffuse into and through the damaged area, and then rejoin. The first chapter is a review of background in the published literature as well as previous not-yet-published work in our laboratory. The second chapter describes the creation of new building-block molecules (monomers) that will help control the temperature range necessary to induce self-healing after incorporation into the polymer segments. The third chapter details the process of forming the segments, the incorporation of self-healing functionalities on the ends of the segments, the joining of the segments into longer polymeric chains, and the testing of all of the physical properties of these new materials, including their self-healing capabilities. The fourth chapter represents a preliminary study of a new method of preparing ion-containing polymers. The latter materials have potential use in various membrane technologies including fuel cell devices for the harnessing of renewable energy.
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Idage, S. B. "Synthesis and characterization of polymers containing i) arylene sulfone ether and ii) aromatic azomethine linkages". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1991. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3042.
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Luo, Shih-Ci, i 羅仕頎. "Synthesis and Characterization of Triazole Metal Complexes Containing Ether Linkage". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/hgk35e.
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CHIU, PEI-FANG, i 邱沛芳. "Design and Synthesis a Water-soluble Group for Ether-linkage of 10-Hydroxycamptothecin Prodrug". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/686w4t.
Streszczenie:
碩士嘉南藥理大學
藥學系
105
Camptothecin has good anti-cancer activity, and current clinical use of two derivatives are Topotecan and Irinotecan which improve poor water solubility of Camptothecin by chemical modification. However, the lack of drugs specificity of tumor will cause severe side effects. Therefore, our laboratory designed and synthesized two glucuronide prodrugs of Camptothecin (9-ACG and 10-HCG) which will mainly be activated at tumor site expressing large number of β-glucuronidase. According to previous studies, 9-ACG and 10-HCG was 1800 and 20 times soluble than 10-HCG, respectively; 9-ACG and 10-HCG was 30-fold and 10-fold less toxic than the parent drug to cells, respectively; Enzyme kinetic studies showed that β-glucuronidase exhibited 520 times higher catalytic efficiency for 10-HCG than for 9-ACG, and molecular modeling studies predicted that 10-HCG would have a higher binding affinity to enzyme than 9-ACG. In this study, we design and synthesize the target compound 10-HCPG by creating N-methyl piperazine on the benzyl group of 10-HCG, expect for good water solubility, stable in blood, low cytotoxicity, good affinity with β-glucuronidase and specific to tumor cells.
7
Huang, Yi-Hsiung, i 黃益雄. "Design,synthesis and investigation on the blue phase liquid crystal materials with ether linkage". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/93150914622866018677.
Streszczenie:
碩士大同大學
化學工程學系(所)
98
ABSTRACT The primary research work of this study is an attempt to correlate the structure-property relationship of the formation of blue phases in chiral liquid crystals in terms of variation of the structure of the rigid cord, achiral alkyl chain length (m) and chiral alkyl chain length (n) possessing ether linkage attached to the chiral tail in the chiral liquid crystal materials. Thus, the optically active alcohols, 2-octanol, 1-butyloxy-2-propanol, 1-pentyloxy-2-propanol, 1-hexyloxy-2-propanol, were designed and synthesized by reacting (S)-propylene oxide with alkyl alcohols under basic condition. In consequence, five novel homologous series of chiral materials, (R)-6-(1-methylheptyloxy)naphth-2-yl 4’-octyloxybenzoate, I(m), (R)-6-(1-butyloxy-2-propyl)naphth-2-yl 4-octyloxybenzoate, II(m), (R)-6-(1-pentyloxy-2-propyl)naphth-2-yl 4-octyloxybenzoate, III(m), (R)-6-(1-hexyloxy-2-propyl)naphth-2-yl 4-octyloxybenzoate, IV(m), (R)-4-(1-butyloxy-2-propyl)biphenyl 4-octyloxybenzoate, V(m), derived from these alcohols were synthesized for the investigation of the effect of the aliphatic alkyl chain length (m), ether linking group, chiral tail alkyl chain length (n) and rigid core structures on the mesomorphic and electro-optical properties. The mesomorphic phases and their corresponding transition temperatures were primarily characterized by the microscopic textures and DSC thermograms, and the ferroelectric phases were further identified by the measurements of electric switching behavior and dielectric constant ε'. The results of compounds I(m) composed of the rigid core structure of PhCOONa and chiral group of optical activity 2-octanol, showed that compound I(m=6) exhibits the mesophases sequence of BPIII-BPII-N*, compound I(m=7) exhibits the mesophases sequence of BPII-BPI-N* and compounds I(m=8,9) exhibits the mesophases sequence of BPII-BPI-N*-TGBA*-SmA*. With the exception of I(m=8) that exists the widest temperature range of enantiotropic BPII and BPI phases, the rest of compounds in series of I(m) possess BPII and BPI phases are monotropic. Compounds I(m) display frustrated phases demonstrated that these compounds possess high chirality. The results of compound II(m=6, n=4), composed of the same rigid core structure as compound I(m) but differed in the chiral group where an additional ether linkage is introduced, shows the mesophases sequence of BPII-BPI-N*, compounds II(m=7, 8, 9, n=4) exhibit the mesophases sequence of BPII-BPI-N*-TGBA* and compound II(m=8, n=4) displayed an additional SmA* phase. All compounds posses enantiotropic BPII and BPI phases and the thermal stability of BPI and TGBA* phases increase from compounds at m=7 to m=8 and m=9. When extending the alkyl length (n) of chiral tail, the thermal stability of TGBA* phase decreases and when n=5 and 6, the BPI is suppressed. The widest temperature range of frustrated (BP and TGBA*) phases for these compounds appeared at n=4. The results of compounds V(m=7-9, n=4), composed of the same chiral group but differed in the rigid core structure (PhCOOPhPh) as compounds II(m), show the mesophases sequence of BPII-BPI-N*-SmC*, compound V(m=9, n=4) exhibit an additional BPIII phase. The thermal stability of BPII and BPI phases obtained from compounds V(m) are decreased and the TGBA* phase is suppressed as compared to that of compounds II(m). The physical properties of the chiral materials in ferroelectric SmC* phases were measured. The maximum magnitudes of spontaneous polarization measured for the materials in the SmC* phase are in the range of 21.7 to 28.5 (nC/cm2). These results also show that the maximum Ps values have no significant correlation to the change of achiral alkyl chain length (m). In conclusion, the chiral materials composed of the rigid core structure of PhCOONa and the chiral group of an additional ether linkage at terminal tail of the molecules, have higher thermal stability of frustrated (BP and TGBA*) phases. All series of compounds display that achiral alkyl chain length (m) of the molecules have no correlation to the thermal stability of the frustrated phases, nevertheless, chiral alkyl chain length (n) of molecules show an increasing in thermal stability of frustrated phases in decreasing n. Among all compounds, compound II(m=7, n=4) has the widest temperature range of enantiotropic blue phases (cal. 12.5℃). Keywords: Chiral material, Blue phase, frustrated phases, electro-optical property, switching behavior, dielectric constant ε’
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Chen, Pei-Min, i 陳佩敏. "Tandem Cyclization of Enynes Containing an Ether Linkage and a Cyclopropyl Group via Ruthenium Metal Complex". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/72759808192027849035.
Streszczenie:
碩士國立臺灣大學
化學研究所
102
We study chemical reactions of [Ru]Cl ([Ru] = Cp(PPh3)2Ru) with three 1,8-enyne compounds containing cyclopropyl group (1, 7 and 11) in which the triple bond is associated with propargylic alcohol and the ole&;#64257;nic group has various substituted methyl groups. The reaction of [Ru]Cl and 1, containing one methyl group added to the internal carbon of the allyl group, affords the vinylidene complex 2 with a newly formed seven-membered ring. Furthermore, tandem cyclization reaction of 1 in MeOH/CHCl3 catalyzed by [Ru]NCCH3+PF6－ at 60 oC leads to the product 6 with spiro-cyclopropyl ring, formed possibly via sequential allenylidene vinylidene cyclization followed by a nucleophilic addition of alkoxide. In CHCl3, the catalytic reaction by [Ru]NCCH3+ PF6－ gives the isolable organic cyclization intermediate enyne 5. Treatment of the propargylic alcohol 7 containing two terminal methyl groups at the O-allylic group, with [Ru]Cl yields a mixture of two diastereomers of the vinylidene complex 8 containing a newly formed six-membered ring in a ratio of ca. 10:1. Among diastereoisomers only the anti-isomer is isolated for complex 8. The cyclization reaction is proposed to proceed via the formation of a six-membered ring boat-like transition state with bulkiest group in the pseudo-equatorial position to reduce the 1,3-diaxial interactions. The catalytic reaction by [Ru]NCCH3+PF6－ in CHCl3 at 60 oC affords anti-9 and syn-9 in a ratio of 3:1. The thermal energy increases amount of product syn-9. The subsequent cyclization carried out in a cosolvent of ROH/CHCl3 at 60 oC affords bicyclic product 10. In the reaction of [Ru]Cl with 11, containing no methyl group, no C&;#8722;C bond formation is observed. The reaction of 11with [Ru]Cl in the presence of NH4PF6 in CH2Cl2 affords a mixture of the allenylidene complex 12 and phosphonium acetylide 13. Interestingly, thermal treatment of 11 leads to a ring expansion of the cyclopropyl group, giving the vinylidene complex 16 with a five-membered ring. This ring expansion proceeds by C-C bond formation between Cβ of the cumulative double bond and a methylene group of the cyclopropyl ring. Reaction of 1,3-diol 18 with [Ru]Cl in CH2Cl2 yields a mixture of the alkoxy carbene 17 and 19 in a ratio of 1:2. The spontaneous dehydration of 19 to 17 by elevating temperature is failed. Fortunately, complex 17 could be the only product when the reaction is carried out in MeOH. Overall, tandem cyclizations of two 1,8-enynes with methyl-substituents have been achieved. Ring-expansion of a cyclopropyl group in a 1,8-enyne with no methyl-substituent is also accomplished.
9
Leu, Tsu-Shang, i 呂祖尚. "Novel High Performance Polymers Containing Naphthalene Pendant Group and Flexible Ether Linkages". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/97042813376615081494.
Streszczenie:
博士國立成功大學
化學工程學系
87
Abstract High performance resins are very useful in highly demanding environments to provide special properties, such as thermal stability, good chemical resistance, high dimensional stability, low water absorption and high mechanical strength. Unfortunately, most high performance polymers suffer from their poor solubility in organic solvent, extremely high melting points, and high melt viscosity for fabrication. The processability of high performance polymers can be improved by the reduction of their molecular weight. However, this approach results in a significant decrease of their final thermal and physical properties. Therefore, one successful approach to increase solubility and processability of polymers without sacrificing their thermal and physical properties is by the modification of polymer structure. In this thesis, we plan to combine the special features of naphthalene structure (rigid, low moisture absorption and low coefficient of thermal expansion) with bismaleimides and polyimides (high crosslink density, good thermal and electrical properties) in order to produce a new high performance material. The goal of this study is to synthesize a new epoxy, bismaleimide and diamine monomers. A series of novel high performance polymers containing naphthalene pendant group and flexible ether linkages have been prepared which include epoxy resins, polyaspartimides, polyaminobismaleimides and polyimides. The primary aim of this work was to illustrate the effect of function groups on the properties of polymers, such as solubility, bulk density, thermal properties, moisture absorption, dynamic mechanical properties, dielectric constant, coefficient of thermal expansion and mechanical properties. Novel bismaleimide (BMI) and epoxy resin with naphthalene side group were synthesized from the intermediates, bis(4-amino-3,5-dimethylphenyl)naphthylmethane (BADN) and bis(4-hydroxy-3,5-dimethylphenyl)naphthylmethane (BHDN), which were obtained from the reactions between 1-naphthaldehyde and 2,6-dimethylaniline or 2,6-dimethylphenol, respectively. The monomers were characterized by fourier transform infrared spectroscopy, elemental analysis, mass spectrometry, nuclear magnetic resonance spectrometry and potentiometery. Their corresponding bismaleimide bis(4-maleimido-3,5-dimethylphenyl)naphthylmethane (BMDN) and the diglycidyl ether of BHDN (DGEBN) were cured with 4,4''-diaminodiphenyl methane (DDM) at various mole ratio and their curing behaviors investigated by differential scanning calorimetry (DSC) and FTIR. Thermogravimetric analyses (TGA) indicated that the cured systems of bismaleimide and epoxy resins were stable up to 416-424℃ and 377-395℃, respectively, in nitrogen atmosphere, and the former afforded a relatively higher char yield than the latter. In addition, the cured bismaleimide possessed better Tg, moisture resistance, lower coefficient of thermal expansion and dielectric constant than that of the epoxy system. A bismaleimide, bis(4-maleimidophenoxy-3,5-dimethylphenyl)naphth- ylmethane (BMPDN), containing a pendant naphthalene and aryl ether linkage was synthesized from bis(4-hydroxy-3,5-dimethylphenyl)-naphthylmethane (BHDN) through a diamine, [bis(4-aminophenoxy-3,5-dimethylphenyl)naphthylmethane (BAPDN)], and maleic anhydride by the usual two step procedure that included ring opening addition to give bismaleamic acid, followed by cyclodehydration to bismaleimide. A series of polyaspartimides, polyaminobismaleimides were prepared by the polyaddition of this bismaleimide with diamine (DDM) at various mole ratio via a Michael-type addition in the melt. The new BMI was found to possess the processability and solubility. In addition, it also exhibited increasing thermal stability and better physical properties with decreasing DDM concentration. A series of novel polyimides containing pendant naphthalene and flexible ether moieties were prepared from various diamines [including bis(4-amino-3,5-dimethylphenyl)naphthylmethane, bis(4-aminophenoxy-3,5-dimethylphenyl)naphthylmethane and bis(4-aminophenoxy-3,5-dimethylphenyl)methane] with various aromatic tetracarboxylic dianhydrides via a two-step and one-step methods. All polyimides, except those without naphthalene pendant group, were readily soluble in common organic solvent, such as chloroform. Differential scanning calorimetry (DSC) revealed that the naphthalene bearing diamine monomers had a low entropy, and formed amorphous polyimides. They retained high moduli even at high temperatures by dynamic mechanical analysis (DMA), and had their coefficients of thermal expansion (CTEs) in the range of 46.86-67.14ppm by thermomechanical analysis (TMA). The glass transition temperature of polyimides were found to be 268-294℃, 298-326℃ and 270-315℃ respectively by DSC, DMA, and TMA. Thermogravimetric analyses indicated that they were fairly stable up to 489-571℃ (10wt% loss in N2). In addition, they had a tensile strength in the range of 56-97Mpa, and an elongation to break of around 3%. These polyimide films have dielectric constants ranging from 2.71 to 3.28 with moisture absorptions of less than 0.98%.
10
Huang, Perng-Chih, i 黃鵬誌. "Synthesis and Properties of Aromatic Polyamides and Polyimides Bearing Ether and Sulfone Linkages in the Main Chain". Thesis, 1997. http://ndltd.ncl.edu.tw/handle/48753303488700673361.
Książki na temat "Ether linkage":
1
Patai, Saul. Chemistry of the Ether Linkage. Wiley & Sons, Limited, John, 2010.
2
Patai, Saul. Chemistry of the Ether Linkage, Part 1. Wiley & Sons, Incorporated, John, 2018.
3
Cook, Diana Lynn. Synthesis of polybenzimidazoles containing arylene sulfone and ether linkages. 1993.
Części książek na temat "Ether linkage":
1
Smith, Dennis W., Junmin Ji, Sridevi Narayan-Sarathy, Robert H. Neilson i David A. Babb. "Fluorosilicones Containing the Perfluorocyclobutane Aromatic Ether Linkage". W ACS Symposium Series, 308–21. Washington, DC: American Chemical Society, 2000. http://dx.doi.org/10.1021/bk-2000-0729.ch020.
2
Hagen, A. P. "By Cleavage of Ether Linkages". W Inorganic Reactions and Methods, 209–10. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145197.ch167.
3
Skovby, Michael H. B., Claus A. Heilmann i Jørgen Kops. "All-Aromatic Liquid-Crystalline Polyesters of Phenylhydroquinone with Ether and Ketone Linkages". W ACS Symposium Series, 46–61. Washington, DC: American Chemical Society, 1990. http://dx.doi.org/10.1021/bk-1990-0435.ch004.
4
Subramaniam, Ram, i D. Allen Butterfield. "Structure-Activity Correlation of Subtilisin Immobilized on Modified Poly (Ether) Sulfone Membrane by Covalent and Non-Covalent Linkages". W Biofunctional Membranes, 201–8. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4757-2521-6_14.
5
Calvert, Jack, Abdelwahid Mellouki, John Orlando, Michael Pilling i Timothy Wallington. "Rate Coefficients and Mechanisms for the Atmospheric Oxidation of the Ethers". W Mechanisms of Atmospheric Oxidation of the Oxygenates. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199767076.003.0006.
Streszczenie:
The presence of ethers in the atmosphere is almost entirely the result of direct emissions from anthropogenic sources (e.g., Arif et al., 1997; Intergovernmental Panel on Climate Change, 2001; Johnson and Andino, 2001; http://en.wikipedia.org/wiki/Ethers; and references therein). These sources can be quite varied and species dependent; for example, many ethers are commonly used as industrial solvents; many are formed as combustion intermediates and in the burning of biomass; various branched ethers (e.g., methyl tert-butyl ether) are (or have been) used as fuel additives to increase octane number and reduce CO emissions; dimethyl ether has being proposed as an alternative diesel fuel; many fluorinated species have been manufactured, evaluated and used as possible chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) replacement compounds; some halogenated species are used as inhalation anaesthetics or as chlorofluorocarbon replacements; and polybrominated diphenyl ethers (PBDEs) are used as flame retardants. There are no major routes to ether formation in the atmosphere itself. The atmospheric behavior of the simple aliphatic ethers, to a first approximation, mirrors that of the alkanes. Reaction with OH is the dominant removal pathway, and occurs via abstraction of an H-atom. In general, however, the ethers are more reactive than the alkanes, as the ether linkage leads to a weakening of the neighboring C—H bonds, and thus imparts an “activation effect” on the OH reaction. The major oxidation steps occurring subsequent to abstraction are also similar to those occurring in atmospheric alkane chemistry, involving the formation of a peroxy radical and an alkoxy radical prior to end product formation; However, less is know about the quantitative details of these processes than is the case for the alkanes. In general, unimolecular decomposition of the alkoxy radicals [e.g., CH3CH2OCH(O•)CH3 in the above reaction sequence] is more rapid than for an alkane-derived radical of similar structure. The major end product of ether oxidation is quite often an ester, the analog to the carbonyl compounds (aldehydes and ketones) generated from alkane oxidation.
6
Bronfman, Alejandra. "Receivers". W Isles of Noise. University of North Carolina Press, 2016. http://dx.doi.org/10.5149/northcarolina/9781469628691.003.0003.
Streszczenie:
Picking up in the early 1920s, this chapter tracks the shift of radio technology from military to commercial uses. It follows linkages among the changing material conditions for Caribbean workers, the radio industry’s search for materials like mica and bakelite, and the generation of new markets. Having placed broadcasting in its ecological and political contexts, the chapter uses the trajectories of two amateur radio operators, John Grinan, a New Yorker/Jamaican son of a plantation owner and a member of the team which produced the first transatlantic wireless signals, and Frank Jones, an American plantation manager in Cuba, famous for his self-promoting shortwave transmissions to recover the world of the tinkerers’ romance with an ether jammed with distant sounds. It traces the creation of audiences and publics for the emerging technology, arguing that radio appealed to listeners not because it shrank distances, but because it underscored them, demarcating the Caribbean as exotic and remote. Ironically, it was the deeper technological connections that would propel the mapping of these imagined boundaries between the “tropics” and “the world.”
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Han, Chang Dae. "Rheology of Thermoplastic Polyurethanes". W Rheology and Processing of Polymeric Materials: Volume 1: Polymer Rheology. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780195187823.003.0016.
Streszczenie:
Thermoplastic polyurethane (TPU) has received considerable attention from both the scientific and industrial communities (Hepburn 1982; Oertel 1985; Saunders and Frish 1962). Applications for TPUs include automotive exterior body panels, medical implants such as the artificial heart, membranes, ski boots, and flexible tubing. Figure 10.1 gives a schematic that shows the architecture of TPU, consisting of hard and soft segments. Hard segments, which form a crystalline phase at service temperature, are composed of diisocyanate and short-chain diols as a chain extender, while soft segments, which control low-temperature properties, are composed of difunctional long-chain polydiols with molecular weights ranging from 500 to 5000. The soft segments form a flexible matrix between the hard domains. TPUs are synthesized by reacting difunctional long-chain diol with diisocyanate to form a prepolymer, which is then extended by a chain extender via one of two routes: (1) by a dihydric glycol chain extender or (2) by a diamine chain extender. The most commonly used diisocyanate is 4,4’-diphenylmethane diisocyanate (MDI), which reacts with a difunctional polyol forming soft segments, such as poly(tetramethylene adipate) (PTMA) or poly(oxytetramethylene) (POTM), to produce TPU, in which 1,4-butanediol (BDO) is used as a chain extender. There are two methods widely used to produce TPU: (1) one-shot reaction sequence and (2) two-stage reaction sequence. The reaction sequences for both methods are well documented in the literature (Hepburn 1982). It should be mentioned that MDI/BDO/PTMA produces ester-based TPU. One can also produce ether-based TPU when MDI reacts with POTM using BDO as a chain extender. TPUs are often referred to as “multiblock copolymers.” In order to have a better understanding of the rheological behavior of TPUs, one must first understand the relationships between the chemical structure and the morphology; thus, a complete characterization of the materials must be conducted. The rheological behavior of TPU depends, among many factors, on (1) the composition of the soft and hard segments, (2) the lengths of the soft and hard segments and the sequence length distribution, (3) anomalous linkages (branching, cross-linking), and (4) molecular weight.
Streszczenia konferencji na temat "Ether linkage":
1
Gershenson, J. K., B. D. Solomon, D. R. Shonnard, D. W. Watkins i J. W. Sutherland. "Production Decision Making in the Face of Uncertainty About Air Toxics Regulation and Global Climate Change Policy". W ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/ts-23414.
Streszczenie:
Abstract There is an urgent need to better understand and quantify firm-level decisions made in response to environmental policy. It is to be expected that in the face of new/stricter regulations (e.g., tightened regulations relating to airborne particulate emissions) that the desired intent of the regulation will be achieved (e.g., reduced large-plant emissions in the U.S.). However, the secondary environmental and economic impacts of these policies/regulations are poorly understood. These secondary effects, those beyond the primary environmental effects intended by the policy and what is normally addressed in regulatory impact analyses, are caused by companies’ decisions to pass problems down their supply chain or overseas. As problems are passed down the supply chain, the resources available to address them diminish and the more unrestrained the regulatory restrictions become. A governmental policy decision therefore has a range of potential industrial responses. Each of these responses in turn has their own environmental and economic consequences. Consequently, the ultimate effect of a regulatory policy may be very different from the original intent of the policy. The EPA would certainly not want to establish a new regulation that actually worsens the global environment. A prominent example of a secondary environmental effect caused by a firm-level reaction to environmental regulation is methyl tert-butyl ether (MTBE). MTBE was introduced as an automobile fuel additive to help solve urban air quality problems (CO and O3) only to discover that it adversely affects groundwater quality due to its mobility, odor, and persistence. Although this outcome was caused not only by the firm-level decision, it stands out as an example of why a better understanding of the secondary effects of environmental regulations is critically needed in order to protect the environment and to eliminate costly remediation measures. This paper is intended as a framework for future research that combines the elements of supply chain decision making, industrial ecology, and environmental policymaking to shed light on the effect of supply chain decisions on the impact of environmental regulation. The overall goal of our research is to develop a comprehensive framework to account for the interrelationships between competing policy pressures and to apply it to an important industrial sector, chemical manufacturing. This effort seeks to establish a procedure for characterizing the linkage between environmental regulations and their ultimate environmental and economic impacts. The effort will consider the probabilistic nature of industry decisions as well as a wide range of industry responses. With a linkage established that maps regulatory changes to their primary and secondary environmental effects, policy decisions may be made that achieve true environmental improvement. This paper is intended to be a starting point for conversations on how to proceed with this framework. We suggest and describe two major steps with two concomitant objectives. 1) Develop a complete framework for major decisions that industrial facilities can make in response to global climate change policies. The framework will take the form of a set of taxonomies. There will be one taxonomy for each link in the chain between the various policy options and the multitude of potential secondary impacts. This regulation-reaction-impact chain may include intermediate links such as firm size/type and incentives and disincentives. While this typology of responses may appear to be elementary, it can be much more complex given the often competing considerations of cost, profits, and regulatory compliance facing U.S. industry. 2) Identify the relationships among the before-mentioned taxonomies. These relationships will form the web that describes the regulation-reaction-impact process. We recognize that this web of taxonomies may well depend upon the specific industrial sector being considered.
2
Qi, Yinghua, Jianfu Ding, Michael Day, Jia Jiang i Claire L. Callender. "Design, synthesis, and properties of cross-linkable fluorinated poly(arylene ether ketone)s". W Photonics North, redaktorzy John C. Armitage, Simon Fafard, Roger A. Lessard i George A. Lampropoulos. SPIE, 2004. http://dx.doi.org/10.1117/12.567379.