Showing papers on "Ether published in 1993"
TL;DR: In this article, a versatile in-situ crosslinking technique was developed to crosslink the sulfonated poly (arylene ether sulfone) electrolytes during membrane processing in order to substantially reduce water swelling without impairing other membrane properties such as proton conductivity.
421 citations
236 citations
TL;DR: In this article, a new monomer containing pendant sodium sulfonate groups was synthesized by the sulfonation of 1 with fuming sulfuric acid and the polycondensation proceeded smoothly at 170°C and produced the desired poly(ether sulfone)s with inherent viscosities up to 1.2 dL/g.
Abstract: Poly(ether sulfone)s containing pendant sodium sulfonate groups were prepared by the aromatic nucleophilic substitution reaction of 4,4′-dichlorodiphenylsulfone (1) and sodium 5,5′-sulfonylbis (2-chlorobenzenesulfonate) (2) with bisphenols (3) in the presence of potassium carbonate in N,N-dimethylacetamide. A new monomer 2 containing the sodium sulfonate groups was synthesized by the sulfonation of 1 with fuming sulfuric acid. The polycondensation proceeded smoothly at 170°C and produced the desired poly(ether sulfone)s containing the sodium sulfonate with inherent viscosities up to 1.2 dL/g. The polymers were quite soluble in strong acid, dipolar aprotic solvents, m-cresol, and dichloromethane. The thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight losses of the polymers were observed in the range above 460°C in nitrogen atmosphere. Both the glass transition temperatures and hydrophilicity of the polymers increased with increasing their concentrations of sodium sulfonate groups. © 1993 John Wiley & Sons, Inc.
182 citations
TL;DR: In this paper, a reactive distillation column for the synthesis of methyl tert-butyl ether (MTBE) was simulated using a steady-state equilibrium stage model, and two distinctly different composition profiles were obtained, which correspond to high and low conversion of isobutene.
Abstract: A reactive distillation column for the synthesis of methyl tert-butyl ether (MTBE) is simulated using a steady-state equilibrium stage model. For identical column and feed specifications, two distinctly different composition profiles are obtained, which correspond to high and low conversion of isobutene. With the aid of residue curve maps for simultaneous physical and chemical equilibrium, it is shown that the high- and low-conversion steady-state composition profiles obtained in the column simulations correspond to residue curves which have their starting points in distinctly different composition regions
159 citations
TL;DR: In this paper, the melting behavior of these materials was investigated by WAXS and SAXS, and the change of the degree of crystallinity, of the SAXs power Q, and of the long period was determined as a function of temperature during heating.
Abstract: Samples of poly(ether ether ketone) (PEEK), poly(ether ether ketone ketone) (PEEKK), and poly(ether ketone ether ketone ketone) (PEKEKK) were crystallized at different temperatures by stepwise cooling from the melt to obtain samples which show multiple melting peak in a calorimetric investigation. The melting behavior of these materials was investigated by WAXS and SAXS and by DSC. The change of the degree of crystallinity, of the SAXS power Q, and of the long period was determined as a function of temperature during heating. It was concluded that( the additional meltiong peaks are caused by muelting of some thin crystals within lamellar stacks and not by melting of complete lamellar stacks
159 citations
TL;DR: In this paper, a thermoplastic and thermoset polymers containing alternating perfluorocyclobutane and aromatic ether subunits are prepared from aryl poly(trifluorovinyl ether) monomers via the thermal [2π+2π] dimerization of the trifluoric ether functionality.
Abstract: Novel polymers containing alternating perfluorocyclobutane and aromatic ether subunits are prepared from aryl poly(trifluorovinyl ether) monomers via the thermal [2π+2π] dimerization of the trifluorovinyl ether functionality. A model study is described, which probes the nature of the perfluorocyclobutane rings formed during the polymerization reaction. The bifunctional monomer 4,4'-bis(trifluorovinyloxy) biphenyl and the trifunctional monomer 1,1,1-tris(4-trifluorovinyloxyphenyl)ethane are prepared and polymerized to provide thermoplastic and thermoset polymers, respectively. Characterization of the mechanical and dielectric properties of these new polymers is presented
157 citations
TL;DR: In this paper, the authors measured the gas transport properties of polyphenylene ethers poly(2,6-dimethyl-1,4-phenylene oxide)PDMPO, and poly( 2, 6-diphenyl- 1, 4-phosphylene oxide), PDPPO, and the thioether poly(1, 4 -phenylene sulfide), PPS, and showed that substitution of phenyl groups, which leads to polymers that have better thermal and oxidative stability than methyl substituted ones, can be a useful means for increasing free volume
Abstract: Gas transport properties of the polyphenylene ethers poly(2,6-dimethyl-1,4-phenylene oxide)PDMPO, and poly(2,6-diphenyl-1,4-phenylene oxide), PDPPO, and the thioether poly(1,4-phenylene sulfide), PPS, have been measured as a function of pressure and temperature. The PPS material and free volume correlations were used to estimate the behavior of the unavailable poly(1,4-phenylene oxide), PPO. The results show that symmetrical substitution of phenyl groups on the backbone of polyphenylene ether, PDPPO, increases the gas transport properties by one order of magnitude relative to the unsubstituted material, PPO. Symmetrical methyl substitution, PDMPO, however, increase the permeability, apparent diffusion and sorption coefficients even further. The gas transport coefficients correlate with the fractional free volume of the polymers. PDMPO has the largest fractional free volume and gas transport coefficients followed by PDPPO and the PPS. The results show that substitution of phenyl groups, which leads to polymers that have better thermal and oxidative stability than methyl substituted ones, can be a useful means for increasing free volume and gas permeability coefficients. While methyl groups appear to be more effective for the latter, the enhanced chemical stability of phenyl rings may be useful when gas separation membranes are to be used in harsh environments. © 1993 John Wiley & Sons, Inc.
148 citations
TL;DR: In this paper, the authors reported that the ethyl ether layer was the most effective in stabilizing lard against oxidation, with activity equal to butylated hydroxytoluene.
Abstract: Oregano (Origanum vulgare L.) leaves were successively extracted with hexane, ethyl ether, ethyl acetate and ethanol. The ethanol extract was reextracted in a separatory funnel with petroleum ether, ethyl ether, ethyl acetate and butanol. The ethyl ether layer was the most effective in stabilizing lard against oxidation, with activity equal to butylated hydroxytoluene. It also showed antioxidant activity when tested on vegetable oils under storage or frying conditions. The main antioxidant factors isolated from the ethyl ether layer consisted of flavonoids. Chromatographic and spectrophotometric analysis demonstrated the presence of the flavone apigenin, the flavanone, eriodictyol and the dihydroflavonols, dihydrokaempferol and dihydroquercetin.
145 citations
TL;DR: Results indicate that poly(PEG-Lys), a new, water-soluble poly(ether urethane), derived from L-lysine and poly(ethylene glycol), is a promising precursor for the preparation of soluble drug conjugates.
139 citations
TL;DR: In this article, the authors discuss the convergence of HYPERBRANCHED ALLYL ETHER ETHER MALEATE FUNCTIONAL ESTER RESINS in the context of homonymity.
Abstract: SYNTHESIS, CHARACTERIZATION, AND CURING OF HYPERBRANCHED ALLYL ETHER MALEATE FUNCTIONAL ESTER RESINS
128 citations
TL;DR: In this article, Hartree-Fock and MP2 calculations with 3-21G and 6-31G * basis sets were conducted for a group of urethane model molecules and hydrogen-bonded dimers to study the intra-and intermolecular interactions for polyurethanes.
Abstract: Ab initio Hartree-Fock and MP2 calculations with 3-21G and 6-31G * basis sets were conducted for a group of urethane model molecules and hydrogen-bonded dimers to study the intra- and intermolecular interactions for polyurethanes. Conformational structures and energies of internal bond rotations were calculated and compared with available experimental results. Three types of hydrogen bonds that formed between the urethane N-H group and (1) the urethane carbonyl oxygen, (2) the ester oxygen, and (3) the ether oxygen were studied. The vibrational frquency shifts of the N-H, C=O, and C-O-C stretching modes computed for the dimers at the HF/6-31G * level qualitatively agree with the experimental observations of polyurethanes and support the assignment of the 3295-cm -1 band to the N-H stretching mode in the N-H---O-(ether) hydrogen-bonding structure
TL;DR: In this article, the relationship among glass transition, crystallization, melting, and crystal morphology of poly(aryl ether ketone) (PAEK)/poly(other imide) (PEI) blends was studied by thermal, optical and small-angle x-ray scattering (SAXS) methods.
Abstract: The relationships among glass transition, crystallization, melting, and crystal morphology of poly(aryl ether ketone) (PAEK)/poly(other imide) (PEI) blends was studied by thermal, optical and small-angle x-ray scattering (SAXS) methods. Two types of PAEK were chosen for this work: poly(aryl ether ether ketone), PEEK, and poly(aryl ether ketone ketone), PEKK, which have distinctly different crystallization rates. Both PAEKs show complete miscibility with PEI in the amorphous phase. As PAEK crystallizes, the noncrystallizable PEI component is rejected from the crystalline region, resulting in a broad amorphous population, which was indicated by the broadening and the increase of Tg over that of the purely amorphous mixture. The presence of the PEI component significantly decreases the bulk crystallization and crystal growth rate of PAEK, but the equilibrium melting temperature and crystal surface free energies are not affected. The morphology of the PEI segregation was investigated by SAXS measurements. The results indicated that the inter(lamellar-bundle) PEI trapping morphology was dominant in the PEEK/PEI blends under rapid crystallization conditions, whereas the interspherulitic morphology was dominant in the slow crystallizing PEKK/PEI blends. These morphologies were qualitatively explained by the expression δ=D/G, where G was the crystal growth rate and D was the mutual diffusion coefficient. © 1993 John Wiley & Sons, Inc.
TL;DR: In this article, the first living cationic polymerization of α-methylstyrene was achieved with an initiating system that consist of the HCl-adduct of 2-chloroethyl vinyl ether [1a: CH 3 CH(OCH 2 CH 2 Cl)Cl] and SnBr 4 in CH 2 CL 2 at -78°C.
Abstract: The first example of living cationic polymerization of α-methylstyrene was achieved with an initiating system that consist of the HCl-adduct of 2-chloroethyl vinyl ether [1a: CH 3 CH(OCH 2 CH 2 Cl)Cl] and SnBr 4 in CH 2 Cl 2 at -78°C. The number-average molecular weight of the polymers increased in direct proportion to monomer conversion up to 110 000 (DP n =1000) and agreed with the calculated values assuming that one polymer chain forms per 1a molecule. Throughout the reaction, the molecular weight distribution of the polymers stayed very narrow (M w /M n ∼1.1)
TL;DR: The ozonolysis of alkenes in methanolic NaOH or NaOMe with CH 2 Cl 2 as cosolvent leads directly to methyl esters as discussed by the authors.
Abstract: The ozonolysis of alkenes in methanolic NaOH or NaOMe with CH 2 Cl 2 as cosolvent leads directly to methyl esters. The procedure has been used to prepare various α-, β-, and ω-alkoxy esters, acyloxy esters, and α- and β-N-acyl and N-sulfonyl esters from the appropriate unsaturated ethers, esters and amides. Other examples include the formation of dimethyl octanedioate from cyclooctene (75% yield), dimethyl nonanedioate and methyl nonanoate from methyl oleate (77 and 78%, respectively), and tetradecanoic acid γ-lactone from 2-methyl-2-hexadecen-6-ol (80% yield)
Patent•
23 Jul 1993TL;DR: In this article, the side chain of a naturally occurring alpha-amino acid (A-AMAC) was defined as a group R6(A)n- wherein n is 0 or 1, and A represents a divalent C1-C6 alkyl or C2-C 6 alkenyl group optionally interrupted by one or more -O-, or -S- atoms or -N(R7)- groups where R7 is hydrogen or C1 -C6alkyl, and R6 is a phenyl or heterocyclyl
Abstract: Compounds of formula (I), wherein R2 represents a C2-C6 alkyl group which may contain an ether or thioether linkage; R3 represents (a) the side chain of a naturally occurring alpha-amino acid in which any carboxylic acid group may be esterified or amidated, any hydroxyl or thiol group may be acylated or alkylated (etherified) and any amino group may be acylated, or (b) a group R6(A)n- wherein n is 0 or 1, A represents a divalent C1-C6 alkyl or C2-C6 alkenyl group optionally interrupted by one or more -O-, or -S- atoms or -N(R7)- groups where R7 is hydrogen or C1-C6 alkyl, and R6 is a phenyl or heterocyclyl group either of which may be substituted, or (except where n is 0) a hydrogen atom; R4 represents hydrogen or methyl; R5 represents hydrogen, C1-C6 alkyl or phenyl(C1-C6 alkyl), and salts, solvates and hydrates thereof, are inhibitors of metalloproteinases involved in tissue degradation.
TL;DR: In this paper, the MM2 program was used to examine the structures and strain energies 11 hexadentate crown ether ligands and their potassium complexes, and the results established that both the K-O length preference and bonding directionality at the ether oxygen donor atom are important factors in the determination of complex stability.
Abstract: Molecular mechanics calculations with the MM2 program were used to examine the structures and strain energies 11 hexadentate crown ether ligands and their potassium complexes. With the exception of K-O stretching parameters, all force field parameters for interactions involving the potassium ion were obtained by fitting to ab initio potential energy surfaces for selected distortions in K-O(Me)[sub 2] and K-O(Me)(Et). The K-O stretching parameters were optimized relative to crystallographic data. Comparison of the molecular mechanics results to experimental log K values that were available for all 11 crown ethers revealed the complex stability to be strongly correlated with the difference in strain energy between the uncomplexed ligand and its potassium complex. The results establish that both the K-O length preference and bonding directionality at the ether oxygen donor atom are important factors in the determination of complex stability. It is concluded that the failure to consider the orientation of the ether C-O-C moiety, relative to the metal ion, is a serious flaw in the size-match selectivity theory. 78 refs., 9 figs., 4 tabs.
TL;DR: In this article, a new attempt was investigated to utilize inorganic solid acids and bases for the promotion of the reaction of cyanotrimethylsilane (Me3SiCN) with carbonyl compounds.
Abstract: A new attempt was investigated to utilize inorganic solid acids and bases for the promotion of the reaction of cyanotrimethylsilane (Me3SiCN) with carbonyl compounds. Strongly acidic solids, such as Sn4+ ion-exchanged montmorillonite (Sn-Mont) and Fe3+ ion-exchanged montmorillonite (Fe-Mont), as well as basic solids, such as calcium fluoride (CaF2), hydroxyapatite (HAp), calcium oxide (CaO), and magnesium oxide (MgO), catalyzed the reaction of Me3SiCN with aldehydes and ketones to afford the corresponding 2-(trimethylsiloxy)alkanenitriles in good yields. The reactions of dimethyl acetals with Me3SiCN in the presence of solid acids afforded 2-methoxyalkanenitriles. In cyanosilylations of α,β-unsaturated ketones two kinds of adducts were produced selectively, depending on the use of a solid acid or a solid base: 1,4-Adducts (trimethylsilyl enol ether forms) were selectively obtained in the presence of strong solid acids, such as Fe-Mont and Sn-Mont, while 1,2-adducts (trimethylsilyl ether forms) were predom...
TL;DR: Asymmetric dihydroxylation of substituted aryl allyl ethers is described, and para-substituents are shown to favor high enantioselectivity, while ortho-groups have a deleterious effect.
TL;DR: A kinetic study of the reduction of ferrate ion under basic conditions has been completed in this article, where it was shown that a typical aliphatic ether, tetrahydrofuran, is oxidized at a rate comparable to that of a typical ferrate atom.
Abstract: A kinetic study of the reduction of ferrate ion under basic conditions has been completed. The observation that a typical aliphatic ether, tetrahydrofuran, is oxidized at a rate comparable to that ...
TL;DR: Two series of 3-substituted polythiophenes and poly(4-methylthiophene)s having the substituents containing 8 atoms in the backbone with oxygen as the first atom bonded to the thiophene ring were synthesized by chemical polymerization using FeCl 3 as the oxidizing agent.
Abstract: Two series of 3-substituted polythiophenes and poly(4-methylthiophene)s having the substituents containing 8 atoms in the backbone with oxygen as the first atom bonded to the thiophene ring, C 7 H 15 O-, C 4 H 9 OC 2 H 4 O-, and CH 3 OC 2 H 4 OC 2 H 4 O- for the former series and having the first two substituents for the latter series were synthesized by chemical polymerization using FeCl 3 as the oxidizing agent.
TL;DR: In this paper, the crystal structures of α-metalated amines are determined, as are α-lithiated halides and ethers, in order to determine whether they are carbenoids.
Abstract: In order to determine whether α-metalated (lithiated) amines are carbenoids, as are α-lithiated halides and ethers, we have determined the crystal structures of the title compounds. In [α-(dimethylamino)benzyllithium–diethyl ether]2 ([9 · OEt2]2) lithium bridges the anionic carbon and the nitrogen atom which corresponds to the most stable calculated model structure of LiCH2NH2. The C–N bond is only slightly (≈ 3 pm) elongated (compared to the neutral species). If one of the N-methyl groups in [9 7dot; OEt2]2 is replaced by a pivaloyl group as in (S)-α-(methylpivaloylamino)benzyllithium – (–)-sparteine (10 dot; sparteine), a five-membered ring chelate is formed with Li being bound to the benzylic carbon atom and the oxygen atom of the pivaloyl group. In agreement with model calculations avoidance of the bridged structure as in [9 · OEt2]2 is compensated energetically by the chelate. Again a very small C–N bond elongation (≈ 3 pm) is observed. In [3-iodo-2-lithio-1-methylindole – 2 THF]2 ([12 · 2 THF]2) lithium again does not bridge to the indole nitrogen atom because it is a weak donor. The C–N bond length to the anionic C atom is slightly longer (2–3 pm) than in the non-lithiated compound. Other α-lithiated amines, which have been published, although not analyzed so far under this particular aspect, show also a marginal C–N bond lengthening. However, since α-lithiated amines – in contrast to α-lithiated halides and ethers – until now have not been reported in the literature to react with nucleophiles RLi, there is no need to include them into the group of the above mentioned carbenoids – at least not to date.
Patent•
08 Oct 1993
TL;DR: Novel heterocyclic ether compounds of formula (I), wherein A, B and R2 are specifically defined, or pharmaceutically-acceptable salts or prodrugs thereof, which are selective and potent ligands at cholinergic channel receptors, useful in the treatment of cognitive, neurological and mental disorders characterized by decreased cholineergic function.
Abstract: Novel heterocyclic ether compounds of formula (I), wherein A, B and R2 are specifically defined, or pharmaceutically-acceptable salts or prodrugs thereof, which are selective and potent ligands at cholinergic channel receptors, useful in the treatment of cognitive, neurological and mental disorders characterized by decreased cholinergic function.
TL;DR: The experiment implies that the bleaching effect of hydrogen peroxide can be achieved without heat by use of a sodium hydroxide solution.
Abstract: The decomposition rate of 30% hydrogen peroxide was measured when hydrogen peroxide was mixed with 36% hydrochloric acid and anaesthesia either in 5:5:1 solution and in a solution of 20% sodium hydroxide at temperatures of 16 degrees to 20 degrees C and at 45 degrees C, respectively. The effect of ferris chloride on the decomposition of hydrogen peroxide was also observed. The decomposition of 30% hydrogen peroxide in sodium hydroxide solution was faster than that in the mixture of hydrochloric acid and ether at low temperature (16 degrees to 20 degrees C). The decomposition of hydrogen peroxide was accelerated by heat. The experiment implies that the bleaching effect of hydrogen peroxide can be achieved without heat by use of a sodium hydroxide solution. Further study on the rationale of the compound of the McInnes solution (hydrogen peroxide, hydrochloric acid, and anaesthesia ether mixed at a ratio of 5:5:1) is needed.
TL;DR: A Dvorak-Boublik recirculating still has been used to measure isothermal vapor-liquid equilibrium data for 1,2-ethanediol+water and for five different glycol ether+water systems as mentioned in this paper.
Abstract: A Dvorak-Boublik recirculating still has been used to measure isothermal vapor-liquid equilibrium data for 1,2-ethanediol+water and for five different glycol ether+water systems. The glycol ethers are 2-methoxyethanol, 2-ethoxyethanol, 1-methoxy-2-propanol, 2-isoproporyethanol, and 2-butoxyethanol. Each system has been measured at two temperatures in the range 343.15-368.15 K. The reliability of the data has been checked by using a maximum likelihood data reduction
TL;DR: In this paper, twelve α,Ω-bis(N-azacrown ether) compounds have been prepared, characterized, and converted into a previously unknown type of niosome.
Abstract: Twelve novel α,Ω-bis(N-azacrown ether) compounds have been prepared, characterized, and converted into a previously unknown type of niosome. Four are bis(15-crown-5) derivatives having the following spacer chains: (CH 2 ) 12 (1), (CH 2 ) 16 (2), CO(CH 2 ) 20 CO (3), and (CH 2 ) 22 (4)
TL;DR: 4,4'-Dibromodiphenyl ether was not used as a carbon source although transformation by resting cells yielded mononuclear haloaromatic compounds, such as 4,bromophenol and 4-bromocatechol, which yielded the respective (halo-) phenols and ( halo-) catechols.
Abstract: The bacterium Sphingomonas sp. strain SS33, obtained from parent diphenyl ether-mineralizing strain SS3 (S. Schmidt, R.-M. Wittich, D. Erdmann, H. Wilkes, W. Francke, and P. Fortnagel, Appl. Environ. Microbiol. 58:2744-2750, 1992) after several weeks of adaptation on 4,4'-difluorodiphenyl ether as the new target compound, also utilized 4,4'-dichlorodiphenyl ether for growth. Intermediary halocatechols were also mineralized via the ortho pathway by type I enzymes. 4,4'-Dibromodiphenyl ether was not used as a carbon source although transformation by resting cells yielded mononuclear haloaromatic compounds, such as 4-bromophenol and 4-bromocatechol. The same was true for the conversion of 2,4-dichlorodiphenyl ether, which yielded the respective (halo-) phenols and (halo-) catechols.
TL;DR: In this paper, the dielectric relaxation characteristics of amorphous and semicrystalline poly(ether ether ketone) have been investigated as a function of crystallization history; both the glass-rubber (α) relaxation and a subglass (β) relaxation were examined.
Abstract: The dielectric relaxation characteristics of amorphous and semicrystalline poly(ether ether ketone) have been investigated as a function of crystallization history; both the glass-rubber (α) relaxation and a sub-glass (β) relaxation were examined. The characteristics of the a relaxation were highly sensitive to crystallinity owing to the constraint imposed on the amorphous phase dipoles by the presence of the crystalline phase. The magnitude of the a relaxation strength indicated an immobilized rigid amorphous phase fraction in the semicrystalline samples which appeared to relx at temperatures above T g ; finite rigid amorphous fractions were observed for both cold-crystallized and melt-crystallized specimens