Showing papers on "Ether published in 1990"

Silver halide photographic sensitive material

Abstract: PURPOSE: To increase an effect to activate interfaces by incorporating a sulfated oligosaccharide deriv. which is useful as a vehicle when emulsion layers or auxiliary layers are formed on various kinds of supporting bodies. CONSTITUTION: This silver halide photographic sensitive material contains a glycoside of sulfated oligosaccharide expressed by (sugar A)-Q-(sugar)n -Q-(sugar B)-QR or its salt in which >=20% of hydroxyl groups in the sugar part is sulfated with sulfuric acid. In formula, (sugar A) and (sugar B) are same or different monosaccharides. (sugar)n represents a sugar chain with n= 0 to 30 of single monosaccharide or plural kinds of monosaccharides.-Qbetween the monosaccharides is a glycoside bond which represents an ether bond between the first position as the molecular end of the one sugar and a hydroxyl group except for the first position of the other sugar. -QR is a substituent which is bonded with the first position of the molecular end of reduced oligosaccharide. R is C1-C30 alkyl group, alkylene group or alkynyl group which may be substituted or C6-C40 aryl group or heterocyclic group which may be substituted.

Lignin biochemistry: Biosynthesis and biodegradation *

Abstract: Lignin biosynthesis via shikimate-cinnamate pathways in plants, and the biosynthetic differences of guaiacyl-and syringyl lignins between gymnosperms and angiosperms have been elucidated by tracer experiments using 14C labeled precursors and the following enzyme reactions. The formation of guaiacyl lignin but not syringyl lignin in gymnosperms was attributed to the following factors; absence of ferulate-5-hydroxylase, poor affinity of O-methyltransferase toward 5-hydroxyferulate, and lack of activation and/or reduction of sinapatc. A mechanism of lignin-carbohydrate complexes formation in wood cell walls was elucidated based on the reaction of the quinone methide of guaiacylglycerol-β-guaiacyl ether with sugars, and the analysis of DHP-polysaccharide complexes. The main cleavage mechanisms of side chains and aromatic rings of lignin model compounds and synthetic lignin (DHP) by white-rot fungi and their enzymes, lignin peroxidase and laccase have been elucidated using 2H, 13C and 18O-labeled lignin substructure dimcrs with 18O2 and H2 18O. Side chains and aromatic rings of these substrates were cleaved via aryl cation radical and phenoxy radical intermediates, in reaction mediated only by lignin peroxidase/H2O2 and laccase/O2.

Recent Contributions of Kolbe Electrolysis to Organic Synthesis

Abstract: Carboxylic acids can be decarboxylated by anodic oxidation to radicals (Kolbe-electrolysis) and/or carbocations (non-Kolbe electrolysis). The procedure and necessary equipment is simple, a scale-up easy, the choice of carboxylic acids wide, the selectivity towards radicals or carbocations can be controlled by reaction conditions and the structure of the carboxylic acid, the yields are in general good. The radical pathway can be used for the preparation of e.g. 1,n-diesters, pheromones, or rare fatty acids. Electrolysis in the presence of olefins affords additive dimers and monomers or by intramolecular addition five membered carbocycles and heterocycles. By non-Kolbe electrolysis carboxylic acids can be converted into ethers, acetals, olefins or acetamides. Rearrangements and fragmentations lead to stereospecifically substituted cyclopentanoids and one- or four-carbon ring extensions.

Monte Carlo simulations of liquid alkyl ethers with OPLS potential functions

Abstract: Intermolecular potential functions have been developed for use in computer simulations of alkyl ethers. The simple OPLS model was adopted and parameterized to yield good descriptions of bimolecular and ion-molecule complexes as well as to reproduce experimental thermodynamic properties of liquid ethers. The principal testing featured Monte Carlo statistical mechanics simulations for liquid dimethyl ether (DME), ethyl methyl ether (EME), diethyl ether (DEE), and tetrahydrofuran (THF). Average errors of 1–3% are obtained for the computed densities and heats of vaporization including results for THF at pressures up to 5000 atm. The torsional motion about the central CO bonds in EME and DEE was included in the simulations using rotational potential functions fit to results of molecular mechanics (MM2) calculations. The liquid-state environment is found to have negligible effect on the conformational equilibria.

Poly(aryl ether-benzoxazoles)

Abstract: A general method for the preparation of poly(aryl ether-benzoxazoles) has been developed where the generation of an ether linkage is the polymer-forming reaction. The polymers [Ph-C 7 H 3 NO-R 1 -C 7 H 3 NO-PhO-ArO] n (R 1 =-, C(CF 3 ) 2 ; Ar=Ph-C(CF 3 ) 2 Ph, Ph-C(Ph) 2 -Ph, Ph-(uorenylene)-Ph) were prepared by polycondensation of dihalo bisbenzoxazoles with bisphenols in NMP in the presence of K 2 CO 3 . High molecular weight polymers were obtained, with glass transition temperatures ranging from 213 to 300 o C. The resulting polymers were processable from solution or the melt and showed excellent thermal stability and mechanical properties

Process for the production of surfactant mixtures based on ether sulfonates and their use

Abstract: A process for the production of a surfactant mixture for use in enhanced oil recovery wherein the surfactant mixture comprises an alkyl ether sulfonic acid or salt thereof as a principal constituent and at most a substantially equal quantity of alkoxylated alcohol. The surfactant mixture is prepared by reacting an alkyl ether sulfate with a stoichiometric excess of an alkali metal sulfite solution at about 160° C. to 220° C. under mildly alkaline pH conditions, and then extracting sulfate salt therefrom using a substantially water-insoluble alcohol at a lowered temperature.

Chromium compounds and uses thereof

Abstract: Novel chromlum-containing compounds, such as, for example, chromium pyrrolides, are prepared by forming a mixture of a chromium salt, a metal amide, and an electron pair donor solvent, such as, for example, an ether. These novel chromium-containing, or chromium pyrrolide, compounds can be used either unsupported or supported on an inorganic oxide support to trimerize and/or polymerize olefins.

Caesium-selective poly(vinyl chloride) membrane electrodes based on calix[6]arene esters

Abstract: Hexameric calix[6]arene ester compounds have shown an ability to extract large alkali metal ions such as caesium and rubidium in phase transfer studies A potentiometric selectivity study has been made using two ester containing hexameric calix[6]arenes, p-tert-butyl hexaethyl ester (1a) and the unsubstituted hexaethyl ester (1b), as the ionophores for caesium ions Six electrodes were prepared with 2-nitrophenyl octyl ether as the solvent mediator and various amounts of potassium tetrakis(p-chlorophenyl)borate as the ion exchanger in a poly(vinyl chloride) matrix The ligands examined produced electrodes with near-Nernstian slopes; the selectivity coefficients for caesium with respect to rubidium, potassium, sodium, lithium, calcium, magnesium, hydrogen and ammonium were determined Lifetimes of at least 1 month were estimated

Synthesis of aryl-substituted sulfonium salts by the phosphorus pentoxide-methanesulfonic acid promoted condensation of sulfoxides with aromatic compounds

Abstract: Resultats presentes dans un tableau, apres synthese a 20-40°C pendant une heure d'un melange du dialkyl ou diaryl sulfoxyde en presence de P 2 O 5 /MSA. Tous les sels de sulfonium ont ete caracterises par RMN 1 H et 13 C, spectres UV, points de fusion et analyse elementaire

Multi-function additive for lubricating oils

Abstract: OF THE DISCLOSURE A lubricating oil composition is provided which comprises a major amount of an oil of lubricating viscosity and a minor amount of an additive having the formula Mo4S4L6 in which L is a ligand selected from dithiocarbamates, dithiophosphates, dithiophosphinates, thioxanthates, and mixtures thereof and in which the ligands, L, have organo groups having a sufficient number of carbon atoms to render the additive soluble in the oil. In general, the organo groups of the ligands, L, will be the same, although they may be different and they preferably are selected from alkyl, aryl, substituted aryl and ether groups. For example, when L is a dialkyldithiocarbamate or a dialkyldithio-phosphate, the alkyl groups will have from about 1 to 30 carbon atoms.

Synthesis of soluble high molecular weight poly(aryl ether ketones) containing bulky substituents

Abstract: La polycondensation de la 2-t-butyl- ou de la 2-phenyl-hydroquinone avec la 4,4'-difluorobenzophenone donne les poly(aryl ether cetones) correspondants, amorphes et solubles dans CHCl 3 , THF ou le toluene. Le groupe t-butyl peut etre elimine par traitement du polymere par CF 3 SO 3 H pour donner la polyetherethercetone

Poly(ether/ester)s based on poly(butylene terephthalate) and poly(ethylene glycol), 1. Poly(ether/ester)s with various polyether: polyester ratios

Abstract: A series of poly(ether/ester)s 1 based on poly(butylene terephthalate)1 and poly(ethylene glycol) is synthesized. 1H and 13C nuclear magnetic resonance, infrared and differential scanning calorimetry (DSC) measurements prove a block structure of the prepared copolymers. The DSC curves suggest the existence of a three-phase morphology — two amorphous phases for both polyether and polyester segments, and a crystalline phase for the polyester segments. Small angle X-ray scattering (SAXS) measurements lead to the same conclusion. The degree of crystallinity assigned to the polyester fraction differs insignificantly and is similar to that of the homopolymer. SAXS data show approximately the same long spacing for all crystallizable copolymers. The tensile parameters of the studied polymers are similar to those of available commercial products based on poly(butylene terephthalate) and poly(tetrahydrofuran).

Ultrathin multicomponent poly(ether sulfone) membranes for gas separation made by dry/wet phase inversion

Abstract: Asymmetric gas separation membranes were prepared by a dry/wet phase inversion process using poly(ether sulfone) as membrane-forming material. Variations in the composition of multicomponent casting solutions and choice of the coagulation medium resulted in membranes with drastically different gas separation properties. Optimized integral-asymmetric poly(ether sulfone) membranes coagulated in methanol had pressure-normalized CO 2 fluxes of 7.2×10 -5 cm 3 (STP)/(cm 2 .s.cmHg) and a CO 2 /N 2 selectivity of 40. However, asymmetric membranes coated with a thin layer of silicone rubber showed substantially improved gas separation performance. Poly(ether sulfone)/silicone multicomponent membranes showed pressure-normalized CO 2 fluxes of up to 6.2×10 -5 cm 3 (STP)/(cm 2 .s.cmHg) combined with a CO 2 /N 2 selectivity of 60, essentially equal to the intrinsic permselectivity of poly(ether sulfone)

Amide and hydroxymethyl functionalized polyethers as thermoplastic barrier resins

Abstract: Polyethers having improved barrier to oxygen are normally solid, thermoplastic polyethers having aromatic ether repeating units in their backbones and pendent hydroxyl moieties and pendent amido, N-substituted amido and/or hydroxyalkyl moieties. Such polyethers are prepared by reacting diglycidyl ethers of dihydric aromatic compounds such as the diglycidyl ether of bisphenol A with dihydric phenols having pendent amido, N-substituted amido and/or hydroxyalkyl moieties such as 2,2-bis(4-hydroxyphenyl)acetamide and 3,5-dihydroxybenzamide.

Conductive and blocking layers for electrophotographic imaging members

Abstract: An electrophotographic imaging member including a supporting substrate, an electrically conductive layer including at least a partially crosslinked polymer having a backbone derived from an alkyl acrylamidoglycolate alkyl ether, a charge blocking layer including a polymer having a backbone also derived from an alkyl acrylamidoglycolate alkyl ether and at least one photoconductive layer. Preferably, the backbone derived from an alkyl acrylamidoglycolate alkyl ether is a copolymer of methyl acrylamidoglycolate methyl ether and a vinyl hydroxy ester or vinyl hydroxy amide. This imaging member may be prepared by a coating process and employed in an electrostatographic imaging process.

Thermal degradation of poly(aryl‐ether‐ether‐ketone): Experimental evaluation of crosslinking reactions

Abstract: Poly(aryl-ether-ether-ketone) (PEEK) has been heated at 400°C in both nitrogen and air. The extent of thermal degradation has been monitored by a variety of techniques including: solution viscometry, UV-visible spectroscopy, 13C high-resolution cross-polarization/magic angle spinning nuclear magnetic resonance and Fourier transform infrared spectroscopy. The results indicate, that in a nonoxidative environment such as nitrogen, PEEK is relatively stable at 400°C for periods up to 6 h. Under oxidative conditions chain scission reactions occur and crosslinks are formed causing a reduction in the crystallizability of the material and discoloration of the polymer. The spectroscopic evidence suggests that the chain cleavage occurs adjacent to the carbonyl functional groups. Subsequent hydrogen abstraction from the aromatic ring then leads to crosslinking between adjacent aryl rings.

Mechanistic studies of the catalytic dehydration of isobutyl alcohol on NaH-ZSM-5

Abstract: Using in situ FTIR and GC kinetic studies, we have examined the mechanism of dehydration of isobutyl alcohol to butene on well characterized ZSM-5 zeolite (number of active sites determined by various methods). Dehydration takes place on Bronsted-acid sites. The kinetics of water evolution from butanol is followed by in situ FTIR and both the rate constant and the activation energy of water evolution are estimated [k2=k02 exp (–E2/RT), where k02= 2 × 109 s–1 and E2= 19 ± 3 kcal mol–1]. At low temperatures (45–70 °C), elimination of water is accompanied by simultaneous formation of isobutyl ether (which at the given temperatures is adsorbed and desorbed with difficulty, but is able to form inside the channels). At higher temperatures (125 °C), there is a shift in the equilibria of various reaction steps, resulting in the formation of butene. This butene may desorb into the gas phase with traces of ether (in conditions of excess alcohol, flow GC experiments) or form oligomers which remain adsorbed in the zeolite (no excess of alcohol, static IR experiments). The measured rate constant and activation energy [k4=k04 exp(–E4/RT), where k04= 3 × 1014 s–1 and E4= 32 ± 2 kcal mol–1] for butene formation are effective values, containing contributions from several reaction steps, which explains the rather high value of E4.