Search results for "Ether"
showing 10 items of 986 documents
Theoretische analyse der bei einem zweiwegwachstumsmechanismus auftretenden molekulargewichtsverteilungen und ihre anwendung auf die anionische polym…
1967
Es werden mittels der Momentmethode die fur einen abbruchfreien Zweiwegwachstumsmechanismus zu erwartenden Molekulargewichtsverteilungen und ihr Zusammenhang mit dem kinetischen Ablauf theoretisch abgeleitet. Die ermittelten Bezichungen werden auf das Polymerisationssystem Styrol in Cumylmethylather mit Cumylnatrium als Initiator angewandt. Durch Einsetzen der vorher experimentell ermittelten kinetischen Daten in die theoretisch abgeleitete Gleichung werden die Molekulargewichtsverteilungen des untersuchten Systems berechnet und mit den experimentell ermittelten verglichen. Die gute Ubereinstimmung zwischen Theorie und Experiment stellt einen schlussigen Beweis fur das Vorliegen eines Zweiw…
Formation of α-ω(4,7,10,13-pentaoxa-16-azacyclooctadecane) hexadecane micelles in aqueous solution – effect of HCl addition
2003
The structure of aggregates of a new bolaform surfactant [α-ω (4,7,10,13-pentaoxa-16-azacyclooctadecane) hexadecane] in neat aqueous solution has been investigated by small-angle neutron scattering. Preliminary data analysis unequivocally indicates that globular micelles are formed. This finding has been confirmed by the analysis of data obtained upon addition of hydrochloric acid. The observed significant reduction of micelle aggregation number has been attributed to the peculiar complexing ability of the two aza-crown ether units in the surfactant molecule; this is in line with information inferred from the complexation of ions into the non alkylated azacrown ethers. As a consequence of h…
Effects of non-ionic micelles on transient chaos in an unstirred Belousov-Zhabotinsky reaction.
2001
The behaviour of the Ce(IV)-catalyzed Belousov-Zhabotinsky (BZ) system has been monitored at 20.0 degrees C in unstirred batch conditions in the absence and presence of different amounts of the non-ionic micelle-forming surfactants hexaethylene glycol monodecyl ether (C10E6) and hexaethylene glycol monotetradecyl ether (C14E6). The influence of the non-ionic surfactants on both the kinetics of the oxidation of malonic acid (MA) by Ce(IV) species and the behaviour of the BZ reaction in stirred batch conditions has also been studied over a wide surfactant concentration range. The experimental results have shown that, in unstirred batch conditions, at surfactant concentrations below the critic…
CMPO-substituted calix[6]- and calix[8]arene extractants for the separation of An3+/Ln3+ from radioactive waste
2006
Abstract Three calix[6]arene derivatives ( 1a – c ) and two calix[8]arene derivatives ( 2a , b ), with six and eight CMPO residues, respectively, attached to the narrow/lower rim via ether links, were synthesised. Preliminary liquid–liquid extraction studies for Eu(III) and Am(III) from aqueous nitric acid to o -nitrophenylhexyl ether reveal remarkable properties with respect to efficiency and selectivity, especially for the tert -butylcalix[6]arene derivative with a –(CH 2 ) 3 – spacer.
2,4-Dibromophenyl 2,6-dibromophenyl ether
2002
The title compound, C12H6Br4O, is the fourth well characterized of a total of potentially 209 different brominated diphenyl ethers. Salient intermolecular interactions are between ether O and aromatic C atoms, and between a bromine substituent and the aromatic ring system.
Der nachweis der kettenstruktur von aus p-kresol und formaldehyd aufgebauten mehrkernverbindungen. III. Herstellung der methyläther der zwei- und dre…
1963
Es wurden Bedingungen gefunden, um die phenolischen Hydroxylgruppen der aus p-Kresol und Formaldehyd hergestellten Zwei- und Dreikernverbindung vollstandig zu methylieren. Die Ergebnisse der Permethylierung beweisen die Kettenstruktur und die freien Hydroxylgruppen der Ausgangsverbindungen. Die Struktur der Mono- und Dimethylather sowie des Trimethylathers der Dreikernverbindung wurde durch Synthese aus einfacheren methoxylgruppenhaltigen Verbindungen bewiesen. Conditions were found for complete methylation of the phenolic hydroxyl groups of the two nuclei and three nuclei compound produced of p-cresol and formaldehyde. The results of the permethylation established the free hydroxyl groups …
13C NMR spectroscopic study of diphenyl ether and 28 of its polychlorinated derivatives
1993
The 13 C NMR chemical shifts and coupling constants for diphenyl ether and 28 environmentally interesting polychlorinated diphenyl ethers were measured and analysed
2(S)-Amino-3-[1H-imidazol-4(5)-yl]propyl cyclohexylmethyl ether dihydrochloride and 2(S)-amino-3-[1H-imidazol-4(5)-yl]propyl 4-bromobenzyl ether dihy…
2000
(Cyclohexylmethyloxymethyl)(1H-imidazol-4-iomethyl)-(S)-ammonium dichloride, C(13)H(25)N(3)O(+).2Cl(-), and (4-bromobenzyl)(1H-imidazol-4-iomethyl)-(S)-ammonium dichloride, C(13)H(18)BrN(3)O(+).2Cl(-), are model compounds with different biological activities for evaluation of the histamine H3-receptor activation mechanism. Both title compounds occur in almost similar extended conformations.
4-Bromophenyl 2,4-dibromophenyl ether
2002
The title compound, C12H7Br3O, belongs to a group of flame retardants known as polybrominated diphenyl ethers (PBDE). Salient features of the packing of the title compound are infinite intermolecular Br⋯Br contact chains along the b direction.
Calix Crowns Derived from para-Bridged Calix[4]arenes
2000
Two calix[4]arenes, bridged by aliphatic chains of five and eight carbon atoms spanning two opposite para positions, have been converted into their 1,3-crown ether derivatives by reaction with tetraethylene and pentaethylene glycol ditosylates. Of the two possible 1,3-crown derivatives, only the formation of those isomers is observed in which the phenolic units connected at the para positions are etherified. This has been established in one case by a single-crystal X-ray analysis. Preliminary results for the extraction of selected alkali and alkaline-earth metals are reported.