Search results for "Onium"
showing 10 items of 2091 documents
Non-Isomorphic Chlorine—Bromine Substitution in the Copper(I) Halideπ-Complexes with 1-Allyl-4-aminopyridinium
2003
By alternating-current electrochemical synthesis crystals of {Cu[H2NC5H4N(C3H5)]Br2}˙H2O (I), {Cu[H2NC5H4N(C3H5)]Br0.65Cl1.35}˙H2O (II) and {Cu[H2NC5H4N(C3H5)]Cl2} (III) π-complexes have been obtained and structurally investigated. The I and II compounds are isostructural and crystallize in a monoclinic sp. gr. P21/c, I: a = 7.359(2)A, b = 12.3880(6)A, c = 13.637(3)A, β = 107.03(1)°, V = 1188.7(4)A3, Z = 4 for C8H13N2OBr2Cu composition, R = 0.0293 for 2140 reflections. II: a = 7.2771(6)A, b = 12.3338(3)A, c = 13.4366(7)A, β = 107.632(2)°, V = 1149.3(1)A3, Z = 4 for C8H13N2Br0.65Cl1.35Cu composition, R = 0.0463 for 2185 reflections. Metal and halogen atoms form centrosymmetric Cu2X4 dimers. …
Recognition of N-Alkyl- and N-Aryl-Acetamides by N-Alkyl Ammonium Resorcinarene Chlorides
2014
N-alkyl ammonium resorcinarene chlorides are stabilized by an intricate array of intra- and intermolecular hydrogen bonds that leads to cavitand-like structures. Depending on the upper-rim substituents, self-inclusion was observed in solution and in the solid state. The self-inclusion can be disrupted at higher temperatures, whereas in the presence of small guests the self-included dimers spontaneously reorganize to 1:1 host-guest complexes. These host compounds show an interesting ability to bind a series of N-alkyl acetamide guests through intermolecular hydrogen bonds involving the carbonyl oxygen (C=O) atoms and the amide (NH) groups of the guests, the chloride anions (Cl(-)) and ammoni…
STUDIEN ZUM VORGANG DER WASSERSTOFFÜBERTRAGUNG 731HYDROGENOLYSESTUDIEN VON SCHWEFEL-UND PHOSPHOR-VERBINDUNGEN AN RANEY-NICKEL (Ra-Ni)—EINE MATERIALSA…
1985
Abstract The desulfurization and dephosphorization with Raney-Nickel (Ra-Ni) is investigated under standard conditions using the following types of compounds: Mercaptanes. thioethers, di- and trisulfides, sulfonium salts, sulfoxides, sulfones, sulfonic acid derivatives, bidental thioethers before and after the chelation, tertiary phosphines and phosphites, phosphonium salts and amidophosphonium salts, phosphine-metal-complexes, model compounds containing sulfur and phosphorus in the same molecule and samples of aerosil the surface of which is modified with S- and P-functions. The degree of the desulfurization and dephosphorization is dependent on the amount and availability of the “structur…
The thermal decomposition, IR spectrum and crystal structure of ammonium manganese(II) tris(hydrogenselenite), NH4Mn(HSeO3)3
1985
Abstract The compound NH 4 Mn(HSeO 3 ) 3 has been prepared and its IR spectrum and thermal behaviour have been investigated. It crystallizes in the monoc
Novel one-pot synthesis of quaternary ammonium halides: new route to ionic liquids
2004
Treatment of an amide with an alkyl or substituted alkyl halide in the presence of a weak base in a one-pot reaction leads to crystalline quaternary ammonium halides with reasonable chemical yields; some of the compounds show low melting points and a liquid range of over 50–100 °C before decomposition.
Studien zum Vorgang der Wasserstoffübertragung, 73. Die Reduktion prochiraler Alkyl(aryl)ketone zu Carbinolen und Pinakolen mit Alkaliamalgamen
1984
Es werden die Faktoren ermittelt, welche die Stereochemie und das Mengenverhaltnis (C/P) des bei der Reduktion von Acetophenon mit Lithium-, Natrium- und Kaliumamalgam (Li/Hg, Na/Hg, K/Hg) gebildeten Carbinols (C) und Pinakols (P) bestimmen. Das C/P-Verhaltnis wird beeinflust a) durch Protonendonatoren, b) durch quartaren Ammoniumsalze, c) durch bis-tertiare Amine. Bei Anwesenheit von optisch aktiven quartaren Ammoniumsalzen und optisch aktiven bis-tertiaren Aminen wird sowohl beim Pinakol als auch beim Carbinol eine geringe optische Induktion beobachtet. Bei der Reduktion von Pivalophenon mit Li/Hg entsteht das anomale Dimerisierungsprodukt 20. Studies on the Occurrence of Hydrogen Transfe…
Bimodal Effect of Amphiphilic Biocide Concentrations on Fluidity of Lipid Membranes
1996
Abstract Using the spin label method (ESR) it has been shown that biologically active, amphiphilic compounds (quaternary ammonium salts -AS) containing polar heads with single and double positive charge caused, at low concentrations, decrease fluidity of liposome membranes formed with egg yolk lecithin (EYL). At higher concentrations an increase in fluidity was observed. With compounds having a single positive charge minimum fluidity of membrane structure occurs in the range of 1 to 3%, with compounds containing double positive charge -in the range of 4 -6 % . That effect does not depend on polar head size and length of alkyl chains of the AS used. Analysis of the electrostatic interaction …
Micro- and nanostructuring of oligo- and polythiophenes in two and three dimensions
2003
Abstract Oligothiophenes bearing methacrylic functionalities were two-dimensional-structured by stamping techniques. The localised monomer was hardened by radical polymerisation in UV light. The structures in micrometre- and nanometre-scale were characterised electrochemically by SECM. An inverse polymer opal with extremely high inner surface and periodicity was obtained by localising the photosensitive oligothiophene within an opal template of SiO 2 beads. Cyclic voltammetry of the oligothiophenes in aprotic solvents was carried out to examine possible electrochemical conversions. A self-assembling technique for lateral and vertical structuring of polythiophenes with pendant sulfonate and …
Positron Annihilation in Alkali Halides at Low Temperatures
1986
We report on low-temperature positron studies for pure, single crystals of the alkali halides KCl, NaCl and NaF. Strong temperature dependences are observed in the lifetime and angular correlation measurements in the temperature range 10–300 K. Delocalized para-positronium is observed at low temperatures in the three crystals. The broadening, with rising temperature, of the narrow peak in the angular correlation curve can be accounted for by the self-trapping model of positronium. The results are discussed in the light of this model, in terms of positronium localization at imperfections and in terms of positron interactions with imperfections created in the spur of the positron. The increas…
Cellulose Nanocrystals from Lignocellulosic Raw Materials, for Oxygen Barrier Coatings on Food Packaging Films
2017
Cellulose nanocrystals (CNCs) are unique, renewable top-down nano particles from which coatings with improved gas barrier properties and new functionalities can be prepared. In this paper, the potential for obtaining such high performing nanocrystals from low-cost lignocellulosic by-products or raw materials is proved by a comparison study on CNCs obtained both from cotton linters and kraft pulp, by means of the ammonium persulfate (APS) process. Morphological and chemical characterization of the nanocrystals obtained, as well as the main functional properties of the poly(ethylene terephthalate) coated films, showed quite similar characteristics and performances of CNCs obtained from pure c…