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  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of Homo- and Hetero-Bimetallic Complexes Containing the Ni(C6F5)2 Moiety - Crystal Structure of [(C6F5)2Ni(μ-SPh)2Pd(dppe)] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1199-1204 
    Details
    ISSN: 1434-1948
    Keywords: Organometallic compounds ; Nickel complexes ; Crystal structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The compound cis-[Ni(C6F5)2(PhCN)2] has been used as the starting material for the preparation of the bimetallic complexes [(C6F5)2Ni(μ-X)2Ni(C6F5)2]2- (X = SCN, OCN, N3), [(C6F5)2Ni(μ-SCN)2Pd(C6F5)2]2-, [(C6F5)2Ni(μ-NCS)2Pd-(dppe)] [dppe = 1,2-bis(diphenylphosphanyl)ethane], and the trimetallic[(C6F5)2Ni(μ-NCS)2Pd(μ-SCN)2Ni(C6F5)2]2-. The mononuclear compounds [(C6F5)2NiLX] (L = PPh3, P(C6H4MeO-p)3; X = SCN, OCN) are obtained by reaction between [(C6F5)2Ni(&μ-X)2Ni-(C6F5)2]2- and L. The treatment of cis-[Ni(C6F5)2(PhCN)2] with [M(SAr)2(dppe)] leads to the formation of the arylthiolate complexes [(C6F5)2Ni(μ-SAr)2M(dppe)] (Ar = Ph, C6H4Me-p, C6H4NO2-p; M = Ni, Pd, Pt). The X-ray diffraction study of [(C6F5)2Ni(μ-SPh)2Pd(dppe)] shows that both metal atoms, Ni and Pd, are coordinated in a slightly distorted square-planar geometry and the μ-thiolato groups are in the syn conformation.
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  • 2
    Electronic Resource
    Electronic Resource
    Photodegradation of polyethylene films formulated with a titanium-based photosensitizer and titanium dioxide pigment (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 847-856 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This work reports on the photodegradation of low-density polyethylene films formulated with titanium (IV) oxide actylacetonate (TAc) and titanium dioxide pigment in different proportions; no previous reports on the photoactivity of this acetylacotonate have been found. Samples of blow-extruded films were submitted to accelerated UV aging with fluorescent lamps and the polymer degradation measured. The changes in carbonyl groups, molecular weight, and film elongation at break are discussed. The results show that TAc can promote photooxidation and accelerate the film degradation. The retention percent of elongation at break (EB) is apparently proportional to the carbonyl index irrespective of the formulation but has different relations with molecular weight (Mn), time, or the number of chain scissions (n), probably as a result of microstructural differences. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070530702
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  • 3
    Electronic Resource
    Electronic Resource
    Reaction of poly(vinyl alcohol) with n-butyl isocyanate. Chemical hydrolysis of the resulting polymers (1987)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 152 (1987), S. 79-91 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Diese Untersuchung befaßt sich mit einigen kinetischen Merkmalen der Reaktion von n-Butylisocyanat mit Polyvinylalkohol ohne jeden Katalysator und unter Verwendung von Triethylendiamin als Katalysator. Die Struktur der resultierenden Polymeren wurde mit Hilfe der IR-, 1H-, und 13C-NMR-Spektroskopie und chemischer Analyse ermittelt. Es wurden Vinylalkohol-Vinylbutylurethancopolymere (VAL-VBU) erhalten. Es ergab sich eine lineare Abhängigkeit der Reaktionsgeschwindigkeit von Polymer-, n-Butylisocyanat- und Triethylendiaminkonzentration. Die Reaktionsgeschwindigkeitskonstante nimmt mit zunehmender Reaktionszeit ab. Das kann mit der sterischen Hinderung durch die Urethangruppen, die entlang der Polymerkette eingebaut sind, erklärt werden. Die Aktivierungsenergie ergab sich zu 49,9 kJ/mol. Eine kinetische Untersuchung der homogenen Hydrolyse von VAL-VBU-Copolymeren wurde durchgefilhrt als Funktion der Basenkonzentration, der Temperatur und des VBU Gehalts. Es zeigte sich, daß die homogene Hydrolyse als Reaktion 1 . Ordnung verliluft, sowohl im Hinblick auf die Hydroxylionen als auch auf den VBU-Gehalt. Die Aktivierungsenergie filr die basenkatalysierte Hydrolyse betragt 79,3 kJ/mol. Die heterogene Hydrolyse von VAL-VBU-Copolymeren im basischen Medium zeigte, daß keine Hydrolyse unter diesen Bedingungen stattfand.
    Notes: This study is concerned with some kinetic features of the reaction of n-butyl isocyanate with poly(vinyl alcohol) without any catalyst and using triethylene diamine as catalyst. The structure of the resulting polymers was determined by means of IR, 1H- and 13C-NMR spectroscopy as well as by chemical analysis. Vinyl alcohol-vinyl butyl urethane (VAL-VBU) copolymers were obtained. It has been found a linear dependence of reaction rate on polymer, n-butyl isocyanate, and triethylene diamine concentrations. Reaction rate constant decreases as reaction time increases. It can be explained by steric hindrance phenomena due to urethane groups incorporated along the polymeric chain. The activation energy was found to be 49.9 kJ/mol. A kinetic study of the homogeneous hydrolysis of VAL-VBU copolymers has been made as a function of the base concentration, the temperature, and the VBU content. The homogeneous hydrolysis was found to be first order with respect to both hydroxyl ion and VBU contents. The activation energy for the base catalyzed homogeneous hydrolysis was found to be 79.3 kJ/mol. The heterogeneous hydrolysis of VAL-VBU copolymers in basic medium showed that no hydrolysis takes place under the conditions employed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1987.051520108
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  • 4
    Electronic Resource
    Electronic Resource
    Dextran functionalized by cyclic carbonate groups as supports of bioactive compounds (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 206 (1993), S. 77-85 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es werden Aspekte der Reaktion von Dextran mit Ethyl-chlorformiat und Triethylamin als Katalysator behandelt. Mittels 1H- und 13C NMR-Spektroskopie wurden in den gebildeten modifizierten Dextranen cyclische und acyclische Carbonatgruppen nachgewiesen. Vorversuche zeigten, daß die Reaktion cyclischer Carbonatgrupen mit verschiedenen Amin-Modellverbindungen stark vom Basencharakter des Amins abhängt. Phenethylamin und Tyramin wurden quantitativ an aktiviertes Dextran mit cyclischen Carbonatgruppen gebunden. Die Dextran-Phenethylamin- und Dextran-Tyramin-Addukte werden unter den angewendeten Bedingungen (pH 1,0 oder 9,1 bei 37°C) nicht heterogen hydrolysiert.
    Notes: This work deals with some features of the reaction of dextran with ethyl chloroformate using triethylamine as catalyst. The presence of cyclic and acyclic carbonate groups in the resulting modified dextrans was demonstrated by IR, 1H and 13C NMR spectroscopy. Preliminary experiments have shown that the reaction of cyclic carbonate groups with several model amines is greatly dependent on the basic character of the amine. Model amino type drugs (Phenethylamine and tyramine) were quantitatively bound to activated dextran with cyclic carbonate groups. The heterogeneous hydrolysis of dextran-phenethylamine or dextran-tyramine adducts showed that no hydrolysis takes place under the applied conditions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052060108
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  • 5
    Electronic Resource
    Electronic Resource
    Dextran functionalized by 4-nitrophenyl carbonate groups. Aminolysis reactions (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 225 (1995), S. 123-130 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Dextran wurde mit 4-Nitrophenylchloroformat und Pyridin als Katalysator umgesetzt. Die Struktur der modifizierten Dextrane wurde mittels IR-, 1H- und 13C-NMR-Spektroskopie bestimmt. Unter den gewählten Reaktionsbedingungen entstehen nur acyclische Carbonate. Vorversuche zeigten, daß die Reaktion der 4-Nitrophenyl-chloroformat-Gruppen mit verschiedenen Amin-Modellverbindungen stark von der Basizität des Amins abhängt. Die Anbindung der Modellamine Phenethylamin und Tyramin an das modifizierte Dextran war befriedigend. Die Dextran-Phenethylamin-und Dextran-Tyramin-Verbindungen sind gegen heterogene Hydrolyse bei 37°C (pH 9 und pH 1) weitgehend beständig.
    Notes: The modification reaction of dextran with 4-nitrophenyl chloroformate using pyridine as catalyst was studied. The structure of the resulting polymers was determined by means of IR, 1H and 13C NMR spectroscopy as well as by chemical analysis. Under the used experimental conditions only acyclic carbonate groups have been detected. Preliminary experiments have shown that the reaction of 4-nitrophenyl carbonate groups with several model amines is greatly dependent on the basic character of the amine. Model amino-type drugs (phenethylamine and tyramine) were satisfactorily bound to activated dextran with 4-nitrophenyl carbonate groups. The heterogeneous hydrolysis of dextran-phenethylamine or dextran-tyramine adducts showed that no significant hydrolysis takes place under the applied conditions (pH 1 and pH 9, 37°C).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052250111
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  • 6
    Electronic Resource
    Electronic Resource
    Nature et stabilité des complexes métalliques de cryptands dinucléants en solution. I. Polyazapolyoxa macrotricycle cylindrique et monocycle constitutif (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 456-464 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nature and Stability of Some Metallic Complexes of Dinucleating Cryptands in Solution. I. A Polyazapolyoxa Cylindrical Macrotricycle and its Monocyclic SubunitpH-metry and UV spectrophotometry were used to study the complexing properties of the cylindrical macrotricycle, 1,7,13,19-tetraaza-4,16-dioxa-10,22,27,32-tetraoxatricyclo[17.5.5.5]tetratriacontane (1) and of its constitutive monocyclic subunit, 1,7-diaza-4,10-dioxacyclododecane (2) with some transition and heavy metal cations (Cu2+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+, Ag+), in aqueous medium 0.1M Et4NClO4, at 25°. The protonation constants of the ligands as well as the nature and the stabilities of the complexes formed in the pH-regions studied were determined. The tricycle 1 only formed dinuclear M2L complexes with Cu2+, Zn2+, and Ag+, accompanied in the latter case by a protonated mononuclear MLH species, and with Cu2+ and Zn2+ at high pH-values by dinuclear hydroxo complexes. Only mononuclear complexes were evidenced with the other cations, ML being accompanied either by protonated or hydroxy mononuclear species. The mononuclear complexes of 1, when they existed, were more stable than the corresponding complexes of 2, except for cobalt which formed complexes of comparable stability with both ligands. In the other cases (Cd2+, Pb2+, Ag+), the stability differences between the complexes of 1 and 2 increased with the size of the cation.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680219
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  • 7
    Electronic Resource
    Electronic Resource
    Organonickel(II) Complexes with Anionic N-Donor Ligands. Hydration of coordinated nitriles at a nickel(II) site (1997)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 80 (1997), S. 2477-2485 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hydroxo complex (Bu4N)2[Ni2(C6F5)4(μ-OH)2]reacts with 2,3,4,5,6-pentafluoro benzenamine (C6F5-NH2), 1,3-diaryltriaz-1-enes (ArNH—N=N—Ar, Ar = Ph, 4-MeC6H4, 4-MeOC6H4), 7-aza-1H-indole (= 1H-pyrrolo[2.3-b]pyridine; Hazind), N-phenylpyridin-2-amine(pyNHPh), and N-phenylpyridine-2-carboxamide (py-CONHPh) at room temperature in acetone to give the binuclear complexes (Bu4N)2[Ni2(C6F5)4(μ-C6F5NH)2] (1) and (Bu4N)2[{Ni(C6F5)2} 2(μ-OH)(μ-azind)] (2) and the mononuclear complexes Bu4N[Ni(C6F5)2(ArN3Ar)] (3-5), Bu4N[Ni(C6F5)2(pyNPh)] (6), and Bu4N[Ni(C6F5)2(pyCONPh)] (7). The hydroxo.complex (Bu4N)2[{Ni(C6F5)2-(μ-OH)}2] promotes the nucleophilic addition of water to pyridine-2-carbonitrile, 2-aminoacetonitrile, and 2-(dimethylamino)acetonitrile, and complexes 8-10 containing pyridine-2-carboxamidato, 2-aminoacetamidato and 2-(dimethylamino)acetamidato ligands are formed. Analytical (C, H, N) and spectroscopic (IR, 1H and 19F-NMR, and FAB-MS) data were used for structural assignments. A single-crystal X-ray diffraction study of (Bu4N)2[{Ni(C6F5)2}2(μ-OH)(μ-azind)] (2) established the binuclear nature of the anion; the two Ni-atoms are bridged by an OH group and a 7-aza-7H-indol-7-yl group, but the central Ni—O—Ni—N—C—N ring is not planar, the dihedral angle between the Ni—O—Ni and Ni—N—C—N—Ni planes being 84.4°.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19970800815
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  • 8
    Electronic Resource
    Electronic Resource
    Nature et stabilité des complexes métalliques de cryptands dinucléants en solution. III. Le monocycle [22]-Py2N4 (1985)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 840-845 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nature and Stability of Some Metallic Complexes of Dinucleating Cryptands in Solution III. The Monocycle [22]-Py2N4The nature and stability of complexes formed by a new 22-membered monocycle L = [22]-Py2N4 with the cations Mn+ = Cu2+, Co2+, Ni2+, Zn2+, Cd2+, Pb2+, and Ag+ have been determined in aqueous solutions (0.01M NaClO4, 25°) by pH-metry and also, for the copper system, by UV-absorption spectrophotometry. The stepwise protonation constants of the four amine functions of L were 9.1, 8.3, 7.1 and 3.7 logarithms units, respectively. No evidence was found for the protonation of the two pyridine nitrogen atoms. Mononuclear complexes MLn+ were identified in all systems investigated, but the dinuclear species M2L2n+ were only found with Cu2+ and Ag+. The logarithms of the overall stability constants for the copper and silver complexes are CuL2+, 12.9; Cu2L4+, 18.6; Agl+, 6.3; Ag2L2+, 10.9, respectively. Mononuclear hydroxy species MLOH(n-1)+ were identified in all systems except those of copper and silver. No dinuclear hydroxy complexes were detected. The complexing properties of L are compared to those of the large and less rigid bis-dien.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19850680404
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  • 9
    Electronic Resource
    Electronic Resource
    Notizen. Sterisch gesteuerte Reaktionswege von substituierten 2-Norbornyl-Kationen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 815-818 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Steric Control in the Reaction of Substituted 2-Norbornyl CationsThe reaction of camphenilone (1b) with trifluoromethanesulfonic anhydride (Tf2O) yields 7,7-dimethyl-1,exo-2-bis(trifluoromethylsulfonyloxy)norbornane (4b) (60%). 6,6-Dimethyl-2-norbornanone (1c) affords under the same conditions 6,6-dimethyl-2-norbornen-2-yl triflate (5c) (70%). The reaction pathways of the intermediate 2-(trifluoromethylsulfonyloxy)-2-norbornyl cations are mostly controlled by steric factors, the inductive effect playing no significant role.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160237
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  • 10
    Electronic Resource
    Electronic Resource
    Influence of reprocessing on the mechanical properties of a commercial polysulfone/polycarbonate blend (1992)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 32 (1992), S. 861-867 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Commercial polysulfone/polycarbonate (PSU/PC) polymer blends were reprocessed up to five times to determine the influence that reprocessing has on their structure and physical properties. All the high strain properties, mainly ductility, significantly decreased under harsh processing conditions, such as five cycles at 320°C. The results of reprocessing the blends at 320°C have been compared with results at a lower temperature and also with those of the separate components with the aim of clarifying the origin of the degradation. These results plus Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis, and melt flow index measurements (MFI) indicate that the presence of the two polymers together clearly decreases the resistance to degradation of each component. Moreover, degradation under the stated conditions is mainly thermal and does not change the chemical nature of the blends. However, a clear decrease in molecular weight was observed both by viscosimetry and MFI measurements as was a shift to higher temperatures of the low temperature secondary transition of both PC and PSU. Both molecular weight and secondary transition changes usually deteriorate mechanical properties but not in the degree observed here. This probably means that the fine and difficult-to-observe structure of the blend has also changed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760321305
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