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  • 1
    Electronic Resource
    Electronic Resource
    Effect of vertical alignment on the performance of bubble and foam fractionation columns (1975)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 21 (1975), S. 400-402 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690210228
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  • 2
    Electronic Resource
    Electronic Resource
    Origin of disturbances in cocurrent gas-liquid packed bed flows (1995)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 1653-1666 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Visual, video, pressure, and conductance techniques were used to study time-varying disturbances in cocurrent flow in packed beds with vertical and horizontal columns. It is found that the trickle-pulse transition, as defined in previous studies, corresponds to conditions where traveling disturbances finaly become measurable, not the conditions at which infinitesimal disturbances begin to grow. Observations demonstrate that even if the liquid and gas are uniformly distributed initially, segregated, vertical flowing regions with higher or lower than average liquid holdup form after a short distance. Horizontal packed bed experiments, designed to study how regions of differing liquid holdup interact, indicate that the first type of disturbance is infiltration of gas into the liquid region. A simple model suggests that infiltration occurs if the pressure drop exceeds a value necessary to push gas through liquid-filled pores. Once infiltration is significant enough to form a third “bubbly” phase, traveling wave instabilities form and grow into pulses if sufficient column length is available. A three-layer Kelving-Helmholtz stability model is used to interpret the growth of disturbances in horizontal flows. Video obeservations of small-scale events in the bed failed to detect significant correlations between different regions. Thus it should be possible to describe flow behaviour in these systems with volum-averaged equations, as long as the presence of segregated regions is considered. Column diameter or thickness significantly affects the frequency of disturbances.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690410706
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  • 3
    Electronic Resource
    Electronic Resource
    Umwandlung von (20S)-20-(Hydroxymethyl)pregna-1,4-dien-3-on in (20S)-20-(p-Toluolsulfonyloxymethyl)pregna-1,5-dien-3β-ol und -3α-ol: Zwischenprodukte für Vitamin D-Derivate (1996)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 338 (1996), S. 214-219 
    Details
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transformation of (20S)-20-(Hydroxymethyl)pregna-1,4-dien-3-one into (20S)-20-(p-Toluene-sulfonyloxymethyl)pregna-1,5-dien-3β-ol and -3α-ol: Intermediates of Vitamin D DerivativesEfficient three-step approaches to the two 3-epimeric 22-tosylated 1,5-diene-3,22-diols 6 and 7 starting with (20S)-20-(hydroxymethyl)pregna-1,4-dien-3-one (1) were developed and optimized. Isomerization of 1 to the 1,5-dien-3-one 3 and subsequent tosylation furnished the deconjugated 3-ketone 4. The 3β-alcohol 6 was available from 4 by means of in situ generated calcium borohydride. Treatment of 4 with lithium trisiamylborohydride (LS-Selectride) afforded the highest yield of the hitherto unknown 3α-epimer 7. Following the optimized synthesis, 6 and 7 were obtained from 1 in 60 % and 50 % overall yield, respectively.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19963380145
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  • 4
    Electronic Resource
    Electronic Resource
    Lichtinduzierte Umorientierung der optischen Achse in LC-Farbstoff-CopolymerenHerrn Prof. Dr. D. Braun zum 60. Geburtstag gewidmetVortrag anläßlich der Tagung der Fachgruppe “Makromolekulare Chemie” der Gesellschaft Deutscher Chemiker über “Polymere und Licht”. in Bad Nauheim vom 7. bis 9. Mai 1990. (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 183 (1990), S. 103-113 
    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: The influence of linearly and circularly polarized light on the state of order of nematic dye-copolymers is investigated. For a nematic model system we have shown that the optical axis of these systems can be reorientated with linearly polarized light in a well defined manner. Furthermore these investigations prove that the isomerisation cycles of the azo dye is responsible for the described properties. By selection of circularly polarized light the same transmission behaviour as shown by selectively reflecting materials, i. e. cholesteric liquid crystals, was observed.
    Notes: Untersucht wird der Einfluß von linear und zirkular polarisiertem Licht auf den Ordnungszustand von nematischen Farbstoff- Copolymeren. Am Beispiel eines Modellsystems wird gezeigt, daß mit linear polarisiertem Licht die optische Vorzugsachse dieser Systeme gezielt reorientiert werden kann. Die Untersuchungen zeigen, daß der Isomerisierungszyklus des Azofarbstoffes für diese Eigenschaft des Materials verantwortlich ist Nach Bestrahlen der Probe mit zirkular polarisiertem Licht wird für das Polymere das gleiche Transmissionsverhalten beobachtet. Wie es auch selektivreflektierende Materialien, z. B. cholesterische Flüssigkristalle, aufweisen.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1990.051830105
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  • 5
    Electronic Resource
    Electronic Resource
    Über einige neue Imidazolderivate (1967)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 100 (1967), S. 4042-4049 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bifunktionelle Derivate von Diphenylimidazolen und von Diphenyl-[p-phenylen-diimidazolen] wurden synthetisiert. Ausgehend vom 5(4)-Methyl-2.4(5)-diphenyl-imidazol (1) wurden (via Nitrierung) p.p′-disubstituierte Verbindungen erhalten (2-5). Durch Kondensation m-substituierter Benzamidine mit m-substituierten Phenacylbromiden nach einer verbesserten Methode („Zweiphasenkondensation“) entstanden die entsprechenden m.m′-disubstituierten Verbindungen (6-10). Die Kondensation von 1.4-Bis-phenylglyoxyloyl-benzol mit Nitrobenzaldehyden in Gegenwart von Ammoniumacetat lieferte doppelt nitrophenyl-substituierte p-Phenylen-diimidazole (11, 13), die sich zu den entsprechenden Diaminen (12, 14) reduzieren ließen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19671001224
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  • 6
    Electronic Resource
    Electronic Resource
    Synthese von Bis-1.2-diketonen mit Vinylenbrücken (1968)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 101 (1968), S. 1480-1484 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ausgehend vom 4-Methyl-benzil (1) wurde über das 4-Brommethyl-benzil (2) und das entsprechende Nitron 4 das 4-Formyl-benzil (5) dargestellt. Seine Umsetzung mit dem ebenfalls aus der Brommethylverbindung zugänglichen Triphenylphosphoniumsalz 12 nach Wittig lieferte das 4.4′-Bis-phenylglyoxyloyl-stilben (14). Auf ähnliche Weise wurden einige weitere Verbindungen mit endständigen 1.2-Diketon-Gruppierungen dargestellt, die über Brücken mit durchgehend konjugierten Doppelbindungen verknüpft sind.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19681010439
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  • 7
    Electronic Resource
    Electronic Resource
    Notiz zur Synthese neuer Benzilderivate (1969)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 102 (1969), S. 371-373 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19691020141
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  • 8
    Electronic Resource
    Electronic Resource
    Kristall- und Molekülstruktur von Pentacarbonyl-[dimethyl-amino(äthoxy)carben]-chrom(0) (1972)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 67-81 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Crystal and Molecular Structure of Pentacarbonyl[dimethylamino(ethoxy)carbene]-chromium(0)Pentacarbonyl[dimethylamino(ethoxy)carbene]chromium(0) (1) crystallizes in space group P&1macr; with a = 11.84 ± 0.01, b = 9.05 ± 0.01, c = 6.49 ± 0.008 Å, α = 95.73 ± 0.08°, β = 105.21 ± 0.08°, γ = 89.84 ± 0.08°, Z = 2. The structure has been solved by the heavy atom method. Least squares refinement led to an agreement factor of R = 0.054 for 2329 independent nonzero observations. The metal atom is approximately octahedrally coordinated by five carbonyl groups and the carbene moiety. All atoms of the carbene ligand are approximately coplanar; this plane is nearly vertical to the plane defined by the equatorial carbonyl groups. The π-character is higher for the carbene carbon-nitrogen bond (1.328 ± 0.005 Å) than for the Ccarbene-oxygen linkage (1.346 ± 0.005 Å). The distance Ccarbene-chromium is 2.133 ± 0.004 Å; the axial Cr-CCO bond is considerably shortened (1.847 ± 0.005 Å) with respect to the distances found for the equatorial Cr-CCO bonds (average: 1.89 Å).
    Notes: Pentacarbonyl-[dimethylamino(äthoxy)carben]-chrom(0) (1) kristallisiert in der Raumgruppe P&1macr; mit a = 11.84 ± 0.01, b = 9.05 ± 0.01, c = 6.49 ± 0.008 Å, α = 95.73 ± 0.08°, β = 105.21 ± 0.08°, γ = 89.84 ± 0.08°, Z = 2. Die Struktur wurde nach der Schweratom-Methode ermittelt und nach der Methode der kleinsten Quadrate verfeinert. Der Übereinstimmungsfaktor beträgt für die 2329 unabhängigen, von Null verschiedenen Strukturfaktoren R = 0.054. Das Metallatom ist annähernd oktaedrisch von fünf Carbonylgruppen und dem Carbenrest umgeben. Alle Atome des Carbenliganden liegen annähernd in einer Ebene, die nahezu senkrecht auf der Ebene der äquatorialen Carbonylgruppen steht. Die Bindung des Carbenkohlenstoffatoms zum Stickstoffatom zeigt mit 1.328 ± 0.005 Å einen stärkeren π-Bindungsanteil als die Carbenkohlenstoff-Sauerstoff-Bindung (1.346 ± 0.005 Å). Der Abstand CCarben-Chrom beträgt 2.133 ± 0.004 Å, die axiale Cr-CCO-Bindung (1.847 ± 0.005 Å) ist gegenüber den Abständen der äquatorialen Cr-CCO-Bindungen (Mittelwert: 1.89 Å) wesentlich verkürzt.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19721050108
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  • 9
    Electronic Resource
    Electronic Resource
    Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, XXXII1). Das reaktive Verhalten von [(OC)4Mn - S = PR2]2 gegenüber Isothiocyanaten (1984)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 489-501 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Properties of, and Reactions with, Metal-Containing Heterocycles, XXXII1). The Reactive Behavior of [(OC)4Mn - S = PR2]2 Towards IsothiocyanatesBy cleavage of an Mn - S bond and CO elimination the action of the isothiocyanates R' - N = C = S (R' = CH3, C2H5, C6H5) on the dimanganacyclohexadienes [(OC)4Mn - S = PR2]2 (1a, b) [R = CH3 (a), C6H5 (b)] results in the formation of the novel tricyclic compounds (2ax - z, bx - z), in which all three atoms of the heterocumulene have entered into additional bonds. 2ax - z, bx - z are stable towards elevated CO pressure. According to an X-ray structural determination, 2az is present as an enantiomeric mixture and crystallizes in the triclinic space group P1 with Z = 2.
    Notes: Bei der Einwirkung der Isothiocyanate R' - N = C = S (R' = CH3, C2H5, C6H5) auf die Dimanganacyclohexadiene [(OC)4Mn - S = PR2]2 (1a, b) [R = CH3 (a), C6H5 (b)] erhält man durch Öffnung einer Mn - S-Bindung unter CO-Eliminierung die neuartigen, tricyclischen Verbindungen (2ax - z, bx - z), in denen alle drei Atome des Heterocumulens zusätzliche Bindungen eingegangen sind. 2ax - z, bx - z sind gegenüber erhöhtem CO-Druck stabil. Nach einer Kristallstrukturbestimmung liegt 2az als Enantiomerengemisch vor und kristallisiert in der triklinen Raumgruppe P1 mit Z = 2.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19841170207
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  • 10
    Electronic Resource
    Electronic Resource
    Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, XLII. Die P = S-Gruppe als Baustein in der heteroanalogen Alkin-Cyclocotrimerisierung (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1398-1414 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Properties of, and Reactions with, Metal-Containing Heterocycles, XLII The P = S Group as a Building Block in the Heteroanalogous Alkyne CyclocotrimerizationThe S isomeric complexes LnFe(CO)(I) - SPHR½ (3 a - e) [R1 = CH3 (a), C2H5 (b), n-C3H7, (c) t-C4H9 (d), c-C6H11 (e)] are obtained by substitution of CO in LnFe(CO)2I (1) [LnFe = (n-C3F7)-Fe(CO)2] by the phosphane sulfides SPHR1/2 (2a - e). Base supported HI elimination from 3a, b results in the formation of the η2-thiophosphinito complexes (4a, b) which can be regarded as starting points of the P = S heteroanalogues alkyne trimerization. 4b reacts with the electrophilic alkynes 5x - z to give the ferracyclopentadienes (6 bx - z) [R2 = CO2C2H5 (x), CO2CH(CH3)2 (y, CO2C6H11 (z)]. Towards alkynes 6 bx - z behave kinetically labile and are transformed with 5x - z to the bicyclic compounds 7 bx - z under CO separation. According to X-ray structural determinations, 3a, 4 b, und 6 bz crystallize in the monoclinic and triclinic space groups P21/n (3a), C2/c (4b), and P1 (6 bz) with Z = 4, 8, and 2, respectively.
    Notes: Bei der Substitution von CO in LnFe(CO)2I (1) [LnFe = (n-C3F7Fe(CO)2] durch die Phosphansulfide SPHR1/2 (2a - e) [R1 = CH3 (a), C2H5 (b), n-C3H7 (c), t-C4H9 (d), c-C6H11 (e)] erhält man die S-isomeren Komplexe LnFe(CO)(I) - SPHR1/2 (3a - e). Basenunterstützte HI-Eliminierung liefert aus 3a, b die η2-Thiophosphinito-Komplexe (4a, b), welche als Ausgangspunkte der P = S-heteroanalogen Alkintrimerisierung anzusehen sind. Mit den elektrophilen Alkinen 5x - z reagiert 4b zu den Ferracyclopentadienen (6bx - z) [R2 = CO2C2H5 (x), CO2CH(CH3)2 (y), CO2C6H11 (z)]. Diese verhalten sich gegenüber Alkinen kinetisch labil und gehen mit 5x - z unter CO-Abspaltung in die bicyclischen Verbindungen 7 bx - z über. Aufgrund von Röntgenstrukturanalysen kristallisieren 3a, 4 b und 6 bz in den monoklinen bzw. triklinen Raumgruppen P21/n (3 a), C2/c (4b) bzw. P1 (6 bz) mit Z = 4, 8 bzw. 2.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180410
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