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  • 1990-1994  (8)
  • 1950-1954
  • Chemistry  (8)
  • 2,2-Bis(diisopropoxyphosphonyl)propyl methyltin dibromide  (1)
  • 1
    ISSN: 0009-2940
    Keywords: Bis(phosphido)-bridged diiron hexa(penta)carbonyl complexes, molecular structures ; Steric strain ; Iron-iron double bond ; Calculations, EHT ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Unusual Pair of Bis(phosphido)-Bridged Diiron Carbonyl Complexes: [Fe2(CO)n{μ-P(tBu)2}(μ-PCy2)] (n = 5 and 6)Treatment of Na[Fe2(CO)6(μ-CO){μ-P(tBu)2}] with Cy2PCl gives [Fe2(CO)6{μ-P(tBu)2}(μ-PCy2)] (1) which loses CO on heating in toluene to afford [Fe2(CO)5{μ-P(tBu)2}(μ-PCy2)] (2). Complexes 1 and 2 have been characterized spectroscopically and by X-ray analyses. The central Fe2P2 unit in 1 is exactly planar whereas in 2 it is somewhat folded.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 26 (1992), S. 304-313 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Alle Ausgleiche „brauchen Zeit, und alle verlaufen um so langsamer, je weiter der Ausgleich bereits fortgeschritten ist. Hierdurch kommt es, daß die Welt mit Gebilden erfüllt ist, die vom Standpunkt der Gleichgewichtslehre sozusagen keine Existenzberechtigung haben, und daher ihre Existenz nur auf Zeit geniessen“.…„Wir werden bald sehen, daß die stationären Erscheinungen in bestimmtem Sinne die Formen des Lebens sind, und daß alle Organismen sich als Gebilde auffassen lassen, deren verhältnismässige Beständigkeit auf der Ausbildung stationärer, durch Selbstregulierung entstehender Zustände beruht“.Diese Zitate entstammen keinem modernen Lehrbuch der Thermodynamik irreversibler Prozesse und der Selbstorganisation, sondern sie sind 90 Jahre alt und wurden von Wilhelm Ostwald in seinen „Vorlesungen über Naturphilosophie“ formuliert. Die auffallend große zeitliche Lücke zwischen den Ideen und Ansätzen Wilhelm Ostwalds und den heute anerkannten Paradigmen mag an Ostwalds Emeritierung und dem Ausbruch des ersten Weltkrieges gelegen haben, aber auch an innerwissenschaftlichen Gründen, wie etwa dem Mangel an mathematischen Methoden zur Beschreibung komplexer und nichtlinearer Systeme, die erst Jahrzehnte nach der Jahrhundertwende entwickelt wurden. Sich mit Ostwalds Arbeiten auf diesem Gebiet zu beschäftigen, ist heute sicher nicht allein von historischem Interesse, sondern vermag darüber hinaus Denkanstöße zu geben und das Verständnis aktueller Fragen für die dort Tätigen zu vertiefen.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0899-0042
    Keywords: chromatographic resolution of stereoisomers ; molecular modelling ; conformation ; κ-opiate receptor ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The four stereoisomers of the two peripherally selective κ-opioid agonists EMD 60 400 and EMD 61 753 were synthesized, tested for stereoisomeric purity, and examined for affinity to the κ opioid receptor. The relationships between the configuration of these molecules and their biological activity are discussed. © 1994 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 62 (1990), S. 183-190 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Development of chemical engineering - A survey. This article describes the scientific and technological origins of chemical engineering and the concept of chemical technology. The paradigm of unit operations was the result of mass production, continuous and catalytic processes, and knowledge of physical chemistry. The evolution of theory and the institutionalization of chemical engineering are described as constitutive elements.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 64 (1992), S. 794-794 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 859-864 
    ISSN: 0044-2313
    Keywords: 2,2-Bis(diisopropoxyphosphonyl)propyl methyltin dibromide ; synthesis ; crystal structure ; n.m.r. data ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Molecular Structure of 2,2-Bis(diisopropoxyphosphonyl)propyl Methyltin DibromideBy methylation of Me3SnCH2CH[P(O)(OPr-i)2]2 with NaH/MeI Me3SnCH2C(Me)[P(O)(OPr-i)2]2 (1) is obtained, which is converted by bromine into the dibromide MeBr2SnCH2C(Me)[P(O)(OPr-i)2]2 (2). An X-ray crystal structure analysis shows 2 to be monomeric. The tin atom is situated in the centre of a distorted octahedron, in which the functional substituent is intramolecular coordinated as tridentate ligand in a facial mode. The two organo groups are arranged in trans-position (C—Sn—C 155.1°), whereas the oxygen and bromine atoms are orientated cis to each other. The six-membered ring of the bicyclic molecular fragment of 2 which results from the coordination of the functional organo group to the tin atom shows a boat-conformation, whereas the two five-membered rings exist in twist-conformations. Multinuclear n.m.r. and i.r. data show that 2 retains its solid state structure also in nonpolar solvents.
    Notes: Durch Methylierung von Me3SnCH2CH[P(O)(OPr-i)2]2 mittels NaH/MeI erhält man Me3SnCH2C(Me)[P(O)(OPr-i)2]2 (1), das mit Brom in das Dibromid MeBr2SnCH2C(Me)[P(O)(OPr-i)2]2 (2) überführt wird. Nach der Röntgenkristallstrukturanalyse ist 2 im Festkörper monomer. Das Zinnatom befindet sich im Zentrum eines verzerrten Oktaeders, in dem der funktionelle Substituent intramolekular als tridentater Ligand in facialer Anordnung koordiniert ist. Die beiden Organoreste sind trans-ständig angeordnet (C—Sn—C 155,1°), während sich die Sauerstoff- und Bromatome in cis-Anordnung zueinander befinden. Der Sechsring des aus der Koordination des funktionellen Organorestes am Zinnatom resultierenden bicyclischen Molekülfragmentes von 2 weist Wannenkonformation auf, während die beiden Fünfringe in Twist-Konformationen vorliegen. Multikern-NMR- und IR-Daten belegen, daß 2 seine Festkörperstruktur auch in unpolaren Lösungsmitteln beibehält.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0170-2041
    Keywords: Azapeptides ; Renin inhibitor ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A highly potent renin inhibitor of the azapeptide type (2) is synthesized by starting from the hydrazine derivative 3. This peptide analogue inhibits renin in the same range (nanomolar) as its purely peptidic original 2a, but reveals much higher specificity for renin than 2a does.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0268-2605
    Keywords: Organolead ; organomercury ; organotin ; toxicity ; lipid metabolism ; arachidonic acid ; Lands cycle ; cell culture ; HL-60 cells ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The concentration of free fatty acids within cells is mainly dependent upon the following enzyme activities: liberation by phospholipase A2 (PLA2), activation of free acids by acyl-CoA-synthetase and re-esterification by lysophospholipid acyltransferase (LAT). In many cell types, especially those of the haematopeotic system, this deacylation-reacylation cycle (‘Lands cycle’) plays an important role in the regulation of free fatty acid concentration, above all that of arachidonic acid.We have shown here that heavy-metal compounds affect this cycle mainly at two points and thereby lead to an increase of free fatty acids. On the one hand, organometals cause an inhibition of the reacylation of lysophospholipids; and on the other, the induction of PLA2 activity produces the same result. All compounds investigated such as methylmercury chloride (MeHgCl), diethyltriethyl-, and trimethyl-lead chloride (Et2PbCl2, Et3PbCl, Me3PbCl) as well as trimethyltin chloride (Et3SnCl) and di-t-butyltin dichloride (t-Bu2SnCl2) show at least one of these effects. In the case of Et3PbCl, the use of PLA2-inhibitors or pertussis toxin causes a drastic decrease in the amount of arachidonic acid liberated. These experiments demonstrate that the organometallic compounds inhibit the reacylation and/or stimulate the deacylation of fatty acids that are involved in many important biological or pathological mechanisms. The results suggest that in differentiated HL-60 cells the organometal compounds stimulate the Lands cycle by increasing the activity of the PLA2, possibly via a signal-transduction mechanism, and this effect is intensified via an inhibition of reesterification.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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