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  • 1990-1994  (181)
  • 1970-1974  (77)
  • 1830-1839  (10)
  • Chemistry  (268)
  • 1
    Electronic Resource
    Electronic Resource
    The kinetics of diastereomeric amino acids with o-phthaldialdehyde (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 3 (1991), S. 471-475 
    Details
    ISSN: 0899-0042
    Keywords: amino acids ; kinetics ; epimers ; OPA ; postcolumn reaction detection ; fluorescence detection ; amino acid racemization ; dating methods ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of the reaction of the amino acid epimers L-isoleucine, D-alloisoleucine, L-threonine, and D-allo-threonine with o-phthaldialdehyde and mercaptoethanol were determined at 25°C. L-Isoleucine reacts faster than its D-epimer whereas L-threonine reacts slightly slower than its D-epimer. In the case of isoleucine, the consequence can be an allo/iso ratio which in the worst case is 25% too low if these amino acids are quantified by liquid chromatography and o-phthaldialdehyde fluorescence detection. The effect on dating of fossils by amino acid racemization is discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530030611
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  • 2
    Electronic Resource
    Electronic Resource
    Über ein Oxidchlorid des Calciums: Ca4OCl6 (1991)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 596 (1991), S. 89-92 
    Details
    ISSN: 0044-2313
    Keywords: Calcium oxychloride ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: An Oxychloride of Calcium: Ca4OCl6Ca4OCl6 (hexagonal, P63mc, Z = 2), a = 905.8(3), c = 686.3(4) pm, (R = 0.031) crystallizes as colourless needles from reducing melts (CaCl2, Ca) that contain small amounts of „oxygen“. It contains „isolated“ tetrahedral units [Ca4O] and is isotypic with e.g., Ba4OCl6, Yb4OCl6 and K6HgS4. Ca4OCl6 does not form in the dehydration process of, for example, CaCl2 · 6 H2O.
    Notes: Ca4OCl6 (hexagonal, P63mc, Z = 2, a = 905.8(3)); c = 686.3(4) pm, (R = 0,031) kristallisiert in Form farbloser Nadeln aus „reduzierenden Schmelzen“ (CaCl2, Ca), die wenig „Sauerstoff“ enthalten. Es enthält „isolierte“ tetraedrische [Ca4O]-Einheiten und ist isotyp mit z. B. Ba4OCl6, Yb4OCl6 oder K6HgS4. Ca4OCl6 entsteht nicht beim Entwässern von z. B. CaCl2 · 6 H2O.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19915960112
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  • 3
    Electronic Resource
    Electronic Resource
    Thermodynamic cycle-perturbation study of the binding of trifluoroacetyl dipeptide anilide inhibitors with porcine pancreatic elastase (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 773-780 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The variety of results of crystallographic studies of the serine proteases complexed with isocoumnrin inhibitors presents a challenging problem to modeling methods and molecular energetics. Therefore, the thermodynamic cycle-perturbation technique has been used to study a model system of elastase and two peptidic inhibitors. Using the program AMBER, the technique correctly predicts changes of the binding constants for the trifluoroacetyl dipeptide inhibitors in comparison with available experimental (kinetic and crystallographic) data. However, the absolute values obtained are shown to be sensitive to the specific electrostatic interaction potential parameters used in the simulations. The reader and user are cautioned that thermodynamic cyle-perturbation results may be too optimistic by underestimating the accuracy of free energy values. This is especially a matter of concern for those cases where a direct comparison with experimental values is not possible, viz., (1) the simulation of binding of novel compounds, (2) structurally uncertain binding sites, or (3) structurally different binding modes. With our best 4-31G* ESP (electrostatic potential) charges we were able to reproduce experimentally determined free energy differences (ΔΔA) with an accuracy of about 1.5 kcal/mol. Dynamically induced structural changes in the binding site of elastase, and particularly changes in hydrogen-bond patterns of the binding site, are also reported.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360300712
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  • 4
    Electronic Resource
    Electronic Resource
    Correlation between microscopic structural parameters and macroscopic flow behaviour of some polymer-surfactant systems suitable for tertiary oil recovery (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 57-77 
    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: Einige für den kombinierten Polymer-Tensid-Einsatz in der tertiären Erdölförderung (EOR) diskutierte Substanzen wurden mittels statischer und dynamischer Lichtstreuung charakterisiert und bezüglich ihrer Anwendbarkeit in unterschiedlich salinaren Modellwässern durch rheologische und rheologisch-dynamische Messungen unter-sucht.Als Polymere wurden Xanthan sowie unterschiedlich hydrolysierte Polyacrylamide verwendet, als Tensid ein Ethylenglykolsulfonat. Es ließen sich Korrelationen zwischen mikroskopischen Strukturparametern (z. B. hydrodynamischer Radius, Trägheitsradius, Molekulargewicht, Gestaltparameter der gelösten Polymeren) und makroskopischem Verhalten wie Viskosität aufstellen, welche für den EOR-Einsatz wichtige rheologische Parameter darstellen.Mit ergänzenden Messungen (Oberflächenspannung, zeitabhängiges Viskositätsverhalten) können Aussagen über die Effizienz und Langzeitstabilität eingesetzter Polymer-Tensid-Slugs in unterschiedlich salinaren Lagerstätten gemacht werden.
    Notes: Some materials, suitable for application in polymer-surfactant flooding used in tertiary oil recovery (EOR), have been characterized by static and dynamic light scattering and studied in respect to their suitability in various model brines by measuring their rheological and dynamic-rheological behaviour. Xanthan and polyacrylamides of different degree of hydrolysis have been used as polymers, an ethylene glycol sulfonate as surfactant.Correlations have been established between microscopic structural parameters (Hydrodynamic radius, radius of gyration, molar mass, shape of the polymers) and the macroscopic behaviour, such as viscosity and elasticity, being important rheological parameters for EOR application. Additional investigations on surface tension and long term viscosity study lead then to a judgement for the efficiency and long term stability of polymer-surfactant slugs in various reservoirs of different salinity.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.051950104
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  • 5
    Electronic Resource
    Electronic Resource
    Model connective tissue systems. A physical study of gelatin gels containing proteoglycans (1971)
    New York : Wiley-Blackwell
    Biopolymers 10 (1971), S. 1351-1364 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The swelling behavior of gelatin gels containing proteoglycans (sulphated proteoglycans from bovine intervertebral discs and a hyaluronate proteoglycan from bovine synovial fluid) when immersed in osmotically active solutions of dextran have been measured. The presence of the proteoglycans markedly affects the internal osmotic contribution to the swelling pressure of the gel. These internal osmotic pressures are considerably in excess of the sum of the osmotic activities of the individual components. This behavior is understood in terms of an entropic interaction between the gelatin and the proteoglycan molecules. By use of the “dilute solution” treatment of Flory, the osmotic pressure excesses are related to the volumes and hence dimensions of the interact acting species. A comparison of these values with those calculated by other means shows good agreement. The osmotic behavior of the complex gels can be understood on a mechanistic basis, if we regard the gelatin and sulphated proteoglycans as spheres and the hyaluronate proteoglycan as a rod.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360100808
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  • 6
    Electronic Resource
    Electronic Resource
    Glykoside von Aminozuckern, II. Zur Synthese von 2-Amino-2-desoxy-α-D-glucopyranosiden (1970)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 1792-1796 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Glycosides of Amino Sugars, II. Synthesis of 2-amino-2-deoxy-α-D-glucopyranosidesThe synthesis of glycosides and disaccharides of 2-amino-2-deoxy-D-glucose has been explored using trifluoroacetyl as the N-blocking group. Because of its high tendency for neighboring group participation only β-D-glycosides were formed. The corresponding α-disaccharide could be obtained as the main product when employing 2.4-dinitrophenyl as the N-protecting group.
    Notes: Die N-Trifluoracetyl-Schutzgruppe wurde zur Synthese von Glykosiden und Disacchariden der 2-Amino-2-desoxy-D-glucose benutzt. Sie zeigte eine hohe Tendenz zur Nachbargruppen-beteiligung unter Bildung von -β-D-Glykosiden. Das entsprechende α-Disaccharid wurde als Hauptprodukt bei Verwendung der N-2.4-Dinitrophenyl-Schutzgruppe erhalten.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19701030614
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  • 7
    Electronic Resource
    Electronic Resource
    Di- und Polyaminozucker, XV.XIV. Mitteil.: W. Meyer zu Reckendorf, Tetrahedron Letters [London] 1970, 287 Synthese der 2.4-Diamino-l.6-anhydro-2.4-didesoxy-D-talose (1970)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 2424-2427 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Di- and Polyamino Sugars, XV. XIV. Mitteil.: W. Meyer zu Reckendorf, Tetrahedron Letters [London] 1970, 287. Synthese der 2.4-Diamino-1.6-anhydro-2.4-dideoxy-D-talose. Synthesis of 2,4-Diamino-1,6-anhydro-2,4-dideoxy-D-taloseDehydrogenation of the amino reductone 1 with iodine yields a triulose which is isolated as the phenylhydrazone-phenylazo derivative 2. Spontaneous cyclization of 2 forms the 1.6-anhydro compound 3. On hydrogenation 2as well as 3are transformed into the title compound.
    Notes: Die durch Dehydrierung des Aminoreduktons 1 mit Jod entstehende Triulose wird als Bis-phenylhydrazon 2 isoliert, das die Konstitution eines Phenylhydrazon-benzolazo-Derivates besitzt. 2 cyclisiert leicht zur 1.6-Anhydro-Verbindung 3, die, wie auch 2, bei der katalytischen Hydrierung die Titelverbindung liefert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19701030814
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  • 8
    Electronic Resource
    Electronic Resource
    Die Kondensation von cyclischen arylkonjugierten α-Brom-ketonen mit Formaldehyd (1970)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 2084-2090 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensations of Cyclic Aryl-conjugated α-Bromoketones with FormaldehydeReactions of carbocyclic and heterocyclic α-bromoketones with formaldehyde yield α-epoxy-α-methylketones or α, β-unsaturated α-(hydroxymethyl)ketones.
    Notes: Die Umsetzung einer Reihe von carbocyclischen und heterocyclischen α-Brom-ketonen mit Formaldehyd ergibt α-Epoxy-α-methyl-ketone oder α. β-ungesättigte α-Hydroxymethyl-ketone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19701030710
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  • 9
    Electronic Resource
    Electronic Resource
    Synthese von 2.-3[Carboxymethylen]- und 2.-3[2-Hydroxy-äthyliden]-2.3-didesoxy-D-mannose  -  Monosacchariden mit einem Cyclopropanring (1972)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 673-685 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of 2.-3(Carboxymethylene)- and 2.-3(2-Hydroxyethylidene)-2.3-dideoxy-D-mannose  -  Monosaccharides with a Cyclopropane RingThe anhydro derivative 1 yielded the cyclopropane carboxylic ester 2 in a PO-activated olefination reaction. Under mild conditions 2 could be hydrolised to the free carboxylic acid 5. By reduction the cyclopropyl carbinol 13 and the cyclopropane carbaldehyde 21 were formed. The latter could be rearranged to the cyclobutene derivative 25. Attempts to synthesize a cyclopropanol were unsuccessful.
    Notes: Durch PO-aktivierte Olefinierung entstand aus der Anhydro-Verbindung 1 der Cyclopropancarbonsäureester 2, der unter milden Bedingungen zur freien Carbonsäure 5 hydrolysiert werden konnte. Reduktion lieferte das Cyclopropylcarbinol 13 und den Cyclopropan-carbaldehyd 21, der zum Cyclobutenderivat 25 umgelagert wurde. Die Synthese eines Cyclopropanols gelang nicht.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19721050233
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  • 10
    Electronic Resource
    Electronic Resource
    Über Verbindungen mit Urotropin-Struktur, XLVII. Ein neuer Weg zu 1.2- und 2.6-disubstituierten Adamantanen (1970)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 863-867 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Compounds with Urotropin Structure, XLVII. A New Syntheses of 1,2 - and 2, 6-Disubstituted Adamantanes
    Notes: Kondensation des Pyrrolidin-Enamins von Cyclohexanon-(4)-carbonsäure-(1)-äthylester (1) mit 2-Brommethyl-acrylsäureester liefert Adamantandion-(2.6)-carbonsäure-(1)-äthylester (2). Durch selective Reduktion der Carbonylgruppe in 6-Stellung entsteht aus 2 Adamantanon (2)carbonsäure-(1)-äthylester (7). 1-Brom-adamantandion-(2.6) (8) ist durch Silbersalzabbau der aus 2 erhaltenen Säure 5 zugänglich. Aus der Bromverbindung ist durch Reduktion Adamantandion-(2.6) (12) und durch Favorski-Reaktion Noradamantanon-(4)-carbonsäure-(1) (10) erhältlich.Condensation of the pyrrolidine enamine of ethyl 4-oxocyclohexane-1-carboxylate (1) with ethyl 2-(bromomethyl) acrylate yielded ethyl 2.6-dioxoadamantane-1-carboxylate (2). Selective reduction of the carbonyl group at the 6-position in 2 leads to ethyl 2-oxoadamantane-1-carboxylate (7). 1-Bromo-2.6-dioxoadamantane (8) is accessible by silver salt degradation of the acid 5 obtained from 2. The bromo compound is reduced to 2.6-dioxoadamantane (12) and undergoes the favorski reaction to yield 4-oxonoradamantane-1-carboxylic acid (10).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19701030328
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