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  • Chemistry  (4)
  • enthalpy  (1)
  • resistance
  • 5'-O-demethyl-8-O-methyl-dioncophylline A
  • 1995-1999  (1)
  • 1970-1974  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Thermodynamics of the Second Dissociation Constant and Standards for pH of 3-(NMorpholino) Propanesulfonic Acid (MOPS) Buffers from 5 to 55°C (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 73-87 
    Details
    ISSN: 1572-8927
    Keywords: Dissociation constant ; buffers ; NaMOPS ; temperature dependence ; emf ; Gibbs energy ; enthalpy ; entropy ; heat capacity ; zwitterion ; liquid junction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The second dissociation constant pK2 of 3-(N-morpholino)propanesulfonic acid (MOPS) has been determined at eight temperatures from 5 to 55°C by measurements of the emf of cells without liquid junction, utilizing hydrogen electrodes and silver–silver chloride electrodes. The pK2 has a value of 7.18 ± 0.001 at 25°C and 7.044 ± 0.002 at 37°C. The thermodynamic quantities ΔG°, ΔH°, ΔS°, and ΔC p o have been derived from the temperature coefficients of the pK 2. This buffer at ionic strength I = 0.16 mol-kg−1 close to that of blood serum, has been recommended as a useful secondary pH standard for measurements of physiological fluids. Five buffer solutions with the following compositions were prepared: (a) equimolal mixture of MOPS (0.05 mol-kg−1) + NaMOPS, (0.05 mol-kg−1); (b( MOPS (0.05 mol-kg−1) + NaMOPS (0.05 mol-kg−1) + NaCl (0.05 mol-kg−1); (c) MOPS (0.05 mol-kg−1) + NaMOPS (0.05 mol-kg−1); + NaCl (0.11mol-kg−1); (d) MOPS (0.08 mol-kg−1) + NaMOPS (0.08 mol-kg−1); and (e)MOPS (0.08 mol-kg−1) + NaMOPS (0.08 mol-kg−1) + NaCl (0.08 mol-kg−1).The pH values obtained by using the pH meter + glass electrode assembly are compared with those measured from a flow–junction calomel cell saturated with KCl (cell B), as well as those obtained from cell (A) without liquid junction at 25 and 37°C. The conventional values of the liquid junction potentials E j have been obtained at 25 and 37°C for the physiological phosphate reference solution as well as for the MOPS buffers (d) and (e) mentioned above.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022692629289
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  • 2
    Electronic Resource
    Electronic Resource
    Die analytische Chemie im Dienste1 Plenarvortrag auf der Festsitzung der Gesellschaft Deutscher Chemiker anläßlich der ACHEMA am 20. 6. 1970 der Werkstoffentwicklung (1971)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 2 (1971), S. 135-144 
    Details
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Analytical Chemistry used for developing new materials. The development of new materials constantly confronts the analyst with difficult new problems. Of particular importance for this work would be all methods permitting to lay bare the phase interface and to study their structure and perturbations of this structure. The analyst has to solve these problems in close contact with the technologists specializing in this modern technique.
    Notes: Die Entwicklung neuer Werkstoffe stellt den Analytiker vor immer neue diffizile Aufgaben. Insbesondere dürften alle Verfahren, mit denen es gelingt, Phasengrenzflächen freizulegen und ihren Aufbau sowie Störungen in diesem Aufbau zu studieren, für diese Aufgaben von großer Bedeutung sein. Der Analytiker muß diese Aufgaben in engster Fühlung mit den Technologen, die sich dieser modernen Entwicklung verschrieben haben, lösen.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19710020305
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  • 3
    Electronic Resource
    Electronic Resource
    Die Bildung von L-3-Acylamino-6,7-dihydroxy-hydrocumarinen aus N-Acyl-3-(3,4-dihydroxyphenyl)-L-alaninenHerrn Dr. O. Isler zum 60. Geburtstag gewidmet (1970)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 53 (1970), S. 1708-1712 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aus den N-Acyl-3-(3,4-dihydroxyphenyl)-L-alaninen 1a, 1b und 1c entstehen bei der Oxydation unter anderm die L-3-Acylamino-6,7-dihydroxy-hydrocumarine 2a, 2b und 2c. Diese Reaktion stellt einen präparativ brauchbaren Weg zur Synthese von 3-(2,4,5-Tri-hydroxyphenyl)-L-alanin (6-Hydroxy-L-DOPA, 3) aus 3-(3,4-Dihydroxyphenyl)-L-alanin dar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19700530719
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  • 4
    Electronic Resource
    Electronic Resource
    Versuche zur Synthese von 9β, 10α-Steroiden; B,C,D-tricyclische VerbindungenHerrn Dr. O. Isler zum 60. Geburtstag gewidmet (1970)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 53 (1970), S. 964-973 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a search for a new and efficient synthesis of the compound 7, the cyclization of 5 (obtained by a Michael-reaction from 3 and 4) was studied. Treatment of 5 with strong acid furnished the known dienedione 8. Mild acidic conditions gave the bridged alcohol 9 and other, unidentified products, rather than the desired enone 6. Under basic conditions, 5 did not cyclize to 6, but underwent retro-Michael reaction. Attempts were then made to convert the dienedione 8 to the 14α-enone 19. However, both catalytic hydrogenation and lithium-ammonia reduction of 8 yielded mainly 14β-products. In some hydrogenation experiments, isomerization of the dienedione 8 to the phenols 13 (major) and 14 (minor) occurred. The stereochemistry of the new isomeric des-A-androst-9-en-5, 17-diones (16, 17 and 20) was determined by chemical and spectroscopic methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19700530512
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  • 5
    Electronic Resource
    Electronic Resource
    Eine Synthese O,O-di- und N-mono-acylierter L-CyclodopaderivateHerrn Dr. O. Isler zum 60. Geburtstag gewidmet (1970)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 53 (1970), S. 1704-1708 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Am Beispiel der Synthese von O,O-Diacetyl-L-cyclodopa-methylester (12) wird eine allgemein anwendbare Methode zur selektiven Acylierung der phenolischen Hydroxylgruppen oder des Indolin-Stickstoffs am Cyclodopa (8) beschrieben. Die Verwendung von L-DOPA (5) als Ausgangsmaterial für die Cyclisierung erlaubt die Darstellung grösserer Mengen solcher Derivate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19700530718
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