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  • 1
    ISSN: 0947-3440
    Keywords: Thioketones ; Sulfurization ; Sulfur ylides ; Sulfur heterocycles ; Conformational analysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By treatment with elemental sulfur and a catalytic amount of sodium thiophenolate in acetone at room temp., the title compound 9 is converted to the bis-spiro derivatives of 1,2,4,5-tetrathiane, 13, and 1,2,3,5,6-pentathiepane, 14. The initial attack by the phenyl oligosulfide anion takes place at the C-atom of the thiocarbonyl group. There is 13C NMR evidence for the twist conformation 15 of the tetrathiane ring; dynamic 1H NMR led to ΔG≠ = 15.9 ± 1.0 kcal mol-1 for the enantiomerization. For the pentathiepane 14, twelve coalescence phenomena in the 1H and 13C NMR spectra point to ΔG≠ = 13.4 ± 0.2 kcal mol-1; the process is interpreted as a stereomutation on the pseudorotation circuit for twist-chair and chair. The MS of 13 reveals a diversity of fragmentation patterns with several “thiologous” sequences. By prolonged treatment with the thiophenolate catalyst, 13 and 14 are converted to a γ-butyrodithiolactone 36 in a Baeyer-Villiger type reaction.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0947-3440
    Keywords: 1,2-Dithiin ; Cycloadditions ; Sulfur extrusion ; Thiophenes ; Reaction mechanisms ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetracyanoethylene combines with two molecules of thiobenzophenone in refluxing benzene to give the tetrasubstituted 1,2-dithiin 8 (21-29%) besides the corresponding thiophene derivative 9 (40-52%). The X-ray analysis of the ruby-red 8 reveals a half-chair conformation with a torsion angle of 58.9° at the disulfide bond. The thermal desulfurization 8 → 9 (benzonitrile, 100°C) proceeds with t1/2 = 26.7 h, whereas the sulfur loss induced by triethyl phosphite is a billion times faster. The mechanisms of the formation of 8 and its sulfur extrusion are discussed in the light or recent literature.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 586 (1954), S. 52-69 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 224 (1884), S. 156-178 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 302 (1898), S. 153-171 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ein neuer Vertreter der Antibiotikaklasse mit Thiotetronsäure-Struktur aus Streptomyces olivaceus Tü 3010Ein lipophiles Antibiotikum wurde aus dem Kulturfiltrat von Streptomyces olivaceus Tü 3010 isoliert. Seine Struktur wurde spektroskopisch mittels 1H- und 13C-NMR-2D-Experimenten wie COLOC und NOESY, FD- und GC-MS, sowie durch chemischen Abbau und Derivatisierung bestimmt. Das Antibiotikum Tü 3010 wurde als (2S)-4-Ethyl-2,5-dihydro-3-hydroxy-2-[(1E)-2-methyl-1,3-butadienyl]-5-oxo-2-thienylacetamid (1) bestimmt; somit ist es ein neuer Vertreter der Naturstoffe mit Thiotetronsäure-Struktur. Der Metabolit zeigt antibakterielle Aktivität besonders gegen Streptomyceten.
    Notes: A lipophilic antibiotic was isolated from the culture filtrate of Streptomuces olivaceus Tü 3010. Its structure was elucidated spectroscopically using 2D-1H- and 13C-NMR experiments (e. g. COLOC, NOESY), FD- and GC-MS, and by chemical degradation and derivatization. The antibiotic Tü 3010 was identified as (2S)-4-ethyl-2,5-dihydro-3-hydroxy-2-[(1E)-2-methyl-1,3-butadiyl]-5-oxo-2-thienylacetamide (1), therefore it is a new member of natural compounds with thiotetronic acid structure. The metabolite shows antibacterial activity especially against Streptomycetes.
    Additional Material: 1 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1988 (1988), S. 655-661 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Rhizocticine  -  neue Phosphono-Oligopeptide mit antifungischer AktivitätDer weltweit benutzte Stamm Bacillus subtilis ATCC 6633 produziert zwei neuartige hydrophile Peptidantibiotika, L-Arginyl-L-2-amino-5-phosphono-3-cis-pentensäure (L-Arg-L-APPA, Rhizocticin A) und L-Valyl-L-arginyl-L-2-amino-5-phosphono -3-cis-pentensäure (L-Val-L-Arg-L-APPA, Rhizocticin B). Neben den Rhizocticinen A und B, den Hauptkomponenten, wurden geringe Mengen an Tripeptid-Analogen entdeckt, die L-Ile bzw. L-Leu anstelle von L-Val enthalten. Der C-terminale Rest wurde NMR-spektroskopisch als die ungesättigte Phosphono-Aminosäure-L-APPA bestimmt, die vorher nur als D-Enantiomer bekannt war. Enzymatische Spaltungen von Rhizocticin B ergaben neben L-APPA auch Rhizocticin A.
    Notes: The widely used and well-known bacterial strain Bacillus subtilis ATCC 6633 was found to produce two novel, antifungal hydrophilic peptide antibiotics, L-arginyl-L-2-amino-5-phosphono-3-cis-pentenoic acid (L-Arg-L-APPA, rhizocticin A) and L-valyl-L-arginyl-L-2-amino-5-phosphono-3-cis-pentenoic acid (L-Val-L-Arg-L-APPA, rhizocticin B). Besides rhizocticin A and B, the main components, small amounts of related tripeptides were detected. Instead of the L-Val of rhizocticin B they contain L-Ile or L-Leu and are referred to as rhizocticins C and D, respectively. The C-terminal residue was identified by NMR spectroscopy as the unsaturated phosphono amino acid L-APPA, known till now only as D enantiomer. Enzymatic cleavages of rhizocticin B yielded both L-APPA and rhizocticin A.
    Additional Material: 3 Ill.
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  • 9
    Publication Date: 2006-06-13
    Description: From a broad point of view, we will be concerned with studying global ocean circulation patterns on the basis of ocean surface determinations with geoid undulation information. In addition, we will study local variations of the gravity field implied by the altimeter data. These general goals are reflected in the title of our investigation. To meet our general goal, we have defined a number of specific objectives: (1) sea surface topography representation; (2) mean sea surface determination; (3) development of local geoid models; (4) mean sea surface comparisons; (5) sea surface topographic files; and (6) gravity anomaly determination.
    Keywords: OCEANOGRAPHY
    Type: JPL, TOPEX(Poseidon Science Investigations Plan; p 118-120
    Format: text
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  • 10
    Publication Date: 2019-07-13
    Description: Cycles 4 to 54 of TOPEX data have been analyzed through comparisons with the mean sea surface given on the disturbed geophysical data record (GDR). Two inverted barometer correction procedures were considered for the data reduction. One used a constant atmospheric pressure for all data while the one adopted for use, for most computations, introduced a cycle average pressure. The maximum difference between the two estimates was 3.0 cm with a clear annual signal. With the modified correction the TOPEX sea surface was compared to The Ohio State University (OSU) mean sea surface, given on the GDR, to estimate three translations ( delta x = -2.3 cm; delta y = 25.0 cm; delta z = -0.3 cm) and a bias (43.3 cm) between the two surfaces. The only significant translation is delta y which indicates the reference frame of the TOPEX system differs from that used in the OSU mean sea surface system. The bias between the TOPEX mean sea surface and the OSU mean sea surface was used to estimate an equatorial radius of 6,378,136.55 m based on an 18-cm biased estimate of the TOPEX altimeter. Examination of the average difference, by cycle, between the TOPEX sea surface and the OSU mean sea surface suggested a bias change of 3.1 +/- 2.2 mm/yr with a positive sign indicating the average ocean surface is rising or the altimeter measured distance is decreasing. Models were implemented that solved directly for a bias, bias rate annual/semiannual, and tide correction terms. The computations indicated that a simultaneous solution for this bias, bias rate, and annual/semiannual terms gave the most accurate results. Nonsimultaneous solutions led to slightly different bias rate values. The root mean square difference between the TOPEX sea surface and OSU sea surface, after translation and bias correction, was +/- 17 cm for a typical cycle. Some locations were indentified where the difference could reach 2.3 cm and were repeated over several cycles indicating errors in the mean sea surface. Most of the large differences occur in regions lacking altimeter data prior to the TOPEX/POSEIDON mission and/or areas of significant bathymetric signature. Geoid gradients are needed for the reduction of individual track data to a reference track. The accuracy of the determination of such gradients was determined through the comparison of predicted along-track gradients to the observed gradients. Among four mean sea surfaces tested the best agreement was found with the OSU mean sea surface placed on the TOPEX geophysical data record.
    Keywords: OCEANOGRAPHY
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; C12; p. 24,657-24,667
    Format: text
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