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  • 1
    Electronic Resource
    Electronic Resource
    Degradation of diphenylether by Pseudomonas cepacia (1989)
    Springer
    Archives of microbiology 152 (1989), S. 515-519 
    Details
    ISSN: 1432-072X
    Keywords: Diphenylether ; Degradation pathway ; Phenol ; 2-Pyrone-6-carboxylic acid ; Ether cleavage ; Pseudomonas cepacia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The microbial degradation of hard coal implies the cleavage of diaryl ether linkages in the coal macromolecule. We investigated the biodegradation of diphenylether as a model compound representing this substructure of coal. A bacterial strain isolated from soil and identified as Pseudomonas cepacia, was able to grow with diphenylether as sole source of carbon. During microbial growth, three metabolites were detected in the culture supernatant by high pressure liquid chromatography. As product of ring hydroxylation and subsequent rearomatization, 2,3-dihydroxydiphenylether was identified by UV, mass and nuclear magnetic resonance spectrometry and gas chromatography analyses. The cleavage of the ether linkage led to the formation of phenol and 2-pyrone-6-carboxylic acid, the latter being not further degraded by Pseudomonas cepacia. The possible cleavage mechanism of the ether linkage is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425479
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  • 2
    Electronic Resource
    Electronic Resource
    Degradation of diphenylether by Pseudomonas cepacia Et4: enzymatic release of phenol from 2,3-dihydroxydiphenylether (1993)
    Springer
    Archives of microbiology 159 (1993), S. 323-329 
    Details
    ISSN: 1432-072X
    Keywords: Diphenylether degradation ; Arylether linkage ; 2,3-Dihydroxybiphenyl dioxygenase ; 2-Pyrone-6-carboxylic acid ; Pseudomonas cepacia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 2,3-Dihydroxybiphenyl dioxygenase from Pseudomonas cepacia Et 4 was found to catalyze the ring fission of 2,3-dihydroxydiphenylether in the course of diphenylether degradation. The enzyme was purified and characterized. It had a molecular mass of 240 kDa and is dissociated by SDS into eight subunits of equal mass (31 kDa). The purified enzyme was found to be most active with 2,3-dihydroxybiphenyl as substrate and showed moderate activity with 2,3-dihydroxydiphenylether, catechol and some 3-substituted catechols. The K m-value of 1 μM for 2,3-dihydroxydiphenylether indicated a high affinity of the enzyme towards this substrate. The cleavage of 2,3-dihydroxydiphenylether by 2,3-dihydroxybiphenyl dioxygenase lead to the formation of phenol and 2-pyrone-6-carboxylate as products of ring fission and ether cleavage without participation of free intermediates. Isotope labeling experiments carried out with 18O2 and H2 18O indicated the incorporation of 18O from the atmosphere into the carboxyl residue as well as into the carbonyl oxygen of the lactone moiety of 2-pyrone-6-carboxylate. Based on these experimental findings the reaction mechanism for the formation of phenol and 2-pyrone-6-carboxylate is proposed in accordance with the mechanism suggested by Kersten et al. (1982).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00290914
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  • 3
    Electronic Resource
    Electronic Resource
    Kondensierte Ringsysteme, XV. Über die Reaktion von α-Chlorsulfoxiden mit Kalium-tert-butylat am Beispiel der Synthese von Oxapropellenen (1984)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 966-981 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensed Ring Systems, XV. About the Reaction of α-Chloro Sulfoxides with Potassium tert-Butoxide by the Example of the Synthesis of OxapropellenesThe synthesis of dithia- 1a - 3a and oxathiapropellenes 1b - 3b is described. From 1b - 3b the α-chloro sulfoxides 4 - 6 and α-chloro sulfones 4a - 6a are prepared, or which in most cases several stereoisomeric racemates are obtained. The constitution, configuration, and conformation of the α-chloro sulfoxide 4, the main product obtained from 1b, was elucidated by X-ray structure analysis. Only in that way it was possible to deduce the constitutions and configurations of the other stereoisomeric α-chloro sulfoxides 4 - 6 and α-chloro sulfones 4a - 6a, respectively, using 13C NMR spectroscopy. By the reaction of the α-chloro sulfones 4a - 6a with potassium tert-butoxide (Ramberg-Bäcklund reaction) the corresponding oxapropellenes 7 - 9 are obtained only in low yields (〈 10%). Contrary, the α-chloro sulfoxides 4 - 6, und analogous conditions give yields of 80 - 90% (from 4, 6) and 25% (from 5).
    Notes: Es wird die Synthese der Dithia- 1a - 3a und Oxathiapropellene 1b - 3b beschrieben. Aus 1b - 3b werden die α-Chlorsulfoxide 4 - 6 und α-Chlorsulfone 4a - 6a hergestellt, von denen meist mehrere stereoisomere Racemate erhalten werden. Konstitution, Konfiguration und Konformation des Hauptprodukts der aus 1b erhaltenen α-Chlorsulfoxide 4 wurden durch Röntgenstrukturanalyse ermittelt. Erst dadurch wurde es möglich, mit Hilfe der 13C-NMR-Spektroskopie die Konstitutionen und Konfigurationen der anderen stereoisomeren α-Chlorsulfoxide 4 - 6 und α-Chlorsulfone 4a - 6a aufzuklären. Bei der Reaktion der α-Chlorsulfone 4a - 6a mit Kalium-tert-butylat (Ramberg-Bäcklund-Reaktion) erhält man die entsprechenden Oxapropellene 7 - 9 nur in geringer Ausbeute (〈 10%), während die α-Chlorsulfoxide 4 - 6 unter analogen Bedingungen Ausbeuten von 80 - 90% (aus 4, 6) und 25% (aus 5) ergeben.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19841170311
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  • 4
    Electronic Resource
    Electronic Resource
    Kondensierte Ringsysteme, XVII. Propellane mit Benzol-Dewarbenzol-Struktur - Kristall- und Molekülstruktur von 1′,8′:3,5-Naphtho[5.2.2]propella-3,8,10-trien (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 1540-1545 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Condensed Ring Systems, XVII. Propellanes with Benzene-Dewar-Benzene Structure  -  Crystal and Molecular Structure of 1′,8′:3,5-Naphtho[5.2.2]propella-3,8,10-trieneThe syntheses of the propellanes 7-9, which have a benzene-Dewar-benzene structure, are described. As a second example of a 1,4-bridged Dewar-benzene, the crystal and molecular structure of 1′,8′:3,5-naphtho[5.2.2]propella-3,8,10-triene (9) is elucidated by X-ray structure analysis. 9 has a long central bridge bond of 1.565 Å, which, however, is clearly shorter than the corresponding bond of 3,4:5,6-dibenzo[6.2.2]propella-3,5,9,11-tetraene (10: 1.586 Å), due to the smaller C5-bridge. The dihedral angle of 116.6° between the cyclobutene rings of the Dewarbenzene system of 9 is insignificantly larger than the analogous angle of 10 (115.9°). The molecule lies on a crystallographic mirror plane.
    Notes: Die Synthesen der Propellane 7-9, die eine Benzol-Dewarbenzol-Struktur besitzen, werden beschrieben. Als zweites Beispiel für ein 1,4-überbrücktes Dewarbenzol wird die Kristall- und Molekülstruktur von 1′,8′:3,5-Naphtho[5.2.2]propella-3,8,10-trien (9) mittels Röntgenbeugung bestimmt. 9 besitzt eine lange zentrale Brückenbindung mit 1.565 Å, die jedoch aufgrund der kleineren C5-Brücke deutlich kürzer als die entsprechende Bindung im 3,4:5,6-Dibenzo[6.2.2]-propella-3,5,9,11-tetraen (10: 1.586 Å) ist. Der Faltungswinkel zwischen den beiden Cyclobutenringen des Dewarbenzol-Systems beträgt 116.6° und ist damit nur unwesentlich größer als der von 10 (115.9°). Das Molekül liegt auf einer kristallographischen Spiegelebene.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861190509
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  • 5
    Electronic Resource
    Electronic Resource
    Kondensierte Ringsysteme, XVIII Zur Synthese von Cyclobuten-Derivaten aus den entsprechenden Thiolanen - Kristall- und Molekülstruktur von 2,5-o-Benzeno-3,4-benzo[4.2.2]propella-3,7,9-trien (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 5-9 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cyclobutene derivatives are prepared from the corresponding thiolanes in better yields by using the chloro sulfoxides than the chloro sulfones, which are intermediates in the Ramberg-Bäcklund reaction. This is established by the synthesis of 2,5-o-benzeno-3,4-benzobicyclo[4.2.0]octa-3,7-diene (6) from 2,5-o-benzeno-3,4-benzo-8-thiabicyclo[4.3.0]non-3-ene (1). On the same way 2,5-o-benzeno-3,4-benzo[4.2.2]propella-3,7,9-triene (8) can now be prepared in better yields and its X-ray structure analysis is described.
    Notes: Cyclobuten-Derivate lassen sich aus den entsprechenden Thiolanen über die Chlorsulfoxide in besseren Ausbeuten herstellen als über Chlorsulfone, die bei der Ramberg-Bäcklund-Reaktion als Zwischenprodukte auftreten. Dieses wird durch die Synthese von 2,5-o-Benzeno-3,4-benzobicyclo[4.2.0]octa-3,7-dien (6) aus 2,5-o-Benzeno-3,4-benzo-8-thiabicyclo[4.3.0]non-3-en (1) bewiesen. Auf dem gleichen Syntheseweg konnte jetzt auch das 2,5-o-Benzeno-3,4-benzo[4.2.2]propella-3,7,9-trien (8) in besserer Ausbeute erhalten werden, dessen Röntgenstrukturanalyse beschrieben wird.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200103
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  • 6
    Electronic Resource
    Electronic Resource
    Zintl-Phasen mit Schichtanionen: Darstellung und Kristallstrukturen der isotypen Verbindungen SrSn2As2 und Sr0,87Ba0,13Sn2As2 sowie eine Einkristallstrukturbestimmung von KSnSbProfessor Hans-Georg von Schnering zum 60. Geburtstage gewidmet (1991)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 598 (1991), S. 93-102 
    Details
    ISSN: 0044-2313
    Keywords: Zintl phases ; earth alkaliarsenostannate(2-) ; potassium stibostannate(1-) ; preparation ; crystal structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zintl-Phases with Layer Anions: Preparation and Crystal Structures of the Isotypic Compounds SrSn2As2 and Sr0.87Ba0.13Sn2As2 and a Single Crystal Structure Determination of KSnSbThe metallic reflecting compounds SrSn2As2 and Sr0.87Ba0.13Sn2As2 were prepared from the melt, they crystallize in the trigonal rhombohedral system (space group R3m, Z = 3) with lattice constants see "Inhaltsübersicht".In the crystal structure of the isotypic compounds threebonded Sn atoms and threebonded As atoms together form puckered layers which are isostructural to grey As. The mean values of the bond lengths Sn-As are 277.6pm (SrSn2As2) and 279.1 pm (Sr0.87Ba0.13Sn2As2) resp. Along [001] the alkaline earth atoms occupy the octahedral interstices of As atoms between each second SnAs layer. The single crystal structure determination of KSnSb confirms the results of the X-ray powder analysis, but leads to slightly different values for the bond lengths.
    Notes: Die metallisch glänzenden Verbindungen Sr2Sn2As2 und Sr0,87Ba0,13Sn2As2 wurden aus Schmelzreaktionen ausgehend von den Elementen erhalten. Sie kristallisieren trigonal rhomboedrisch, Raumgruppe R3m, Z = 3, mit den Gitterkonstanten: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} {\rm SrSn}_{\rm 2} {\rm As}_{\rm 2} {\rm :\qquad\qquad a = 420,4\,\, pm,\, c = 2672,8\,\, pm,\, c/a = 6,358} \\ {\rm Sr}_{{\rm 0,87}} {\rm Ba}_{{\rm 0,13}} {\rm Sn}_{\rm 2} {\rm As}_{\rm 2} {\rm : a = 422,7\,\, pm,\, c = 2687,8\,\, pm,\, c/c = 6,359}{\rm .} \\ \end{array} $$\end{document} In den Kristallstrukturen der isotypen Verbindungen bilden dreibindige Sn-und As-Atome gemeinsam zum grauen Arsen isostrukturelle Schichten aus gewellten Sechsringen. Die mittleren Bindungslängen Sn—As betragen 277,6 pm (SrSn2As2) und 279,1 pm (Sr0,87Ba0,13Sn2As2). Entlang [001] besetzen die Erdalkaliatome aus As-Atomen gebildete Oktaederlücken zwischen jeder zweiten SnAs-Schicht. Die Einkristallstrukturbestimmung von KSnSb bestätigt die aus Pulverdaten abgeleiteten Ergebnisse, führt aber zu leicht unterschiedlichen Bindungslängen.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19915980109
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