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  • Organic Chemistry  (646)
  • Inorganic Chemistry  (637)
  • 1980-1984  (1,283)
  • 1920-1924
  • 1984  (1,283)
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  • 1980-1984  (1,283)
  • 1920-1924
Year
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 326 (1984), S. 139-144 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quantum-Chemical Calculations on Allyl-Type Radicals: Cycloalkenyl- and Cycloalk-1-enylmethyl RadicalsThe ability of the MINDO/3-HE-method for predicting various molecular properties was tested for cycloalkenyl- (1 to 4), cycloalk-1-enylmethyl-(5 to 8), and for the resonance-stabilized cyclic radicals (9 to 12). Close by it was established that the calculated heats of formation are largely correct. The electronic distribution in the allylic part of 1 to 12 is evidently too levelled.Based on the defination of allyl resonance energy (ARE - SZWARC (1948)) a mean value for the ARE of 1 to 8 is derived to 55 ± 12 kJ · mol-1.
    Additional Material: 3 Tab.
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  • 2
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optically pure aryl-substituted 5,6-dimethylidene-2-bicyclo[2.2.1]heptyl benzoates 12-21 were prepared; their UV absorption and CD spectra are reported. The (-)-(1S,2S)-esters 17-21 with carbonyl groups in endo-position exhibit typical excitonsplit Cotton effects whereas the corresponding (-)-(1S,2R)-esters 12-16 with carbonyl groups in exo-position do not present such effects. The chiral exciton coupling between the exocyclic diene and a remote p-substituted benzoate chromophore can be used for unambiguous assignment of the absolute configuration of 5,6-dimethylidene-2-endo-bicyclo[2.2.1]heptyl derivatives. The method is applied to establish the absolute configuration of 5,6-dimethylidene-2-exo and -2-endo-bicyclo[2.2.2.]octyl p-bromobenzoates (-)-24 and (-)-25.
    Additional Material: 10 Ill.
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  • 3
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Vibrational Spectra and Tentative Structural Characterization of Aluminum Chalcogenide Halides AlSX and AlSeX (X = Cl. Br. I)The title compounds have been prepared according to known procedures. X-ray rotation photographs show a lattice constant along the needle axis (= monoclinic b axis) of 12.0 to 12.8 Å. The Raman and FIR spectra have been registered and assigned, based on characteristic frequency shifts within a series of compounds with different chalcogenide or halide atoms. We propose a dimeric structure for AlSX and AlSeX with planar four-membered Al2S2 (Al2Se2) rings and short (“terminal”) Al—X bonds, which is strongly supported by frequency calculations (approximate normal coordinate analyses) on 5 different structure models. Al is coordinatively saturated by long X—Al interactions, leading to a chain structure.
    Notes: Die Aluminium-sulfid- und -selenidhalogenide AlSX und AlSeX (X = Cl, Br, I) wurden nach bekannten Verfahren dargestellt. Aus Drehkristall-Röntgenaufnahmen ergaben sich in Richtung der Nadelache (b = Achse einer monoklinen Elementarzelle) Gitterkonstanten von 12,0 bis 12,8 Å. Die Raman- und FIR-Spektren wurden registriert und mit Hilfe der innerhalb der Verbindungsreihen charakteristischen Bandengruppen zugeordnet. Aufgrund von Frequenzberechnungen für 5 Strukturmodelle wird eine dimere Struktur mit planaren Al2S2- bzw. Al2Se2-Vierringen und kurzen („terminalen“) Al—X-Bindungen vorgeschlagen. Über längere Al—X-Brückenbindungen wird Al koordinativ abgesättigt und eine Kettenstruktur ausgebildet.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 196-198 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaktionen von 4-Chlor-9H-xanthen-9-thion mit Tetrachlor-O-benzochinon4-Chlor-9H-xanthen-9-thion (1) reagiert mit Tetrachlor-o-benzochinon zu dem cyclischen Acetal 2. Zur Struktursicherung wurde 2 auf unabhängigen Wegen aus Tetrachlor-o-benzochinon und 4-Chlor-9-diazo-9H-xanthen oder 4-Chlor-9H-xanthen-9-on-hydrazon sowie aus Tetrachlorbrenzcatechin und 4,9,9-Trichlor-9H-xanthen synthetisiert. Die Spaltung der Acetalgruppe in 2 mit Salzsäure, Malononitril, Cyanessigsäure-ethylester und Hydrazinhydrat wurde studiert.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1984 (1984), S. 186-190 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reaktionen mit 2-Methyl- und 2-Styryl-4-thiochromonenDiazoalkane reagieren mit 2-Methyl- und 2-Styryl-4-thiochromonen zu 1,3-Dithiolanen 1 und/oder Ethylenen 2-4. Letztere werden mit Thionylchlorid zu den entsprechenden Ketonen gespalten während beim Schmelzen mit Schwefel die entsprechenden Thioketone entstehen. 2-Methyl-und 2-Styryl-4-thiochromone kondensieren mit CH-aciden Verbindungen wie Malononitril und Cyanessigsäure-ethylester zu 5. Oxidation der 2-Methyl- und 2-Styryl-4-thiochromone mit gelbem Quecksilber(II)-oxid oder mit Tetrahalogen-o-benzochinon ergibt die entsprechenden Ketone. Die biologische Aktivität ausgewählter Verbindungen gegenüber Gram-positiven und Gramnegativen Bakterien wurde untersucht.
    Notes: Diazoalkanes react with 2-methyl- and 2-styryl-4-thiochromones to yield the 1,3-dithiolanes 1 and/or ethylenes 2-4. The latter are cleaved with thionyl chloride to give the corresponding ketones, while on fusion with sulfur they afford the corresponding thioketones. By condensation with compounds containing active hydrogen, such as malononitrile and ethyl cyanoacetate, the 2-methyl- and 2-styryl-4-thiochromones yield the compounds 5. Oxidation of 2-methyl- and 2-styryl-4-thiochromones was accomplished by yellow mercury(II) oxide as well as with tetrahalo-o-benzoquinones to give the corresponding ketones. The biological activity of some selected compounds prepared during this work has been tested towards Gram-positive and Gram-negative bacteria.
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  • 6
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carbonyl und Thiocarbonylverbindungen: Reaktionen von 4-Chlorxanthion mit Diazoalkanen und Ch-aciden verbindungenWährend 4-Chlorxanthion 1 mit Diazomethan das Dithiolan 2 ergibt, entstehen mit anderen Diazoalkanen die Episulfide 3-5, deren Entschwefelung zu den entsprechenden Ethylenen 6-7 führt. Malononitril und Cyanessigsäure-ethylester reagieren mit 1 zu den Cyanderivaten 8a, b. Mit Hydrazinen und p-Toluidin ergibt 4-Chlorxanthion (1) die Hydrazone 9a, b und die Schiff-Base 9c. In Abhängigkeit von den Reaktionsbedingungen liefert die Oxidation des Hydrazons 9a die Diazoverbindung 10 oder das Ketazin 11. Hydroxylamin reagiert mit 1 zum Oxim 9d, das mit Phenylisocynat zum N-Phenylcarbamat 9e reagiert.
    Notes: While 4-chloroxanthione 1 gives with diazomethane the dithiol 2, it reacts with other diazoalkanes to give the episulfides 3-5, desulfurization of which forms the ethylenes 6 and 7. Malononitrile and ethyl cyanoacetate react with 1 to give the cyano derivatives 8a, b. With hydrazines and p-toluidine, 4-chloroxanthione (1) give the hydrazones 9a, b and the Schiff's base 9c, respectively. The hydrazone 9a on oxidation may give either the corresponding diazo compound 10 or the ketazine 11 according to the reaction conditions. The title compound 1 reacts with hydroxylamine to yield the oxime 9d which forms the N-phenylcarbamate 9e when treated with phenyl isocyanate.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 326 (1984), S. 994-998 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 519 (1984), S. 213-216 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Chalcogenolates. 145. Trimethylgermyl and Trimethylstannyl CarbonatesThe hitherto unknown salts of the hemiesters of carbonic acid Li[O2C—OGe(CH3)3] and Li[O2C—OSn(CH3)3] have been prepared by reaction of Li[OGe(CH3)3] and Li[OSn(CH3)3], respectively, with CO2 at 0°C.Both compounds were characterized by means of diverse spectoscopic methods.
    Notes: Die bisher nicht bekannten Halbestersalze der Kohlensäure Li[O2C—OGe(CH3)3] und Li[O2C—OSn(CH3)3] wurden durch Umsetzung von Li[OGe(CH3)3] bzw. Li[OSn(CH3)3] mit CO2 bei 0°C hergestellt.Beide Verbindungen wurden mit verschiedenen spektroskopischen Methoden charakterisiert.
    Additional Material: 2 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 519 (1984), S. 204-212 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Chalcogenolates. 144. Synthesis and Properties of Alkali Metal t-Butyl Carbonates. Reinvestigations of Trimethylsilyl CarbonatesThe t-butyl carbonates M[O2C—OC(CH3)3], where M = Li, Na, K, Rb, Cs, have been prepared by reaction of the corresponding t-butoxide with CO2 and characterized by means of diverse methods.The equivalent conductivities of the [O2C—OC(CH3)3]- ion in aqueous solution have been determined and the Stokes radius, the radius of the hydrated ion, and the diffusion coefficient were calculated.The dissociation constant of t-butyl carbonic acid in water at 25°C is Ka = (1.63 ± 0.03)· 10-8. The thermodynamic data of dissociation were calculated.New data of trimethylsilyl carbonates [O2C—OSi(CH3)3]- are given.
    Notes: Die t-Butylcarbonate M[O2C—OC(CH3)3] mit M = Li, Na, K, Rb, Cs wurden durch Umsetzung des entsprechenden t-Butoxids mit CO2 hergestellt und mit verschiedenen Methoden charakterisiert.Die Äquivalentleitfähigkeiten des [O2C—OC(CH3)3]--Ions in wäßriger Lösung wurden bestimmt und der Stokessche Radius, der Radius des hydratisierten Ions und der Grenzwert des Diffusionskoeffizienten berechnet.Die Dissoziationskonstante der t-Butylkohlensäure in Wasser beträgt Ka = (1,63 ± 0,03)· 10-8 bei 25°C. Die thermodynamischen Standardgrößen der Dissoziation wurden ermittelt.Für Trimethylsilylcarbonate [O2C—OSi(CH3)3]- werden neue Daten mitgeteilt.
    Additional Material: 5 Tab.
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  • 10
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of 1,4-Pentadien-3-ones, 22. - Synthesis and Structure of the Epimers of 3,5-Diaryl-4-hydroxy-1,4-thiazinane 1,1-DioxidesDistyrylsulfones 1 react with the ambident nucleophile hydroxylamine only by double addition of nitrogen to give 4-hydroxy-1,4-thiazinane derivatives 3. In solution 3 consists of a temperature-dependent equilibrium mixture of two epimers. When heated or when crystallized one of the epimers is depopulated. The above phenomena and structures are elucidated by an X-ray analysis and by NMR spectroscopy.
    Notes: Distyrylsulfone 1 reagieren mit dem ambidenten Nucleophil Hydroxylamin ausschließlich unter doppelter Addition des Stickstoffs zu 4-Hydroxy-1,4-thiazinan-Derivaten 3. Diese bilden in Lösung temperaturabhängige Epimeren-Gleichgewichte. Sowohl beim Erwärmen als auch beim Auskristallisieren erfolgt Depopulation eines Epimers. Strukturen und Phänomene werden durch Röntgenstrukturanalyse und NMR-Spektroskopie geklärt.
    Additional Material: 5 Ill.
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