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  • 1
    Publication Date: 1982-01-01
    Print ISSN: 0002-7863
    Electronic ISSN: 1520-5126
    Topics: Chemistry and Pharmacology
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  • 2
    Publication Date: 1983-10-01
    Print ISSN: 0022-3263
    Electronic ISSN: 1520-6904
    Topics: Chemistry and Pharmacology
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 104 (1982), S. 312-313 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 48 (1983), S. 3544-3545 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 483-491 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Gas Phase Reactions, 23. Thermal Decomposition of Open-Chain Dialkyl Sulfides, Disulfides and DiselenidesThe thermal decomposition of the dialkyl chalcogenide derivatives RSR, RSSR and RSeSeR (R = CH3, CH2CH3, CH2CH2CH3, CH(CH3)2, C(CH3)3) in a heated flow tube is analyzed and optimized using PE spectroscopy. Whereas high-temperature pyrolysis 〉1000 K yields mixtures of thermodynamically favored final products like H2, CH4, CS2, and HCCH, the lowest thermal reaction channel produces homogeneously olefin, H2S, and sulfur or olefin, alkaneselenol, H2Se, and selenium, respectively. The decomposition temperatures increase from RSeSeR via RSSR towards RSR and also with decreasing size of the alkyl groups. Based on the experimental data the possible course of the thermal decomposition is discussed.
    Notes: Die thermische Zersetzung der Dialkyl-chalkogenid-Derivate RSR, RSSR und RSeSeR (R = CH3, CH2CH3, CH2CH2CH3, CH(CH3)2), C(CH3)3) in einem beheizten Strömungsrohr wird PE-spektroskopisch analysiert und optimiert. Während sich bei Hochtemperatur-Pyrolysen 〉1000 K Gemische thermodynamisch günstiger Endprodukte wie H2, CH4, CS2 und HCCH bilden, entstehen im niedrigsten thermischen Reaktionskanal einheitlich Olefin, H2S und Schwefel bzw. Olefin, Alkanselenol, H2Se und Selen. Die Zersetzungstemperaturen steigen von RSeSeR über RSSR zu RSR sowie jeweils mit abnehmender Größe der Alkylreste. Anhand der Meßdaten wird der mögliche thermische Zersetzungsverlauf diskutiert.
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 273-281 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Gasphase Reactions, 39. Photoelectron Spectroscopic Evidence and Matrix Isolation of Thio-para-benzoquinonesThe thermal decomposition of 1,4-di(heteroallyl) substituted benzenes H2C=CHCH2X—C6H4—XCH2CH=CH2 (X = O, S) in the gaseous phase produces para-benzoquinone, monothio or dithio para-benzoquinone, with 1,5-hexadiene as leaving molecule. The PE spectroscopic evidence can be further substantiated applying the shortway pyrolysis techniques to register also, after isolation in an argon matrix at 10 K, the UV and IR spectra of the short-lived species. Ionisation and electron excitation energies as well as other molecular properties of the violet 2,5-cyclohexadiene-1,4-dithione S=C[HC=CH]2C=S correlate satisfactorily with precalculated MNDO values.
    Notes: Bei der thermischen Zersetzung 1,4-di(heteroallyl)substituierter Benzole H2C=CHCH2X—C6H4—XCH2CH=CH2 (X = O, S) in der Gasphase lassen sich PE-spektroskopisch para-Benzochinon, Monothio- oder Dithio-para-benzochinon sowie als Abgangsmolekül 1,5-Hexadien nachweisen. Zusätzlich gelingt es, die kurzlebigen Moleküle nach Kurzweg-Pyrolyse in einer Argon-Matrix bei 10 K zu isolieren und ihre UV- und IR-Spektren aufzunehmen. Ionisierungs- und Elektronenanregungsenergien sowie weitere Moleküleigenschaften des violetten 2,5-Cyclohexadien-1,4 dithions S=C[HC=CH]2C=S stimmen mit vorausberechneten MNDO-Werten zufriedenstellend überein.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2595-2608 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Gas Phase Reactions, 21. Thermal Generation of Alkyl- and HalogenketenesThermal gas phase reactions for the generation of ketenes can be optimized PE-spectroscopically. To eliminate HX from acetyl derivatives R2CH—COX increasing temperatures are required in the sequence HO2CCH3 ≍ HCl 〈 HBr 〈 H2O ≍ ROH ≪ CH4. By adding NH3, HCl can be removed from the gaseous mixture and thus the PE spectra of pure alkyl ketenes R2C=C=O (R e.g. H, CH3, C2H5) may be recorded. „Fulvene ketene“ (4) is obtained from cyclopentadienecarbonyl chloride (this from the dimer) and ethyleneketene (7) by pyrolysis of cyclopropyl spirosubstituted Meldrum's acid (6). Chloro- and bromoketenes are generated as follows: ClHC=C=O from ClH2C—COCl, Cl2C=C=O from Cl3C—COBr with Zn, BrHC=C=O from 2-bromocyclobutanone and NC—HC=C=O from NC—H2C—COCl. The PE spectra are assigned by radical cation state comparison based on MNDO calculations.
    Notes: Thermische Gasphasenreaktionen zur Ketenerzeugung lassen sich PE-spektroskopisch optimieren: Bei Acetylderivaten R2CH—COX werden HX-Abspaltung in der Reihenfolge HO2CCH3 ≍ HCl 〈 HBr 〈 H2O ≍ ROH ≪ CH4 steigende Temperaturen benötigt. HCl läßt sich mit NH3 aus dem Gasgemisch abscheiden, und es können so die PE-Spektren reiner Alkylketene R2C=C=O (R z.B. H, CH3, C2H5) aufgenommen werden. „Fulvenketen“ (4) wird aus Cyclopentadiencarbonylchorid (dieses aus dem Dimeren), Ethylenketen (7) durch Pyrolyse von Cyclopropyl-spirosubstituierter Meldrumsäure (6) gewonnen. Chlor- und Bromketene konnten wie folgt erhalten werden: ClHC=C=O aus ClH2C—COCl, Cl2C=C=O aus Cl3C—COBr mit Zn, BrHC=C=O aus 2-Bromcyclobutanon und NC—HC=C=O aus NC—H2C—COCl. Die PE-Spektren werden durch Radikalkationzustands-Vergleich, gestützt auf MNDO-Rechnungen, zugeordnet.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2609-2621 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Gas Phase Reactions, 22. Thermal Generation of C4H4O: Vinylketene and EthylideneketeneThermal HX elimination from unsatured carboxylic acid derivatives H3C—RC=CH—COX represents another method to generate the short-lived isomers C4H3RO with R=H, CH3 in the gas phase. The temperature-dependent changes of amounts of products in the heated flow system are analyzed by photoelectron spectra: based on MNDO calculations and in accordance with literature data, the vinylketene structure H2C=CR—HC=C=O is assigned to the thermolysis product. The isomeric alkylideneketenes H3C—RC=C=O with R=H, CH3 are produced in the 760 K short-path pyrolysis of alkylidenemalonates and rearrange on prolonged residence time in the heating zone into the thermodynamically more stable vinylketene derivatives.
    Notes: Die thermische HX-Abspaltung aus ungesättigten Carbonsäure-Derivaten H3C—RC=CH—COX ist eine weitere Methode, die kurzlebigen Isomeren C4H3RO mit R=H, CH3 in der Gasphase zu erzeugen. Die temperaturabhängigen Änderungen der Produktmengen im beheizten Strömungs-system werden mit Hilfe von Photoelektronen-Spektren analysiert: Gestützt auf MNDO-Rechnungen und übereinstimmend mit Literaturbefunden wird dem Thermolyseprodukt die Vinylketen-Struktur H2C=CR—HC=C=O zugeordnet. Die isomeren Alkylidenketene H3C—RC=C=C=O mit R=H, CH3 entstehen bei 760 K-Kurzwegpyrolyse von Alkylidenmalonaten und lagern sich bei längerer Verweilzeit in der Heizzone in die thermodynamisch stabileren Vinylketen-Derivate um.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 492-503 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Gas Phase Reactions, 24. The Thermal Generation of Thiocarbonyl CompoundsThiocarbonyl derivatives R1R2C=S with R1, R2 = H, CH3, C6H5 can be generated thermally in the gas phase from a variety of precursors. Especially advantageous are the cleavage of propene from allyl sulfides or, for their preparation in pure form, the pyrolysis of dithietane or trithiolane derivatives. Photoelectron spectroscopy proves to be well-suited for gas analysis in the flow tube used, for the optimization of the decomposition conditions, and via assignment of the observed ionization patterns for the characterization of the thioaldehydes and thioketones prepared.
    Notes: Thiocarbonyl-Derivate R1R2C=S mit R1, R2 = H, CH3, C6H5 lassen sich in der Gasphase thermisch aus vielerlei Ausgangsverbindungen erzeugen; vorteilhaft sind insbesondere die Propen-Abspaltung aus Allylsulfiden oder für ihre Reindarstellung die Pyrolyse von Dithietan- und Trithiolan-Derivaten. Die Photoelektronen-Spektroskopie bewährt sich zur Gasanalyse im verwendeten Strömungsrohr, zur Optimierung der Zersetzungsbedingungen und über die Zuordnung der beobachteten Ionisierungsmuster zur Charakterisierung der hergestellten Thioaldehyde und Thioketone.
    Additional Material: 4 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 115 (1982), S. 1339-1348 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Gas Phase Reactions, 30. Thioacrolein: The Most Stable Isomer C3H4S and its PE Spectroscopic Proof in the Gas PhaseThe ensemble C3H4S contains 13 valence-„normal“ isomers, of which according to MNDO calculations thioacrolein, H2C=C(H)—(H)C=S, should be the energetically most stable. Expectedly, diallyl sulfide decomposes on pyrolysis at 660 K to yield propene and thioacrolein, which can be cool-trapped in a preparative way as mixture of Diels-Alder dimers. Heating of the isomeric dimers leads in a retrodiene splitting to pure thioacrolein, identified by its PE spectrum which is similar to that of acrolein.
    Notes: Das Ensemble C3H4S enthält 13 valenz-„normale“ Isomere, unter denen nach MNDO-Berechnungen Thioacrolein, H2C=C(H)—(H)C=S, das energetisch stabilste sein sollte. Erwartungsgemäß zerfällt Diallylsulfid bei 660K-Pyrolyse zu Propen und Thioacrolein, welches sich in einer Ausfrierfalle präparativ als Diels-Alder-Dimerengemisch abfangen läßt. Erhitzen der isomeren Dimeren führt unter Retrodien-Spaltung zu reinem Thioacrolein, das sich durch sein dem Acrolein ähnliches PE-Spektrum identifizieren läßt.
    Additional Material: 4 Ill.
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