Gasphasen-Reaktionen, 91 [1-3]. Thermische und heterogen-katalysierte N₂-Abspaltung aus Azo-Verbindungen R–N=N–R (R = CH₃, C₃H₅, C₆H₅)

Gas phase reactions, 91 [1-3]. Thermal and heterogeneously catalyzed N₂ elimination of azo-compounds R–N=N–R (R = CH₃, C₃H₅, C₆H₅)

  • Thermal decompositions of azo compounds in the gas phase under reduced pressure are further investigated using photoelectron spectroscopic gas analysis. Passing diallyl, diphenyl and phenylmethyl derivatives either through a short-pathway pyrolysis (SPP) apparatus or through an external thermal reactor (ETR) results in the following fragmentations: Under nearly unimolecular conditions (SPP, 10-4 mbar pressure), diallyldiazene decomposes above 600 K to N2 and hexadiene-1,5 with the allyl radical as a detectable intermediate. The PE spectra recorded for diphenyldiazene above 1000 K (ETR, 1-2 mbar pressure) show N2, benzene, as well as traces of diphenyl. Phenylmethyldiazene yields above 800 K (SPP) predominantly N2, toluene, diphenyl and ethane with the methyl radical as the only detectable intermediate. Insertion of quartz wool into the pyrolysis tube (ETR) lowers the fragmentation temperatures, and in addition, above 850 K, HCN and aniline are PE spectroscopically identified. Surprisingly, this second reaction channel can be heterogeneously catalyzed: phenylmethyldiazene decomposes under 10-2 mbar pressure at a [Ni/SiO2] catalyst surface selectively to HCN and aniline.

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Metadaten
Author:Hans BockGND, Bodo Berkner
URN:urn:nbn:de:hebis:30:3-620330
DOI:https://doi.org/10.1515/znb-1992-1108
ISSN:1865-7117
ISSN:0932-0776
Parent Title (German):Zeitschrift für Naturforschung, B
Publisher:Verlag der Zeitschrift für Naturforschung
Place of publication:Tübingen
Document Type:Article
Language:German
Date of Publication (online):2014/06/02
Year of first Publication:1992
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2024/01/27
Tag:Azo Compounds; Gas Phase Thermolysis; Heterogeneous Catalysis; Photoelectron Spectra
Volume:47.1992
Issue:11
Page Number:10
First Page:1551
Last Page:1560
Institutes:Biochemie, Chemie und Pharmazie / Biochemie und Chemie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung-Nicht kommerziell-Keine Bearbeitung 3.0