Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 1,2-Styryl migration  (1)
  • 13C, D labelling  (1)
  • PAH formation  (1)
  • 1
    ISSN: 0947-3440
    Keywords: Ethynylbenzene ; pyrolysis of ; Scavenging of radicals ; PAH formation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pyrolysis of ethynylbenzene (1) in helium was studied in a tubular flow reactor at 10.7 mbar/1030°C and reaction times ranging from 5 to 30 ms. Reactive intermediates such as radicals and carbenes were scavenged with dimethyl disulfide (DMDS), Qualitative and quantitative analysis of the scavenging products and of the stable pyrolysis products were carried out by GC-MS analysis. - The radicals phenyl (2a), o-, m-, and p-ethynylphenyl (1c, d, e), 2- and 1-phenyl-vinyl (1a, b) 1- and 2-naphthyl (3a, b), methyl, hydrogen atoms, and radicals resulting from the addition of phenyl and ethynylphenyl radicals to the triple bond of ethynylbenzene were detected. Carbenes, such as phenylvinylidene, occur only in small traces and obviously play no role in the overall pyrolysis. Concentration profiles of the radicals and of some important pyrolysis products are presented and discussed. Based on the detected radicals, a reaction scheme for the pyrolysis of ethynylbenzene is proposed. Results of pyrolyses of mixtures of ethynylbenzene and ethyne show that naphthalene (3), acenaphthylene (12), and other compounds are produced by a sequence of ethyne addition and cyclization reactions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1434-193X
    Keywords: Pyrolysis ; 1,3-Hexadien-5-ynes ; Cyclization, radical ; 13C, D labelling ; Naphthalene isotopomers ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal cycloisomerization of the isotope-labelled 1-phenyl-1-buten-3-ynes 1 {including the [3-13C,4-D]1-phenyl-1-buten-3-yne (6) and the [4-D]1-phenyl-1-buten-3-yne (9) formed as intermediates} has been studied. The investigations were performed in a quartz flow system at a temperature of 650 °C (1, 6) [and over the range 625-750 °C for (9)] at a reaction time of 0.3 s in the presence of different diluent gases (H2, N2, N2-toluene). Spectroscopic analyses of the naphthalene isotopomers formed allow the evaluation of competing radical reaction channels in addition to reactions occuring by electrocyclic and carbene-like ring closure.[1] A mechanistic analysis for the conversion of 1 undoubtedly suggests a predominant reaction course via phenyl-type radical intermediates (1c/6c), followed by their exocyclization to the indenylcarbenyl radicals 1f/6f and the homoallyl-like rearrangement of the latter to the 1,2-dihydronaphthyl radicals 1i/6i at 650 °C. With increasing temperature, other competing reactions (endocyclizations of vinyl- and phenyl-type radicals as well as neophyl-like rearrangements of the indenylcarbinyl radicals 1f/6f) gain in importance.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1434-193X
    Keywords: Enyne pyrolysis ; 13C,D labelling ; Alkenylidene carbenes ; 1,2-Styryl migration ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal conversion of [4-13C,4-D]- (1) and [4-13C]-1-phenyl-1-buten-3-yne (7) has been studied in a quartz tubular reactor at 650 °C (1, in the presence of N2 and N2/toluene, respectively) and at 600 and 620 °C (mixture of 1 and 7, in N2 only) at a reaction time of approximately 0.3 s. The liquid pyrolyzates were analyzed spectroscopically. By means of a special calculation method reported recently, the naphthalene isotopomers formed by reaction pathways other than those proceeding via cinnamylidene carbenes were arithmetically eliminated and the reaction events proceeding via carbene intermediates were mechanistically analyzed. The result of this analysis undoubtedly suggests a complex reaction in which the rates of the partial reactions may be placed in the following order: 1,2-D(H) 〉〉 1,2-styryl 〉 1,6-C,H.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...