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Thermisches Verhalten von o-Dipropenylbenzol, Beispiel einer aromatischen [1,7]-sigmatropischen H-Verschiebung


Heimgartner, Heinz; Hansen, Hans-Jürgen; Schmid, Hans (1970). Thermisches Verhalten von o-Dipropenylbenzol, Beispiel einer aromatischen [1,7]-sigmatropischen H-Verschiebung. Helvetica Chimica Acta, 53(1):173-176.

Abstract

cis,cis-, cis,trans- and trans,trans-o-Dipropenylbenzene (cis,cis-, cis,trans- and trans,trans-1) were prepared. At 225° cis,cis-1 isomerises to give cis,trans-1 and vice versa. The isomerisation follows 1.order kinetics. At equilibrium 89% cis,trans- and 11% cis,cis-1 are present. It is shown by deuterium labelling that the isomerisation is due to aromatic [1,7a] sigmatropic H-shifts. trans,trans-1 rearranges at 225° to yield 2,3-dimethyl-1,2-dihydronaphthalene (3). This can be visualized by disrotatory ring closure of trans,trans-1 followed by an aromatic [1,5s] H-shift. When cis,cis- or cis,trans-1 are heated for 153 hrs a t 225° a small amount (3%) of 1-ethyl-1,2-dihydronaphthalene (5) is formed.

Abstract

cis,cis-, cis,trans- and trans,trans-o-Dipropenylbenzene (cis,cis-, cis,trans- and trans,trans-1) were prepared. At 225° cis,cis-1 isomerises to give cis,trans-1 and vice versa. The isomerisation follows 1.order kinetics. At equilibrium 89% cis,trans- and 11% cis,cis-1 are present. It is shown by deuterium labelling that the isomerisation is due to aromatic [1,7a] sigmatropic H-shifts. trans,trans-1 rearranges at 225° to yield 2,3-dimethyl-1,2-dihydronaphthalene (3). This can be visualized by disrotatory ring closure of trans,trans-1 followed by an aromatic [1,5s] H-shift. When cis,cis- or cis,trans-1 are heated for 153 hrs a t 225° a small amount (3%) of 1-ethyl-1,2-dihydronaphthalene (5) is formed.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:German
Date:1970
Deposited On:29 Dec 2014 15:03
Last Modified:08 Dec 2017 09:13
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:0018-019X
Funders:Schweizerischer Nationalfonds
Publisher DOI:https://doi.org/10.1002/hlca.19700530124

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