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Thermisches Verhalten von 1,2-Dipropenylbenzolen


Heimgartner, Heinz; Hansen, Hans-Jürgen; Schmid, Hans (1972). Thermisches Verhalten von 1,2-Dipropenylbenzolen. Helvetica Chimica Acta, 55(5):1385-1403.

Abstract

1-cis,2-cis-Dipropenylbenzene (cis,cis-1) isomerises thermally at 215-235° with 1st order kinetics to give trans,cis-1, and vice versa. At equilibrium 89% trans,cis- and 11% cis,cis-1 are present. It is shown by thermal rearrangement of cis,cis-2', 2"-d2-1 that the isomerisation is attributable to aromatic [1,7a]-sigmatropic H-shifts. trans,trans-1 rearranges thermally at 225-245° to yield 2,3-dimethyl-1,2-dihydronaphthalene (2). The formation of 2 can be visualized by disrotatory ring closure followed by an aromatic [1, 5s]-sigmatropic H-shift. 2 is also formed when cis,cis- or trans,cis-1 are heated for 153 h a t 225°. Besides 2 a small amount (3%) of 1-ethyl-1,2-dihydronaphthalene (5) is formed. The rearrangement of trans, trans-1 and trans, trans-2'.2"- d2-1 shows a secondary isotope effect kH/kD = 0.90.

Abstract

1-cis,2-cis-Dipropenylbenzene (cis,cis-1) isomerises thermally at 215-235° with 1st order kinetics to give trans,cis-1, and vice versa. At equilibrium 89% trans,cis- and 11% cis,cis-1 are present. It is shown by thermal rearrangement of cis,cis-2', 2"-d2-1 that the isomerisation is attributable to aromatic [1,7a]-sigmatropic H-shifts. trans,trans-1 rearranges thermally at 225-245° to yield 2,3-dimethyl-1,2-dihydronaphthalene (2). The formation of 2 can be visualized by disrotatory ring closure followed by an aromatic [1, 5s]-sigmatropic H-shift. 2 is also formed when cis,cis- or trans,cis-1 are heated for 153 h a t 225°. Besides 2 a small amount (3%) of 1-ethyl-1,2-dihydronaphthalene (5) is formed. The rearrangement of trans, trans-1 and trans, trans-2'.2"- d2-1 shows a secondary isotope effect kH/kD = 0.90.

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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:1972
Deposited On:29 Dec 2014 15:08
Last Modified:08 Dec 2017 09:12
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:0018-019X
Funders:Schweizerischer Nationalfonds
Publisher DOI:https://doi.org/10.1002/hlca.19720550505

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