The thermal unimolecular isomerisation of bicyclo[3,1,0]hex-2-ene and decomposition of cyclohexa-1,4-diene
- 1 January 1966
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc. A
- p. 553-556
- https://doi.org/10.1039/j19660000553
Abstract
The thermal isomerisation of bicyclo[3,1,0]hex-2-ene in the gas phase, in the range 313–347°C, has been found to be homogeneous and first-order. The rate constants for decomposition were independent of pressure in the range 3–30 mm. and fitted the Arrhenius equation, k= 1014·50 exp(–50,200/RT) sec.–1. The reaction yields two primary products, cyclohexa-1,3- and -1,4-diene. In the temperature range studied, the 1,3-diene is thermally stable, but the 1,4-diene decomposes to benzene and hydrogen. A brief investigation of the thermal decomposition of cyclohexa-1,4-diene from 303 to 343° showed the reaction to be first-order and predominantly homogeneous; it is probably molecular. The rate constants fitted the Arrhenius equation, k= 1012·02exp(–42,690/RT) sec.–1. The decomposition of cyclohexa-1,3-diene occurs at much higher temperatures (above 400°) by a complex process. The mechanisms for the isomerisation of the bicyclohexene and the decompositions of the cyclohexadienes are discussed.Keywords
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