Thermal reversible isomerisation of 2-ethyl-cis-penta-1,3-diene to 4-methyl-trans-hexa-1,3-diene
Frey, H. M.; Solly, R. K.
Журнал:
Journal of the Chemical Society A: Inorganic, Physical, Theoretical
Дата:
1969
Аннотация:
The reversible isomerisation of 2-ethyl-cis-penta-1,3-diene to 4-methyl-trans-hexa-1,3-diene is an example of the now well-authenticated 1,5-hydrogen migration reaction which occurs in a number of diene systems. The reaction is almost certainly unimolecular and the first-order rate constants, obtained in the temperature range 190â 250° fit the Arrhenius equations, k 1= 10<sup>10·77</sup> exp (â 31,640/R T) sec.<sup>â 1</sup>; k â 1= 10<sup>11·03</sup> exp (-34,530/R T) sec.<sup>â 1</sup>. Equilibrium constants have been determined by direct analysis in the range 230â 340° and hence enthalpy and entropy differences between the isomers have been evaluated. The A factors of the isomerisations are discussed and compared with estimated values.
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