Propene ionization energy

For a very userid discussion of Ihe chemicaJ propenics of metab. as related lo their ionization energies, see Ahrens, L. H. Ionization Poitntinlsi Pergamon Oxford, 1983. 

The ionization energies of the carbon-chlorine bond for (E)-l-chloro-2-butene and 3-chloro-2-methyl-l-propene in the gas phase are 672 and 706 kj mole", respectively. Using molecular orbital concepts, explain this energy difference based on the stability of the carbocations. 

In contrast, ions with internal energy > 1.3 eV underwent isomerization to ionized propene to a substantial extent (up to 80 %). Thus, the barrier for the isomerization 1 - 3 is indeed in the range 1.3 < 1.6 eV, as predicted by theory. The upper value is... 

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