1. Interaction of p orbitals in polyenes at the Huckel level of theory
butadiene
methyl
allyl
ethene
Energy eV
Stabilization
energy eV
12.3
14.5
24.8

2. 2 x 2 x Stabilization Energy 2x (-11.4 eV) 2x (-17.6 eV)
Energy of electon on isolated
p orbital
2 x
2x (-11.4 eV)
2 x
Energy of electon on p orbital of ethylene
2x (-17.6 eV)
Stabilization energy
2 x 6.2 = 12.4 eV

3. Electronic excitation and UV Absorption spectra
butadiene hv
butadiene *
ethene
ethene * hv
DE = 17.1 eV
DE = 11.4 eV
exp 174 nm
exp 216 nm