So the prof got to Diels-Alder without discussing it in the context of molecular orbital theory. Instead we got a resonance picture of what happens... this is what he told us:
1,3-butadiene has both an electrophilic and a nucleophilic terminal carbon atom because we can draw resonance structures showing dipolar terminal carbon atoms ...
For ethene we can similarly draw a dipolar resonance structure.
From there we're told to simply use Coulomb's law - opposite charges attract - to complete the mechanism.
So, how adequate is his electrostatic explanation? Is it adequate - probably ... if one simply wants to learn it for a test. But is it conductive to further understanding of chemistry? I feel rather short-changed here since I'm paying him the big-bucks (tuition is insane) and the book goes into far greater detail ...
ETA: I asked the guy about and grilled him on the electrostatic explanation. For example I raised Martin's excellent point about the fact that the dieneophile cannot be that polarized - otherwise wouldn't it be a liquid instead of a gas due to the strong intermolecular attractions?
He instead went on a tangent on electron-withdrawing groups and how the electrostatic explanation can explain these ... what do you think?
