There may be an MO energy diagram in your textbook in the chapter on conjugated dienes. The general pattern is, if you start with X atomic orbitals, you will get X molecular orbitals, half of them bonding and half antibonding. The diagram will be something like
Atomic 2p orbitals MOs
___ (antibonding, empty)
___ (LUMO, antibonding, empty)
___ ___ ___ ___
(one electron in each)
___ (HOMO, bonding, two electrons)
___ (bonding, two electrons)
("HOMO" = "highest occupied molecular orbital, and "LUMO" = lowest unoccupied molecular orbital".)
The reactions on the attachement are Diels-Alder reactions, also covered under reactions of conjugated dienes. It will probably have similar reactions illustrated. The first reaction is between cyclopentadiene (the "diene") and maleic anhydride (the "dieneophile") and gives the product endo-norbornene-5,6-cis-dicarboxylic anhydride. This is a popular lab experirment so it may be in your lab manual. The second is a little simpler in that you do not get a bicyclic product. I can't illustrate it at the moment, but the easiest way to do these reactions is to use an easy one as a model. If the dieneophile is an alkene, you always get a cyclohexene product. The reaction is stereospecific, so if you start with a trans dienophile, those groups will still be trans to each other in the product.
Steve
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