Talk:Mod:ialrirpl

Introduction Missing.

Cope rearrangement Some conformers successfully identified - although not all of them. What can you say about their relative energy? Why do a frequency calculation and what do you conclude from yours? Chair and Boat structures successfully identified but you did not try with QST2 method for example. How did you check these structures were TS and not minimum? IRC calculation successfully done and interpreted. Any conclusions about the preferred mechanism regarding the energy difference?

Diels-Alder Plot orbitals wrt the symmetry element (i.e. plane) you are trying to indicate. What can you conclude from the forming bond lengths by comparing with data such as van der Waals radii or standard sp2-sp2/ sp3-sp3 carbon bond lengths? The lowest imaginary frequency indicates the reaction is concerted, at least around the TS in the harmonic approximation (the IRC allows us to confirm this). Why is the reaction allowed? Woodward-Hoffmann rules give FMO symmetry requirements, which are corroborated by ab initio calculations. Secondary Orbital overlap should involve the interaction between the pi orbitals of the carbon or oxygens which are not involved in bond formation. Your endo pi orbitals on the oxygens are actually orthogonal and the is no obvious overlap. Secondary orbital overlaps are a way of explaining reactivity based on an AO FMO approach, however, calculations may not support it and whether they actually exist is a cause of debate (http://pubs.acs.org/doi/abs/10.1021/ar0000152).

Overall All the results are present but there needs to be more analysis. Some of the questions asked in the exercise (e.g. about van der Waals radii) not answered. No literature references.