Talk:Mod:joto1357

Part 1.1: Energies and structures for 1 and 2 are fine. Why is 1 lower in energy? Why is 2 kinetically preferred? You give the same energies for 3 and 4, which is odd (4 should be lower). I can’t see your structure 3 (empty blue box – I’ve tried 2 different browsers) but structure 4 looks OK. There is no H-bonding here – so you need to think more about why 4 is lower in energy than 3.

1.2: Your first Jmol structure is actually (the wrong diastereomer of) the product, 6. The other non-rotatable ones are hard for me to see. Your explanation of the stereocontrol is confused (and confusing). You’ve missed the key point for the Grignard addition (coordination to the carbonyl, with the carbonyl on the face predicted by the modelling).

1.3: Judging by the energies and structures, you have only found one of the two isomers unfortunately (i.e. within error, the two you’ve given are the same). It is, however, the more stable of the two. Why is the alkene unreactive?

1.4: You have only given 2 structures when you were meant to model 4 (axial and equatorial amide for each of 13 and 14). You haven’t labelled your structures and they’re not rotatable, so it’s hard to tell which is which. The ensuing discussion is really unclear.

1.5: Again, your discussion of the orbitals is confusing. You should have discussed the difference in the C=C stretches between the various compounds.

Mini-project: Well done for choosing your own (and a good one at that). However, you state that you were using the predicted spectra to find out why the endo predominates. It certainly won’t do that! Rather, you were aiming to confirm the structural assignment. Although you successfully calculated the spectra, you haven’t really done this! You should have tabulated the calculated 13C data, and more fully compared them (quantitatively) to the experimental ones, as well as looking for the KEY differences between the two isomers.

Overall – you got most of the calculations done. But your discussion is often confusing, both from a chemical and a language perspective.