Talk:Mod:KRMO
Comments
Cyclopentadiene and Taxol
Cyclopentadiene
No discussion of kinetic vs thermodynamic control. What does this mean for the molecules? Deeper discussion of what is going on here needed, and some bond angles included.
Taxol
Shouldn’t assume the lowest energy is a chair, this is not always the case! Would have been nice to see all 4 conformations modelled. Good discussion of hybridisation. Hyperstable olefins could be delved into a little more!
NMR
You didn’t need to model both – you were told to use what you had learnt previously. This implies 18 would be the lowest energy. NMR table should be lined up so we can compare lit and computed more easily, and to show clearly you can assign and compare the values.
Good you noticed the S. could you have corrected this? If so, how?
Could have plotted differences between obs and calcd NMR spectra “There could be a difference even between the two different chair confirmations in terms of NMR output, but how much difference this actually makes, if any, is unknown” – how could you have worked this out? Would a computational experiment have answered this question?! The point of this practical is to teach new techniques, so you could have tried calculating chair conformations to find an answer here!
Epoxide
Crystal structure
Shi - Good discussion here! A figure would have been nice to describe what you say
Jacobsen – need to say a bit more. What about the structure around the metal centre?
NMR
What configurations are possible? Does the NMR show you have drawn the right configuration? You can’t tell by NMR!
Absolute configuration
Good that you’ve compared many literature values – this is not a reliable source, although it is worth quoting the Shi/Jacobsen rotations
Would like to see your calculations for the Gibbs free energies
A conclusion for this section would be nice. No mention of VCD/ECD, or how the techniques you have used compare and how reliable they are.
QTAIM and NCI
NCI
Be more confident – don’t say “possibly again due to lone pair repulsion” but state it is :)
More discussion on how these interactions affect product formation needed
QTAIM
More discussion needed.
Suggestion
Good suggestion, but it doesn’t have an optical rotation in the range you quote!!