Talk:Mod:BYL109 module 3

Cope Rearrangement

Presentation:

Data all clearly tabulated. Good use of diagrams. Jmol used appropriately. Slightly funny order with IRC calculations after activation energies. Appropriate links to files.

Results:

Investigated anti and gauche conformers including gauche 3 – correctly noting it as the lowest energy conformer at this level of theory. Rationalised this well with use of hyperconjugation and MOs. Reoptimised anti 2 isomer – note: you cannot compare energies between different methods (HF and DFT), they’re calculated on different energy scales. Frequency analysis included: IR spectra? Thermochemical data at 0K?

TS: Results generally good. IRC carried out for both chair and boat TS – v.good. Activation energies calculated for chair and boat for both levels of theory at 0K and 298K.

Understanding:

Good introduction. The steps taken are clear – could expand on why certain methods/levels of theory/keywords etc. Conclusion for this section given at very end of report – generally good, but seems to be a little muddled e.g. the comment ‘The Cope Rearrangement occurs via either a chair or boat transition state, the mechanism of which is not defined’ – but you CAN comment on this, as you have actually investigated it in this work!

Diels Alder

Presentation:

As above

Results:

MOs of reactants good with correct symmetries noted. TS MOs also good – with a good explanation of HOMO/LUMO interactions. Noted the C-C bond forming distance is < 2 x radius of C, suggesting this bond is forming.

Endo/exo: TS MOs good. Correctly note endo is lower in energy. Have considered steric effects and secondary orbital overlap. Apply the secondary orbital overlap effect to your results…is it apparent?

Understanding:

Good introduction to the section. Steps taken clear, again could expand on reasoning why. HOMO/LUMO interactions and allowed/forbidden reactions considered well. For endo and exo have considered secondary orbital overlap – but is this effect apparent in your results?