Talk:Irb10organicmodule

1.1 Part 1 (17.5/45%)

1.1.1 Formation and Hydrogenation of Cyclopentadiene Dimer (7/10%)

You get the molecules and the energies right. However, it doesn´t look like you understood kinetic vs thermodynamic control of a chemical reaction. The endo product is under kinetic control because it forms faster, due to a lower activation energy than the exo dimer. If the exo dimer was the product of the dimerisation at room temperature, the reaction will be controlled thermodynamically. You can alter different reaction conditions (temperature, pressure or solvent) to affect the final composition of the product. The same applies to compounds 3&4. About compound 5 you were´t asked to do it, if you would have added a bit more of discussion about it, I will have given you some extra marks for it.

(7/10%)

1.1.2 Atropisomerism in an Intermediate related to the Synthesis of Taxol (3.5/10%)

The lowest energy chair conformation you got for compound 9 is a little too high, anyways, you get the correct ranking, so I am not going to take out any mark from this, as you have done the 4 possible conformations of each compound. However, you don´t comment about the thermodynamic control of this reaction, that you could have noticed by reading Paquete´s paper. (3.5/5%)

The explanation about the hyperstabilization of the alkenes is poor, you could have done some research in the literature or in your notes. Have a look at this paper (http://pubs.acs.org/doi/abs/10.1021/ja00398a003). Sorry I can´t give you any marks for this as you were expected to provide a reasonable explanation not just a mere statement. Also, you could have calculated the energies of the saturated alkenes. (0/5%)

1.1.3 Taxol NMR - Spectroscopic Simulation using Quantum Mechanics (7/25%)

You missed the two possible conformation for this compound and you get a huge energy for this compound, is not correct. The correct conformation has around 65 kcal/mol. (0/5%)

Where is the H-NMR spectra? You just provide the C-spectra. (5/10%)

I don't understand how you have done this comparison, you should have shown both the calculated and the reported peaks. You should have extended your discussion here. (2/10%)

1.2 Part 2 (24/55%)

1.2.1 The Crystal Structures of the Shi Catalyst and the Jacobsen Catalyst (4/5%)

Well done finding the structures. However you should have explained better what the difference of the C-O bond lengths could mean, in the Shi catalyst. (4/5%)

1.2.2 The Calculated NMR Properties of the Epoxides (2/5%)

Well done, but you should have put the units in your graph detailing the deviation of your values from the literature and explain how you have done this, because it´s not clear. Again you have only done the C-NMR, why you don´t like the H-NM? (2/5%)

1.2.3 The Assignment of the Absolute Configurations for Alkenes 2 and 4 (12/35%)

OR (6/15%)

Trans-stilbene: Well done, even though your value differs with the literature value, you have done a good job finding literature for it and it is "quite" similar. However, you don´t describe which one is the negative and the positive, is it RR or SS? And you don´t represent the two enantiomers, so how do I know these calculations are done by you?

1,2-Dihydronaphtalene: again well done finding literature value. However, is it obvious that there is something wrong with one of your enantiomers, and not with the software. They should both have the same value, negative sign. Again, which one is SR and RS?

Enantiomeric excess:

Well done with the calculations for the Jacobsen catalyst, but you confused the values -3383.259559 is the sum of electronic and thermal free energies of the (S,R) not (R,S).

Also, you could have given more details about how you have calculates this. You wouldn´t have had this confusion if you knew which enantiomer you were calculating the OR for.

Also, why you haven´t done the enantiomeric excess for the Shi catalyst? (6/20%)

1.2.4&5 NCI and QTAIM Analysis for the Transition State (2/6%)

NCI: where is the molecule? You just made a description of what I can see, what do you think that the attractive and repulsive interactions that you describe imply? (1/3%)

Electronic Topology: how can you see the process of forming new bonds? you could have been more specific here and explain better this using the calculations from the electronic topology. (1/3%)

1.2.6 New Candidates (4/4%)

Ok

General Comments:

I think that there are some concepts from organic chemistry that you need to revise. Also, in your answers, you need to be more accurate and provide reasonable explanations of your statements.

Mark: 42%