Talk:Mod:Salvatore89

First week feedback

Overall I think your answer to question 1 is good and cover all the information required. You also gave a good assessment of the computational results.

My comments on this one are mostly about presentation of data, feel free to decide whether to follow them or not:

Table 1: shorten exo-cyclopentadiene dimer to exo-DiCy? as at the moment the table may be too wide. I would generally include one reaction scheme with numbering in each answer so the reader can easily follow your thought rather than having to flip between pages for structures.
After table 1: ‘prduct’
You'll probably want to report the energy of the TS? Is the energy reasonable? Is it the lowest energy TS? This is the most important question for all TS calculations, and a frequent mistake made by beginner. One does need to think of all chemically possible TS's and compare them. Obviously this isn't within the scope of Module 1 and will be covered properly in Module 3. You won't get/lose any mark for this here, but it's important to remember that. .
Hydrogenated Dicy: Good list of bond angle deviation! A good way to convey your point over is to include a thounsand-word-worth picture highlighting the atoms in the highly strained area. Computational chemists frequently overestimate organic chemists' ability to read table. This often leads to people like me giving up after the first page of any computational paper.
You may want to use sub-headers to separate different sections between the same questions to ease my marking checklist.
Lastly, good scientific writing requires you to cite references to support your statements. A common mistake is citing too much even when not needed. But in your case, you could do with a few. Keep them separated for each question.

Final feedback

Q1

"In general periyciclic reactions" should be "In general pericyclic reactions"

Correct energies for 1 and 2. Good analysis on the origin of the difference in energy.

Ambitious attempt at the TS of dimerisation, although to be honest I think something's wrong with it: 1 H atom being shared between two C's.

Correct energies for 3 and 4 and good analysis to follow. I like your list of bond angles, but the numbering was not displayed in your Jmols. You did include pictures to show these, but forgot to update the text.

Q2

"calculated by Alliger MM2 molecualar mechanics and Merk Molecular Force Fields MMFF94 methods". Should be "Allinger" and "Merck"

Good concise report of energies, comparison between MM2 and MMFF94.

Good grasp of hyperstable olefins. However, hydrogenation of these compounds are not necessarily endothermic (your calculation did not include energy of H2 to balance the equation).

Q3

First half is fine. Correct MOs, correct analysis and selectivity.

Second half: I would have appreciated the structure of your monohydrogenated product here.

Your vibrational frequencies are correct. You've shown that you fully appreciate the role of the signa*-pi interaction in these structure.

Another piece of information, which could have been discussed in the bond lengths of C-Cl and C=C bonds.

Q4

The real risk of Ac group is actually the number of possible local minima due to orientation of acetyl groups.

MM2 energy difference is more pronounced between A/A' adn B/B' than with Me group. Are the pictures from PM6 or MM2 calculation? You structure A looks like it could be further optimised by moving the OH group closer to the C=O+.

I'm happy with your use of MOs, but a distance measurements for MM2 structures (between the acetyl and the carbocation would have been quite informative, particularly when it comes to the disfavoured intermediates).

You forgot to calculate the stabilisation energy from neighbouring group participation.

Mini project

Correct conversion from Hartree to kJ.mol-1. Correct calculation for ratio of syn:anti under thermodynamic conditions at 298 K.

Another, more plausible explanation, for the different between your calculated ratio and the observed one is that they are not in equilibrium (barrier of rotation is too high which you found out ourselves) and the ratio is kinetic control -> what we should have been calculating are the transition states of the reaction to make this compound, which is of course outside the scope of this module. Maybe you'll want to revisit this in Module 3.

What's "st. dev." in your table? It shouldn't be standard deviation, which is a statistical value.

What's the key difference between the two experimental set of 13C chemical shifts?

Interesting comparison between calculated and experimental IR.