ChemWiki - User contributions [en]

Talk:Mod:pg1910w

2014-04-07T13:55:13Z

Na2011: Created page with "= Comments = Overall - 91% An excellent report. Well done. I can tell you were really interested as you’ve made the report really interesting to read. Main fault is that you d..."

= Comments =
Overall - 91%
An excellent report. Well done. I can tell you were really interested as you’ve made the report really interesting to read. Main fault is that you didn’t make time at the end to read through and check it all, as there are a lot of spelling and grammar mistakes! This is understandable due to the time pressure though, just be aware of this for future reports  Otherwise only a few points:
=== Cyclopentadiene 8/8===
Nice pie charts! Good way to clearly illustrate the data. This is the only report I’ve seen with this –great! And good discussion

=== Taxol 10/12===
Nice bar chart to present differences – again a great way of clearly showing the result. Excellent discussion but no mention of hyperstable olefins!

=== Spectroscopy 20/25 ===
The way this is written is quite confusing! In future reports, be sure to go through and re-read it to make sure it flows before submission. A conclusion would have been good as you don’t say which you have decided to model and why. Why do present carbonyl down data and show a picture of carbonyl up?!

13C – What does sulphur do to NMR? You state this could be a reason for thwe divergence, but haven’t given reasons why. Heavy atoms need extra corrections in NMR!

1H - good

== Epoxide ==

=== NMR 5/5 ===
Fantastic NMR and discussion

=== Crystal structure 5/5 ===
Great!

=== Absolute Configuration 35/35===

All fantastic. Good point about ORP and literature values, and excellent discussion. Nice you included VCD and discussed it appropriately. TS analysis great.

== QTAIM, NCI, Suggestion 8/10 ==

Excellent and well laid out, but no suggestion!

Talk:Mod:ECJ1C5911

2014-04-07T12:22:17Z

Na2011: Created page with "Overall - 100% A really fantastic report – well done! Can hardly fault it. Well thought out and presented as a great story, which shows you really understood what you were d..."

Overall - 100%

A really fantastic report – well done! Can hardly fault it. Well thought out and presented as a great story, which shows you really understood what you were doing.

The only things to note were: In the spectroscopy taxol section, you analyse the twist boat, when you've said the chair was most stable - why is this? This section is really well thought out and presented with great arguments, but your use of the twist boat does make me wonder if you also saw deviations with the chair and couldn't explain this. Would have liked to see some explanation of your choice, then I'd be really convinced!

Sorry - not much feedback for the rest of the report, all fantastic. You've covered everything asked, done some great analysis, and included an interesting discussion. Well done!

Talk:Mod:DJW404

2014-04-07T12:09:51Z

Na2011: Created page with "= Comments = Overall - 86% A great report. The layout was a bit cramped and hard to follow, and sometimes things were not discussed fully, overall good though! === Cyclopentadie..."

= Comments =
Overall - 86%
A great report. The layout was a bit cramped and hard to follow, and sometimes things were not discussed fully, overall good though!
=== Cyclopentadiene 5.5/8 ===
Really nice figures, but a confusing layout with table 1 in the next section! Otherwise good and great explanation but the discussion was a bit brief. More discussion of the transition state would have been good, and hydrogenation.

=== Taxol 12/12 ===
All values correct and great discussion inc olefinic strain.

=== Spectroscopy 19/25 ===
I think you tried to do too much here and missed some key points. It’s great that you modelled both and came to the conclusion of which is more likely by comparing the differences to the literature, but you should have included tables of NMR values, and most importantly, discussed the reasoning for any differences seen. Why is there such a large deviation next to the sulphur? Great graphs but more discussion required.

== Epoxide ==

=== NMR 4/5 ===
Why didn’t you do all of the enantiomers?! Fine to do one, but say why!

=== Crystal structure 3.5/5 ===
Shi-Again, why? You state some facts but don’t give any reasoning.
Jacobsen-good

=== Absolute Configuration 32/35===

==== TS ====

Great! Would have been nice to include some calculations though!

====ORP====

Good. In table you have data that is ‘inferred to be’… what does this mean? If you couldn’t find it, say that! Don’t present data that isn’t real!

== QTAIM, NCI, Suggestion 10/10 ==

All excellent. Great suggestion.

Talk:Mod:bigbang007

2014-03-20T14:33:40Z

Na2011: Created page with "= Comments = Overall - 77% === Cyclopentadiene 7/8 === Good intro. Nice figures and correct values. Why is the angle bending energy such a big difference? Looking into the ang..."

= Comments =
Overall - 77%

=== Cyclopentadiene 7/8 ===
Good intro. Nice figures and correct values.
Why is the angle bending energy such a big difference? Looking into the angles and their deviation from ideality should be included.

=== Taxol 7/12 ===
Why is 10 more stable? What are the favourable/unfavourable interactions?
Why is the bridgehead olefin more stable?
You've pointed out the correct things, but gone into no real depth as to why these things are occuring.

=== Spectroscopy 18/25 ===
Why did you choose 17? 'Use what you've learnt previously'... Pick the lowest energy from you simulations above! Didn't you find the carbonyl down was more stable?
You should have put the NMR data into tables! This would have allowed a direct and easy comparison between experimental and lit values.
Good you plotted the differences. What about error bars to see the statistical significance of the differences? Would have given much more value to a graph like this. Otherwise use a bar chart to plot differences only.
You haven't pointed out the large deviation from one atom in the 13C NMR! All points are good comparatively except one - why this one in particular? Have a look in to heavy atoms and NMR.

== Epoxide ==

=== NMR 5/5 ===
Good!

=== Crystal structure 5/5 ===
Great! Really nice figures and good points.

=== Absolute Configuration 32/35===

==== TS ====

Good! An introduction to what you've done for all of the abs config sections would have been good to explain what you've done and why.

====ORP====

Good.

====ECD/VCD====

Good. Didn't have to do this but it's good you state the reasons why.

== QTAIM, NCI, Suggestion 3/10 ==

NCI, QTAIM - no discussion of what you can see going on for either of these really :(
Suggestion - good, but it's very hard to epoxidise a a tetra subs alkene! And you were told ORP > +/- 500!

Talk:Mod:yas1c

2014-03-20T14:22:04Z

Na2011: Created page with "= Comments = Overall - 78% === Cyclopentadiene 7/8 === Great intro. Really nice figures, well done. Great discussion of results and nice addition of a reference to other compu..."

= Comments =
Overall - 78%

=== Cyclopentadiene 7/8 ===
Great intro. Really nice figures, well done. Great discussion of results and nice addition of a reference to other computational studies.
Why is the angle bending energy such a big difference? Looking into the angles and their deviation from ideality could be included. Otherwise, good reasoning.

=== Taxol 11/12 ===
Great, all structures modelled nicely and a good discussion. Again, looking at bond angles would have been useful for a better explanation of the strain.

=== Spectroscopy 21/25 ===
Really good. Nicely laid out. Good graph to clearly depict the differences between literature and experimental values. This should have been included for 1H too!
The reason for the large deviation in C 14 is heavy atom coupling. Have a look into this. You would need to apply a spin-orbit correction here.

== Epoxide ==

=== NMR 0/5 ===
You haven't done the NMR for the epoxides!

=== Crystal structure 2/5 ===
Shi-You should have included all of the Mercury Conquest figures, with bond lengths annotated to show what you mean.
What do you mean 'the shortening of the anomeric C-O bond is insignificant'? This implies you've done something to see statistical significance. If so, include it. If not, it's not insignificant if you've seen shortening, so you should provide a reason for this.
You haven't given any reasoning for what you've seen here.
Jacobsen-Where is the space filling model? Why not include this?!

=== Absolute Configuration 34/35===

==== TS ====

Great! Analysis is really thorough and it's well presented :)

====ORP====

Nice!

====VCD====

How useful is this for your compounds? Fine to use, but discuss it's usefulness.

== QTAIM, NCI, Suggestion 3/10 ==

NCI, QTAIM - should have actually discussed these!
Suggestion - good, but it's very hard to epoxidise a a tetra subs alkene!

Talk:Mod:ckl2111C

2014-02-28T17:28:12Z

Na2011:

= Comments =

== Cyclopentadiene ==

Excellent TS discussion! Perfect answer :)

== Taxol ==

Again excellent. Really interesting discussion.

=== NMR ===

Intro - good. But you worked out previouly 10 is most stable, you can use this to pick the enantiomer to model!

NMR - Great. Nicely presented and good discussion. To take it a step further you could have done some statistical analysis on the differences and presented and discussed this in your report too.

== Epoxide ==

=== Crystal structure ===
Well done! Loads of interesting information.

=== NMR ===

No discussion here! What do the NMR tell you? Do you think it was necessary to compute both enantiomers?

=== Rotations ===

Great discussion. You say you don't trust the literature references (good!) but did you look and see if Shi and Jacobsen have refs?

=== TS ===

Great free energy and ee calculations.

Good pointing out ECD/VCD and why you haven't done it!

=== QTAIM and NCI ===

Nice!

=== Suggestion ===

Good! What is the ORP though?

==Overall==
A fantastic report. Lots of information and interesting discussion. Well done!

Talk:Mod:ckl2111C

2014-02-28T17:27:05Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Excellent TS discussion! Perfect answer :) == Taxol == Again excellent. Really interesting discussion. === NMR === Intro - good. But you ..."

Talk:Mod:Rhysxyz

2014-02-28T15:05:46Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Where is the reaction profile?! You should have included it! Would have been a nice addition! Hydrogenation - true, but what are the differ..."

= Comments =

== Cyclopentadiene ==

Where is the reaction profile?! You should have included it! Would have been a nice addition!

Hydrogenation - true, but what are the differences between configurations? You are correct, but this section could have been more in depth.

== Taxol ==

Energies not minimised for 5. Would have been nice to see a breakdown of all of the energy contributions and more discussion. Same for parents.

=== NMR ===
1H NMR – Why are there so many peaks for the modelled NMR? Think about how the program sees the model vs the NMR machine (static vs real!)

13C NMR- Have a look in to heavy atoms and the effect they have on NMR. This is the reason for the large deviations you have seen. A closer look will show this comes from the carbon next to the sulfurs.

The tables should be aligned so you can clearly see comparisons and assignments

== Epoxide ==

=== Crystal structure ===

Good. Jacobsen a bit brief.

=== NMR ===

Trans-stilbene 1H reasoning same as above.

=== Rotations ===

Good. But was there only 1 lit value? I assume there were more that didnt match so well. It's OK to not trust it! Explain why :)

=== TS ===

Great. Possibly more in depth but good overall.

=== QTAIM and NCI ===

Good figures but again more discussion would have helped!

=== Suggestion ===

What is the ORP? Tetra subsituted are hard to epoxidise!

==Overall==

Generally a good report, but discussion is lacking and a few key things missed! Well done.

Talk:Mod:js3311y31c

2014-02-28T14:55:00Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Excellent discussion of endo, exo and hydrogenation - well done!! == Taxol == Correct values. Would have been good to include all the diffe..."

= Comments =

== Cyclopentadiene ==

Excellent discussion of endo, exo and hydrogenation - well done!!

== Taxol ==

Correct values. Would have been good to include all the different energy values in the table so we can see all the contributions.

Very interesting and thorough discussion :)

=== NMR ===

For both, it would have been nice to include the spectra in your report. However, your figures and analysis were so good I'll let it go!! Good to see some stats and different data presentation.

== Epoxide ==

=== Crystal structure ===
Excellent! Great discussion. Good figures and loads of interesting information.
=== NMR ===

Good. Some suggestions for the differences should have been included rather than just stating they're there.

=== Rotations ===

Good! Don't put too much faith in the lit values though.

=== ECD ===
OK to do and include, but you haven't discussed what it shows. In this case, including it is irrelevant!

=== TS ===

Good table and a great discussion

=== QTAIM and NCI ===

Good

=== Suggestion ===

Good, but you were told to find ORP>+500!

=== Overall ===

An excellent report - well done!

Talk:Mod:tjasdo23klfu10ddj123

2014-02-28T14:27:46Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Good. Values are all correct. Interesting discussion! == Taxol == Excellent discussion of 9 and 10! For the olefins, there’s a lot more y..."

= Comments =

== Cyclopentadiene ==

Good. Values are all correct. Interesting discussion!

== Taxol ==

Excellent discussion of 9 and 10! For the olefins, there’s a lot more you could have said; you’ve said they are hyperstable but haven’t really explained why.

=== NMR ===

1H NMR – Good discussion

13C NMR- Have a look in to heavy atoms and the effect they have on NMR. This is the reason for the large deviations you have seen. A closer look will show this comes from the carbon next to the sulfurs.

The tables should be aligned so you can clearly see comparisons and assignments

== Epoxide ==

=== Crystal structure ===
Well done! Loads of interesting information.

=== NMR ===

Good. Nice conclusion.

=== Rotations ===

How reliable are the literature values? Are these the only ones you found? There’s likely to be a greater variation than this!

=== TS ===

Free energy only calculated for half! What about the other catalyst? This section is worth the most if you check the mark scheme so sadly lots of marks lost here :( .

=== QTAIM and NCI ===

More information could have been teased out here, more discussion would have helped!

=== Suggestion ===

Good, but you were told to find ORP>+500!

Talk:Mod:AER1116

2014-02-14T12:42:24Z

Na2011:

= Comments =

== Cyclopentadiene ==

Values are all correct.

Could have discussed more. What interactions make this the more favourable TS?

Same for hydrogenation - here the bond angles are key in the energy differences.

== Taxol ==

You need to model all of the chairs and boats. I think if you do so, you'll find that your reasoning for obtaining 10 instead of 9 is wrong ( although this is the right conclusion!).

You have not explained why the alkenes are so slow to react! What makes one so much more thermodynamically stable?

your lowest energy is very high.

By modelling the parents you may have found some interesting results!

=== NMR ===

1H NMR - Have you modelled a chair or boat? Could this be a reason for the differences?!

13C NMR - atom 18 has a very large deviation - why do you think this is? Need to apply corrections when heavy atoms are present!

== Epoxide ==

=== Crystal structure ===
Good.
=== NMR ===

Good!

=== Rotations ===

Good, but could have had a more in depth discussion.

=== TS ===

Great TS analysis.

=== QTAIM and NCI ===

NCI is brief but correct.

QTAIM is also brief, but OK.

=== Suggestion ===

Told to go lower than -500 or greater than 500, but otherwise ok!

A concluding statement would have been nice.

Talk:Mod:AER1116

2014-02-14T12:41:53Z

Na2011:

Talk:Mod:fkl114318

2014-02-14T12:33:20Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Great intro and discussion of cpd. Values are all correct. Very good figures in hydrogenation :)Need more discussion of bond angles here t..."

= Comments =

== Cyclopentadiene ==

Great intro and discussion of cpd.

Values are all correct.

Very good figures in hydrogenation :)Need more discussion of bond angles here though - this is a key difference.

== Taxol ==

There is a lot more information that could have been included here. The cyclohexane ring leads to chair and boat conformers, which would show the lowest energy.

What about modelling the parent hydrocarbons? This would have shown you where the energy differences come from.

=== NMR ===

Missing any discussion of why the values don't correlate. What effect do the sulfur atoms have?

You were told to use what you have previous learnt to model one!

== Epoxide ==

=== Crystal structure ===
Great, lots of good information.
=== NMR ===

You have calculated the NMR but not made any comparisons or drawn any conclusions!

=== Rotations ===

Nice layout and discussion

You have included the VCD but not mentioned it or drawn any conclusions?

=== TS ===

Great TS analysis, well done!

=== QTAIM and NCI ===

NCI needs more discussion. There's a lot of information shown you can talk about!

Good QTAIM.

=== Suggestion ===

None!

Talk:Mod:AER1116

2014-02-14T12:31:33Z

Talk:Mod:DV2412

2014-02-14T12:20:37Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Values are all correct. Great discussion! Figures would have been a nice addition to the discussion of transition states etc, but good. == ..."

= Comments =

== Cyclopentadiene ==

Values are all correct. Great discussion!

Figures would have been a nice addition to the discussion of transition states etc, but good.

== Taxol ==

It may have been nice to see all of the possible conformations modelled to confirm what you say, but otherwise good.

Values aren't quite right - check the conformations of the chair are exact! Still correct conclusions and a great discussion.

=== NMR ===

1H NMR - great!

13C NMR- What about the sulfur atoms? These need to be corrected for so could explain differences?

== Epoxide ==

=== Crystal structure ===
Great, lots of good information.
=== NMR ===

Nice. Good use of figures too.

=== Rotations ===

Great! Nice lit refs!

=== TS ===

Where are your free enery calcs? You must have done them, so it would have been nice to see them!

Good conclusion.

=== QTAIM and NCI ===

Nicely done

=== Suggestion ===

Good, but tetra substituted alkenes are very hard to epoxidise!

Talk:Mod:DZC1990

2014-02-14T12:14:21Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Values are all correct. Great discussion! Have a look at bond angles for the hydrogenation products around the sp2 carbon – this is a key ..."

= Comments =

== Cyclopentadiene ==

Values are all correct. Great discussion!

Have a look at bond angles for the hydrogenation products around the sp2 carbon – this is a key reason for the differences seen!

== Taxol ==

You have found the lowest energy conformations, however is there anything special in the structure that will lead to different conformations…? There is a ring… the conformations of this need to be investigated!

Good discussion

=== NMR ===

Why did you choose 17? You were told to use what you had learnt previously, which means 18 is the likely structure!

Which conformer of 17 have you modelled? Chair or boat? This could be the reason for the differences seen in the 1H in the literature.

13C NMR- Great – corrections due to sulphur taken in to account- nice!

== Epoxide ==

=== Crystal structure ===
Great, lots of good information.
=== NMR ===

Fantastic, well done.

=== Rotations ===

Great! Good you ref Shi and Jacobsen

=== TS ===

Great.

=== QTAIM and NCI ===

Nicely done

=== Suggestion ===

Good, but tetra substituted alkenes are very hard to epoxidise!

Talk:Mod:yrtaxol

2013-12-20T15:59:21Z

Na2011: Created page with "==Cyclopentadiene== Good. Nice figures. ==Taxol== There are two twist boats and two chairs for each. These could have all been modelled and shown. Great investigation and di..."

==Cyclopentadiene==

Good. Nice figures.

==Taxol==

There are two twist boats and two chairs for each. These could have all been modelled and shown.

Great investigation and discussion of hyperstability – well done!

==Spectroscopy==

Great layout and tables for NMR, very nicely done. Could have plotted differences in a bar chart for easy visualisation.

Fantastic discussions, well done.

==Crystal structures==

Thorough discussion and lots of interesting points. Again, nice figures.

==NMR==

Glad you realised not to compute both, good!

==Absolute configuration==

OR – is there only one lit value?! I don’t think these are that reliable if you investigate further!

VCD – good

Ee – great!

==NCI, QTAIM==

Good. Nice diagrams, discussion could have been more thorough but overall very good.

==Suggestion==

Great, well done!

Talk:Mod:AGB201113

2013-12-20T15:33:16Z

Na2011: Created page with "==Cyclopentadiene== Good calculations and conclusions, you should discuss bond angles here. What about thermodynamic vs kinetic control of the hydrogenation? ==Taxol== Discus..."

==Cyclopentadiene==

Good calculations and conclusions, you should discuss bond angles here.
What about thermodynamic vs kinetic control of the hydrogenation?

==Taxol==

Discussion of parent hydrocarbons is lacking here. These could have been modelled. A more in depth discussion is needed.

==Spectroscopy==

Why did you choose 17?
Carbon NMR - What about spin orbit coupling? Corrections?
Would be nice to see some graphs plotting the differences between computed vs experimental.
Overall this section has the core analysis but much more depth is needed.

==Crystal structures==
A figure would have been nice to explain what you’re trying to say, otherwise good

==NMR==

“Again, the computed chemical shifts are a good match to the literature values. However, the computed chemical shifts tend to be of a higher field than the literature values, which is not expected and not what we have seen in the previous cases. Since we expect Gaussian to exaggerate the deshielding effect this is something that is unexpected and could be a source of investigation in another review.”
Some suggestions from you would have been good!

What can you conclude then? What was the reasoning for calculating the NMR?

==Absolute configuration==

Optical rotations – The literature agreement isn’t very good! This is only one value, I’m sure you found more? What do these show? And what do they mean for the compounds in question?!

Enantiomeric excess – values are not correct, check the way to calculate this!

==NCI, QTAIM==
NCI – good. More on QTAIM would have been nice.

==Suggestion==
Great, nice suggestion!

Talk:Mod:sc4011 1C

2013-12-19T14:33:22Z

Na2011: Created page with "===Cyclopentadiene=== Great discussion ===Taxol=== Again, great discussion. All correct, good discussion of conformations, bond angles etc. For future reference, watch your En..."

===Cyclopentadiene===

Great discussion

===Taxol===
Again, great discussion. All correct, good discussion of conformations, bond angles etc.

For future reference, watch your English…
“In order to determine which of the two ketone atropisomers is gonna be the oxy-Cope product” ;)

===Spectroscopy===
If anything, there’s too much information here, you were told to carry out simulations using previous results, so it would have been fine to explain that only. You came to the right conclusion though so no problem!
Nice tables for NMR.

===Crystal structures===
Excellent. Very thorough

===NMR===
Great. Good that you’ve plotted the differences.

===Absolute configuration===
Can you determine the enantiomer from the literature values? There’s a wide range out there so these aren’t very reliable. Otherwise very good.

===NCI, QTAIM===
Very thorough, well done

===Suggestion===
Great! Very nice suggestion

A really good report - well done :)

Talk:Mod:npa11 1C

2013-12-19T12:10:38Z

Na2011: Created page with "Sorry to not give you much feedback, but this is a great report and hard to fault! It's very well presented and laid out, and it concise where it needs to be, but there are som..."

Sorry to not give you much feedback, but this is a great report and hard to fault!

It's very well presented and laid out, and it concise where it needs to be, but there are some very thorough spot on discussions where needed too.

Fantastic - well done :)

Talk:Mod:1CSam11

2013-12-03T12:46:02Z

Na2011: Created page with "= Comments = == Cyclopentadiene and Taxol == CPD – excellent discussion. No mention of the kinetic product for 3 vs 4 though, how could you work out which this is? Taxol –..."

= Comments =

== Cyclopentadiene and Taxol ==

CPD – excellent discussion. No mention of the kinetic product for 3 vs 4 though, how could you work out which this is?

Taxol – points are all correct but the data could have been presented in a much less complicated way! Very thorough though, well done!

=== NMR ===

Good reasoning and choice of molecule – again very thorough! Just to point out – you missed some data out (you have a note to put it in!) not that it matters as it wasn’t completely necessary to do all of this!

Nice corrections in NMR, well done.

Great that you plotted a graph of the difference between calculated and observed values! Discussion underneath this to conclude the section would have tied it up nicely, there is still one carbon that is fairly different, is this significant?

== Epoxide ==

=== Crystal structure ===

Same as above! Very thorough. Why have you got multiple hits for the crystal structures? Maybe discuss the differences? Was it necessary to include multiple?

=== NMR ===

Again, very thorough. I’d say less is more here though. It would have been fine to state that you couldn’t calculate an absolute configuration from NMR, different enantiomers cannot be definitively told apart purely by NMR (which you do!). Check the mark scheme – this section is a large proportion of your report and is actually only worth 5%!

=== Absolute configuration ===

Correct re the literature not being an accurate source, so you can’t give a definite answer from these calculations.

A discussion of ECD/VCD would have been enough as it states in the script it’s not possible to run these measurements experimentally for these molecules

==Overall==

Your report becomes very hard to mark. I think you do understand what you’re doing, but it’s hard to tell as there is too much information here. Being concise is a good skill to develop so try this next time. Read the directions in the script carefully and make sure you include what you’re asked to and when you’re supposed to (the NCI and QTAIM should have been done just for the catalysts later on). If it says the instrumentation isn’t correct for these molecule (ECD/VCD) then don’t include this – a brief discussion is enough extra. This is especially the case for the NMR where you state it’s not possible to deduce the enantiomer and then go on to try!

Talk:Mod:KRMO

2013-12-03T12:35:55Z

Na2011: Created page with "= Comments = == Cyclopentadiene and Taxol == Cyclopentadiene No discussion of kinetic vs thermodynamic control. What does this mean for the molecules? Deeper discussion of what..."

= 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!!

Talk:Mod:JPSO

2013-12-03T12:24:35Z

Na2011: Created page with "= Comments = == Cyclopentadiene and Taxol == CPD - Good discussion and all values correct Taxol – what about chair conformations? Do you expect boats to give the lowest valu..."

= Comments =

== Cyclopentadiene and Taxol ==
CPD - Good discussion and all values correct

Taxol – what about chair conformations? Do you expect boats to give the lowest values? From looking at the pictures I think you have modelled some chair conformations!
Good discussion re bond angles and hyperstabilty.

=== NMR ===

You have now decided chairs are the lowest energy! Should have tried all in the section above and extrapolated from there.
Align the table to make computed and literature comparable. Good discussion

== Epoxide ==

=== Crystal structure ===
Excellent discussion
=== NMR ===

Good!

=== Absolute configuration ===

Good that you weren’t convinced by the literature! Very good discussion and calculations. Some suggestions from you as to why the selectivities are as they are would have made a nice addition to the report

=== QTAIM and NCI ===

good but for both you could have gone a bit deeper into the discussion!

=== Suggestion ===

Good suggestion, but it doesn’t have an optical rotation in the range you quote!!

Talk:Mod:OJA692728

2013-12-03T12:19:53Z

Na2011: Created page with "= Comments = == Cyclopentadiene and Taxol == Excellent discussion! And nice figures to demonstrate your explanation. Well done! Could you have a think about the transition state..."

= Comments =

== Cyclopentadiene and Taxol ==
Excellent discussion! And nice figures to demonstrate your explanation. Well done! Could you have a think about the transition states and maybe model them to work out the kinetic product?
Your reasoning for not modelling all of the conformers is fine, but the calculations could have been a nice addition to your report to confirm your reasoning.
Some discussion of bond lengths and an explanation of your thoughts behind why these molecules are hyperstable could have been added to the section about 9 and 10.

=== NMR ===

The tables should be aligned so you can directly compare computed and literature
What was your reasoning for choosing 17? Your script says to use what you have learnt previously to model one. Is there a reason you would choose this one?
It would have been interesting to include some statistical analysis here to see how the computed and experimental values really differ. There are a few atoms that you have not mentioned which do not correlate. Look again at 17 and 18 – they contain sulphur. Therefore corrections need to be carried out because of spin-orbit coupling errors caused by heavy atoms.

== Epoxide ==

=== Crystal structure ===
Very good discussion
=== NMR ===

NMR results are fine, but you haven’t mentioned anything to do with different conformers here?

=== Absolute configuration ===

Discussion of literature values for ORP needed – how many values did you find? And how many matched the value you expected?
Very good discussion of transition states. Nice figures again

=== QTAIM and NCI ===

Nicely done

=== Suggestion ===

You were told to find something with an ORP greater than 500! Otherwise good.

Talk:Mod:Ivona1Ciss11

2013-11-15T14:58:10Z

Na2011: Created page with "= Comments = == Overall == Generally you gave the right answers, however the discussion lacked depth. Next time make sure you check the mark scheme – the absolute configurat..."

= Comments =

== Overall ==

Generally you gave the right answers, however the discussion lacked depth.

Next time make sure you check the mark scheme – the absolute configuration is worth 35% and you virtually skipped this section.

== Cyclopentadiene ==

Good. Correct values and a great explanation

== Taxol ==

What about the other conformations… twist boat?

There is more to the alkenes. They are hyperstable. You titled a section in cyclopentadiene with this but it should be here with a discussion!

=== NMR ===

Greater discussion needed here, especially for carbon NMR. How did you do this? Did you use any corrections? There are heavy atoms present!!

Good reasoning for boat.

== Epoxide ==

=== Crystal structure ===

Good

=== NMR ===

Overall OK. Discussion again though!

=== Rotations ===

Good that you found literature values! BUT one value is not total confirmation of the enantiomer – there are many other techniques available and the point of this section was to investigate how useful they are. A more extensive literature search would also highlight some unexpected rotational values.

You haven’t done anything with other alkenes!

=== TS ===

Not done

=== QTAIM and NCI ===

NCI – discuss features more. Is there any repulsion? What is causing the forces you see?

QTAIM – Does the location of the BCPs show anything?

=== Suggestion ===

OK – tetrasubstituted alkenes do not work with these catalysts

Talk:Mod:jk1911251192

2013-11-15T14:46:46Z

Na2011: Created page with "= Comments = == Overall == A great report! Nice layout (apart from lack of tables!) and very thorough, only a couple of mistakes, well done! == Cyclopentadiene == Good. Corre..."

= Comments =

== Overall ==

A great report! Nice layout (apart from lack of tables!) and very thorough, only a couple of mistakes, well done!

== Cyclopentadiene ==

Good. Correct values and a great explanation!

== Taxol ==

Values would be nicer in tables here! Was a bit complicated to read this way! However all values were correct.

Discussion of bond angles needed here.

=== NMR ===

Very thorough discussion, great!

== Epoxide ==

=== Crystal structure ===

Perfect

=== NMR ===

Excellent

=== Rotations ===

Great!

=== TS ===

Great.

=== QTAIM and NCI ===

Nicely done, very thorough 

=== Suggestion ===

OK, but you were told to find something with an optical rotation of greater than 500 or less than -500!

Talk:Mod:annyding

2013-11-15T14:41:55Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Good. Calculations and explanations are all correct. Could have discussed bond angles in 3 + 4. How could you find out the main product? == ..."

= Comments =

== Cyclopentadiene ==

Good. Calculations and explanations are all correct. Could have discussed bond angles in 3 + 4. How could you find out the main product?

== Taxol ==

Study the structure more closely! Taxol has a cyclohexane ring therefore there are 4 structure possible for 9 and 4 for 10! These need to be optimised.

Total energies here are higher than optimum. Final conclusion being 10 is correct – just not from the right numbers!

Explanation not correct due to not identifying the chairs and boats originally. Need to look at the sp2 carbonyl angles.

What about some information on hyperstable olefins? This is why you modelled the parent hydrocarbons!

=== NMR ===

Overall needs more discussion. You say ‘geometry as low as possibly, however this could not be sure’… This is not true! The above exercise would have shown this!

1H NMR – Literature values in comparison would have been good here

13C NMR- Good with shift and spin orbital coupling

== Epoxide ==

=== Crystal structure ===
Great. Nice figures and discussion

=== NMR ===

I am assuming you realised both enantiomers would have given the same NMR – this needs to be stated though!!

Need to discuss NMR more

=== Rotations ===

Literature values should be equal but opposite – this is definitely not the case for 3!!

RR/SS calcs good.

Nice discussion of VCD/ECD!

=== TS ===

Great.

=== QTAIM and NCI ===

Nicely done, very thorough 

=== Suggestion ===

OK, but you were told to find something with an optical rotation of greater than 500 or less than -500!

Talk:Mod:qwt11

2013-11-15T14:29:44Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Excellent. All calculations correct. Nice layout but section headings would be useful. == Taxol == Energies not minimised – Possibly due..."

= Comments =

== Cyclopentadiene ==

Excellent. All calculations correct.

Nice layout but section headings would be useful.

== Taxol ==

Energies not minimised – Possibly due to just modelling one identical chair confirmations. Would have been nice to see a comparison of the different chairs and boats.

Good discussion.

=== NMR ===

1H NMR – Good – you’re quoting individual values for methyl groups – experimentally these are rotationally averaged – you need to do this in your calculations for comparison. This isn’t a problem with out-of-date NMR!

13C NMR- Good

Free energy – You mention a comparison of 17 and 18, but don’t discuss it. A conclusion for this section would be nice.

== Epoxide ==

=== Crystal structure ===
Great. Nice figures and discussion

=== NMR ===

Good that you realised both enantiomers would give the same results.

=== Rotations ===

Good you looked at what Shi/Jacobsen report.

No discussion of VCD/ECD

=== TS ===

Great.

=== QTAIM and NCI ===

Nicely done

=== Suggestion ===

Good – but these catalysts will not work with tetra substituted alkenes.

User talk:Aln09

2013-10-26T16:42:52Z

Na2011:

= Comments =

== Cyclopentadiene ==

Values are all correct. Great discussion – well done!

== Taxol ==
Found all conformations, correct calculations and values.

Could have more discussion around olefins and hydrogen interactions

=== NMR ===

1H NMR – Good – a more in depth discussion of what you can see and the final assignment would have been nice but otherwise all correct

13C NMR- Not here 
== Epoxide ==

=== Crystal structure ===
Great – you found the correct structures and good discussion
=== NMR ===

Excellent discussion. Minor point – but it would be nice to see the NMRs and structures in the report.

=== Rotations ===

Could look at what Shi/Jacobsen report? Otherwise good method and calculations are correct. Excellent and very thorough discussion!

No discussion of VCD/ECD

=== TS ===

Great.

=== QTAIM and NCI ===

Nicely done

=== Suggestion ===

None provided

Talk:Mod:LT611

2013-10-26T16:42:14Z

Na2011:

= Comments =

== Cyclopentadiene ==

Values are all correct. Good discussions of angles, strain and transition states

Nice reference!

== Taxol ==

Great – you noticed all of the conformations and all calculations are correct –well done!

Nice inclusion of angles in discussion.

Could have discussed heat of hydrogenation? This may have given some interesting results!
=== NMR ===

“it is expected that the lowest energy conformation should be a chair and therefore the lowest energy conformer was not found”. –Are you sure?!

1H NMR – Good – a more in depth discussion of what you can see and the final assignment would have been nice but otherwise all correct

13C NMR- Great – corrections due to sulphur taken in to account- nice! Are you sure the large difference would be due to incorrect reporting? Is there nothing else that could be influencing things here…?

== Epoxide ==

=== Crystal structure ===
Only minor points - figure numbers and references in the text would be useful here. Nice description of changes but a figure would be good here.
=== NMR ===

Would be nice if the rows matched up. Good that you realised both enantiomers would give the same results.

=== Rotations ===

Could look at what Shi/Jacobsen report? Otherwise good method and calculations are correct. Would be nice to see some workings.

No discussion of VCD/ECD

=== TS ===

Great.

=== QTAIM and NCI ===

Nicely done

=== Suggestion ===

Good!

Talk:Mod:XIR511

2013-10-26T16:41:19Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Excellent introduction! Values are all correct. Good discussion – could have discussed angles though == Taxol == You imply you have cal..."

= Comments =

== Cyclopentadiene ==

Excellent introduction!

Values are all correct.

Good discussion – could have discussed angles though

== Taxol ==
You imply you have calculated the boat structures, but haven’t included them. It’s not necessarily the case the chair is lowest.
Good discussion of olefins

=== NMR ===
“Discrepancies may be primarily due to the fact that there are four possible minimum energy conformers of the hexane ring (i.e. two chair and two twist-boats), making it impossible to know which isomer was investigated in the laboratory”- Are you sure?

1H NMR – Good

13C NMR- Are there really no differences between lit and experimental? What influence do the sulfur atoms have?
== Epoxide ==

=== Crystal structure ===
Great – you found the correct structures and good discussion with some interesting points

Small point – you say “Further, an investigation of different bond lengths showed that the C=N bond is slightly longer than would be expected in an uncoordinated bond; 0.13nm compared to 0.127nm.” – if it was 0.130 – write this! Otherwise rounding gives the same number!
=== NMR ===
Good you noted both enantiomers would yield the same NMR. I’m sure there is reliable trans-stilbene data though!
=== Rotations ===

Could look at what Shi/Jacobsen report?

No discussion of VCD/ECD

=== TS ===

Would be nice to see workings and more information here, as the K value isn’t correct.

=== QTAIM and NCI ===
NCI – Nice

QTAIM – A little bit more information can be seen here. What happens near highly electronegative atoms?

=== Suggestion ===
Good.

User talk:Aln09

2013-10-26T16:27:37Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Values are all correct. Great discussion – well done! == Taxol == Found all conformations, correct calculations and values. Could have mor..."

= Comments =

== Cyclopentadiene ==

Values are all correct. Great discussion – well done!

== Taxol ==
Found all conformations, correct calculations and values.
Could have more discussion around olefins and hydrogen interactions

=== NMR ===

1H NMR – Good – a more in depth discussion of what you can see and the final assignment would have been nice but otherwise all correct
13C NMR- Not here 
== Epoxide ==

=== Crystal structure ===
Great – you found the correct structures and good discussion
=== NMR ===

Excellent discussion. Minor point – but it would be nice to see the NMRs and structures in the report.

=== Rotations ===

Could look at what Shi/Jacobsen report? Otherwise good method and calculations are correct. Excellent and very thorough discussion!
No discussion of VCD/ECD

=== TS ===

Great.

=== QTAIM and NCI ===

Nicely done

=== Suggestion ===

None provided

Talk:Mod:LT611

2013-10-26T16:19:11Z

Na2011: Created page with "= Comments = == Cyclopentadiene == Values are all correct. Good discussions of angles, strain and transition states Nice reference! == Taxol == Great – you noticed all of ..."

= Comments =

== Cyclopentadiene ==

Values are all correct. Good discussions of angles, strain and transition states
Nice reference!

== Taxol ==

Great – you noticed all of the conformations and all calculations are correct –well done!
Nice inclusion of angles in discussion.
Could have discussed heat of hydrogenation? This may have given some interesting results!
=== NMR ===

“it is expected that the lowest energy conformation should be a chair and therefore the lowest energy conformer was not found”. –Are you sure?!
1H NMR – Good – a more in depth discussion of what you can see and the final assignment would have been nice but otherwise all correct
13C NMR- Great – corrections due to sulphur taken in to account- nice! Are you sure the large difference would be due to incorrect reporting? Is there nothing else that could be influencing things here…?

== Epoxide ==

=== Crystal structure ===
Only minor points - figure numbers and references in the text would be useful here. Nice description of changes but a figure would be good here.
=== NMR ===

Would be nice if the rows matched up. Good that you realised both enantiomers would give the same results.

=== Rotations ===

Could look at what Shi/Jacobsen report? Otherwise good method and calculations are correct. Would be nice to see some workings.
No discussion of VCD/ECD

=== TS ===

Great.

=== QTAIM and NCI ===

Nicely done

=== Suggestion ===

Good!

Rep:Mod:nat1234

2013-10-02T14:49:27Z

Na2011:

[[Mod:writeup]]
[[image:Image capture test.PNG|200px|right|caption]]
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<jmolApplet>
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Rep:Mod:nat1234

2013-10-02T14:45:15Z

Na2011:

[[Mod:writeup]]
[[image:Image capture test.PNG|200px|right|caption]]
<jmolFile text="Explanatory text for link">test.mol</jmolFile>

File:Test.mol

2013-10-02T14:43:55Z

Na2011: uploaded a new version of "File:Test.mol"

Rep:Mod:nat1234

2013-10-02T14:37:23Z

Na2011:

[[Mod:writeup]]
[[image:Image capture test.PNG|200px|right|caption]]

File:Image capture test.PNG

2013-10-02T14:36:41Z

Na2011: uploaded a new version of "File:Image capture test.PNG"

test1

Rep:Mod:nat1234

2013-10-02T14:35:22Z

Na2011: Created page with "Mod:writeup caption"

[[Mod:writeup]]
[[image:image_capture_test.png|200px|right|caption]]

File:Image capture test.PNG

2013-10-02T14:32:47Z

Na2011: test1

test1