DAT IR/NMR compared to destroyer IR/NMR question

[wall1two]

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a lot of people lately have been saying they are getting 4-5 questions in IR/ NMR i was wondering how those compare in difficulty compared to destroyer. im not looking for specifics of your test obviously, i just want to know if i should be cramming H/C NMR values or if knowing about splitting, and down field level in comparison to each-other will be enough to land a boss score.


and p.s. what would elute from silica gel column chrom first, an ester (ethyl acetate) or butanol? the solvent is an ether

 

[Kahr]

I'd definitely know splitting, also the factors affecting deshielding, you'll also want to be able to identify how many C/H signals there are in a molecule, this one is a big must and easy to get down.

For the specifics in IR/NMR, I wouldn't try to memorize everything, but if you want to it wouldn't hurt, and it really isn't too much to do thoroughly. I think practice is your best bet. I felt Destroyer was perfectly reasonable in all the NMR/IR problems, but I will say I saw only 1 question from IR/NMR on the actualy test, which clearly isn't the norm.

For your elution question. The ester will for sure elute first, as the alcohol is far more polar; I believe the only way the solvent affects anything is by changing the distance all the substances travel, but the order of elution should remain unchanged. Make absolutely certain you know the order of polarity for the functional groups.

 

[qkchen]

appreciate the insight. what about IR questions regarding how IR actually works, so how much should be know about that. i just know the basic wavenumbers that the major functional groups correspond to.

 

[wall1two]

you are the man khan

 

[olive6]

i thought they were moderately hard...gotta watch out for symmetry and such!

here's an awesome website with a ton of practice problems...i just looked them over and i feel like it helped out a TON

http://orgchem.colorado.edu/hndbksupport/spect.html

 

[milka]

Back to the elution question....I thought that the alcohol would come out first based on eluting order of functional groups
http://orgchem.colorado.edu/hndbksupport/chrom.html

 

[jefff]

from my experience, on dat real exam nmr and ir were were on par/easier than dat destroyer