NMR/IR How hard?

[NumbaOneStunna]

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How hard were these questions on your test? There is a lot of depth to these things, so it's hard to be fully prepared for anything. For IR are these enough values:
Aromatic C-C, C=C, C=O, C triple bond N, C-H(aldehyde), sp3 sp2 and sp C-H (all diff), N-H (primary and secondary), O-H (alcohol), O-H (acid) ?

Are we expected to be able to tell the difference btwn a internal alkyne and a alkyne on the outside and very small stuff like that? Or are we supposed to be able to know what a general amide, carboxylic acid, alcohol, amine, alkene etc ?

For NMR just knowing the concepts + these shifts: carboxylic acid, aldehyde, aromatic H, alkene, Alkane, alkane with carbon bounded to electronegative atom good?


Thanks guys, I'm flippin out my DAT is tomorrow.

Oh and this site is awesome for IR

http://www.chemistry.ccsu.edu/glagovich/teaching/316/index.html

 

[Murl]

First of all good luck, and calm down. Download Chad's video on IR/NMR and you should be good. If you can figure out how many peaks there are that should narrow it down to no more than 2 answers, then you need to know that the Hydrogens connected to the most electronegative atom will be more downfield or deshielded. Watch this video and if you have trouble after that send me a PM and I will be glad to help you.

http://www.coursesaver.com/showthread.php?t=2791

 

[sixkiller]

While you should know values to be on the safe side, you should probably know a few other things....

Like how conjugation (especially in alpha/beta unsaturated ketones) will decrease the frequency of absorption (right shift) as does extensive hydrogen bonding (H-bonded dimers in carboxylic acids).

For NMR, you should have a basic guideline for the values but pay more attention to traps....probably the most common trap for nmr type questions (a favorite trap among ochem test writers) is when spin-spin splitting is applied to equivalent hydrogens.

Always, always, always examine a structure for symmetry and quickly determine which are equivalent hydrogens.

Another thing to note is how the chemical shift changes between primary, secondary, and tertiary...chemical shift increases for aliphatic hydrogens with increasing alkyl substituents.

Try to memorize some basic c-nmr values just because so many students brush it off.

Probably not be important, but just to be complete, you may want to brush up on diastereotropic and enantiotropic hydrogens.

 

[sixkiller]

How hard were these questions on your test? There is a lot of depth to these things, so it's hard to be fully prepared for anything. For IR are these enough values:
Aromatic C-C, C=C, C=O, C triple bond N, C-H(aldehyde), sp3 sp2 and sp C-H (all diff), N-H (primary and secondary), O-H (alcohol), O-H (acid) ?

Are we expected to be able to tell the difference btwn a internal alkyne and a alkyne on the outside and very small stuff like that? Or are we supposed to be able to know what a general amide, carboxylic acid, alcohol, amine, alkene etc ?

For NMR just knowing the concepts + these shifts: carboxylic acid, aldehyde, aromatic H, alkene, Alkane, alkane with carbon bounded to electronegative atom good?


Thanks guys, I'm flippin out my DAT is tomorrow.

Oh and this site is awesome for IR

http://www.chemistry.ccsu.edu/glagovich/teaching/316/index.html

You should know that as well.