Nmr

[topdent1]

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Would anyone add any chemical shift values that you should *PROBABLY* know for the test?

Methyl: 1-2
Alkene: 5-6
Aromatic: 7-ish
Aldehyde: 9-10
Ketone: 2
Alkyl Halide: 3-4
Carboxy Acid: 10-12
Alcohol: 2-5

 

[LuckMC11]

do we have to really know these shifts/ranges?!

 

[2PacClone23]

no ^

 

[Baylor2011]

Yes, you should know generally where things show up on an NMR. Such as where alkanes show up, carbonyls, ethers, aromatics, aldehydes, and carboxylic acids. You should also know how to read an NMR spectra, as well as make one if they give you a compound and ask which spectra is correct for the given compound.

 

[LuckMC11]

alright thanks baylor.

how do u make an NMR spectra diagram based on the information given?

 

[iamgosu]

alright thanks baylor.

how do u make an NMR spectra diagram based on the information given?

we did this in o-chem class before, but it's relaly hard to do without the chemical shift table...

but the best way would be look at the multiplicity of the peaks. if you see a singlet corresponding to 9 H's (area under the singlet is 9), you can deduce this is likely to be a t-butyl group or something.
if it's a triplet corresponding to 3 H's, it's likely the CH3-CH2-R

it's actually kinda fun figuring out the puzzle, but very time consuming if the compound is large.

 

[LuckMC11]

oh yea i know how to do that, isnt the NMR spectra diagram like the diagram with the ppm and the peaks? i thought that was what baylor was talking about..? or is it what iamgosu is talking about constructing just the compound from the NMR data?

 

[Baylor2011]

They probably won't ask you for the compound based on NMR spectra, because they'd have to supply you with a chemical shift table, but they may give an easy one...never know. More likely scenario is giving you a compound, and picking the best spectra as an answer choice