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Can someone help me deduce the structure by H1 NMR, IR and MS

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hellen:
      Hello, everyone! I am a green hand and wish your *delete me* thanks!

       the compound is white solid, melting point:130--132?,dissolve in alcohol and water,don`t dissolve in chloroform.  In addition C13 NMR show the C of -CO-, the C of -CH2- and the C of the -CH3, but haven`t the C13 NMR ( the result is told by my coworker)

     As so far, I known these. Please help me, thank you very much!

hellen:
sorry,I forgot  I have the HPLC and UV of the compound too!

PLEASE *delete me* THANKS!!

kiwi:
hard to make a call without details of the synthesis, but here goes.

1)product is clearly polar (solubility)
2)contains an ethyl group (1H NMR)
3)contains a carboxy group (IR, NMR)

from the IR looks like you have NH stretches up around 3300cm-1. It can't be propionamide (mp ~80 degC, and the br s is all wrong for an amide). with the limited information available, maybe ammonium propionate? but this doesn't fit all the data (MS), so any further info would help

Sam (NG):

--- Quote from: kiwi on April 29, 2007, 08:17:29 AM ---hard to make a call without details of the synthesis, but here goes.

1)product is clearly polar (solubility)
2)contains an ethyl group (1H NMR)
3)contains a carboxy group (IR, NMR)

from the IR looks like you have NH stretches up around 3300cm-1. It can't be propionamide (mp ~80 degC, and the br s is all wrong for an amide). with the limited information available, maybe ammonium propionate? but this doesn't fit all the data (MS), so any further info would help

--- End quote ---

according to my spectroscopy textbook, the chemical shift for an amide proton can be anywhere between 5 and 12 ppm, and a search on the net revealed N-H protons at 5.6, can you please explain why this is not correct?

english:
It may help if you follow the spectral analysis in this order:

MS ---> IR ---> H NMR

Remember that the highest m/z value is usually your molecular mass (molecular fragments, along with their abundance, are usually just used to validate the compound; you can generally ignore these for the overall determination in a problem like this).  Then use IR to determine what functional groups are present.  With that information, you can deduce the mass due to carbon and hydrogen only.  You should now have a decent molecular formula.

Now use your H NMR to get the structure.

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