August 07, 2020, 11:45:32 AM
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Topic: Need help with this spectra please!  (Read 328 times)

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Offline jshuss23

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Need help with this spectra please!
« on: April 14, 2020, 07:15:18 PM »
Hey guys

Can someone help me analyze this HNMR spectra. It belongs to benzoic acid and the solvent used was ethanol. I'm trying to identify each peak to which hydrogen it belongs to, explain the splitting patterns and integration values. I've been stuck on this because I only know how to analyze spectra for simple compounds such as alkanes. I've tried to look in my textbook but they give more specific examples for the easier to analyze compounds. What I know is that aromatic compounds have more complicating spectras because hydrogens that are not directly next to one another can split each other. Also I know that the carboylic acid hydrogens can exchange with D20 so that could explain why I don't see a peak at 12 or higher? (I'm not sure if that is right). I still however don't know how to analyze this and assign the specific peaks. Can anyone help? Because of the virus situation we don't have access to tutors at school for help, and I really need to figure this spectra out. I would really appreciate any feedback!

Offline OrganicDan96

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Re: Need help with this spectra please!
« Reply #1 on: April 15, 2020, 06:40:17 AM »
in situations like this its probably a good idea to think about what the spectrum should look like based on the structure.

Offline Babcock_Hall

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Re: Need help with this spectra please!
« Reply #2 on: April 15, 2020, 07:55:29 AM »
In D2O a carboxylic acid proton will be replaced by deuterium.  Deuterium nuclei do not appear in H-1 NMR spectra.  Aromatic compounds do not always follow first-order rules of coupling, which is a complicating factor for beginning students.
« Last Edit: April 15, 2020, 09:35:30 AM by Babcock_Hall »

Offline kriggy

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Re: Need help with this spectra please!
« Reply #3 on: April 16, 2020, 04:19:18 AM »
Show us the spectra and work you have done. You should have three sets of peaks with 1:2:2 ratio from this only you can assign one proton signal and we then continue with the rest based on interaction constants.

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