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Topic: How to do NMR interpretation?  (Read 11530 times)

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Offline goldy

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How to do NMR interpretation?
« on: August 31, 2010, 10:01:47 AM »
Hello everybody,
I am new in NMR interpretation. SO Can anybody suggest me how to start NMR interpretation. I have 1H and 13C NMR spectrum but I could not start my analysis because I could not get the idea how to start. I am reading the NMR books.

Offline azmanam

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Re: How to do NMR interpretation?
« Reply #1 on: August 31, 2010, 10:52:10 AM »
Knowing why you got a question wrong is better than knowing that you got a question right.

Offline goldy

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Re: How to do NMR interpretation?
« Reply #2 on: September 02, 2010, 01:40:22 AM »
start here:

http://www.chemicalforums.com/index.php?topic=33208.0
Thank you so much. When I do the interpretation of some examples given in internet or some link I can do that easily but when I go to my real NMR data than it is so confusing and very difficult to interpret.

Offline orgopete

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Re: How to do NMR interpretation?
« Reply #3 on: September 04, 2010, 04:16:15 PM »
I agree with azmanam's method of assigning structures to spectra. That is how I have done them as well. I think of it as the molecular model approach or Tinker Toy method. Find the pieces and then assemble them together. I am also a proponent of a trial and error method as well. For example, if you had a compound with a MF of C4H9Cl, how many possible compounds can you form? If you simply counted the number of signals, you could determine two of the structures without a spectrum. For the other two, you would need the integrals.

If you contact me, I can send you a pdf file with several worked examples using this method. I have some easy ones and some difficult ones as well. You can get an idea of how to tame NMR spectra into submission.
Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

Offline goldy

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Re: How to do NMR interpretation?
« Reply #4 on: September 06, 2010, 03:47:59 AM »
I agree with azmanam's method of assigning structures to spectra. That is how I have done them as well. I think of it as the molecular model approach or Tinker Toy method. Find the pieces and then assemble them together. I am also a proponent of a trial and error method as well. For example, if you had a compound with a MF of C4H9Cl, how many possible compounds can you form? If you simply counted the number of signals, you could determine two of the structures without a spectrum. For the other two, you would need the integrals.

If you contact me, I can send you a pdf file with several worked examples using this method. I have some easy ones and some difficult ones as well. You can get an idea of how to tame NMR spectra into submission.
How do I contact you? It would be better if you can attach the PDF file along wiht this site.

Offline demoninatutu

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Re: How to do NMR interpretation?
« Reply #5 on: September 06, 2010, 09:48:46 PM »
Goldy, looking at what you wrote on your other thread, it looks like you've separated a compound from plant material and now you're trying to analyse it, is that right? Is this for an original research project or as a teaching lab project?

Your 'Problem in Compound Identification' thread suggests you might not be dealing with a pure sample. If your sample isn't pure then you won't have a realistic chance of interpreting the NMR spectra (though enantiomers normally have identical spectra).

If you are working from a genuine 'mystery' compound then you will also need a mass spectrum — preferably with elemental analysis if that's an easy option (it's easy on some spectrometers, not on others).

Offline orgopete

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Re: How to do NMR interpretation?
« Reply #6 on: September 08, 2010, 09:55:15 PM »
Click on the envelope under by name should send me a message.

Re: posting

I think azmanam's post is quite well done and he probably would not make further edits. Upon posting, I reviewed my examples and made a number of additional edits. Even though English is my native language, I don't always write as though it is. For me, letting things stew for a while is often helpful. By not posting, I can continue to edit it, especially if anyone gives me feedback on what part may be good and what may be confusing. I was also a little more ambitious in writing several examples, often with different objectives in them, such as on how to use coupling.
Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

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