Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: goldy on August 31, 2010, 10:01:47 AM
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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.
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start here:
http://www.chemicalforums.com/index.php?topic=33208.0
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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.
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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.
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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.
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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).
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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.