1H NMR: Unsymmetric Peak Multiplicity and J Values

  • #1

Homework Statement:

How to find multiplicity and J values for non symmetric 1H NMR spectra?

Relevant Equations:

I have tried to figured this out but I can't, I need help on how to find the multiplicity of some of these arrangements of peaks. For example, there is one that looks like (from left to right), a doublet, 2 triplets, and then another doublet. I will Attach crude drawings below, but hopefully I can just get an answer on how to do this exercise.
The peaks all look unfamiliar, no symmetry, or very little, and they all integrate to a small number of hydrogen while being surrounded by a large number.

Here are the images.


1.)
NMR Multiplets 1.jpg


2.)
NMR Multiplets 2.jpg


3.)
NMR Multiplets 3.jpg


4.)
NMR Multiplets 5.jpg


5.)
NMR Multiplets 6.jpg


Thanks for any explanations. I don't expect anyone to do it for me, I just have no other resources to figure this out.
 

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Answers and Replies

  • #2
TeethWhitener
Science Advisor
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Without knowing exactly where these appear in your spectrum, it's tough to say, but I'm guessing these are in the aromatic region of the spectrum (between about 7 and 10 ppm). The aromatic region of proton NMR spectra can give some very complicated peak splittings. Aromatic protons often couple to multiple non-equivalent protons, and even protons that are further than nearest neighboring carbons, which distorts and splits peaks further than what you normally see in the aliphatic region of the spectrum. Here's a link that might help:
https://chem.libretexts.org/Bookshe...Diagrams_Explain_the_Multiplicity_of_a_Signal
 
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