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Wize University Chemistry Textbook > Structure Elucidation (IR Spectroscopy, NMR, Mass Spectrometry)

1H NMR

Introduction to NMRPrevious Section
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Proton (1H) NMR


For organic compounds the 1H isotope is 100% abundant, so 1H NMR is very sensitive and useful for a range of organic molecules. A small amount of sample (5-10 mg) is dissolved in 0.7-1 mL of deuterated solvent, such as CDCl3 or C6D6. This introduces two main questions:

Why must deuterated solvents be used for 1H NMR?





What is used to calibrate shifts in 1H (and 13C) NMR?




Common 1H NMR Shifts



Downfield = Deshielded; Upfield = Shielded



Multiplicity of signals (coupling) in 1H NMR is related to number of hydrogens on neighbouring atoms (3 bonds or less). The number of peaks per signal is counted and assigned an abbreviation: 1 = s (singlet); 2 = d (doublet); 3 = t (triplet); 4 = q (quartet); more = m (multiplet)
Multiplicity = 2nI + 1
Where n = number of atoms
I = atom spin (1/2 for 1H and 13C)


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checklist
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  1. Grab a piece of paper and try this problem yourself.
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  3. View the solution and report whether you got it right or wrong.



checklist
Mark Yourself Question
  1. Grab a piece of paper and try this problem yourself.
  2. When you're done, check the "I have answered this question" box below.
  3. View the solution and report whether you got it right or wrong.




Extra Practice
(Duplicated) (Duplicated)
The 1H NMR spectrum belongs belongs to which of the four molecules?
Assign the 1H and 13C NMR spectra of the following molecule:
How many different 1H and 13C NMR signals would you expect for the following molecules? Include the expected multiplicity and relative integration for the signals in the 1H NMR spectrum
The 1H NMR spectrum belongs belongs to which of the four molecules?
(Duplicated)
The 1H NMR spectrum belongs belongs to which of the four molecules?
Lab techniques: 1H NMR
The 1H NMR spectrum provided belongs to which of the following molecules?
Lab techniques: 1H NMR
The 1H NMR spectrum provided belongs to which of the following molecules?
Lab techniques: 1H NMR
The 1H NMR spectrum belongs to which of the following molecules?
How many different 1H and 13C NMR signals would you expect for the following compounds? Include the expected multiplicity and relative integration for the signals in the 1H NMR spectrum
Which of the indicated protons will be the most deshielded in an 1H-NMR spectrum?
Proton NMR
Which of the indicated protons will be the most deshielded in an 1H-NMR spectrum?
NMR
How many different 1H and 13C NMR signals would you expect for the following compounds? Include the expected multiplicity and relative integration for the signals in the 1H NMR spectrum
Assign the 1H and 13C NMR spectra of the following compound:
Practice Question: 1H NMR 3

Practice Question: 1H NMR 1

Practice Question: 1H NMR 2

(Duplicated) (Duplicated)
The 1H NMR spectrum belongs belongs to which of the four compounds?
The 1H NMR spectrum belongs belongs to which of the four compounds?
(Duplicated)
The 1H NMR spectrum belongs belongs to which of the four compounds?
How many different signals would you see in the 1H NMR spectrum of the following compound?
1H NMR
A triplet peak in 1H NMR spectra tells us what information?
Spectroscopy
Analyze the spectroscopic data to properly identify the unknown molecules.
IR Spectroscopy, NMR and Mass spectrometry
From the spectra provided, identify the structure of the unknown molecule.
MS:
IR: