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77

 For the prediction of the idealized line spectrum of, e.g., R2CH-CH3, it is answer the following questions based on the formula of the molecule (You can find a short summary here):
  1. Number and type of groups of equivalent protons (This has been covered here)
    in this example: a) >CH-
    b) -CH3
  2. relative position of the signals in the NMR spectrum (chemical shifts have been covered here)
    in this example: a) d = 1.4 ... 2.1 ppm
    b) d = 0.9 ... 1.9 ppm
  3. relative intensities of the signals (That's been covered there)
    in this example: a) 1
    b) 3
  4. Multiplicity of the line splitting and the intensities of the individual lines (This line of thought has been pursued starting on page 74)
    in this example: a) M = 4 (Quartet), I = 1 : 3 : 3 : 1
    b) M = 2 (Doublet), I = 1 : 1
Please note:
Since the relative intensity of the entire quartet a) is Irel = 1, (it is caused by a single proton!), the ratios of the individual lines of the quartet are 1/8 : 3/8 : 3/8 : 1/8 (Sum of the individual lines = 1!)
In the case of the doublet with the total intensity Irel = 3 (three protons!) the ratio of the relative intensities is 3/2&nbsp: 3/2!
Now draw the idealized line spectrum for R2CH-CH3!

as well as for:
R2CH-CH2R' R2CH-CHR2' , R2CH-CR3' .
In the process make sure to write down all the intermediate results, as shown for step 1 - 4 of our example.

When you are done, compare your answers with our solution!