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105

Great! Your answer is right.

Reason: Due to the coupling to the methyl group -CH3 (n = 3) the CH signal splits up to form a quartet,
while the >CH group (n = 1) causes the CH3 signal to split into a doublet.
If necessary, you can find some more detailed explanations here.

There will be several more problems along these lines later on in this tutorial.

However, before you move on to these sections, you should summarize this section on spin-spin coupling by answering the following questions as concise as possible:
  1. When do you expect to observe direct spin-spin coupling between groups of protons?
  2. How do you determine the multiplicity of a signal due to spin-spin coupling in the case of
    1. one neighboring non-equivalent group of protons?
    2. several neighboring non-equivalent proton groups?
  3. What is the ratio of intensities between the individual lines of a multiplet that is caused by a neighboring non-equivalent group of protons?
  4. How is the coupling constsnt defined, and what causes it?
Compare your answers to our solution!