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Instrumental Analysis

Low resolution proton NMR spectroscopy

  • 3 things to know
  • Components 1 and 2

Overview

Recall questions on counting hydrogen environments, what the relative peak areas give, the chemical shift ranges for hydrogens in common environments, why a deuterated solvent is used, identifying a compound from the number of peaks and the integration ratio, and the deuterium oxide shake.

What you need to know

Answer each one before you reveal it.

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Key term

What does the relative area under each peak in a proton NMR spectrum tell you?

Key term

Why must the solvent used in proton NMR contain no ordinary hydrogen atoms?

Key term

Name a solvent suitable for recording a proton NMR spectrum.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What does the number of peaks in a low resolution proton NMR spectrum tell you?

    Model answer

    It tells you how many different hydrogen environments there are in the molecule.

  2. 2

    What does the relative area under each peak in a proton NMR spectrum tell you?

    Model answer

    The areas are in the same ratio as the numbers of hydrogen atoms in each of the environments.

  3. 3

    How is the relative area of each peak shown on a spectrum?

    Model answer

    It is shown by an integration trace, a stepped line whose vertical rise across each peak is proportional to that peak's area.

  4. 4

    Why must the solvent used in proton NMR contain no ordinary hydrogen atoms?

    Model answer

    Any hydrogen in the solvent would give its own strong signal, which would swamp or confuse the signals from the sample.

  5. 5

    Name a solvent suitable for recording a proton NMR spectrum.

    Model answer

    Deuterated trichloromethane, CDCl₃, is commonly used.

  6. 6

    State the approximate chemical shift of the hydrogens of a methyl group attached to a carbon chain.

    Model answer

    It lies between about 0.7 and 1.2 ppm.

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