6.9.4

Hydrogen-1 NMR 2 (A2 Only)

Test yourself

Making Spectra Clear

The choice of solvent before the spectra is recorded makes the process easier. The process of integration after also makes interpretation of the spectra easier.

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Solvent choice

  • The solvent choice in 1H NMR is crucial because many solvents contain 1H's.
    • If a solvent contains 1H's, they will appear in the spectrum and this will cause confusion.
  • This can be solved by using solvents without any 1H's (e.g. CCl4) or deuterated solvents (e.g. CDCl3, D2O).
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Deuterated solvents

  • Deuterated solvents are the same as many protonated solvents but each 1H has been replaced by a deuterium (2D) atom.
    • Deuterium atoms have an even nucleon number and so will not interfere with the NMR.
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Integration

  • The area ratios of signals in spectra are hard to evaluate at first glance when signal splitting happens.
    • E.g. It is hard to compare the area ratio under a quartet and a singlet.
  • To make it easier, many NMR machines integrate the peaks to then give an accurate ratio.

Examples of 1H NMR

Below are some examples to demonstrate interpreting 1H NMR spectra.

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Example 1: 1,1-dichloroethane

  • The spectrum is shown above and the interpretation is on the next slide.
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Example 1: 1,1-dichloroethane

  • The spectrum shows two peaks representing the two different proton environments.
    • The peak on the left represents the 1H on the -CCl2H because it is deshielded.
    • It is a quartet because the adjacent carbon has three protons attached.
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Example 2: Bromo-dimethyl ether

  • The spectrum is shown above and the interpretation is on the next slide.
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Example 2: Bromo-dimethyl ether

  • The spectrum shows two peaks representing the two different proton environments.
    • Both peaks are singlets because neither of them are adjacent to any carbons with any protons.
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Example 3: Ethanol

  • The spectrum is shown above and the interpretation is on the next slide.
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Example 3: Ethanol

  • The spectrum shows two peaks representing the two different proton environments.
    • The peak on the left represents the 1Hs on the -CH2OH because it is deshielded.
    • The splittings are a triplet and a quartet as expected.

Jump to other topics

1Physical Chemistry

2Physical Chemistry 2 (A2 Only)

3Inorganic Chemistry

4Inorganic Chemistry 2 (A2 Only)

5Organic Chemistry 1

6Organic Chemistry 2 (A2 Only)

6.1Optical Isomerism (A2 Only)

6.2Aldehydes & Ketones (A2 Only)

6.3Carboxylic Acids & Esters (A2 Only)

6.4Aromatic Chemistry (A2 Only)

6.5Amines (A2 Only)

6.6Polymers (A2 Only)

6.7Biological Organic (A2 Only)

6.8Organic Synthesis (A2 Only)

6.9NMR Spectroscopy (A2 Only)

6.10Chromatography (A2 Only)

6.11A-A* (AO3/4) - Organic 2

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