Name: using d2o to identify oh protons
Uploaded: 2024-12-05T18:32:25.000Z
Duration: 48 s
Channel: JoVE

Deuterium is one of the isotopes of hydrogen, whose nucleus is comprised of one proton and one neutron. Hence, it is represented as &#178;H.
The deuterium signals are not detected in a proton NMR spectrum.
Adding D2O solvent to pure ethanol results in substituting its labile &#8211;OH proton with deuterium.
As observed in the proton NMR spectra, the triplet of pure ethanol disappears after the deuterium substitution, indicating that the triplet corresponds to the &#8211;OH proton.
The methylene protons that show up as a multiplet transform to a quartet, further confirming the exchange of labile &#8211;OH proton with deuterium.

&sup1;h nmr of labile protons:  deuterium (&sup2;h) substitution

&sup1;H NMR of Labile Protons:  Deuterium (&sup2;H) Substitution

This lesson illustrates the role of deuterium substitution in simplifying the NMR spectrum of compounds comprising labile protons. One method employed is the use of deuterium. Amongst the three isotopes of hydrogen, deuterium (2H) has a nucleus composed of one proton and one neutron. When the D2O solvent is added to a pure dry ethanol solution, its labile proton is substituted with deuterium.
<img alt="Chromatography result diagram; spectral peaks analysis; separation efficiency evaluation." src="/files/ftp_upload/12280/12280-PT_Figure_1.svg" style="text-align: center; height: 700px;" data-altupdatedat="1761830439000" data-alt="Figure1" />
Figure 1. The comparison of the proton NMR spectra of pure dry ethanol and the same in D2O solvent.
The signals from deuterium are not observed in a proton NMR spectrum, as deuterium&#8211;proton coupling is negligible, and no spin-spin splitting occurs between them. As shown in Figure 1, the NMR spectra of pure ethanol and ethanol in deuterium, the disappearance of the triplet in the latter, confirms that it corresponds to the labile &#8211;OH proton. Furthermore, the methylene protons that initially showed up as a multiplet transform to a quartet, proving that the multiplet is due to the coupling with the &#8211;OH proton and the methyl protons.

This lesson illustrates the role of deuterium substitution in simplifying the NMR spectrum of compounds comprising labile protons. One method employed is ...

h-nmr-of-labile-protons-deuterium-h-substitution

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JoVE Core

Analytical Chemistry

Unit 1

Advanced Nuclear Magnetic Resonance Spectroscopy

advanced-nuclear-magnetic-resonance-spectroscopy

KEY TERMS AND CONCEPTS

using d2o to identify oh protons

Deuterium substitution can help identify labile protons in ¹H NMR spectra. Labile protons are hydrogens that can be replaced by another hydrogen isotope. In this lesson, deuterium is used to simplify the spectrum of ethanol.

Deuterium, or ²H, is one of the three isotopes of hydrogen. Its nucleus contains one proton and one neutron. When D₂O is added to a pure dry ethanol solution, the labile proton on the –OH group is replaced by deuterium.

A proton NMR spectrum does not show signals from deuterium. Deuterium–proton coupling is negligible, so no spin-spin splitting appears between them. In the ethanol spectrum, the loss of the triplet after adding D₂O shows that the triplet belonged to the labile –OH proton.

The methylene protons also change in the spectrum. They first appear as a multiplet, then become a quartet in D₂O. This shift shows that the original multiplet came from coupling with the –OH proton and the methyl protons.

Using D2O to Identify OH Protons

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Deuterium substitution can help identify labile protons in ¹H NMR spectra. Labile protons are hydrogens that can be replaced by another hydrogen isotope. In this lesson, deuterium is used to simplify the spectrum of ethanol. Deuterium, or ²H, is one of the three isotopes of hydrogen. Its nucleus contains one proton and one neutron. When D₂O is added to a pure dry ethanol solution, the labile proton on the –OH group is replaced by deuterium. A proton NMR spectrum does not show signals from...

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key terms and concepts

See how deuterium in D2O replaces a labile –OH proton in ethanol and changes the ¹H NMR pattern, helping students identify proton signals.

Using D2O to Identify OH Protons | JoVE K12

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Using D2O to Identify OH Protons

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