Deuterium: Difference between revisions
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Revision as of 16:48, 13 January 2008
Deuterium, chemical symbol D or 2H is an isotope of the element hydrogen which has an extra proton. A compound containing deuterium is said to be deuterated. Deuterated chemicals are widely use in NMR spectroscopy, either as chemical shift references, as solvents, or to reduce the relaxation rates of NMR signals in large compounds like proteins. Deuterium is a stable, naturally occuring isotope of hydrogen and represents 0.015% of naturally occuring hydrogen, with H-1 representing the remaining 99.985%.
Use in NMR spectroscopy
NMR spectroscopy, which primarily detects the signals of proton atoms, frequently uses a detuerated solvent and/or a deuterated compound as a chemical shift reference. Deuterium atoms also have different relaxation properties so that their use in NMR spectroscopy of large biopolymers such as proteins leads to enhanced signal detection.
Deuterated NMR solvents
Deuterated chemicals that are often used for NMR spectroscopy include:
- d6-acetone (1,1,1,3,3,3-hexadeuteroacetone)
- d3-chloroform (1,1,1-trideutero-chloroform, trideuterochloromethane)
- d-ethanol
- d6-benzene (1,2,3,4,5,6-hexdeuterobenzene)
- d2-methylenechloride
Each of these chemicals have a small proportion of undeuterated content, which give a residual signal that can be used as a (non-zero) reference chemical shift. However, several chemical compounds are specifically used a true reference points.
Chemical shift references
Three deuterated chemicals are widely used reference points for 1H NMR data. In organic solvents, deutero- trimethylsilane (d9-TMS) is used. For aqueous solutions, deuterated DSS or TSP are used instead.