Deuterated chloroform

Deuterated chloroform (CDCl3), also known as chloroform-d, is an isotopologue of chloroform (CHCl3) in which the hydrogen atom ("H") is replaced with a deuterium (heavy hydrogen) isotope ("D"). Deuterated chloroform is by far the most common solvent used in NMR spectroscopy.[2] Most compounds soluble in the commonly used solvent dichloromethane are soluble in chloroform also, but deuterated chloroform is much cheaper than deuterated DCM.[3] In addition, it is chemically unreactive and unlikely to exchange its deuterium with its solute, and its low boiling point allows for easy sample recovery. The properties of CDCl3 are virtually identical to those of regular chloroform, although toxicologically, it is slightly less toxic to the liver than CHCl3, due to its stronger C–D compared to a C–H bond.[4]

Deuterated chloroform
Stereo, skeletal formula of deuterated chloroform
Spacefill model of deuterated chloroform
Names
IUPAC name
trichloro(deuterio)methane[1]
Other names
Chloroform-d
Deuterochloroform
Identifiers
3D model (JSmol)
1697633
ChEBI
ChemSpider
ECHA InfoCard 100.011.585
EC Number
  • 212-742-4
UNII
UN number 1888
Properties
CDCl3
Molar mass 120.384 g mol−1
Density 1.500 g cm−3
Melting point −64 °C (−83 °F; 209 K)
Boiling point 61 °C (142 °F; 334 K)
Hazards
Xn
R-phrases (outdated) R22, R38, R40, R48/20/22
S-phrases (outdated) S36/37
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
2
0
Related compounds
Related compounds
 Chloroform

Deuterated dichloromethane

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

NMR solvent

In proton NMR spectroscopy, deuterated solvent (enriched to >99% deuterium) must be used to avoid recording a large interfering signal(s) from the proton(s) (i.e., hydrogen-1) present in the solvent itself. If nondeuterated chloroform (containing a full equivalent of protium) were used as solvent, the solvent signal would almost certainly overwhelm and obscure any nearby analyte signals. Commercial chloroform-d, however, still contains a small amount (0.2% or less) of non-deuterated chloroform; this results in a small singlet at 7.26 ppm, known as the residual solvent peak, which is frequently used as an internal chemical shift reference. In addition, modern instruments usually require the presence of deuterated solvent, as the field frequency is locked using the deuterium signal of the solvent to prevent frequency drift.

In carbon-13 NMR spectroscopy, the sole carbon in deuterated chloroform shows a triplet at a chemical shift of 77.16 ppm with the three peaks being about equal size, resulting from splitting by spin coupling to the attached spin-1 deuterium atom (CHCl3 has a chemical shift of 77.36 ppm).[3] While the solvent signal is usually large compared to the signals of the analyte (in contrast to proton spectroscopy, since the solvent and the analyte both usually contain carbon-13 at natural abundance), the large range of chemical shifts in carbon-13 NMR spectroscopy results in peaks that are far enough apart to avoid having the large solvent signal obscure signals from the analyte.

It reacts photochemically with oxygen to form phosgene and hydrogen chloride. Therefore, more expensive alternatives like dichloromethane-d2 or benzene-d6 must be used if the analyte is expected to be highly acid-sensitive. To slow this process and reduce the acidity of the solvent, chloroform-d is stored in brown-tinted bottles, often over a base like potassium carbonate.

Hazards

Like nondeuterated chloroform, chloroform-d is hepatotoxic and likely to be carcinogenic. In addition, exposure to light and oxygen results in the formation of highly toxic phosgene.

References
  1. https://pubchem.ncbi.nlm.nih.gov/compound/Chloroform-D
  2. Fulmer, Gregory R.; Miller, Alexander J. M.; Sherden, Nathaniel H.; Gottlieb, Hugo E.; Nudelman, Abraham; Stoltz, Brian M.; Bercaw, John E.; Goldberg, Karen I. (2010). "NMR Chemical Shifts of Trace Impurities: Common Laboratory Solvents, Organics, and Gases in Deuterated Solvents Relevant to the Organometallic Chemist" (PDF). Organometallics. 29 (9): 2176–2179. doi:10.1021/om100106e.
  3. The Theory of NMR – Solvents for NMR spectroscopy
  4. Goldstein, Robin S. (2013). Toxic interactions. Hewitt, William R., Hook, Jerry B. Burlington: Elsevier Science. ISBN 978-1-4832-6970-2. OCLC 896796140.
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