Deuterated chloroform

Template:Chembox AllOtherNamesTemplate:Chembox headerbarTemplate:Chembox IndexlistTemplate:Chembox JmolTemplate:Chembox ChEMBLTemplate:Chembox ECHATemplate:Chembox E numberTemplate:Chembox IUPHAR ligandTemplate:Chembox UNIITemplate:Chembox CompToxTemplate:Chembox headerbarTemplate:Chembox headerbarTemplate:Chembox GHS (set)Template:Chembox headerbarTemplate:Chembox Datapage checkTemplate:Chembox Footer

Deuterated chloroform

Template:Chembox image sbs cell
Template:Longitem	Template:Unbulleted list
Template:Longitem	1697633
ChEBI	Template:Unbulleted list
ChemSpider	Template:Unbulleted list
DrugBank	Template:Unbulleted list
EC Number	Template:Unbulleted list
KEGG	Template:Unbulleted list
Template:Longitem	Template:Unbulleted list
RTECS number	Template:Unbulleted list
UN number	1888
Template:Longitem	Template:Chem2
Molar mass	120.384 g/mol
Appearance	Colorless liquid
Odor	chloroform-like
Density	1.500 g/cm3
Melting point	Template:Chembox CalcTemperatures
Boiling point	Template:Chembox CalcTemperatures
NFPA 704 (fire diamond)	Template:NFPA 704 diamond
Template:Longitem	Chloroform Deuterated dichloromethane

Deuterated chloroform, also known as chloroform-d, is the organic compound with the formula Template:Chem2. Deuterated chloroform is a common solvent used in NMR spectroscopy. The properties of Template:Chem2 (chloroform) are virtually identical.

Deuterochloroform was first made in 1935 during the years of research on deuterium.

Preparation

Deuterated chloroform is commercially available. It is more easily produced and less expensive than deuterated dichloromethane. Deuterochloroform is produced by the reaction of hexachloroacetone with deuterium oxide, using pyridine as a catalyst. The large difference in boiling points between the starting material and product facilitate purification by distillation.

Template:Chem2

Treating chloral with sodium deuteroxide (NaOD) gives deuterated chloroform.

NMR solvent

In proton NMR spectroscopy, deuterated solvent (enriched to >99% deuterium) is typically used to avoid recording a large interfering signal or signals 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. 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. Commercial chloroform-d does, however, still contain 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 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 (Template:Chem2 has a chemical shift of 77.36 ppm).

Deuterated chloroform is a general purpose NMR solvent, as it is not very chemically reactive and unlikely to exchange its deuterium with its solute, and its low boiling point allows for easy sample recovery. It, however, it is incompatible with strongly basic, nucleophilic, or reducing analytes, including many organometallic compounds.

Hazards

Chloroform reacts photochemically with oxygen to form chlorine, phosgene and hydrogen chloride. To slow this process and reduce the acidity of the solvent, chloroform-d is stored in brown-tinted bottles, often over copper chips or silver foil as stabilizer. Instead of metals, a small amount of a neutralizing base like potassium carbonate may be added. It is less toxic to the liver and kidneys than Template:Chem2 due to the stronger Template:Chem2 bond as compared to the Template:Chem2 bond, making it somewhat less prone to form the destructive trichloromethyl radical (Template:Chem2).