CDCl3

CDCl3, short for deuterated chloroform, is the deuterium-substituted isotopologue of chloroform (CHCl3). It is commonly used as a solvent for nuclear magnetic resonance (NMR) spectroscopy because replacement of most hydrogen with deuterium greatly reduces interfering 1H signals and provides a stable deuterium lock for the instrument. CDCl3 is a colorless, volatile liquid with physical properties similar to CHCl3, including a boiling point around 61°C.

Commercial CDCl3 is highly enriched in the deuterated form, typically with more than 99% CDCl3. In practice, trace amounts of nondeuterated CHCl3 remain and give a small residual proton signal in 1H NMR, usually near 7.26 ppm, which is widely used as an internal chemical shift reference. In 13C NMR, the carbon of CDCl3 resonates near 77.0 ppm and appears with splitting due to coupling to deuterium.

CDCl3 dissolves a broad range of organic compounds and is particularly valued for its low background in both 1H and 13C spectra. It is not universal for all samples, as it can exchange with acidic protons or react with strong bases, and it is relatively nonpolar. The solvent is typically stored in amber glass bottles and handled under appropriate ventilation, because it is volatile and toxic; exposure may cause dizziness or central nervous system effects. Like other chloroform derivatives, CDCl3 can slowly decompose under light and air to produce hazardous byproducts, so it is kept away from strong oxidants and light.