Buying Deuterated Chloroform: Silver Foil Benefits & TMS Considerations

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SUMMARY

The discussion centers on the purchase of deuterated chloroform, specifically products stabilized with silver foil. Silver foil effectively scavenges chlorine ions and prevents the formation of harmful byproducts like phosgene and DCl, which can occur when chloroform is exposed to light and oxygen. Additionally, the inclusion of TMS (tetramethylsilane) in deuterated chloroform is debated, with 1% v/v considered excessive for high-field NMR instruments, as it can produce overly strong peaks that may interfere with sample analysis.

PREREQUISITES
  • Understanding of NMR spectroscopy, particularly at 500 MHz
  • Knowledge of deuterated solvents and their applications
  • Familiarity with TMS as a chemical shift reference
  • Awareness of chemical stability and reactivity of chloroform
NEXT STEPS
  • Research the effects of silver foil on solvent stability in organic chemistry
  • Learn about the optimal concentration of TMS for various NMR applications
  • Investigate the chemical reactions of chloroform under light and oxygen exposure
  • Explore best practices for using deuterated solvents in high-field NMR spectroscopy
USEFUL FOR

Chemists, NMR spectroscopists, and researchers working with deuterated solvents or analyzing samples using high-field NMR instruments will benefit from this discussion.

Umabel
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I was looking around to purchase some deuterated chloroform online. A few of the products offered include "stabalized with silver foil". What is the silver foil preventing the solvent from doing? FYI, this silver foil is probably inside the bottle.

One more thing, is there reason why you want to have 1% v/v TMS included in the solvent? I've seen 0.03% TMS, but 1% seems to be too many resonating protons for a 500 Mhz NMR instrument...
 
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1% is way too much for a high field instrument, IMO. Your TMS peak will be way too strong for most samples unless they are pretty concentrated, like in a C13 analysis. The 1% level has been used since low field CW instruments have been used and may be a throwback to those days.

Silver foil will scavenge any Cl- or chlorine active species from the bottle. For critical applications, it may help to remove any trace DCl. The chloroform solvent can react with light and oxygen to form phosgene and DCl.
 
Thanks.