[Messi]

Hey guys,

How long can I leave my sample in chloroform before I put it in the NMR machine? Is it OK if I leave my sample in there for 2-3 hours then take the NMR of it?

How about 2-3 days?

Thanks!

[discodermolide]

Chloroform has a tendency to decompose to produce HCl and even phosgene. That's why the bottle has silver wool in it to help prevent this.
So 2-3 hours is OK but 2-3 days probably not. You can check this by NMR of course.

[Babcock_Hall]

Some compounds degrade on their own; others react with some NMR solvents.  I have synthesized one that seemed to react with DMSO, but I did not fully characterize the process.

[OC pro]

For most of the compounds they are ok even for several weeks in the NMR tube. When I did PhD we had to wait sometimes for more than a week to get a 1H and 13C spec. I never saw any degradation in CDCl3. And I worked with highly sensitive pyrrole compounds.

[Messi]

Thanks guys. Good stuff! I'll def keep that in mind!

Regarding a C13 NMR, what's a good standard amount of time to leave my sample in the NMR machine for?

[OC pro]

Depends on the machine and of course sample amount. I you have enough material and use 50mg+ for 13C then ~100 scans should be ok. But for normal 10-20mg samples I would do at least make 1024 scans (~2h) for 13C and DEPT. So ~4h altogether.

[Messi]

Boy oh boy is your guys' help invaluable! You guys are simply awesome!

Thanks OC Pro!