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Chemistry Forums for Students => Organic Chemistry Forum => Organic Spectroscopy => Topic started by: kriggy on March 08, 2016, 11:05:34 AM

Title: problems with APT spectra
Post by: kriggy on March 08, 2016, 11:05:34 AM

Hi guys, Im trying to asign signals of a compound I made few days ago (to be more exact: figure out the position of nitro group because it could be para to the lactam nitrogen, Im pretty sure my structure is correct but you never know..) Anyway, I got this APT spectrum

(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F0nHR2lK.png&hash=a749e8ccdf4f43aedc121a96f684ec4ba167c3fe)

Im not realy sure because it is method I never used before so there is my problem:
the signal at 23,52 is the methyl (confirmed by HMQC), therefore signals going down should be CH and CH3 right? Then, the carbonyl carbons that I suspect (no crosspeak in HMQC) to be at 168 and 160 should point to the other direction? Also, shouldnt the DMSO signal point down if it has two CH3 groups?

Title: Re: problems with APT spectra
Post by: Babcock_Hall on March 08, 2016, 12:20:07 PM

Is this DMSO left over from the reaction scheme, or was d₆-DMSO the NMR solvent?

Title: Re: problems with APT spectra
Post by: kriggy on March 08, 2016, 04:18:02 PM

Its DMSO-d₆.
 

Title: Re: problems with APT spectra
Post by: Babcock_Hall on March 08, 2016, 06:39:38 PM

Deuterium is spin-1, and I am not sure what to expect in this experiment.

Title: Re: problems with APT spectra
Post by: kriggy on March 09, 2016, 10:42:26 AM

Ok, I did consult it with our NMR specialist and we figured out, that the problem is most likely in the software because when she opened the spectrum in Jeol delta (we have the spectrometer from JEOL) the spectrum showed totaly different.