While I run H nmr for an isolated cpd using CD3OD as a solvent, the CH3O group which should appear at 3.8 ppm is lost. It only could be detected through HSQC cross peak.
PLease give structure. It is supposed that whatdisappears is the MeO signal of your compound. 3.8 should be a methyl ether, which is hard to deprotect.
Ahmed
In the 1H NMR of CD3OD solution you will see two peaks from the undeuterated solvent molecules at 3.31 and 4.78 ppm. You are saying that your compound has a CH3O- group but you did not see it in 1D but you saw it in HSQC 2D ! Please, provide me with the structure and spectra in order to help since that is so strange to me ! CH3O- is an isolated A3 spin system and no cross peak should be seen.
Good luck
If I understand correctly, you are searching for the residual methyl group signal of your solvent while investigating your compound in a MeOD solution. If this is the case you may run into a relaxation issue. If the relaxation of your compound is vastly different to your solvent fast pulsing or long delays could lead to a decreasing solvent signal when you optimise your sequence for the solute molecule. This could be entirely different for correlation spectrocopies as you are using different pathways for signal relaxation.
Try to do a single excitation spectrum without any dummy scans to observe the methyl group of your solvent. Protons can't disappear, they either undergo a reaction and appear in a different spot or you loose the signal during the applied sequence...
Good luck!
The MeO of penicillic acid what i meant Peter. this molecule has two Tautomers, and i think as MeO is a good leaving gp, so it could be replaced by CD3O of the solvent and its signal disappeared.
CD3O should be obvious from the 13C spectrum, due to the couplings of carbon to deuterium (see solvent signal for reference about how it should look)
Thanks Jani, but i mean the MeO gp of penicillic acid which lost in the spectra not the solvent . Although its carbon signal appears around 60 ppm.
What I meant was that if the CH3O moiety would have been replaced by a CD3O moiety as you suggested, the carbon signal would not be a singlet, but look similar to the carbon signal from CD3OD i.e. it should have 7 peaks, about 21 Hz from each other.
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