During my research, I've prepared some volatile low molecular weight product. Unfortunately,after FCC and removal of the solvent, the 1HNMR sample still consist of impurities (mainly H2O, DCM, H-grease) and could not be conventionally removed by oil pump. Here comes the problem: these solvent could be easily removed in Mnova software, but I am wondering is this acceptable in preparing supporting information?
PS:
A second question: In a few cases, inseperatable E/Z isomers are in the same spectrum, is this acceptable?
Thank you for sharing your opinion or experience.
Leave the impurities alone and just mark them for what they are.
As for the E/Z. It depends on the molecule, but you may be able to see slightly different shifts for one or the other by NMR. You may want to consider a 2D technique like HMBC. It's not a guarantee that you will be able to tell the difference, but it is a possibility.
anyway, NMR spectra edit is not acceptable. this mehtod is efficient for the removal these solvent by adding a little benzene in the sample and vaccumn evaporate all the solvent, this procedure is repeated for 2-3times, then this sample was put in oil pump for removing any volatile matrial. by this way, you may get a very clear NMR spectra.
Many thanks for the answers above. Prof. Chu offered a general efficient method for the removal of solvent residue. However, in my case, the product itself is volatile thus impossible to stand the long-time-vacuum condition.
Editing of any analytical spectra is not accepted. I know it looks bad sometimes, but according to me, if impurities are below 5% of your target peaks, that is okay. Rather leave the extra peaks there and try to assign them, this shows that your work is honest and might help the next person repeating your work if they also find these impurities. I cannot stress enough how important it is to always be transparent with research! Good luck and happy researching!
Hi Sun . I will not talk about the editing spectra, because I agree in a plenty with the others. My suggestion to clean your sample may be chromatography. In my opinion the option is a preparative chromatography like thin layer or gas in a instrument that have option collecting the separated sample.
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