I have a very viscous product, which I want to take for NMR spectroscopy, I was wondering if it needs any additional preparation? It almost doesn't flow at room temp , but can flow if warmed to 50-60 degrees.
No additional/special preparation is required for NMR. You have to check the solubility of your compound (You can try Chloroform and DMSO as these are most commonly used solvents in NMR). Then, You can take Proton as well as Carbon NMR spectra. Good Luck.
Clemens is right: getting viscous stuff into tubes is challenging. However, as Avtar already mentioned, you should dissolve your stuff anyhow and then most likely the solution will have a much lower viscosity. If the stuff still comes with broad lines in the spectrum, heating the sample up will be a good next step. However, be aware that solvents like Chloroform will evaporate very rapidly at elevated temperature. DMSO is better as it has a higher boiling point. And last but not least: whatever solvent you may use, get a deuterated one from your NMR colleague. Good luck!
Both Clemens Anklin and Nikolaus Nestle gave you good advise. Note also that chloroform is an "acidic" solvent which at higher temperatures can react with some compounds (e.g., some amides, amines, etc.). Solvents, like DMSO, can start "smoking" below their boiling points. If you cannot dissolve your material in a suitable NMR solvent, you can still obtain usable spectra using Dr. Anklin's suggested method of preparation, especially if you can safely heat the "neat" sample. I have obtained many spectra on such "neat" samples, [mostly polymers (1H, 13C, as well as 19F), at higher temperatures], over the years. Best of luck in your research! AF
If it is not possible to reduce the viscosity of the sample enough, then you could also try HR-MAS (high resolution magic angle spinning). I have found this very good on semi-solids (such as molecules tethered to solvent-swollen polystyrene beads). Of course, first you need to find someone who has such an NMR probe!
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