The NMR of a series of novel compounds synthesized using identical procedure on different time intervals -all- showed a strong single peak at around 8.46 in proton NMR using DMSO-d6 or MeOD, the intensity of the peak remained the same even after including D2O with the DMSO-d6, through HMQC it was found that this peak relates to a C13 peak at around 166. COSY showed no correlation with other protons. It is conclusively not related to the starting material(s) nor the product nor the solvent used in the synthesis. This peak is puzzling us as it is of a high intensity. I have checked tables online concerning trace elements and solvent impurities but failed to find any relation.
Bear in mind that these products were freeze dried, and prior to that they were neutralized using a resin. I would be grateful if any expert can guide me toward identifying this peak.
Dear Aya,
I fully agree with Clemens answer - the shifts match perfectly. A additional indication for formic acid is a 173 HZ 1H-13C 1J coupling which you may readout on the 13C satellites in the 1H spectrum.
We have made the observation that only after longer time storage of glass-ware in wooden lab furniture we see the signal. Therefore we came to the opinion that formic aid may be a degradation product of formaldehyde know to be of use in production of (older) wood/fibre-sheet furniture...since we know this we try to prevent using glass-ware stored in wood-cabinets or drawers.
I hope this helps
Alfred
Dear Dr Clemens and Dr Alfred. Thanks for your repsones and feedback. It does seem like this is formic acid and we’ll be taking further measures to wash it off and recheck the NMRs. Highly appreciate it.
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