The spectra are from a medicinal plant; the proton has been unhelpful...could anyone help? Please kindly find attached related images:
Dear John; you can specify the the nature of functional group in your sample by FT-IR . this will help you to identify the nature of your sample.please send the IR and mention the solvent used in H-NMR is it CDCl3.May I can help you .
Obviously, the NMR solvent is dmso-d6 (by trace 1H & large splitted 13C peaks). In the sample You have an equilibrium between (may be) acid protons and residual water in 1H spectra - but not so fast. And an 13C signal at ~ 170 ppm. May be a weak (carboxilic?) acid(s) present? The equilibrium may be a cause of poor proton differences in 1H spectra, unsteady 13C signals - and a low information in spectral data. And as a result we have insufficient data for a interpretation of the evidence.
You may change the acidity of a medium or/and derivate the acidic group(-s), after that make the APT or DEPT 13C spectras. And take action to the determination of a number of substances in the sample.
Good luck!
That's Okay : gallic acid, see 13C NMR spectra reference
http://www.chemicalbook.com/SpectrumEN_149-91-7_13CNMR.htm
;-)
Mr. John,
I am agree with Mr. Herbette, it is perfectly a gallic acid, a well known and an ubiquitious phenolic.
When working with natural products is of great help in the interpretation of spectra known the solvents used in extraction and purification of the sample. Obtain a spectrum of APT would help a lot. But I agree that the proposal to be Gallic acid is the most likely.
proton nmr is not giving any aromatic protons strangely. 13C looks like gallic acid as suggested
I proposed gallic acid simply based on the interpretation of the 1H (it shows clearly aromatic proton ortho to OH!) and 13C spectra with confidence. Literature survey now revealed that Zhang et al., Molecules, 2012, 17, 14037-14045 described the NMR data recorded in DMSO-d6: 1H-NMR 6.93 (2H, s, H-2, H-6); 13C-NMR 167.8 (C=O), 145.6 (C-3, 5), 138.2 (C-4), 120.8 (C-1), 109.1 (C-2, 6).
The aromatic protons are clear at 6.9 as a result of the electron releasing of the -OH groups at 3 and 5 positions. Also, the broad signal at about 9 is acceptable as an average for carboxylic and phenolic protons existing at the same compound.
1H and 13C NMR data is clearly suggesting the possible structure of gallic acid, but for your satisfaction you can inject a sample for getting the mass spectra of this sample. You can also compare the mp 253 C (decomp) of this compound.
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