I have done some proton NMR of compounds like N-(2-substitutedphenyl)acetamide derivatives. The chemical shift of amide proton ranges from 8.5 to 9. But some peaks amide proton shows singlet, doublet, and also triplet in different derivatives. From my point of view is that 2 substituents (Subs. is -H, -Cl, -F and -OCH3) are changed splitting happens. Mass spectra and CNMR looks fine. How can Amide proton show splitting among HNMR, any opinions, and suggestions, please?
I think the presence of an electron withdrawing or electron donating 2 substituted derivative could significantly affect how the alpha hydrogen can couple with the NH. Note also that the amide is likely to be in resonance with the C=O group. Hope this helps.
Manzoor
The proton NMR resonances of the N−H protons of amides are usually appeared at room temperature as a broad singlet absorption, which may turn into a broad triplet at higher temperatures. The broad N−H proton resonance is due to the special nuclear properties of N14, the predominant natural isotope of nitrogen. Also, amide exists in two resonance structure where C−N has double bond character which leads to restricted rotation about this linkage and the two amide protons becomes chemically nonequivalents and couple each other too.
Good luck
I think your N-H proton remain a part of resonance with CO which can only seen when NMR you proceed at room temperature but at higher temperature it appeared at triplet and your splitting's are coming due to presence of these attached EWG & ERG.
Adel Amer
Dear, thanks for the information, but the amide has only one proton. And amide is linked with an aryl ring.@ Adel Amer
HI. I have an H-NMR spectra of an amide, precisely the (2E)-3-phenyl-N-propylprop-2-enamide and the signal due to the methylene protons aside of the nitrogen, instead of being a triplet, are shown as a quadruplet. What could be the reason of this behavior?
Carlos Abreu Baez maybe you have an extra coupling with the vinylic proton besides the one with the methylene protons. And due to this, you might end with a dxt or a txd that looks like a quadruplet.
Hi, nice discussion, I also looking suggestion for amide signal when it is an aryl amide substituted on benzene ring and it adjacent to Br and has carboxylic acid on meta to itself. I tried NMR in DMSO to see the exchangeable proton signals. I. Am getting the broad singlet at 13-14 which appeared with DMSO not in MeOD. Should I confirm it as carboxylic or it can be amide too.???
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