I have recorded the 1H-NMR spectrum of one of my compound i.e., RCH2OH. (R=heteryl group) In the spectrum I found that proton in OH group split into a triplet due to adjacent -CH2 . But, the proton in -NH group of the secondary amine does not split and observed as singlets. Secondary amines that recorded for NMR are attached in a file. plz find the attached file. Please justify the reason why OH proton is splitting and NH proton does not.
Thanking you
If you look at your structures you have a lone pair on the ring nitrogen. So the NH proton might be sitting in between the two nitrogen and no longer couple with the CH neighbors
Due to rapid chemical exchange of NH proton there will be no J-coupling.
Dear Devulapally Srikrishna
You can read read the followings:
1) https://www.google.com.eg/search?q=1H+NMR+OF+SECONDARY+AMINES&biw=1280&bih=631&tbm=isch&tbo=u&source=univ&sa=X&ved=0CCUQsARqFQoTCMixoOWP98cCFemmcgodeTwL3A
2) MAGNETIC RESONANCE IN CHEMISTRY
Magn. Reson. Chem. 2007; 45: 749–757
Published online 19 July 2007 in Wiley InterScience
(www.interscience.wiley.com) DOI: 10.1002/mrc.2043
The prediction of 1H chemical shifts in amines:
a semiempirical and ab initio investigation†
Ernani A. Basso,1 Gisele F. Gauze1 and Raymond J. Abraham
Good luck
Yours
Prof. Dr. Talaat El-Emary
Dear Srikrishna, your alcohol and amines both are in different situations. As you can see the alcohol is primary with no conjugation, where as the amine is secondary with conjugation. The hydrogen on amine 'N' is in resonance with pyridine 'N'(might be in equilibrium at room temp.), there by rapid proton exchange leads to no/poor signal. You can try taking 1HNMR at lower temperatures, which might help you to see coupling signals.
Yes, the proton in NH group of secondary amines split due to adjacent protons.
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