On an old exam, my prof. gave a molecule and asked how many H` NMR signals would be produced.
The molecule is CH3CH Cl CH2OH.
When I look at it, I feel like there are only 4 signals. However the answer my prof. gave was 5.
I didn't get a chance to ask, but does any1 see 5 signals?
Could it be the CH2? Is it possible the 2 Hydrogens have different deshielding b/c of the chlorine?
Thank you
The molecule is CH3CH Cl CH2OH.
When I look at it, I feel like there are only 4 signals. However the answer my prof. gave was 5.
I didn't get a chance to ask, but does any1 see 5 signals?
Could it be the CH2? Is it possible the 2 Hydrogens have different deshielding b/c of the chlorine?
Thank you
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The protons of a CH2R unit when bound to a chiral C are not equivalent (google NMR chiral center).
The central C has four different substituents and hence is chiral. The Hs of the CH2OH are .: not equivalent it is an AB system and they will couple to each other and both the OH and CH proton. So Prof is correct.
The central C has four different substituents and hence is chiral. The Hs of the CH2OH are .: not equivalent it is an AB system and they will couple to each other and both the OH and CH proton. So Prof is correct.
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It's the presence of the chiral centre (the carbon which has the chlorine bound to it is chiral). This means that the two protons on the neighbouring CH2 will give two separate signals (look up diastereotopic in an NMR text).