[Fischer]

Hi!
I did a synthesis of cyclohexyl methyl ketone in course lab, and the product was analysed with 1H NMR and I'm now in the task of assigning the peaks correctly. I have attached the important part of the spectra.

The problem is that I'm not very good at NMR, and I thought I had it all figured out but I was completely wrong because I did not think of the structure as a chair conformation which gives different signals for equatorial and axial hydrogens.

My guess was that peak signal 1 and 5 was diethyl ether residues (according to a journal reference we have been given over common solvent contaminations). Signal 2 belongs to the methyl group of the epoxide ring (which I'm still pretty sure it does), and 3 belonged to the -CH2 group closest aligned in space to the oxygen and 4 to the remaining -CH2 groups on the ring. The integrations of the peak areas gave my guess more confidence so I'm a bit confused now.  

So, what's up with those equatorials and axial hydrogens?

[Albert]

I think you shouldn't care about them: low frequency spectra don't give the opportunity to see those signals, because they overlap.

[Fischer]

Hmm ok.
My laboratory teacher told me that I had to take into consideration that the molecule is not planar and that it has axial and equatorial protons. Could anybody help me with the assignment or give me some pointers? I've been looking at it all day and I just can't figure it out.

 

[Albert]

Of course there're particular kinds of couplings which involve axial and equatorial protons, but, as you can see from this 250MHz spectrum of PURE cyclohexyl methyl ketone, it's hard to distinguish them.