[Miep]

Can someone tell me what splitting pattern I should expect when doing a H-NMR of a structure containing a morpholin ring?  I would think the protons (4) close to the nitrogen act the same and couple to the protons close to the oxygen (4) who also act the same.  But it looks like they behave two by two. 
Thanks,
Miep

[sjb]

Is the morpholine ring flat? What solvent are you running the NMR in?

[Miep]

I suppose the ring is flat, NMR was done in chloroform

[sjb]

I was more under the impression that the morpholine ring had a boat like structure (cf cyclohexane), and so you may get axial and equatorial protons - ring flip in tertiary amines can be slow on the NMR timescale, and things like DMSO will probably slow it too (a more viscous solvent). Whilst working on stuff like http://www.wipo.int/pctdb/en/wo.jsp?WO=2008125835 , I always noted 4 distinct peaks for the methylenes of the morpholines.

How is the morpholine substituted?

[sjb]

I was more under the impression that the morpholine ring had a boat like structure...

Or possibly a chair, but certainly not flat (unless we're talking average conformations)...

S

[sanderol]

This is the spectrum:

http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi

So I guess the ring flipping is on a faster time scale then relaxation time in NMR ?? Since you get 2 signals for the ring protons.