[xshadow]

Hi!
I have to answer at this question:

" Explain why the -CH₂- group ot the benzyltriphenyl phosphonium salt gives a doublet with H-NMR spectrum"


The -CH₂- group don't see any Hydrogen in α position
So that doublet can't be come from a  short range coupling

Can it be a long range coupling because we have some insaturations?
I suppose this:



Thanks

[wildfyr]

What is the spin of phosphorous-31?

[xshadow]

What is the spin of phosphorous-31?

I think is 1/2

But here we have a H-NMR spectrum...
I think coupling  with other species different from Hydrogen cannot  be seen with the  Hz  for H<sup>1[/sup

Is it wrong?</sup>

[Babcock_Hall]

One is not observing the other nucleus; one is observing coupling to another nucleus.  A good example is the C-13 satellite peaks in the H-1 spectrum.  One of the joys of phosphorus chemistry is seeing beautiful coupling to other nuclei.

[xshadow]

One is not observing the other nucleus; one is observing coupling to another nucleus.  A good example is the C-13 satellite peaks in the H-1 spectrum.  One of the joys of phosphorus chemistry is seeing beautiful coupling to other nuclei.

so that doublet arise from  the coupling between the -CH₂- and the phosphorus nucleus....

I didn't know this!!
(Usually I've seen ¹H NMR spectrum where hydrgen nucleus  is coupled with another hydrogen nucleus ...and I ignored all other type of coupling)

[Babcock_Hall]

It would be difficult to decouple the other nuclei; therefore, one usually observes it.  The coupling constants can give useful conformational information.

[rolnor]

One is not observing the other nucleus; one is observing coupling to another nucleus.  A good example is the C-13 satellite peaks in the H-1 spectrum.  One of the joys of phosphorus chemistry is seeing beautiful coupling to other nuclei.

I agree, its a nice thing about phosphoros-chemistry! Its great with fluorine-chemistry as well for the same reason.

[xshadow]

Oh understand
Thanks all!!