Chemistry Forums for Students > Organic Spectroscopy

H-1 NMR of a thiol and possible coupling

(1/2) > >>

Babcock_Hall:
We are making a thiol in which a phosphonate is also present.  The literature indicated that the HS should be a triplet from coupling to a -CH2- group.  We see a quartet, which makes sense if there is three-bond coupling to P-31 of the same magnitude.  Does this seem reasonable?

wildfyr:
Yep, phosphorous will do that.

Babcock_Hall:
Yes of course, but why didn't P-31 couple in the previously reported synthesis of this compound?  The other H-1 data are consistent with the published data.  We will report C-13 data on this compound, which is also consistent with the structure.  Only this one minor discrepancy exists, which makes me think that there was a minor reporting error in the previous data.  BTW, the quartet is not perfect, suggesting a slightly difference in the magnitudes of the two coupling constants.

Babcock_Hall:
We also see the signal from the thiol roughly 0.3 ppm upfield from what had been reported.  This does not bother me because it has been said that concentration and temperature affect the chemical shift of sulfhydryl hydrogens.  My working hypothesis is that the previous workers wrote "t" when they meant to write "q."  Adding a few microliters of D2O and shaking might be enough to exchange deuterium into the molecule.  This would cause one signal to go away and another to change its multiplicity.

wildfyr:
Lower field NMR in other paper?

Navigation

[0] Message Index

[#] Next page